DE20111114U1 - Radio link for packet-oriented data transmission - Google Patents

Description

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Description

Radio link for packet-ordered data transmission

The invention relates to a radio link for packet-oriented data transmission with at least one transmitter and at least one receiver.

Such radio links are used to transmit data between one or more transmitters and one or more receivers.

A sensor for generating a large number of instantaneous values of a measurement signal is often provided in the area of the transmitter. Such a sensor can be designed as a digital sensor which displays instantaneous values of a measurement signal at a predetermined rate. It is also possible to provide an analog sensor whose output signal is fed to a digitizing device which supplies digitized instantaneous values of the sensor's measurement signal at a predetermined rate.

In addition, a coding device for converting the instantaneous values into data packets of a data packet stream and a transmitting device for transmitting the data packets as a radio signal are provided in the transmitter. If the receiver then has a receiving unit for receiving the data packets in the form of a radio signal and a decoding device for converting the received data packets into measurement information and an output unit for outputting the measurement information thus obtained, then a measurement can be evaluated in a simple manner even over long distances without the need for a cable connection.

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connection between the sensor and the output unit needs to be provided.

With such radio links, it is often desired to transmit the output signals from several sensors simultaneously. It is also often desired to calculate several output variables based on one sensor output signal and to take these from the receiver's output unit. This often results in the problem that the variables taken from the output unit have large errors that are unacceptable in practical operation.

The object of the invention is to provide a radio link in which the measurement information output at the output unit has only a small error. Finally, a transmitter and a receiver for such a radio link should also be provided.

This object is achieved by the subject matter of the independent claims. Advantageous further developments arise from the respective subclaims.

According to the invention, the coding device is designed in such a way that a first instantaneous measured variable value and at least one second instantaneous measured variable value can be obtained from the measurement signal. The second instantaneous measured variable value can be calculated from the first instantaneous measured variable value. It is also conceivable to calculate the second instantaneous measured variable value from several first instantaneous measured variable values, for example from their course. In this way, several instantaneous measured variable values are formed. In addition, third, fourth, etc. instantaneous measured variable values can also be transmitted. This also allows several measured variables to be transmitted on a single radio link.

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The measured quantities to be transmitted can also differ in terms of their resolution, even though they originate from the same measuring signal.

The data packet stream comprises both data packets that contain information about the first instantaneous measured value and data packets that contain information about the second instantaneous measured value.

The invention thus makes it possible to obtain data resulting from the sensor signal in a simple manner. Data that is provided directly by the sensor as well as data that must first be calculated from the sensor signal can be obtained and transmitted.

The invention can be used advantageously not only for airborne radio links, but also for radio links that are connected to a cable medium. This allows the transmission quality to be improved even further.

The use of airborne radio links has the particular advantage that the transmitter and receiver are not mechanically connected to one another. This makes it easy to transmit measured values that are taken from rotating shafts, wheels or other moving objects.

In the radio link according to the invention, data packets can be provided that contain only information about the first instantaneous measured value, as well as data packets that contain only information about the second instantaneous measured value. By sending at different times, different time requirements can be met.

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for the first instantaneous measured value or for the second instantaneous measured value.

According to the invention, the information about the first instantaneous measured value and/or the second instantaneous measured value, etc. can also be transmitted over several data packets. This makes it possible to generate different resolutions for the measurement information output by the output unit. Instantaneous measured values that must be available with a higher resolution can advantageously be transmitted in such a way that a large number of data packets are used for each instantaneous measured value transmitted. In contrast, for instantaneous measured values that are only required with a small resolution, only one data packet or a few data packets can be used. In this way, the maximum bandwidth of the radio link can be adapted particularly easily and advantageously to the time requirements of the instantaneous measured values to be transmitted.

According to the invention, data packets can also be transmitted which contain information about a first measured value as well as about a second measured value, etc.

In a further development of the invention, the output unit can estimate and output the course of the measured variables represented by the first instantaneous measured variable values and/or the second instantaneous measured variable values, etc., at times between the reception or conversion of data packets.

This ensures that the receiver's output unit always has information about the measurement signal emitted by the sensor, even if no current instantaneous measurement value is being transmitted via the radio link.

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is transmitted. A model of the system scanned by the sensor is used for the estimation. In the event that the second instantaneous measured variable values are calculated with the aid of the first instantaneous measured variable values, particularly accurate operation is achieved if the first instantaneous measured variable values are transmitted more frequently than the second instantaneous measured variable values. This is useful, for example, if the resolution of the first instantaneous measured variable values is significantly lower than the resolution of the second instantaneous measured variable values. In such a case, information about first instantaneous measured variable values reaches the receiver more frequently than about second instantaneous measured variable values. A reliable estimate of the course of the measured variable, insofar as this is represented by the second instantaneous measured variable values, can then be reliably calculated from the first instantaneous measured variable values.

The radio link according to the invention can be used particularly advantageously to display the current driving speed and the distance traveled by a vehicle. The sensor is arranged in the area of a wheel of the vehicle, whereby a sensor is advantageously used which emits a pulse as a measurement signal at least every time the wheel completely rotates. The coding device is then designed in such a way that the current speed of the vehicle is calculated from the measurement signal using a system time. The current speed of the vehicle is then transmitted as the first current measured variable value on the radio link. The number of wheel rotations performed is the sum of the pulses emitted by the sensor and is calculated and transmitted as the second current measured variable value.

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The speed of the vehicle can be calculated from the time interval between two consecutive pulses at the sensor output. Each pulse corresponds to one wheel revolution and thus to a known distance traveled. The second instantaneous measured value represents the total distance traveled up to the time of measurement, which is determined by the sum of all pulses emitted by the sensor up to that point. Both the first instantaneous measured value and the second instantaneous measured value are displayed on the receiver's output unit. The instantaneous speed is transmitted at a rate of, for example, one instantaneous measured value per second. The total distance determined directly in the transmitter, on the other hand, is only transmitted to the receiver at a rate of, for example, 32 seconds per measured value.

In the receiver, each new measured value for the speed is multiplied by the time that has elapsed since the last error-free transmission of such a measured value. This gives an estimated value for the distance traveled in the meantime. This is added to the last error-free total value of the distance traveled and shown on the display.

If an error has occurred in the transmission of the instantaneous measured value for the speed, an incorrect value is received and displayed on the receiver side. The resulting error affects the partial distance travelled, which is calculated in the receiver. Therefore, an incorrect value is also displayed there. After the next error-free transmission of a second instantaneous measured value to the receiver, an error-free value for the total distance travelled is displayed there and used for the further calculation of the estimated value. In this way, a

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Reliable and accurate display of the current speed and the total distance travelled, even if the radio link is occasionally subject to interference.

