JP2001281324A - Code generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a code generator capable of generating a WAAS code at the same time without changing any generation method based on a conventional C/A code generator so as to realize a common-use reception between the C/A code and the WAAS code. SOLUTION: This C/A code generator is constituted of a pair of a G1 coder and a G2 coder generating a M-series code. This C/A code generator consists of a G1 shift resistor constructed of 10 bit shift registers, a G2 shift register constructed of 10 bit shift registers, and a phase selector using outputs from the respective shift registers of the G2 shift register and a GND signal, which are 11 signals in total as inputs, and selecting two outputs so as to output the sum using the two outputs as divisors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a global satellite navigation system (Global Positioning System).
The present invention relates to a receiver for position measurement in a system (abbreviated as GPS).

[0002]

2. Description of the Related Art FIG. 3 shows a method of generating a C / A code according to the prior art, which will be described. The C / A code generator shown in FIG. 3 is a GLOVAL POSITIONING SY
This is proposed in STEM (vol). 3, a G1 generator 201 and a G2 generator 202 are M-sequence code generators, perform addition modulo 2 on outputs from a plurality of stages of the shift register, and output the G1 shift register 205 and the G2 shift register 206. And input. The initialization circuit 104 receives the signal X1 as an input, and sets the G1 shift register 205 and G2
The shift register 206 is set to an initial state, that is, the value of each stage of the register is set to “1”. In the C / A code, the shift register 308 and the shift register 30
When the value of each stage of 9 is "1", a code epoch is output, and the code epoch is synchronized with the navigation data of 50 bps.

The C / A code in the GPS system is
GOLD obtained by the sum modulo 2 of a pair of M sequences
The C / A code corresponding to each of the plurality of satellites is obtained by taking the sum of the code obtained by changing the phase shift amount of the G2 generator 202 and the G1 code modulo 2. In order to change the amount of phase shift in the G2 generator 202, the phase selector 203 takes two signals S1 and S2 from each stage of the G2 shift register 206 and takes a sum modulo 2 of the two signals. I am taking it.

FIGS. 4 and 5 show RTCA / DO-229A.
1 shows a code generator configured to generate both a WAAS signal and a GPS C / A code. The code generator of FIG. 4 uses the delay value G2DELAY of the G2 coder 302 as an input to the counter 305, and after the lapse of the delay value, releases the gate 306 so that the G2 coder 302 operates according to the clock from the code clock circuit 303. It is what was constituted.

On the other hand, the code generator shown in FIG. 5 uses the G2 shift register 309 after the G2 DELAY value shown in FIG.
Is held in the initial setting register 307 directly via the data bus, and is written directly to the G2 shift register 309.

The code generators shown in FIGS. 4 and 5 differ from the C / A code generator using the phase selector 203 shown in FIG. 3 by changing the shift phase amount of the G2 shift register 309. Both the A code and the WAAS code are generated. In addition, in this code generator, in order to obtain a GPS C / A code and a WAAS code, the G1 coder 301 and the G2 coder 302 each take a sum modulo 2 at the last stage to generate a code. This means that the WAAS code cannot be generated by taking the conventional C / A code generation method shown in FIG. 3, that is, taking the sum of two signals S1 and S2 from each stage of the G2 generator 202 modulo 2. caused by.

To realize a shared receiver capable of receiving GPS codes and WAAS codes, FIG. 4 or FIG.
When the code generator shown in FIG. 3 is used, the conventional code generator shown in FIG. 3 cannot be used. That is, the conventional C /
There is a problem that the method of generating the A code must be changed.

[0008]

SUMMARY OF THE INVENTION According to the present invention, in order to realize shared reception of a C / A code and a WAAS code, the W / C code generation method is changed without changing a conventional C / A code generator.
An object of the present invention is to provide a code generator capable of simultaneously generating an AAS code.

[0009]

In order to achieve the above object, a code generator according to the present invention comprises a 10-bit C / A code generator comprising a pair of M-sequence code generation G1 coder and G2 coder. A G1 shift register and a G2 shift register, each of which is constituted by a shift register, and an output from each shift register of the G2 shift register and a total of 11 signals of a GND signal. And a phase selector for outputting. Further, the code generator of the present invention is characterized by selecting and outputting any of the C / A code and the WAAS code. In addition, the GP of the present invention
The S receiver is characterized in that the code generator is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIG. In FIG. 1, a G1 coder 10
1. The G1 coder 102 and the G2 coder 102 have the same functions as the G1 generator 201 and the code clock generator 103 shown in FIG. 3 and the code clock generator 303 shown in FIGS. 4 and 5, respectively. The G1 initial setting register 106 and the G2 initial setting register 107 are 10-bit parallel registers, hold data from the data bus, and synchronize the data with the setup signal to transfer the data to the G1 coder 101.
And in each register in the G2 coder 102 at the same time.

