JP2012008012A - Receiver - Google Patents

Abstract

【Task】
In GNSS, the inversion of the correlation signal between the I phase and the Q phase can occur every 20 msec. Therefore, when the positioning data is unknown, the coherent correlation cannot be performed beyond 20 msec.
[Solution]
A base station data detector that obtains first positioning data from data received by the base station GNSS signal receiver, a base station GNSS signal generator that generates a GNSS signal from the base station data detector, and a transmission from the mobile station The mobile station GNSS signal receiving unit that receives the received GNSS signal, the generated data generated by the base station GNSS signal generating unit, and the received data received by the mobile station GNSS signal receiving unit Is composed of a correlation unit that acquires the second positioning data and an error detection unit that calculates a difference between the first positioning data and the second positioning data, and the base station GNSS signal generation unit converts the first positioning data into the first positioning data. A receiver which is corrected so as to match the positioning data of 2.
[Selection] Figure 2

Description

The present invention relates to high sensitivity and high accuracy when receiving and demodulating positioning data transmitted from a GPS (Global Positioning System) satellite.

The GPS receiving device is a device that receives positioning data sent from a GPS satellite and measures a position and the like, and is used, for example, for position measurement of a portable terminal or a car navigation system.

A GPS satellite transmits positioning data called a C / A code (Coarse and Acquisition Code). On the other hand, the GPS receiver demodulates the positioning data transmitted from a plurality of GPS satellites, and measures the propagation time of radio waves from the GPS satellites to the GPS receiver. Then, the pseudo distances for a plurality of GPS satellites are calculated from the measured propagation times of radio waves, and their own positions and the like are measured based on the calculated pseudo distances.

GPS satellites transmit radio signals in the L1 frequency band. In this radio signal, a pseudo noise code PN code and positioning data are modulated by the DS spread spectrum modulation method. The receiver receives this and performs positioning and surveying (Patent Document 1).

In the GPS receiver, the positioning signal in the L1 band is synchronized by a signal processing circuit. Since the 1-bit length of the positioning data transmitted by the positioning signal in the L1 wave band is 20 msec, in the synchronization processing, an appropriate point is selected from the starting points for every 1 ms of the C / A code, and then 20 msec is obtained therefrom. Between the received signals between them, coherent addition, that is, coherent correlation is taken, several patterns are prepared, and the result of comparing the addition results has been processed for bit synchronization.

Also, in GPS, the correlation signal of I (carrier positive phase) and Q (carrier phase 90 degrees) can be inverted every 20 msec, so if the positioning data is unknown, the coherent correlation is performed over 20 msec. Can not do it.

Such a correlation calculation method by coherent addition of received signals affects the case of accurate bit synchronization and extraction of positioning data with high accuracy. On the other hand, regarding the problem of increasing the sensitivity of GPS signals, As with the high accuracy, the method of obtaining the coherent correlation between the received signal and the PN code gives a limit.

Also in this case, when the positioning data is unknown, since the inversion of the correlation signal between the I phase and the Q phase can occur every 20 msec, the time width must be 20 msec or less.

In the past, under the restriction that coherent correlation exceeding 20 msec cannot be calculated in this way, for each satellite, the code phase is used by using a delay lock loop generally used to maintain code phase synchronization, A Costas loop, which is a typical method for generating a synchronization signal, is used to detect carrier frequency, carrier phase, and positioning data, and the delay lock loop and the Costas loop operate independently of each other.

  If the code detection and the carrier detection are performed independently as described above, the phase relationship between the code tracking signal 603 and the carrier tracking signal 605 in the navigation data 601 is not uniquely determined in the signal relationship diagram shown in FIG. Therefore, for example, when a received signal is tracked under a plurality of environments, the phase relationship between the tracking signal under one environment and the tracking signal under another environment is random.

JP-A-11-142501

However, as described above, the disadvantage that the coherent correlation cannot be obtained in the time of one bit of the positioning data, that is, the time width of 20 msec or more, is a great limitation on the high accuracy and high sensitivity.

