JPS63106581A - Gps navigation apparatus - Google Patents

Abstract

PURPOSE:To execute highly accurate position measurement stably, by allotting a long time to PN code matching and Doppler frequency matching for radio waves of low reception level. CONSTITUTION:Radio waves from reception satellites are received 10 sequentially with the respective time slot lengths, position measurement computation 5 for a reception point is conducted on the basis of the received waves, and a prescribed number of reception satellites are selected 8. Then, a time slot length to be assigned to each reception satellite within the period of a reception cycle of a unit determined by a period of one bit of orbit data is computed 9 in accordance with the reception level in the past of each reception satellite so that the length be enlarged when the level is low, and a reception control 10 on each reception satellite is conducted so that the wave of each satellite be received in sequence with the computed time slot length. On the occasion, a long time is allotted to PN code matching and Doppler frequency matching for satellite waves of low reception level, and thereby the satellite waves of low level are caught with high accuracy and without fail.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is a one-channel sequential GPS system.
(Global Positioning System
>Relating to navigation equipment.

[Prior Art] As a conventional GPS navigation device, there is one shown in FIG. 5 (for example, Japanese Patent Laid-Open No. 15573/1983).

In the figure, 101 is an antenna, 102 is a high frequency amplifier, 103, 105, 106 are mixers, 104 and 107
are first and second intermediate frequency amplifiers, 108 is a phase detector, 109 is a numerically controlled oscillator for carrier phase synchronization, 110
is a code generator, 111 is a numerically controlled oscillator for code phase synchronization, 112 is a frequency multiplier, 113 is a reference oscillator, 114
indicates the central processing unit.

In this device, as shown in Fig. 6, the time To (20 IIIS) for one satellite data is divided into a number of equal times determined according to the positioning dimension into time slots with a time interval of TO, and each slot is The signals are assigned to the satellites (■ to ■) for sequential reception, and the positioning calculation unit in the central processing unit 114 performs positioning of the receiving point. Note that the number of slots is 4 in three-dimensional positioning, but may be increased to 5, for example, by adding spare satellites to this number.

However, in such conventional one-channel sequential satellite navigation devices, PN code matching and Doppler frequency matching are performed at exactly the same time intervals for all satellite radio waves, so satellite radio waves with low reception levels are There was a problem in that it was difficult to precisely match the PN code and Doppler frequency, and as a result, the positioning accuracy also decreased.

[Objective of the Invention] The present invention improves the above problems and provides a one-channel system that can accurately match the PN code and Doppler frequency even with satellite radio waves with a low reception level, thereby making it possible to perform highly accurate positioning. The purpose is to provide a Kesiyar type satellite navigation device.

[Summary of the Invention] In order to achieve the above object, the present invention provides a one-channel sequential satellite navigation device including a satellite selection means 8 for selecting a predetermined number of receiving satellites, and a unit defined by a period of one bit of orbit data. Satellite reception slot length calculation means 9 calculates the time slot length to be assigned to each reception satellite within the reception cycle period TO according to the past reception level of each reception satellite so that the time slot length is longer when the level is lower; a reception control calculation means 10 that performs reception control for each reception satellite so as to sequentially receive each reception satellite with a time slot length, and one channel for sequentially receiving each reception satellite with a respective time slot length under the control of the means 10; The configuration includes a sequential reception means 11 and a positioning calculation means 5 that performs positioning calculation of the reception point based on the received radio waves, and it takes a long time to match the PN code and Doppler frequency for satellite radio waves with a low reception level. This makes it possible to reliably capture low-level satellite radio waves with high precision.

[Example] An embodiment of this invention will be described below.

FIG. 1 is a block diagram of a GPS navigation device for a vehicle according to an embodiment of the present invention.

In the figure, 1 is an antenna for receiving radio waves from GPS satellites.

A frequency converter 2 includes a reference oscillator, a multiplier, a mixer, an amplifier, etc., and converts the frequency of the received signal sent from the antenna 1 using the output signal of the multiplier as a reference.

3 is a pseudorange measuring device, which includes a correlator, a PN coco generator, a code phase setting switch, and a pseudorange measuring device. The correlation with the generated PN code is taken and PN demodulation is performed.

Reference numeral 4 denotes an orbit data demodulator, which includes a bandpass filter, a phase detector, a carrier NGO, a carrier frequency switch, etc., and sends the correlation output signal of the pseudorange measuring device 3 to the phase detector via the bandpass filter. Find the phase and phase difference of the received signal.

Reference numeral 5 denotes a positioning calculator which determines the position of the object to be positioned based on the pseudorange measurement results, and also determines the speed and direction from the Doppler frequency shift of the received signal.

Reference numeral 6 denotes a display device such as a CRT, which displays the positioning results obtained by the positioning calculator.

A reception level detector 7 detects the reception level I of satellite radio waves for each satellite as shown in FIG. The figure shows the satellite
Detection states of reception levels 11 to I4 for (2) are shown.

