DE2450289A1 - PERSONAL PAGE SYSTEM - Google Patents

Description

Dr.-Ing. Hon ke.

■ '■ "Dipl.-Ing. GesthuyoGil " ■ "''.

D r. M a s c h · ·· '

Patent application. 'Food, 21-. Oct 1974

(44 866 / We) ''

Hasler AG, Bern

Paging system

The invention relates to a paging system with a transmitter, which transmits on an angle-modulable frequency, and with • * r; '' '' several recipients that can be called individually by call telegrams.

While most known'Personensuchanlagen send out a call code, which consists of a few consecutive signals that are selected from a larger number of frequencies, when using integrated circuits, it is advantageous to use call 'telegrams that contain a larger number of consecutive signals , but only two or three different ones. I ₁ - With this type of transmission, the receiver must recognize when the individual bits of the call telegram are to be queried. In known people search systems, the individual signal steps are characterized in that there are pauses between them, during which no signal is sent. However, compared to the transmission without a break between successive steps, this doubles the transmission time.

It is known from the technology of data transmission that the individual To transmit bits synchronously and to recover the clock from the received characters. Complex circuits are necessary for this, which are either started at a certain tent point

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and then deliver a precisely timed clock or there are circuits known that regulate the clock continuously through the signal transitions. These circuits generally require a certain amount of time to set and are therefore not usable for short calls. It is an object of the present invention to provide a paging system indicate whose evaluation part in the receiver is made up of purely digital circuits and avoids circuits that use capacitors included, such as monostable multivibrators. It is also an object to specify a paging system which enables a call with the shortest possible call telegrams and false calls excludes with great certainty.

It is also an object of the invention to provide a paging system which can transmit commands simultaneously with the call, through which switching processes can be triggered in the receiver. The invention The system is characterized by the fact that the call telegram consists of a number of consecutive steps of the same length and that in the transmitter and in each receiver a frequency divider is provided to which the transmission frequency is supplied and at the output of which the clock signal for the steps of the call telegram is directly available.

An exemplary embodiment of the invention is described below with reference to the figures:

Figure 1 is a block diagram of a transmitter, Figure 2 is a block diagram of a receiver, Figure 3 shows the composition of a call telegram,

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FIG. 4 shows a more detailed illustration of the in FIG

Circuit according to Figure 2 contained Decodexs.

In Figure 1 is the simplest embodiment of a code telegram transmitter shown for inductive calls. 1 is a carrier frequency generator, which has a frequency in the range of 30 - 60 kHz outputs and can be modulated in its frequency or in its phase by a voltage supplied to its input 2. Hereinafter the transmission with frequency modulation is described. The modulated voltage is passed on line 3 to an amplifier 4 which feeds the induction loop 5. The modulated voltage becomes by a divisor — divided by -p 6. At the exit of the divider appears on line 7 a pulse train with the divided frequency, which represents the bit clock for the transmitted telegram and to the telegram generator 8 is directed. This telegram is structured in a way that will be described later and is dependent on the number on the 'number transmitter 9 set number. Each call system has a transmitter with a specific carrier frequency and a number of receivers. Different systems can have different transmission frequencies from each other in order to avoid mutual interference.

The receiver according to FIG. 2 contains an antenna which consists of a magnetic core 21 and a coil 22. It lies in one Matched circuit consisting of antenna coil 22 and capacitor 23. The voltage emitted by the antenna is in an amplifier 24 amplified and limited in the limiter 25. A phase-controlled loop (phase locked loop) 26, which is used for demodulation Line 27, the HF signal, which has been freed from interference. Line 28

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2450283 '

outputs the data signal and a control message (lock signal) on line 29 when the control loop is regulated. The receiving frequency is divided by a divider-by-p 30 in the same ratio as in the divider 6 of the transmitter. Three mutually phase-shifted pulse series of the clock frequency go on lines 31, 32 and 50 to the decoder 33, which is described in detail below. If the call telegram assigned to the receiver in question is received, the decoder switches on the audio frequency generator 34, the voltage of which is amplified by an amplifier 35 and excites the loudspeaker 36 so that the call sounds from the receiver in question. The structure of a call telegram is shown in FIG. The duration of a call is 36 steps and is made up of the synchronization character 13, the two message bits 14, the call address 15, which consists of five call words of 4 bits each, and the parity word 16. This can be followed directly by the next call telegram with a synchronization character 13. If the transmitter is not switched off, an abbreviated synchronization signal 17 can be sent out during the pauses in the call.
Each word consists of 4 bits labeled a, b, c, d.

The word number can be appended as an index. The synchronization character comprises Io bits, namely the sequence 0001111101. There are 5 different call words are provided, which are coded in a 2-out-of-4 code. The four call words are A .. .D, the two consecutive ones contain the same bits, the selective call and a call word E,

which alternately contains the bits zero and one, the group call assigned.