Therefore, a method using non-coherent correlation that reduces the influence of waveform inversion by performing a correlation operation with a squared value instead of coherent correlation is also conceivable. Since this method is effective only about half, and improvement in accuracy cannot be expected unless long-term correlation is obtained in this method, it is not practical to perform GPS positioning in real time.

  In addition, even if an attempt is made to use a reference signal for performing a correlation calculation as a received signal at a location different from the analysis location, as described above, code tracking and carrier tracking are performed independently. The phase of the received signal was not uniquely determined, and the correlation result did not lead to higher accuracy.

In order to solve the above problems, the present invention provides:
A receiver of a base station in a mobile radio system,
A base station GNSS signal receiver;
A base station data detector that obtains first positioning data from the data received by the base station GNSS signal receiver;
A base station GNSS signal generator that generates a GNSS signal from the base station data detector;
A mobile station GNSS signal receiving unit for receiving a GNSS signal received by the mobile station transmitted from the mobile station;
A correlation unit that obtains second positioning data by performing a correlation operation between the generation data generated by the base station GNSS signal generation unit and the reception data received by the mobile station GNSS signal reception unit;
An error detector that calculates a difference between the first positioning data and the second positioning data;
Consisting of
The receiver is characterized in that the base station GNSS signal generation unit corrects the first positioning data to match the second positioning data using the error detected by the error detection unit.

Further, the present invention is the receiver characterized in that the correlation calculation time width of the correlation unit is longer than one bit length of the positioning data.

Further, according to the present invention, when the base station data detection unit detects the first positioning data and when the correlation unit detects the second positioning data, the code phase is detected using a delay lock loop. The receiver is characterized in that a Costas loop is used to detect the carrier frequency and the carrier phase and other data.

In the conventional method, since the positioning data is unknown, there is a limitation that the coherent correlation must be performed in a time width of 20 msec or less. However, according to the present invention, since the positioning data can be handled as a known one, the coherent correlation is performed. The correlation time width can be set to 20 msec or more.

This makes it possible to improve the accuracy of GPS positioning in a mobile station such as a GPS mobile phone. For example, taking a coherent correlation with a time width of 1 sec results in an improvement of 10 log (1 / 0.02), that is, 17 dB.

Such high sensitivity greatly expands the use range of the mobile station, so that the user's merit is also great. In addition, when it is assumed to be used under normal received signal strength, the increased sensitivity can be used for compensation of antenna gain reduction.

That is, even if the antenna gain is reduced, the same gain as before can be obtained, and this makes it possible to reduce the size and cost of the apparatus.

  Further, in the present invention, the base station installed in a place where the reception environment is excellent has the phase determined uniquely by the code tracking signal and the carrier tracking signal being generated from the same oscillator. When the received signal of the base station is used as a reference signal for correlation with respect to the signal, high accuracy can be realized.

It is a conventional GNSS system. It is a GNSS system concerning the present invention. This shows the limitation of the conventional correlator. 1 shows a correlator according to the present invention. It shows that the detection of direct waves is facilitated by the present invention. It shows the relationship among navigation data, code signal and carrier signal.

A preferred embodiment of the present invention will be described using a GNSS (Global Navigation Satellite System) broader than GPS, taking a mobile phone system as an example, with reference to the drawings.

FIG. 1 is a general form of a GNSS mobile phone system. That is, the base station 111 performs positioning calculation using the GNSS signal received by the mobile station 101.

In the mobile station 101, the GNSS signal is received by the GNSS antenna 103 and converted into a digital signal by the receiving unit 105. The GNSS signal transmission unit 107 modulates the digital signal to a transmission frequency to the base station and transmits the modulated digital signal via the transmission antenna 109.

In the base station 111, the GNSS signal transmitted from the transmission antenna 109 of the mobile station 101 is received by the reception antenna 113, converted into a digital signal by the GNSS signal reception unit 115, and a GNSS signal is extracted.