The invention can also be used advantageously to display the current heart rate and the heart rate variability of a living being. For this purpose, the sensor is designed as a heart rate sensor that can be arranged in the area of the nervous system of the living being. Such a sensor emits at least one pulse as a measurement signal when a heartbeat is sensed. The coding device is designed in such a way that the current heart rate can be calculated as a first instantaneous measurement value from the measurement signal using a system time. The heart rate variability can be derived, for example, from the ratio of the longest interval between two heartbeats to the shortest interval between two heartbeats within a predetermined period of time. It can be obtained as a second instantaneous measurement value from the course of the measurement signal.

The radio link according to the invention can also be used particularly advantageously for transmitting the information contained in the electrical pulses generated by a voltage-frequency converter. The coding device is designed in such a way that the instantaneous frequency of the electrical pulses can be obtained and transmitted as a first instantaneous measured value. The total number of pulses generated by the sensor can be obtained as the sum of the pulses and transmitted as a second instantaneous measured value.

As a practical application of this design, a device is conceivable in which an analog quantity such as a line

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power or a temperature is converted into a continuous pulse sequence using a voltage-frequency converter. The frequency of the pulses in this pulse sequence is used as the first instantaneous measured value. The second instantaneous measured value is the result of the integral of the measured value and represents the work performed when a power sensor is used or the amount of heat transferred when a temperature sensor is used.

In this embodiment of the invention, the integral of the measurement signal can advantageously be formed by simply counting the pulses of the pulse sequence, without causing an error in the long term, for example due to accumulation. This count is transmitted over the radio link at a low transmission rate, while the current value determined in each case is

tane frequency with a high transmission rate. In the receiver, an accumulation of errors, such as can occur when integrating the first instantaneous measured value, is avoided or corrected at regular intervals by a current second instantaneous measured value.

The invention can also be used in connection with a heartbeat sensor, for example in sports competitions, where athletes' biodata is projected onto a display visible to spectators so that it can be seen by spectators. From such biodata, conclusions can be drawn about an athlete's fitness and enthusiasm, for example, which makes the sports competitions more attractive for spectators. In the case of animals that are led by people, undesirable overloads can also be avoided.

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Finally, the invention also includes the individual components of such a radio link, such as its transmitter or its receiver.

One idea underlying the invention is that when transmitting measured values over a faulty radio link, isolated errors can occur on the receiver side. As long as the measured value transmitted on the receiver side is only used to be read sporadically by a person, this does not need to be critical. In the event of an error, a new reading will produce a correct value with a certain probability. However, if the transmitted measured value is mathematically processed on the receiver side to form another measured value, for example by an integration process, errors are added up,

which has a negative impact on the resulting measured value in the long term. The errors caused by this consist of both transmission errors and rounding errors.

Such errors could be reduced by increasing the bandwidth of the radio link if the transmission frequency and the resolution of the transmitted measured value values are increased at the same time. However, this results in increased costs, which is not desirable. The invention takes a different approach. According to the invention, the bandwidth of the radio link is selected so that the transmission of the first measured value values takes up most of the available bandwidth. In order to reduce the error in the transmission of the second measured value values, a correction is applied according to the invention, which only needs to be carried out relatively rarely compared to the transmission rate of the first measured value values. As a result, a bandwidth is sufficient for the transmission of the second measured value values, which

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is lower than that for the transmission of the first measured value.

The course of the measured quantity represented by the second measured quantity values at times between the error-free reception of corresponding data packets is determined on the receiver side and displayed if necessary. Whenever a complete and error-free value for the second measured quantity value has been received, the estimate made by the receiver is corrected by the correct value calculated in the transmitter.

The invention further makes use of the following approach. The expected second measured variable values are therefore not only formed on the transmitter side, but also on the receiver side. The first measured variables formed on the receiver side are regularly compared with the second measured variable values determined on the transmitter side. It is particularly advantageous that no transmission errors on the transmitter side are included in the formation of the second measured variable values. When using voltage-frequency converters in which the second measured variable values are formed by counting pulses, no further errors arise apart from the error caused by the temporal resolution in connection with the temporal spacing of the pulses.

According to the invention, the resolution of the second measured variable values can be greater than that of the first measured variable values. However, more data packets are then required to transmit the second measured variable values than to transmit the first measured variable value.

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When using a voltage frequency generator, the first measured value values are determined from the frequency of the pulses generated by the sensor, at periodic intervals. Their value corresponds to the inverse of the time interval between two pulses. When calculating the first measured value values, rounding errors inherently occur, which should be kept as low as possible in relation to the constant reading on the receiver side. However, small deviations can be neglected or are accepted by the user.

The sum of these errors over a longer period of time cannot be predicted in terms of their size and sign. This could result in significant errors occurring on the receiver side. Such errors are kept small or completely avoided by the method according to the invention.

Parallel to the first measured value, which is typically transmitted with a width of several bits, the error-free second measured value with a low bandwidth is transmitted on the transmitter side with just one or a few bits, which can even be appended to the data for the first measured value for the sake of simplicity. The curves of the second measured value required for a continuous display on the receiver side are estimated on the receiver side using the curve of the first measured value and added to the last fully transmitted second measured value. In this way, the curve of the second measured value can still be displayed at a rate that is higher than the actual transmission rate of the second measured value.

According to the advantageous embodiment of the invention described above, the complete transmission of each second measured value takes several times the time required for

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the transmission of a first measured value is required. This effect is intensified by the fact that the second measured value is often required with a higher resolution than the first measured value. This is particularly evident when transmitting the current speed and distance traveled by a vehicle. To display the speed of a vehicle in a given speed range between 0 km/h and 250 km/h, for example, it is often sufficient to display the speed to an accuracy of 1 km/h, which requires a total of 250 resolution steps. For the distance traveled by the vehicle in a range between 0 km and 100,000 km, with a resolution of "100 m", 1,000,000 resolution steps are required for a complete display, i.e. 4,000 times more than for the complete display of the speed.

With the invention, in which the second measured variable values are further calculated on the receiver side, the accumulation of an error can occasionally be observed. However, as long as the transmission time of the second measured variable values is much shorter than the entire period in which measured variable values are transmitted, it can be assumed that the duration and thus the extent of the error accumulation is limited to a time that does not exceed the transmission time for the second measured variable values determined on the transmitter side.

In a particularly advantageous embodiment of the invention, the transmitter has in particular an input unit for inputting or generating a data packet or data set or data item and a transmitter control unit for processing the data packet and for inserting a predetermined test code resulting from the content of the data packet into the

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Data packet. Furthermore, a transmitter unit that can be operated by the transmitter control unit is provided for sending the data packet, whereby the transmitter is designed in such a way that the data packets can be sent out regularly one after the other. 5

The signals from such a transmitter can be scanned particularly easily by a receiver. In the simplest case, with only one transmitter, only a single activity of the transmitter needs to be detected in order to predict the transmitter's further activities. In systems with multiple transmitters, the transmitters' transmission times can be predicted just as easily if all of the transmitters' transmission repetition times in the radio link have been communicated to the receiver beforehand. The receiver then only needs to detect the activities on the radio link and try to receive data packets at the possible subsequent times and at multiples of the repetition times. A transmission method clocked in this way can be used advantageously for radio links where it is not particularly important whether each data packet in the data stream is transmitted or not. The invention can therefore be used particularly well for radio links for transmitting measured values where the transmitted measured value changes very slowly compared to the transmission frequency of the measured values.