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The five code words are: A = 0011
y B = 0110

C = 1100

D = 1001

E = 0101

The group call word Ξ can be any of the code words A.. . . Replace D. The recipients with the DABBA call programs would respond to the group call DABBE

DABBB
"'' · .- ■■■ DABBC

DABBD

speak to. In addition to dpm, the recipient with the DABBA call telegram would also respond to group calls such as B. Address DEBBA and DiCBBiD. In this way, diverse group call combinations can be obtained. With group call telegrams which have a Ξ contain up to 4, with those containing two E, up to 16 subscribers can be called at the same time, etc. The call telegram EEEEE calls all recipients at the same time. The parity word 16 is formed by taking the longitudinal parity of the five

Call words 15 (w.... W, _) and the one from the last two bits of the synchronization character 13 and the two message bits 14 formed word w is calculated in a known manner. It is advantageous to if the parity bits do not have the order corresponding to the word bits.

FIG. 4 shows a block diagram of the decoder 33 including the Divider 30. The decoder has three inputs, as already shown in Figure 2, namely the input 27 for the high-frequency signal, the

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Input 28 for the data signal and input 29 for the control message. The high-frequency signal goes through gate 49 and "switch 55 to divider-by-p 30. This outputs a continuous pulse train on line 50 when high-frequency signal and control message are present and switch 55 is in the position shown. For an average input frequency of 51.2 kHz and ρ = 512, this pulse frequency is <= about 100 Hz. The pulse intervals are not constant because the high-frequency signal is frequency-modulated; however, this has no effect, as the bit clock passes through both the transmitter and the receiver The bit clocks are counted in the bit counter 51 modulo 4; its position therefore corresponds to the bit positions a, b, c, d in each word are counted; its position corresponds to the number (0)... (6) of the respective word W ₀ ... w,.

The divider \ ind the counters emit the following clock pulses: The divider 30 applies three pulses during each step, namely a sampling pulse on line 31 in the middle of each step, thereafter Line 32 an interrogation pulse and at the end of each step on line 50 a counting pulse which goes on to the bit counter 51; the Bit counter 51 four pulses a, b, c, d, which correspond to the four bits of each word and the functions A, B, C, D already described; the word counter 43 finally receives the word pulses (0) ... (7) corresponding to its respective position. With the help of the signals mentioned a code telegram individually assigned to the receiver is compiled with the code matrix 56 and the word counter 57.

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. In the comparison circuit 54, the received code telegram compared with this code telegram generated in this way and at the same time with the function E bit by bit. Will be a deviation from both Functions are determined so the divisors and counters are at the end of the that word is deferred and the operations just described begin again. The word counter 53 reaches the position 7, it sends a signal to the audio frequency generator on line 41 34, which puts this into operation, so that it gives a tone frequency signal to the loudspeaker 36 via the line 42 and the callsign is audible will.

The signal on line 41 simultaneously toggles switch 55, so that now no longer the high-frequency input signal but the audio frequency on line 42 comes to the input of divider 30. The audio frequency is divided in the divider 30 and in the bit counter 51 until the latter emits a pulse on line 52 and the word counter 53 on Position zero switches on, whereby the signal on line 41 ends becomes, which turns off the tone generator 34 and switches the switch 55 back '. This means that the counter is also used to determine the Ringing tone length and avoiding the use of the monostable multivibrator otherwise customary for this purpose. If so received duration of the ringing tone is too long, the line 42 can over the switch -n with the input of a later stage of the divider 30 are connected.

The comparison circuit 54 includes an exclusive-OR circuit 61, at whose input the data signal (line 28) and the output signal of the word counter 57 (line 70) is a second Exclusive-OR circuit 62, at the input of which the data signal and the function E output by bit counter 51 are, and

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two AND gates 63 and 64, respectively, the outputs of the two exclusive OR circuits with the control inputs of the flip-flops 65. 66 connect. Their 1-outputs are connected via a further AND gate 67 to the control input of a flip-flop 68, at whose 1-output the jerk part signal for the divider 30 and the counters 51, 53, for the two flip-flops 65 and 66 and for the Parity circuit 43 appears. Flip-flop 68 is set to zero by the data signal on line 28. Its circuit is such that if there is a 1 at the output of gate 67, the state of line 72 also goes to 1 without looking at the state at the zero input of the flip-flop. The other input of the gates 63 and 64 is connected to the output 31 of the divider 30 via the gate 69 and receives an interrogation pulse approximately in the middle of each step except during the two message bits 44. If there is a difference in a word between the received and the internally generated Code word is determined, the flip-flop 65 is set. If a received word is not the same as the group call word E, then the flip-flop 66 is set. At the end of each word, the position of the two flip-flops is queried by means of gate 67. If both flip-flops are set to 1, ie if the received word was not the same as the code word assigned to the receiver or the same as the group call code word E, then the flip-flop 68 is set and thus all dividers are reset. The reset signal blocks the progression of the dividers and counters as long as it lasts.
The interrogation of the gate 67 is done by means of a plate 30 on

Line 32 emitted pulse, shortly before the end of each word (d) but not at position 7 of the word counter.