Further, the code phase / carrier frequency / phase / data detection unit detects the code phase, the carrier frequency, and the carrier phase from the GNSS signal to obtain positioning data. This detection method is general, and for each satellite, a code phase is obtained by a delay lock loop, and a carrier frequency and a carrier phase are obtained by a Costas loop.

Further, the positioning calculation unit 119 calculates code pseudo distances and satellite positions from a plurality of satellites based on the positioning data, and calculates the position of the mobile station.

The base station obtains the number of visible satellites and the estimated value of the carrier Doppler frequency for each visible satellite and sends them to the mobile station, and the code phase / carrier frequency / phase / data detector used in the base station. Various forms of the GNSS mobile phone system are considered, such as means for the mobile station to execute the process 117.

Next, FIG. 2 shows a preferred embodiment according to the present invention.

A feature of the present invention is that positioning data is known when a GNSS receiver installed in a place where the reception environment of the base station is excellent receives a GNSS signal and the mobile station analyzes the GNSS signal received by the received signal. As a result, the condition that the signal processing must be performed within the range of the 1-bit width of the positioning data as described above is relaxed, and the accuracy of positioning can be improved by extending the correlation time. There is.

First, the GNSS signal is received by the GNSS antenna 103 of the mobile station 101 and the GNSS antenna 201 installed in a place where the reception environment of the base station 217 is excellent, and is digitized by the receiving units 105 and 203, respectively.

In the mobile station 101, the GNSS signal digitized by the receiver 105 is transmitted from the GNSS signal transmission unit 107 to the base station 217 via the transmission antenna 109. In the base station 217, the code phase / carrier frequency / phase / data detection unit 205 detects the code phase, the carrier frequency, and the carrier phase using the GNSS signal digitized by the receiver 203, and obtains the positioning data. get.

In the code phase / carrier frequency / phase / data detection unit 205, for example, the detection of the code phase is synchronized and held by a delay lock loop (DLL), and the detection of the carrier frequency and the carrier phase is synchronized by a Costas Loop (Costas Loop). Tracked and realized.

  When implementing the delay lock loop and the Costas loop, each synchronous clock is generated from one oscillator, and since it is installed in an excellent reception environment, the detected code signal and carrier signal The phase relationship of is uniquely determined. Therefore, the secondary effect that the code signal and the carrier signal can be obtained without being affected by the fading signal such as the reflected wave, which is an unexpected signal, occurs.

Next, in the base station 217, after detecting the code frequency, the carrier frequency, the carrier phase, and the positioning data, the GNSS signal generation unit 209 generates a GNSS signal for each satellite.

On the other hand, the GNSS signal received by the mobile station 101 is transmitted to the GNSS signal receiving unit 115 of the base station 217. The correlator 207 performs correlation calculation using the GNSS signal for each satellite generated by the base station and the GNSS signal received by the mobile station, thereby identifying the satellite.

  Here, since the phases of the code signal and the carrier signal are synchronously tracked so as to be uniquely determined as described above, in this means using these as reference signals for the correlation calculation, the accuracy is improved. I can expect.

Since the positioning data is unknown in the conventional technique, the coherent correlation could not be calculated with a time width of 20 msec or more, which is the 1-bit width of the positioning data as described above. Since the code phase / carrier frequency / phase / data detection unit 205 acquires positioning data by receiving a GNSS signal at a high S / N ratio at the base station, when analyzing the GNSS signal from the mobile station Since the positioning data can be handled as known, the time width of the 20 msec is not limited.

Next, the code phase error detector 211 detects the code phase error based on the correlation value obtained by the correlator 207, and the carrier frequency / phase error detector 213 detects the carrier frequency error and the carrier phase error.

The code phase error detection unit 211 detects a code phase error by a code phase error detection method used by a delay lock loop or the like, and the carrier frequency / phase error detection unit 213 uses a carrier frequency / phase used by a Costas loop or the like. A carrier frequency error and a carrier phase error are detected by an error detection method.