The phase selector 108 receives the value of each stage of the G2 register 105 and a total of 11 signals connected to GND, and selects two signals S1 and S2.
It is configured to output the sum of the signals modulo 2, or to select and output one signal. When the C / A code of the GPS satellite is received, the phase selector 108 can select a desired C / A code by selecting the two signals S1 and S2 and taking the sum modulo 2. .

On the other hand, in the case of a WAAS code, it can be obtained by selecting and outputting the output of the tenth stage of the G2 register 105. In this embodiment, WAAS
When the code is selected, G is used as the signals S1 and S2.
By selecting the output of the tenth stage of the 2 register 105 and the terminal connected to GND and taking the sum modulo 2, it is realized that the output of the tenth stage is equivalently selected. . That is, the provision of the phase selector 108 described above has an advantage that the C / A code can be generated by the conventional method shown in FIG. 3, and at the same time, the signal of the last stage of the G2 register 105 can be selected. By shifting the phase, W
There is an advantage that an AAS code can be generated.

Next, the operation of the code generator will be described. The G1 shift register 104 and the G2 shift register 105 change the state of the shift register at a certain time via the data bus 109, respectively, into the initial setting register 106 and the G2 initial setting register 107.
To hold. Immediately before this time, the operation of the shift register is synchronized with the value held in the G1 initialization register 106 in the G1 shift register 104 and the value held in the G2 initialization register 107 in the G2 shift register 105 in synchronization with the setup signal. A start state is set, and a transition is made in accordance with the code clock from the code clock circuit 103, and a code having a desired phase is output.
FIG. 2 shows the above operation sequence.

As described above, a desired state can be set in the G1 shift register 104 and the G2 shift register 105 and the operation can be started from that state. For example, even in an area such as an urban area where satellite signals are easily interrupted, The code state estimated from the elapsed time of the interruption is represented by G1
Shift register 104 and G2 shift register 105
, Satellite signals can be captured in a short time. The generation of the WAAS code can be realized by setting a desired phase state in the G2 shift register 105 and the G1 shift register 104.

[0015]

According to the code generator of the present invention, C /
An A code can be generated without changing the conventional C / A code generation method, a WAAS code can be output, and a shared receiver capable of receiving both GPS and WAAS signals can be realized. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a code generator of the present invention.

FIG. 2 is a diagram showing a state transition in a code generation period.

FIG. 3 is a diagram showing a conventional C / A code generator.

FIG. 4 is a diagram showing a conventional C / A code and WAAS code generator.

FIG. 5 is a diagram showing a conventional C / A code and WAAS code generator.

[Explanation of symbols]

 101 G1 coder 102 G2 coder 103 Code clock generator 104 G1 shift register 105 G2 shift register 106 G1 initial setting register 107 G2 initial setting register 108 Phase selector 109 Data bus 201 G1 generator 202 G2 generator 203 Phase selector 204 Initializing circuit 205 G1 Shift register 206 G2 shift register 301 G1 coder 302 G2 coder 303 code clock generator 304 initialization circuit 305 counter 306 gate 307 G2 initialization register 308 G1 shift register 309 G2 shift register

Continuation of the front page (72) Inventor Nobuhiro Tsuda 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo F-term in Japan Radio Co., Ltd. (reference) 5J049 AA18 AA21 CB05 5J062 AA02 CC07 DD05 DD15 5K022 EE02

Claims (3)

[Claims] 1. A pair of M-sequence code generation G1 coder and G
In a C / A code generator composed of two coders,
A G1 shift register and a G2 shift register each composed of a 10-bit shift register, and a total of one of an output from each shift register of the G2 shift register and a GND signal.
A phase selector which receives one signal, selects two outputs, and outputs a sum modulo 2. 2. The code generator according to claim 1, wherein any of a C / A code and a WAAS code is selected and output. 3. A GPS receiver comprising the code generator according to claim 2.