By providing a predetermined check coding in the data packet, which results in particular from the content of the data packet transmitted in each case, correctly transmitted data packets can be easily distinguished from defective data packets, so that only error-free data packets need to be further processed on the receiver side.

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In accordance with the transmitter according to the invention, the receiver according to the invention of the radio link has a receiving unit for receiving data packets and a receiver control unit connected to the receiving unit, with which the received data packets can be processed and output. The receiver control unit can determine a check code for each data packet, whereby a comparison of the check code with the content of the data packet can be used to determine whether the data packet was received correctly or with errors. If an error-prone data packet is received, the data packet in question is discarded.

The receiver according to the invention is designed in such a way that the time at which a data packet is expected to arrive can be determined. This can be done, for example, by temporarily scanning all activities on the radio link, whereby a particularly energy-saving use of the receiver is made possible if it only scans whether there is any activity at all. At predetermined time intervals, an attempt is then made to receive data packets from the time at which an activity is detected. Such a simple solution is particularly useful if the time intervals between the data packets sent by the respective transmitters are known to the receiver.

In a further development of the invention, the transmitter control unit is designed such that at least one duplicate of the data packet can be created, the data packet and/or the duplicate each having type information. With such type information, the receiver can determine whether the received data packet is a data packet itself or a duplicate of a data packet.

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The transmitter is designed in such a way that a data packet and a duplicate can be sent out regularly one after the other, and the time offset between each data packet and its duplicate can be varied according to a predetermined offset rule and offset information. The offset information can be provided in a data packet or in a duplicate. By sending one or more duplicates of the transmitted data packet, the receiver can obtain the data contained in the data packet from the duplicate sent out subsequently when a defective data packet is received. When several duplicates are sent out, the receiver then has several options for reconstructing the defective data in the data packet. The time offset between each data packet and its duplicate is known to both the transmitter and the receiver according to the offset rule. In a particularly simple embodiment of the invention, the receiver can predict the expected arrival time of all subsequent duplicates based on a single offset information in a single data packet. This results in particularly secure operation because only a small amount of information about the timing of sending data packets and duplicates needs to be transmitted.

The offset information can be generated from a predetermined counting sequence, in particular using a counter reading that counts the data packets sent by the sender. It is not necessary for the receiver to actually receive every data packet sent by the sender, because the times at which data packets are to be sent are known to the receiver. The receiver can therefore also operate the counter without actually having to receive all the data packets sent. Nevertheless,

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The relative position between duplicates and data packets can be reconstructed because the counter reading maintained by the server is always up to date.

By providing type information in the data packet or in the duplicate, the receiver can easily distinguish between data packets and duplicates at any time. This is particularly useful when locking in a transmitter according to the invention and a receiver according to the invention at the start of operation of the radio link.

Furthermore, each data packet or its duplicate can be provided with identity information assigned to the associated transmitter, which can contain information about the type or meaning of the data packets. For example, within the radio link, a specific sub-ID of the respective transmitter can be assigned to a transmission rate or a transmission grid of the data packets. In addition, a specific sub-ID can be assigned to a meaning of the data transmitted with the data packets. For example, transmitted speed data can be easily distinguished from transmitted route data. The identity information can also contain part of unique information about the respective transmitter. This makes it particularly easy to determine within the radio link whether the transmitters switched on in the radio link really belong to the intended system. Transmitters belonging to another system with a different radio link can thus be identified particularly easily, and the reception of unwanted data from these systems can then be suppressed.

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According to the invention, a search mode and a transmission mode are provided for receiving a data stream containing data packets. In the search mode, the following steps are carried out:

Scanning the data stream for the presence of data packets,

Predetermining the times at which a further data packet is expected to arrive.

In such a search mode, in the simplest case it is sufficient to scan activities on the radio link caused by data packets. The times for the arrival of further data packets after a data packet scanned first are then determined from multiples of a previously known interval between the respective data packets, which are added to the time of arrival of the first data packet. In the transmission mode, one data packet is then evaluated selectively, whereby a comparison of the test coding with the content of the data packet is used to determine whether the data packet was received error-free or with errors. In the selective evaluation according to the invention, a receiver that carries out the method according to the invention can be selectively switched on or off.

The invention can be advantageously improved by scanning the data stream for the presence of duplicates belonging to the data packets. If a displacement rule for a temporal displacement between data packets and duplicates is then determined from at least one displacement information item taken from the data packets and/or their duplicates, an increased transmission reliability is achieved. Then, when a defective

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data packet, the transmitted information can still be taken from the duplicate.

In a special embodiment, the receiver is designed in such a way that identity information associated with the sender of the data packet or duplicate can be decoded from each data packet or from each duplicate. This is used in particular to determine the time interval between two data packets, whereby this is determined by data packets with matching identity information. This enables particularly fast and precise synchronization of the radio link.

To determine the time at which a data packet is expected to arrive, a signal delivered by the receiving unit to the receiver control unit can also be repeatedly and selectively evaluated in a search mode of the receiver. A selective evaluation can, for example, consist in checking the signal delivered by the receiving unit for activities at regular intervals. With the receiver according to the invention, times for an expected arrival of a data packet are calculated from a starting time when a first data packet arrives and from a predetermined interval time that can be reconstructed in particular from the content or from the temporal position of the first data packet. It is also possible to reconstruct the interval time between two consecutive data packets directly from the received data packet, for example by evaluating a specific identifier such as the sub-ID. This results in a quick and economical calculation of the regular interval time between two consecutive data packets.

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Deviating from the method explained above for finding the interval time between two consecutive data packets, times for an expected receipt of a data packet can also be calculated from an interval time between two data packets, which is determined from a start time when a first data packet is received and from a repetition time when a further data packet is received.

The invention is also implemented in a combined transmitting/receiving module for a radio link, which has a transmitter according to the invention and/or a receiver. The receiver and the transmitter can also be operably connected to one another to avoid collisions between data packets or their duplicates. When scanning a data packet sent by another transmitter, the receiver can temporarily suppress the transmitter connected to it or cause it to send data packets at a different time interval.

The radio link according to the invention enables long-term operation of the transmitter and receiver when they are powered by batteries. This opens up application possibilities, particularly in connection with sports watches that evaluate speed and heart rate sensors. The system according to the invention can be used advantageously in unidirectional and bidirectional systems, each of which consists of a receiver and several transmitters. The system according to the invention has a high level of immunity to transmitters of similar neighboring systems and to collisions between the transmitters of a system. It also has a high level of immunity to interference from external radiation. Finally,

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From an end user's perspective, this ensures easy commissioning and uncomplicated operation.