Next, the detected code phase error, carrier frequency error, and carrier phase error are fed back to the GNSS signal generation unit 209, and the GNSS signal generation unit 209 corrects the GNSS signal for each satellite. Since the GNSS signal generated by the GNSS signal generation unit 209 by this feedback loop is equivalent to the GNSS signal received by the mobile station 101, the positioning calculation unit 215 uses the GNSS signal generated by the GNSS signal generation unit 209. 101 positioning calculations can be performed.

As described above, in the conventional positioning calculation, as shown in FIG. 3, since the received signal received by the mobile station is compared with the PN code, the positioning data is unknown. Synchronization processing was performed by the following coherent correlation calculation. In the present invention, as shown in FIG. 4, if received signals from all visible satellites received by the base station are targeted for correlation, they are moved into that. Since satellites to be received by the station are also included, positioning data can be handled as known data, and the coherent correlation time can be set to an arbitrary length.

In addition, as shown in FIG. 5, since the base station is installed at a position excellent in reception environment, only direct waves arrive from the GNSS satellite, but direct waves and reflected waves arrive at the mobile station. It can be a multipath situation.

Even in such a case, according to the present invention, since the correlation calculation between the multipath wave of the mobile station and the direct wave of the base station is performed, the received wave of the mobile station having the strongest correlation value is Since it is a direct wave, it becomes easy to detect the direct wave from the received signal of the mobile station, and this also makes it possible to enhance the positioning.

In the present invention, the protocol of signals communicated between the transmitting antenna of the mobile station and the receiving antenna of the base station is not limited at all.

Further, in the base station, the error detection means for detecting various errors by correlating the GNSS signal obtained from the received signal of the mobile station and the GNSS signal obtained from the received signal of the base station is It is not limited.

Further, the means for calculating the positioning from the GNSS signal is not limited at all.

  Furthermore, regarding the installation location of each calculation unit such as the GNSS signal generation unit according to the present invention, this may be in the mobile station or in the base station. Not what you want.

101 ... Mobile station, 103 ... GNSS antenna of the mobile station,
105: Mobile station receiver 107: Mobile station GNSS signal transmitter,
109 ... mobile station transmit antenna, 111 ... conventional base station,
113 ... a receiving antenna of the base station, 115 ... a GNSS signal receiving unit of the base station,
117 ... code phase / carrier frequency / phase / data detection unit of base station,
119 ... conventional positioning calculation unit of the base station,
201 ... GNSS antenna of the base station, 203 ... Receiver of the base station,
205 ... code phase / carrier frequency / phase / data detector of the base station according to the present invention,
207 ... base station correlator, 209 ... base station GNSS signal generator,
211... Base station code phase error detector,
213 ... Carrier frequency / phase error detector of the base station,
215 ... the positioning calculation unit of the base station according to the present invention,
217 ... A base station according to the present invention,
601: Navigation data, 603: Code signal, 605: Carrier signal.

Claims (3)

A receiver of a base station in a mobile radio system,
A base station GNSS signal receiver;
A base station data detector that obtains first positioning data from the data received by the base station GNSS signal receiver;
A base station GNSS signal generator that generates a GNSS signal from the base station data detector;
A mobile station GNSS signal receiver provided in a base station that receives the GNSS signal received by the mobile station transmitted from the mobile station;
A correlation unit that obtains second positioning data by performing a correlation operation between the generation data generated by the base station GNSS signal generation unit and the reception data received by the mobile station GNSS signal reception unit;
An error detector that calculates a difference between the first positioning data and the second positioning data;
Consisting of
The receiver, wherein the base station GNSS signal generation unit corrects the generated data so that the first positioning data matches the second positioning data using the error detected by the error detection unit. The receiver according to claim 1, wherein the correlation calculation time width of the correlation unit is longer than one bit length of the positioning data. When the base station data detection unit detects the first positioning data, the code phase synchronization tracking detection uses a delay lock loop, and the carrier frequency and carrier phase synchronization tracking detection uses a Costas loop,
The receiver according to claim 1, wherein the tracking signal for implementing the delay lock loop and the tracking signal for implementing the Costas loop are generated from the same oscillator.