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The synchronization signal 13 is constructed in such a way that it is certain to be during of the 4th to 8th pulse the flip-flop 68 is set. This position is maintained until the data signal goes to zero. In addition to the dividers - via the

_, ORJ gate 47 - also the flip-flops 65 and 66 reset so that on Control input of the flip-flop 68 the state zero occurs. Is that possible now If the data signal is at zero, namely at the point in time designated by 18 in FIG. 3, then flip-flop 68 goes to the zero position, the reset signal Line 72 disappears and divider 30 begins to operate. First of all, bits 01 and the same appear in the data signal at the output of the gate 570 connected to the line (0) of the word picker 57. Flip-flops 65 and 66 do not flip 1

The two gates 63 and 64 are during the two message bits 14 blocked by the signal appearing at the blocking input of gate 69.

The parity circuit 43 is used to calculate the longitudinal parities. The following is calculated for the first bit of each word: 'ρ = aQ + an + a _? + a »+ a . + a_ (modulo 2)

and in a corresponding way p, »ρ and p ,.

The parity circuit receives the clock pulses a, b, c, d, which appear in each word during the corresponding step, furthermore the clock pulse on line 31 approximately in the middle of each step, which samples the data signal appearing on line 28. The circuit contains four flip-flops which correspond to the four steps of one Word are assigned and the ones occurring in the corresponding step count modulo 2. During the steps of the sixth Word "w £ the flip-flops are queried one after the other and with · Help

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an AND gate at the output of each flip-flop and the AND gate 576 queried. The parity word formed from the received data goes on line 70 to comparator 54 and is compared there with the received parity word. In the event of inequality, a provision is made at the end of the word in the same way as at the previous word.

The message circuit 45 is used to convert the received message bits 47 into control signals.

It comprises a flip-flop 73, which through the output (7) of the Divider 53 is set and reset by the negated rule message. The 1 output of flip-flop 73 is connected to the input of one Gate 74 connected, the other inputs of which are connected to the query pulse line 31 and to the output (0) of the word counter 53 are. The output of gate 74 supplies the shift pulses for a two-stage shift register 75, with the two stages of the AND gates 76 and 77 are connected, at the outputs of which signals for triggering switching processes can be picked up. This

but only happens when the word counter 53 comes to the position. Flip-flop 73 is set and gates 76 and 77 become opened, so that, for example, output 37 goes to 1 if the first call telegram intended for the station in question Message bit equal to 1 waiv .. The flip-flop 73 remains in position 1, until the transmitted carrier signal is switched off.

It is not necessary to reset the shift register 75; the Stored bits are shifted out of the shift register on the first call after the carrier is switched on again.

5.0 9 8 8 4 / 0.7 U k ORIGINAL

Claims (8)

Claims 1.] Personal call system with a transmitter that is based on an angle-modulated Frequency sends, and with several by call telegrams individually callable recipients, characterized that the call telegram consists of a number of consecutive steps of the same length, that in the transmitter and in each Receiver is provided with a frequency divider to which the transmission frequency is supplied and at the output of which the clock signal for the steps of the call telegram is directly available. 2. System with several call systems according to claim.1> different carrier frequencies, characterized in that the ratio of carrier frequency to clock signal at least for one Part of the systems is the same and independent of the carrier frequency. 3 · Plant according to claim 1, characterized in that each call telegram contains a synchronization signal and a combination of code words which are coded according to an n / 2-out-of-n code and identify the called recipient. 4. Systems according to claim 3, characterized in that a message code word can be used in each call telegram and that at least one recipient contains a switch that after, the recognition of the call address assigned to the recipient and one responds to a specific message code word. Pall 532 5. Systems according to claim 4, characterized in that the receiver contains a circuit which during reception a carrier frequency emits a signal that the receiver also contains a memory, which the switch in switched on Holds position and is only reset at the end of the signal emitted when the carrier frequency is received, with which the said switch also returns to its rest position. 6. ι- plant ■ according to claim 1, characterized in that In addition to the divider for generating the bit clock, the receiver contains the following circuits: - a bit counter, which from the bit clock frequency the word r clock generated, - a word counter connected to the output of the bit counter, _λ · - an adjustable code matrix, which is queried in word cycle and for generating a call telegram assigned to the receiver serves, - a comparison circuit that compares the received and internally generated call telegrams bit by bit and if they do not match an error memory provides for triggering a reset pulse for all dividers and counters, - a tone generator circuit, which at a certain position of the word counter is energized and feeds a loudspeaker. 7. Systems according to claim 3 »characterized in that · that ■ 24.5 " Group call telegrams can be transmitted with at least one of the code words is a specific group call word which is used for all recipients replaced the individual code word at the relevant point in the call telegram. 8. Anlage.nach patent claims 6 and 7, characterized by a device in the comparison circuit, which checks each received code word bit for bit to see if it is equal to the Is a group call word, and if it is not »a second error memory (66) and at the end of a word the reset pulse only triggers if both error memories are set are. 9 · System according to claim 6, characterized in that a changeover switch is provided in the receiver circuit which is shown in the specific position of the word counter connects an input of the bit * counter to the output of the ring tone generator, in such a way, that., divider and bit counter count the periods of the audio frequency and that with the first pulse emitted by the bit counting the word ■ ■ » counter advances and the call signal switches off. / " \ " ■ '-' ■ '■ 509884/0744