In the protocol according to the invention, the information is transmitted in the form of recurring transmission packets with typically 8 to 16 data bits as well as various control and check bits. In addition, a number sequence generator can be used to provide transmission packets scattered over the time range redundantly to the regular transmission packets that follow one another at fixed intervals. After a synchronization phase, the location of all incoming packets can be calculated for the receiver. Low power consumption is achieved by switching the receiver and transmitter on and off in a targeted manner.

The invention can be used particularly advantageously in applications that require unidirectional transmission of data at a low data rate. This results in advantages in long-term operation, such as when monitoring measurement data that changes at a rate in the range of a few hertz. This can be used advantageously for the regular transmission of speed information. After a short preceding synchronization time, data transmission is possible with the invention. Short-term operation, such as the remote control of devices, can be achieved with additional process effort.

It is also possible to split up route information accumulated in the transmitter into individual data areas and to send these data areas individually - each with at least one redundancy packet - to the receiver, whereby they

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There they are reassembled into the original route information.

Systems with multiple transmitters that are to be received by a receiver at as consistent a rate as possible despite the occurrence of collisions between data packets and other interference can be achieved using the redundancy functions according to the invention while at the same time ensuring extremely economical long-term battery operation. These include, for example, sports computers, medical devices for patient monitoring, alarm systems, monitoring systems in the industrial and home user sectors and measurement data transmissions.

The invention results in an improved transmission protocol, particularly for sports computers such as those for bicycles, which allows a single receiver to be used for all transmitters in a system. All transmitters then transmit on a common frequency, with a maximum number of 4, 6 or 8 transmitters having proven to be effective. The invention enables a high transmission rate to be achieved in a given time frame, while avoiding collisions between the various transmitters or sensors in a system. The radio link according to the invention has a high level of immunity to atmospheric interference and transmitters from other systems. The invention also results in a very low average activity of the receiver and transmitter components, so that a low power consumption of the radio link can be achieved.

The invention accordingly also includes a protocol for data transmission in which data words are converted into one or more data packets before being sent. Each transmitter on the radio link has a different sub-ID, which

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indicates the respective sensor type within a system. Sensors for a heartbeat, a wheel revolution or a pedal frequency can be distinguished using the sub-ID. In addition, each transmitter module has a unique ID or serial number, independent of the sub-ID. This is written to a non-volatile memory area of the transmitter during a production test, for example, or is randomly determined when a new battery is inserted. Each sub-ID is assigned a specific, fixed packet repetition time or packet frequency. The packet frequency is independent of the respective frequency with which the measured values arrive or change. In parallel to the term packet frequency, a term "time slot" can also be used. This is a grid of time intervals that correspond to the packet length. The distance between two packets

of a transmitter is always an integer number of timeslots. The packet spacing of the individual sub-IDs always differs by an even number.

To avoid collisions within a radio link system, the aim is to ensure that for each transmitter, the collision of its packets with packets from another transmitter in the same system is not interrupted for longer than one packet in a row. The transmitters according to the invention have a different fixed packet frequency depending on the sub-ID, which they receive through coding within the system. This coding varies in stages, in such a way that the peri-

The length of the packet frequency from transmitter to transmitter is increased by twice the packet length. It is easy to understand that with two transmitters that have two different packet frequencies, two packets in a row cannot actually collide.

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However, the basic rule is that with a number of N transmitters, in the worst case N-I packets from one of the transmitters can be disrupted in succession. However, this case is unlikely and in reality of lesser importance. In order not to exceed a prescribed maximum transmission time, the frequency of the packets sent could now be multiplied by N. With four transmitters, four times more packets per second would have to be transmitted in this case than with a "normal" data transmission. However, this requires increased power consumption at the transmitter and receiver. According to the invention, a similar effect is achieved with reduced effort.

The throughput of the entire time slice with transmitted packets is calculated from the sum of all packet frequencies and the respective packet duration. This parameter, which can also be called "occupancy", provides a measure of the system's resistance to external interference. The more packets are on the radio link and the longer they are, the higher the probability that a short interference pulse will collide with one of these packets.

To avoid collisions between two transmitters on neighboring radio links that overlap, in addition to the fixed packets that are sent and received at a constant frequency, each transmitter can send a packet with a variable position or a redundancy packet between two fixed packets. The time slot in which the redundancy packet is placed is determined by a number sequence generator, the sequence of which can depend on the ID of the respective transmitter. The algorithm for the number sequence is known to both the transmitter and the receiver. After a synchronization time, the respective IDs are also known.

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of the individual transmitters are stored in the receiver so that these can also be used as parameters in the number sequence. The transmitter can therefore calculate in advance in which time slot the next redundancy packet is to be expected and switch on the receiving device accordingly at the exact time. Start information for the number sequence generator transmitted in each data packet marks a zero crossing of the number sequence so that the transmitter and receiver can be synchronized using this data packet.

The ID of the transmitter is transmitted periodically within the data packets, one piece at a time. In total, only as many components of the serial number need to be transmitted as are used to individualize the number sequence running through the number sequence generator. This speeds up the transmission of the ID or serial number of the transmitter. In the same way, multi-digit cumulative route information can be transmitted reliably in a simple manner.

Before a receiver of a radio link knows which transmitters of the radio link belong to its radio link based on their ID, it must receive the IDs of the respective transmitters correctly at least once and store them permanently. To do this, a corresponding mode is selected in the receiver and at the same time it is ensured that all transmitters of the own system are active. It must also be ensured that no transmitters of a second, similar system crosstalk. In such a state, the IDs can be reliably learned.

In normal operation, the receiver according to the invention switches on at the respective time of arrival of the fixed packets and ignores the redundancy packets. If, due to external interference,

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If a fixed packet cannot be received correctly or at all due to interference or collisions in the radio link, the receiver attempts to replace the missing fixed packet with the next redundant packet or further redundant packets. This is achieved using the number sequence known to both sides to calculate the timing of the redundant packets. When the interference in the radio link stops, the receiver restricts itself to receiving fixed packets again. This keeps power consumption low.

When locking between a transmitter in a radio link and the receiver or when waking up from a mode with reduced energy consumption, the receiver can also react to the transmitters of a neighboring system. However, the IDs of the system's transmitters, which have been learned in a special mode, can be used to determine whether the transmitters found during locking belong to the system itself or not.

The transmitters can be designed as microcontrollers with an internal EEPROM for the ID number. The respective sub-ID and the packet frequency of the system can be set using external pins or can be configured using entries in the EEPROM. The ID is read from the EEPROM after a reset or generated randomly. For test purposes, the entire ID is sent out once shortly after the reset. When using microprocessors with an integrated EEPROM, the ID can also be written serially into the module during the test and checked for correct writing by resetting again.