8 is a satellite selector which selects a satellite to be received. For example, in three-dimensional positioning, four satellites or five satellites including one reserve satellite are selected for use in positioning.

In this example, it is assumed that four satellites ■ to ■ have been selected.

9 is a satellite reception slot length calculator, and satellite selector 8
As shown in FIG. 3, the slot length of the receiving satellite is calculated to be longer as the reception level is lower. However, this calculation is not necessarily a proportional calculation;
This can be done by selecting binary values depending on the level, or by using an arithmetic expression other than proportionality.

Further, as the reception level 11, in addition to the level detected at the previous cycle time, an average value of the reception levels of the past several times, an extrapolated value of the previous and previous detection values, etc. may be used.

10 is a reception control calculator, and P in the pseudo distance measuring device 3
A PN code selection signal, code phase slot length data and carrier frequency data are sent to the carrier NGO in the N code generator and orbit data demodulator 4, respectively.

Antenna 19 Frequency converter 2. The pseudorange measuring device 3 and the orbit data demodulator 4 together constitute a receiving means 11.

Next, the positioning method of the GPS navigation device having the above configuration will be explained using the flowchart shown in FIG.

In FIG. 4, the system program starts when the power is turned on.

In step 401, initial values necessary for calculations such as time and position settings are set.

In step 402, Doppler frequency tuning is performed for the selected satellite.

In step 403, synchronization timing control is performed on the selected satellite to determine the pseudorange.

In step 404, the quality of the synchronization is determined based on the correlation result of the synchronization. If sufficient synchronization accuracy is obtained, the process proceeds to step 405; otherwise, the process returns to step 402.

In step 405, it is determined whether there is a request to collect orbit data of the receiving satellite. Since the trajectory data is updated with new data every hour, the trajectory data is collected, for example, every hour. If there is a request to collect trajectory data, the process proceeds to step 406; otherwise, the process proceeds to step 407.

In step 406, the phase-detected signal is passed through a filter and subjected to A/D'iJ conversion to demodulate the data.

In step 407, the vehicle position is calculated by solving a navigation equation using the satellite position and the pseudorange measurement results.

In step 408, based on the positioning results, the vehicle position is displayed on the map displayed on the display 6, and information regarding satellites is also displayed as necessary.

In step 409, as shown in FIG. 2, the reception level is determined from the A/D conversion value of the demodulated satellite data signal.

In step 410, the optimum satellite combination is selected from the reception levels 1 to 14 of each satellite and the satellite arrangement. Among li, levels of 1=5 or higher indicate reception levels of other satellites received before the previous time.

In step 411, as shown in FIG. 3, based on the reception level of each satellite as shown in FIG. .

The calculation of this slot length is, for example, a proportional calculation, that is, based on the relative ratio of the reception level of each satellite ■i, the time to receive each satellite radio wave within a period corresponding to 1 bit of orbit data T +
decide.

As described above, in this example, radio waves can be received in longer time slots for satellites with low reception levels, and even if the reception level is low, PN code matching and Doppler frequency matching can be performed accurately and reliably, resulting in high-precision positioning. It becomes possible to do this.

Note that the present invention is not limited to the above-mentioned embodiments, but can be implemented in other embodiments by making appropriate design changes.

[Effects of the Invention] As described above, according to the present invention, in a one-channel sequential satellite navigation device, radio waves with a low reception level can be received with a longer time slot length, so that the reception level of the radio waves can be lowered. At the very least, PN code matching and Doppler frequency matching can be performed accurately and reliably, and highly accurate positioning can be performed stably.

4. Brief description of the drawings Fig. 1 is a block diagram of a GPS navigation device according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the radio wave reception level, and Fig. 3 is a time chart showing an example of setting the time slot length. , 4th
The figure is a flowchart of positioning processing, FIG. 5 is a block diagram of a conventional satellite navigation device, and FIG. 6 is a time chart showing a conventional time slot length setting method.

1... antenna 2...Frequency converter 3... Pseudo distance measuring device 4... Orbit data demodulator 5...Positioning calculator 6...Indicator 7... Reception level detector 8...Satellite selector 9...Satellite reception slot length calculator 10...Reception control calculator Agent Patent Attorney Yasuo Miyoshi Figure 4

Claims (1)

[Claims] A satellite selection means for selecting a predetermined number of receiving satellites, and a time slot length to be assigned to each receiving satellite within a unit receiving cycle period determined by a period corresponding to 1 bit of orbit data, based on the past reception level of each receiving satellite. Satellite reception slot length calculation means that calculates the length of a satellite reception slot so that the lower the level is, the longer the time slot length is; and reception control calculation means that performs reception control for each reception satellite so as to sequentially receive each reception satellite at the calculated time slot length; A one-channel sequential receiving means that sequentially receives each receiving satellite at each time slot length under the control of the means, and a positioning calculation means that performs positioning calculation of a receiving point based on received radio waves. GPS navigation device.