Finally, it is also conceivable to provide the radio link according to the invention in a fitness computer in which a transmitter is connected to a sensor for measuring the heartbeat of a user.

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or to measure its step frequency. Such a fitness computer can have a receiver with a display to show the value transmitted by the sensor.

The disclosure of the invention also includes the following items, described in bullet points with features according to numbers 1 to 5:

1. Use of a radio link according to the invention.

2. Transmission of a measurement signal with a radio link according to the invention, which comprises the following steps: generating a plurality of instantaneous values of a measurement signal,

Converting the instantaneous values into data packets of a data packet stream, wherein a first instantaneous measured variable value and at least one second instantaneous measured variable value are obtained from the measurement signal, and wherein both data packets are generated which contain information about the first instantaneous measured variable value and data packets are generated which contain information about the second instantaneous measured variable value or the second instantaneous measured variable values,
Sending the data packets as a radio signal, receiving the data packets as a radio signal, converting the received data packets into measurement information,
Output of measurement information.

3. Transmission of a measurement signal using a radio link according to the invention as per item 2, whereby data packets are generated which exclusively contain information about the first mo-

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instantaneous measured value, and that data packets are generated which contain exclusively information about the second instantaneous measured value.

4. Transmission of a measurement signal with a radio link according to the invention according to item 2 or item 3, wherein the information about the first instantaneous measurement value and/or about the second instantaneous measurement value is transmitted in each case distributed over several data packets.

5. Transmission of a measurement signal with a radio link according to the invention according to one of the numbers 2 to 4, wherein the course of the measurement represented by the first instantaneous measurement values and/or by the second instantaneous measurement values is estimated and output at times between the reception and/or the conversion of data packets.

Protection for a procedure is not sought.

The invention is illustrated in the drawing using an embodiment.

Figure 1 shows a schematic representation of a motor vehicle equipped with the radio link according to the invention;

Figure 2 shows a voltage-time diagram of an electrical signal emitted by the sensor of the radio link of Figure 1,

Figure 3 shows the format of a data packet transmitted in the radio link from Figure 1,

Figure 4 illustrates the temporal sequence of data packets of the radio link from Figure 1 and

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Figure 5 illustrates the contents of the data packets according to Figure 4.

Figure 6 shows a schematic representation of a radio link according to the invention, which has three transmitters and one receiver,

Figure 7 illustrates the signals emitted by the transmitters of Figure 1 in terms of their temporal sequence,

Figure 8 illustrates the structure of a data packet sent by a transmitter from Figure 6 or its du

replica.

Figure 1 shows a radio link according to the invention which is used to measure the distance travelled and the current speed of a motor vehicle. In this view, only one wheel 1 of the motor vehicle can be seen, which has several spokes, with a permanent magnet 2 attached to one spoke. In the area of the wheel 1 there is also an inductive sensor 3 which is connected to a coding device 5 via a sensor line 4. The coding device 5 is in turn connected to a transmitting device 6 which can transmit radio signals via a transmitting antenna 7.

The inductive sensor 3, the coding device 5 and the transmitting device 6 form a transmitter 8, which provides a radio link with the receiver 9 also shown in Figure 1.

The receiver 9 is divided into a decoder 10, which is connected to a receiving antenna 11 and to an output unit 12. The output unit 12 is in turn connected to a two-part display unit 13. The

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Display unit 13 is designed such that a speed of "10 km/h" of the vehicle is displayed in a first display area I, while a distance traveled by the vehicle "130 km" is displayed in a second display area II.

Figure 2 illustrates the temporal sequence of the signals emitted by the inductive sensor 3 via the sensor line 4 when the impeller 1 is rotated about its axis. In the present case, the impeller 1 completes six revolutions, being braked from a high speed to a low speed. As can be seen particularly clearly in Figure 2, a total of three pulses Ul, U2 and U3 are generated in the range from 0 to approximately 1 see. At time t = 2 see the pulse U4 is generated, at time t = 3 see the pulse U5 is generated and at time t = 4 see the pulse U6 is generated.

The pulses Ul to U6 form the measurement signal sent out by the inductive sensor 3, which is forwarded to the coding device 5. In the coding device 5, current speed values are calculated from this measurement signal by dividing the circumference of the impeller 1 by the time interval between two consecutive pulses emitted by the inductive sensor 3. This speed information is packed into data packets and emitted by the transmitting device 6 via the transmitting antenna 7. In addition, the pulses emitted by the inductive sensor 3 are counted by the coding device 5 and multiplied by the circumference of the impeller 1 to obtain a distance traveled. At equal time intervals, the coding device 5 converts the current value of the distance traveled into a total of four data packets, which are transmitted via the transmitting device 6 and the

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transmitting antenna 7. In an embodiment not shown here, this multiplication can also take place in the receiver 9.

The format of the data packets generated by the coding device 5 is illustrated in Figure 3. This shows a data packet 20 that can be sent by the transmitting device 6. The data packet 20 represents a so-called "raw" data packet that can be provided with synchronization information and validation information by the transmitting device 6 for transmission. Figure 3 therefore only shows those parts of the data packet 20 that are relevant for recording measurement information.

The data packet 20 has an identification bit 21, the content of which indicates whether speed information or route information is being transmitted. In addition, two rank bits 22 are provided, which indicate the rank of a data packet within a series of several data packets with which related components of a single piece of information are transmitted. Two check bits 23 and a total of eight data bits 24 are used to record the data generated by the decoder 10.

In the present case, the eight data bits 24 of the data packet 20 can assume a total of 2 ⁸ (= 256) different values. With a resolution of 1 km/h, this results in a speed range of 0 km/h to 255 km/h, which can be covered by the coding device 5. A binary content of the data bits 24 of "0000 0000" corresponds to the speed 0 km/h and a value of "1111 1111" corresponds to a value of 255 km/h.

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If route information is to be transmitted with the data packet 20, the following procedure is used in the present embodiment. The route information is transmitted as an eight-digit decimal number. With a resolution of "10 m", total distances of 999,999.99 km can be transmitted. This information can be encoded with a total of four data packets 20 if two decimal places are reproduced from the eight data bits of a data packet 20. For this purpose, two binary-coded decimal numbers are transmitted. In this coding, the decimal numbers between 0 and 9 can be represented with four bits each. A total distance of 1,242.42 km, i.e. 1,242,420 m, is represented by the following binary-coded decimal number:

0000 0000 0001 0010 0100 0010 0100 0010 00124242

_{H1 H2} II3 II4

In the coding shown above, the designations Hi, H ₂ , II3 and H ₄ represent the respective numbering of the four data packets used to transmit such route information.

Figure 4 illustrates the timing of the transmission of data packets by the transmitting device 6 via the transmitting antenna 7. As can be seen particularly clearly in Figure 4, one data packet is transmitted at a time interval of 0.1 seconds. Data packets I, which contain speed information, alternate with data packets Hi, which contain route information. The route information

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Hi are coded as explained above with reference to Figure 3.

As can be seen particularly well in Figure 4, a total of three speed information items I are transmitted for each complete transmission of a route information item Hi to H ₄ .

Figure 5 illustrates the content of the individual data packets from Figure 4.

In the first column under the designation "consecutive number" the time at which the data packet sent in the relevant line is shown in Figure 4 is indicated.

As can be seen particularly clearly in Figure 5, the data packets I sent at odd times "1, 3, 5, ..., 21" each have a value "0" in the identification bit 21. This indicates that the value transported in these data packets represents a speed value. In contrast, the data packets sent at even times "2, 4, 6, ..., 20" each have a value "1" in the identification bit 21, which indicates that a distance value is transmitted in each of these data packets. In the case of distance values, the contents of the rank bits 22 provide further information about which digits of the decimal distance information are currently being transmitted. A total of four data packets are provided for transmitting a distance value, so that depending on the rank of a data packet within the distance information, the check bits 23 have one of the binary values "00", "01", "10" or "11".

t r, * *

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• * ♦ *

The data packets thus transmitted by the transmitter 8 are received by the decoder 10 via the receiving antenna 11 and broken down into their individual components.

If the presence of a data packet is identified whose value "0" of the identification bit 21 indicates that it is speed information, this speed information is first checked to see whether it is error-free. To do this, the content of the check bits 23 is compared with the remaining contents of the data packet 20. If this comparison shows that this data packet has been transmitted error-free, the corresponding content of the data bits 24 is decoded and forwarded to the output unit 12. In the present case, the output unit 12 displays the value corresponding to the speed information of the data packet in the first display area I of the display unit 13. Each time another data packet I arrives that contains speed information, the steps described above are followed so that the first display area I of the display unit 13 always displays a current speed value of the vehicle, provided that the data transmission was error-free.

When a data packet Hi is received, which is indicated by the content "1" in the identification bit 21, the decoder 10 first checks, based on the contents of the check bits 23 and the other contents of the data packet in question, whether a data packet has been transmitted without errors. If this is the case, the decoder 10 checks the rank of the current data packet based on the rank bits 22. A comparison is then made as to whether a data packet with such a rank is currently required in order to possibly receive previously received data packets.

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to complete the data packets with route information. This procedure is continued until complete, current route information is available in the decoder device 10. When complete route information is available, this is forwarded to the output unit 12, which displays the route information in the second display area II of the display unit 13.

In the manner described above, speed information and route information are continuously transmitted from the transmitter 8 to the receiver 9.

In the event of transmission disruptions between transmitter 8 and receiver 9, individual data packets may arrive at receiver 9 in a mutilated state, meaning that they cannot be evaluated there. In the event of a defective data packet containing speed information, this can still be tolerated by the user. In the worst case, incorrect speed information is displayed over several transmission periods.

In the event of a faulty transmission of a data packet containing route information, the decoder 10 discards the corresponding data packet. In this case in particular, an estimated change in the route information displayed in the second display area II is calculated in the decoder 10. For this purpose, the speed information decoded in the meantime is converted together with the time elapsed since the last complete route information was received to an estimated route change, which is added to the route information displayed in the second display area II of the display unit 13. In this way, as long as a new active

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The current total distance information is calculated and displayed until an error-free group of data packets containing a current total distance has been received by the receiver 9. The same procedure is followed at times when the current distance information is being transmitted. Every time error-free speed information is received, an estimated change in the distance information is calculated from the past time and added to the last transmitted distance information.

The case of a disturbed transmission of a data packet is illustrated below using Figure 5. In normal, undisturbed operation of the transmitter 8 and the receiver 9, data packets are transmitted, as is illustrated by the data packets with the consecutive numbers 1 to 9. After the transmission of the data packets 2, 4, 6, 8, the receiver 9 has all the information Hi, II2, II3, II4 that is required to calculate a total distance transmitted by the transmitter 8. Based on this total distance, the receiver 9 calculates estimated distance changes based on the speed information transmitted in the data packets 9, 11, 13 and 15 by multiplying the respective speed information by the transmission time between two speed data packets. The value corresponding to _v is added to the last total distance transmitted and displayed. In the present case, in which the data packet 14 with route information II3 is disrupted, no new total route can be derived from the data packets 10, 12, 14 and 16. In this case, the data packets 10, 12, 14 and 16 are discarded and not used any further. Instead, the receiver 9 calculates the total route information based on the value transmitted with the data packets 2, 4, 6, 8, by also using the speed

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speed data packets 17, 19, 21, etc., new distance changes are estimated and added to the last transmitted value of the total distance. This continues until total distance information is again transmitted error-free from the transmitter 8 to the receiver 9. In this case, the total distance information updated with estimated values is replaced by current total distance information transmitted error-free.

When the transmitter 8 and the receiver 9 are operating, it may happen that the total distance counter in the transmitter 8 has a lower value than the total distance counter in the receiver 9. This indicates that a so-called "overflow" of the total distance counter has occurred in the transmitter 8. The receiver 9 takes this into account by assuming that exactly one overflow has occurred. This overflow is then taken into account accordingly in the new display of the total distance information in the receiver 9.

In this case, the "true" distance covered by the wheel 1 is only recorded by the receiver 9. In this case, the transmitter 8 can only store values that are limited by the size of the total distance counter in the transmitter 8. According to the invention, this can be used particularly advantageously to keep the size of the total distance counter in the transmitter 8 comparatively small compared to the size of the total distance counter in the transmitter 9. This reduces the data to be transmitted over the radio link, so that the transmission rate with regard to the speed information can be increased. In a special embodiment of the invention, not shown here, exactly one distance information data packet is sent for every 10 speed data packets.

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In another embodiment not shown here, both speed information and route information are transmitted in a single data packet, whereby, for example, out of a total of 9 data bits in a data packet, 8 data bits are used to transmit speed information, while exactly one data bit is used to transmit part of the route information. In this way, exactly one route information item can be reconstructed from 8 consecutive data packets, while a total of 8 speed information items have been transmitted.

Figure 6 shows a schematic representation of a radio link 101 according to the invention, which comprises a first transmitter 102, a second transmitter 103, a third transmitter 104 and a receiver 105. The first transmitter 102 has a first antenna 6 for transmitting radio signals. The first antenna 106 is connected to a transmitting unit (not shown in this view) which generates the radio signals to be transmitted by the first antenna 106. The first transmitter 102 also comprises a transmitter control unit (not shown in this view) for controlling the transmitting unit. The transmitter control unit receives signals via a first input line 107 from a first sensor 8 which is designed as a revolution counter of a rotor (not shown in this view). The first sensor 108 thus supplies position information about the rotor to the transmitter control unit via the first input line 107. The transmitter control unit converts this position information into digital data and causes the transmitter unit to transmit this digital data via the first antenna 6. Both the current speed and the total distance covered by the wheel are transmitted.

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as explained above with reference to Figures 1 to 5.

The second transmitter 103 has a second antenna 109 and a second input line 110 and is essentially identical to the first transmitter 102 in terms of its other construction. The second transmitter 103 receives signals from a second sensor 111 via the second input line 110, which evaluates position information via a bicycle crank (not shown here). The second transmitter 103 converts this position information into digital signals, which are emitted as radio signals via the second antenna 109. Both the current position information and its integral over time are transmitted, as explained above with reference to Figures 1 to 5.

The third transmitter 104 comprises a third antenna 12 and a third input line 113, via which data from a third sensor 114 is received. In terms of its other construction, the third transmitter 104 is essentially the same as the first transmitter 102. The third sensor 114 determines the current heart rate and its integral over time, which allows a conclusion to be drawn about the energy consumption of a person (not shown in this view) who is moving around on a bicycle. This data is converted into digital data by the third transmitter 4 and transmitted as a radio signal via the third antenna 12. Both the current heart rate and its integral over time are transmitted, as explained above with reference to Figures 1 to 5.

The receiver 105 has a receiver antenna 115 for receiving the signals from the first transmitter 102, the second transmitter 103 and the

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third transmitter 104 emitted radio signals. The radio signals received by the receiver antenna 115 are forwarded to a receiving unit (not shown in this view) which is operably connected to a receiver control unit (also not shown in this view). The receiving unit can be switched on and off by the receiver control unit. The receiver control unit can also switch itself off. The receiver control unit converts the data received by the receiving unit and displays it on a display 116. The display 116 can show which transmitter sent the data shown on the display 116. The contents of the respective data can also be displayed. The receiver 105 also has an operator button 117 with which a user can operate the receiver control unit.

During operation of the radio link 101, the first transmitter 102, the second transmitter 103 and the third transmitter 104 continuously transmit data which is received by the receiver 105, evaluated and displayed on the display 116.

Figure 7 illustrates the radio signals emitted by the first transmitter 102, the second transmitter 103 and the third transmitter 104 with regard to the temporal sequence of the data transmitted by them. Information is only shown for a portion of the data emitted by the first transmitter 102, the second transmitter 103 and the third transmitter 104. In the example shown, only the transmission of the data is illustrated which is marked "I" in Figure 4, i.e. the regularly transmitted speed data. It goes without saying that the data marked "II" in Figure 4 is also shown.

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can be transmitted with a fixed packet and with a redundancy packet.

Figure 7a shows a first timeline 120, which contains a first fixed packet Fl and a first redundancy packet Rl. The first fixed packet Fl and the first redundancy packet Rl are each formed by a data signal that is modulated onto a carrier signal with a carrier signal frequency. In principle, any modulation method can be used for this.

As can be seen particularly well in Figure 7a, the transmission of the first fixed packet Fl begins at time ti. The transmission of the first redundant packet Rl begins at a time t ₂ . The length of the first fixed packet Fl and the length of the first redundant packet Rl essentially match.

Figure 7b uses a second timeline to illustrate the radio signal emitted by the second transmitter 103. It comprises a second fixed packet F2 and a second redundant packet R2, which are modulated as data signals onto a carrier frequency that is identical to the carrier frequency of the first transmitter 102. The second fixed packet F2 is transmitted at a time t1 and the second redundant packet R2 is transmitted at a time t2, the difference _t3 -t2 at the second transmitter 103 being smaller than the difference _t2 -t1 at the first transmitter 102. In this way, a temporal collision of the first fixed packet Fl, second fixed packet F2, first redundant packet R1 and second redundant packet R2 is avoided in such a way that at least one of the data packets per transmitter does not coincide in time with all the data packets of the other transmitter.

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Figure 1c illustrates a third timeline 122 on which a third fixed packet F3 transmitted by the third transmitter 104 and a third redundancy packet R3 are shown.
5

The third transmitter 104 transmits on the same carrier frequency as the first transmitter 102 and the second transmitter 103, with the third fixed packet F3 and the third redundant packet R3 being modulated onto a corresponding carrier signal. As can be seen particularly clearly in Figure 7c, the transmission of the fixed packet F3 begins at time ti, while the transmission of the third redundant packet begins at time t4. The time difference t ₄ -ti of the third transmitter 104 differs from the corresponding time differences t3~ti of the second transmitter 103 and t ₂ -ti of the first transmitter 102.

Figure 7d uses the first timeline 120 to illustrate the time interval to between two fixed packets Fl of the first transmitter 102. The interval to is essentially identical between any two consecutive fixed packets Fl. Accordingly, the fixed packets Fl are transmitted at regular time intervals.

Figure 7e uses the second timeline 121 to illustrate the time interval t ₀ ' between each two second fixed packets F2 of the second transmitter 103. The second fixed packets F2 are transmitted by the second transmitter 103 at regular time intervals.

Figure 7f uses the third timeline 122 to illustrate the third fixed packets F3 emitted by the third transmitter 104. The third fixed packets F3 are each emitted regularly one after the other with a time interval t ₀ '' .

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The respective time intervals to, to' and to ¹¹ differ from one another, so that in most cases the fixed packets transmitted by the first transmitter 102, the second transmitter 103 or the third transmitter 104 do not overlap in time. This enables the operation of several transmitters together with a single receiver.

In the present case, each transmitter does not only regularly send out one type of fixed packet - for example, the speed information. Rather, two types of fixed packets - for example, the integrated route information - are sent out.

Figure 8 illustrates the structure of a data packet 125, which in terms of its structure essentially corresponds to that of the first fixed packet Fl, the second fixed packet F2, the third fixed packet F3 or the first redundancy packet R1, the second redundancy packet R2 or the third redundancy packet R3. The data packet 125 is divided into a first identification area 126, a type area 127, a displacement information area 128, a second identification area 129, a user data area 130 and a check code area 131.

The first identification area 126 is used to record information that indicates the so-called sub-ID of the respective transmitter. The sub-ID of the respective transmitter can record information about the time offset between a fixed packet sent by the transmitter and the corresponding redundancy packet. Similar to the allocation of channels for radio links that use predetermined bandwidths of radio signals, time slice areas can be used in this way when using a

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a single, predetermined transmission frequency. The time slice areas defined in this way are advantageously clearly identified and - each assigned to a transmitter - reproduced in the first identification area of a fixed packet or redundancy packet sent by the transmitter in question.

The type area 127 contains information about whether the respective data packet is a fixed packet or a redundant packet.

The offset information area 128 remains unused in a simple operation of the radio link 101 according to the invention without redundancy packets. In an advantageous development, the information contained in the offset information area 128 together with the information in the first identification area 126 provide information about the time interval at which the redundancy packet appears following a fixed packet. For this purpose, a calculation rule or a counting sequence can be provided in the corresponding transmitter of the data packet 125, according to which the time interval between the fixed packet and the redundancy packet sent out is determined. If such a sequence is controlled by a counter, the respective counter reading can be recorded in the offset information area 128 and sent out.

The second identification area 129 can be used to accommodate a serial number that is assigned only once, which makes it possible to distinguish a transmitter of the radio link 101 from a transmitter of another radio link.

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The payload area 130 receives the data to be transmitted via the radio link 101.

When the data packet 125 is received, the check code area 131 is used to determine whether the transmitted data has undergone undesirable changes in the meantime. A parity method or a checksum method can be used, for example, to generate the content of the check code area 131.

Furthermore, the data packet 125 has scan, synchronization and start data not shown in this view, which are particularly required by the machine processing of the data packet 125 and are designed accordingly.

In the normal case, in which the presence of the first transmitter 102, the second transmitter 103 and the third transmitter 104 is sensed, the receiver 105 goes into an active mode. In the active mode, which represents the normal operation of the radio link, the receiving unit is essentially kept switched off. The receiving unit is only switched on at times when the receiver control unit expects the expected arrival of a fixed packet from one of the transmitters. In the active mode, the exact position of the received fixed packets is constantly checked and, if necessary, minor errors in the position calculation are corrected by the receiver control unit. In the active mode, the data is also transmitted within the radio link 101, evaluated by the receiver control unit and forwarded to the display 116.

Starting from the active mode, the receiver 105 enters a redundancy mode 14 6 if the data in the check code area 131

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When evaluating the data packet, the information contained in a received fixed packet indicates that the data packet was corrupted or incompletely transmitted. In redundancy mode, the receiver control unit switches on the receiver unit when a redundancy packet is to be evaluated for the incorrectly received or not received fixed packet for a specific ID of one of the transmitters. The exact timing of the receipt of the redundancy packet for the relevant fixed packet is determined from the sequence of numbers tracked in the receiver control unit.

After receiving the corresponding redundancy packet, the receiver 105 returns to the active mode in which it evaluates consecutive fixed packets.

A special situation for the receiver 105 is a learning mode in which the radio link 101 is operated shielded from other radio links and interference. In the learning mode, the system scans which transmitters are in the vicinity of the receiver 105. Their IDs are then received and stored permanently in the receiver 105. It must of course be ensured that all transmitters on the radio link 101 are active and that no transmitters on a second radio link interfere with the transmission.

Claims (13)

1. Radio link for packet-oriented data transmission with at least one transmitter (8) and at least one receiver (9),
wherein the transmitter (8) has at least one sensor (3) for generating a plurality of instantaneous measured variable values of a measuring signal, a coding device (5) connected to the sensor (3) for converting the instantaneous measured variable values into data packets of a data packet stream and a transmitting device (6) for transmitting the data packets as a radio signal,
and wherein the receiver (9) has a receiving unit for receiving the data packets present as a radio signal, a decoding device (10) for converting the received data packets into measurement information and an output unit (12) for outputting the measurement information,
wherein the coding device (5) is further designed such that a first instantaneous measured variable value and at least one second instantaneous measured variable value can be obtained from the measurement signal, wherein the data packet stream has both data packets which contain information about the first instantaneous measured variable value and data packets which contain information about the second instantaneous measured variable value or about the second instantaneous measured variable values. 2. Radio link according to claim 1, characterized in that the information about the first instantaneous measured value and/or about the second instantaneous measured value can be transmitted in a distributed manner over a plurality of data packets. 3. Radio link according to claim 1 or claim 2, characterized in that data packets are provided which exclusively contain information about the first instantaneous measured value, and that data packets are provided which exclusively contain information about the second instantaneous measured value. 4. Radio link according to one of the preceding claims, characterized in that the output unit is designed such that the course of the measured variable represented by the first instantaneous measured variable values and/or by the second instantaneous measured variable values can be estimated and output at times between the reception and/or the conversion of data packets. 5. Radio link according to one of claims 1 to 4 for displaying the current driving speed and the distance travelled by a vehicle, wherein the sensor (3) is arranged in the area of a wheel (1) of the vehicle and emits a pulse as a measurement signal at least for each complete revolution of the wheel (1), wherein the coding device (5) is further designed such that, using a system time, the current speed of the vehicle can be obtained from the measurement signal as a first current measurement value and the number of wheel rotations carried out as a second current measurement value. 6. Radio link according to one of claims 1 to 4 for displaying the instantaneous heart rate and the heart rate variability of a living being, wherein the sensor is arranged in the region of the nervous system of the living being and emits at least one pulse as a measurement signal when a heartbeat is sensed, wherein the coding device is further designed such that the instantaneous heart rate can be obtained as a first instantaneous measurement value and the heart rate variability as a second instantaneous measurement value from the measurement signal using a system time. 7. Radio link according to one of claims 1 to 4 for transmitting the information contained in the electrical pulses generated by a voltage-frequency converter, wherein the coding device is designed such that the instantaneous frequency of the electrical pulses can be obtained as a first instantaneous measured value and the number of pulses can be obtained as a second instantaneous measured value. 8. Transmitter having at least one input for inputting a plurality of instantaneous values of a measurement signal, a coding device connected to the input for converting the instantaneous values into data packets of a data packet stream, and a transmitting device for transmitting the data packets as a radio signal, wherein the coding device is further designed such that a first instantaneous measurement value and at least one second instantaneous measurement value can be obtained from the measurement signal, wherein both data packets can be generated which contain information about the first instantaneous measurement value and data packets can be generated which contain information about the second instantaneous measurement value or the second instantaneous measurement values. 9. Transmitter according to claim 8, characterized in that data packets can be generated which exclusively contain information about the first instantaneous measured value, and that data packets can be generated which exclusively contain information about the second instantaneous measured value. 10. Transmitter according to claim 8 or claim 9, characterized in that data packets can be generated which each contain only part of the information about the first instantaneous measured value and/or about the second instantaneous measured value. 11. Receiver with a receiving unit for receiving data packets in the form of a radio signal, with a decoding device for converting the received data packets into measurement information and with an output unit for outputting the measurement information, the decoding device being designed such that data packets containing information about the first instantaneous measurement value can be treated differently from data packets containing information about the second instantaneous measurement value. 12. Receiver according to claim 11, characterized in that the decoding device is designed such that information about the first instantaneous measured value and/or about the second instantaneous measured value can be obtained from a plurality of data packets. 13. Receiver according to claim 12, characterized in that the output unit is designed such that the course of the measured variable represented by the first instantaneous measured variable values and/or by the second instantaneous measured variable values can be estimated and output at times between the reception and/or the conversion of data packets.