JPH03221888A - Receiving equipment - Google Patents

Abstract

PURPOSE:To speed up a trapping speed and to optionally set up priority for improving steering accuracy by setting up the frequency band width of a code tracking loop (CTL) or a carrier tracking loop (KTL) narrower than a value obtained before the arrival of a steady state. CONSTITUTION:A carrier signal modulated by code information is supplied to a CTL 21 and synchronized with code information generated from the inside to extract a carrier, the output signal of the CTL 21 is multiplied by a fre quency signal following the frequency of the output signal by a KTL 17 to extract the phase information of the carrier signal. In the steady state for extracting the phase information, the frequency band width of either one of the CTL 21 and the KTL 17 is set up to a value narrower than the frequency band width obtained before the arrival of the steady state to optionally improve the steering accuracy.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is directed to a G, which is mounted on, for example, a moving object and receives signals from a plurality of artificial satellites to derive position data of the moving object. P S (Global Position
oningsystem (global positioning system) relates to a receiving device used as a receiver.

(Prior art) Recently, mobile objects (
Global location information for aircraft, ships, vehicles, etc.
A positioning system (GPS) has been developed. This GPS is equipped with a GPS receiver on a mobile object, and uses this GPS receiver to transmit multiple (at least 3 or more)
PS Receives a transmission signal containing PN code information sent from a satellite, position information of the satellite itself, exit time information of this position information, etc., and correlates the PN code prepared in advance with the received transmission PN code. and demodulates the data in the transmitted signal. Then, the distance information between the mobile object and each GPS satellite is calculated from the PN code delay amount and the demodulated data, and the position information of the mobile object is obtained geometrically.

In other words, since the demodulated data includes GPS satellite signal transmission time data, the reception time is calculated by adding the delay time data necessary for correlating the receiver's PN code to this data. The radio wave propagation time from the GPS satellite to the mobile object, that is, the distance from the GPS satellite to the mobile object, is detected. This distance information and the position information of the satellite itself in the demodulated data are acquired for each GPS satellite, and the position information of the moving body is calculated from each acquired data.

By the way, when the above-mentioned GPS satellite transmission signals are captured by a GPS receiver, it is desired to increase the capture speed. On the other hand, G
When the PS receiver reaches the stage of capturing the transmitted signals of GPS satellites and measuring the position, it is desired to improve the navigation accuracy. In this way, in order to increase the acquisition speed of GPS transmission signals and to stably track the signals, it is necessary to widen the frequency bandwidth.

On the other hand, in order to improve navigation accuracy, it is necessary to narrow the frequency bandwidth in consideration of cases where the reception environment for GPS signals is not good.

Under these circumstances, conventional GPS receivers select and fix an appropriate frequency band in which both acquisition speed and navigation accuracy are substantially satisfied. However, depending on the usage environment, it may be desirable to prioritize either tracking stabilization or navigation accuracy improvement, and fixing the frequency bandwidth as described above will not meet the user's needs.

(Problem to be solved by the invention) As mentioned above, in conventional receiving devices, the frequency bandwidth is fixed, so the user side prioritizes either increasing acquisition speed or improving navigation accuracy ( I couldn't figure it out.

This invention was made to solve the above problem.
Frequency: 1) To provide a receiving device in which the bandwidth can be arbitrarily adjusted, thereby allowing the user to freely set priorities for increasing acquisition speed and improving navigation accuracy.
target

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object 1, a receiving device according to the present invention is provided with a carrier wave signal modulated with code information, and the code information generated internally. code capturing means for extracting the carrier signal by synchronizing with the carrier wave signal; and carrier wave capturing means for extracting the carrier signal phase information by multiplying the output signal of the code capturing means by a frequency signal that follows the frequency of the output signal. In a steady state in which the output fi phase information is extracted by this carrier wave acquisition means, the frequency bandwidth of at least one of the code acquisition means and the carrier wave acquisition means is set to be lower than the frequency bandwidth before the steady state. and a setting means for narrowing the setting.

(Function) The receiving device having the above configuration extracts a carrier signal by synchronizing the carrier signal modulated with code information by the code capturing means and the code information generated internally, and extracts the carrier signal by synchronizing the carrier signal modulated with the code information by the code capturing means. The frequency of this carrier wave signal is multiplied by a frequency signal that follows it to extract phase information of the carrier wave signal. In the steady state where this phase information is extracted, the frequency bandwidth of at least one of the code acquisition means and the carrier wave acquisition means can be set narrower than the frequency bandwidth before the steady state is reached, so that the navigation accuracy can be adjusted arbitrarily. I am trying to improve myself. Note that until the phase information is extracted, that is, until a steady state is reached, the frequency bandwidth of at least one of the code capture means and the carrier wave capture means is set wide to increase the capture speed and stabilize tracking. This is desirable.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration in which the present invention is applied to the GPS receiver.

First, a GPS satellite signal sent from a GPS satellite (not shown) is generated by modulating a carrier signal with code information and then spreading the spectrum of this carrier signal.

This GPS satellite signal is subjected to the Doppler effect due to a change in the relative distance between the satellite and the moving object, and reaches the receiving antenna 11 of the GPS receiver.

The GPS satellite signal received by this receiving antenna 11 is ω, +
The mixer 12 generates an intermediate frequency signal (IF multiplied signal frequency ω2+) by the local oscillation signal from the local oscillator 13.
ω6). This intermediate frequency signal is amplified by a wideband amplifier 14 and then input to a despreader 15. This despreader I5 matches the output code of the wideband amplifier 14 and the output code of the code generator 16, and
+ω, is extracted.

The code generator 16 inputs the satellite selection signal and generates the code assigned to the selected satellite, i.e., wide.:1).
The same code as the code included in the output of the band amplifier 14,
This occurs at a time specified by a position designation signal generated by a code tracking loop 21, which will be described later. Moreover, in this code generator 1B, the code start position t
-T (t: signal transmission time from the satellite 2+i time, T: reception time), and this information is sent to the pseudorange calculation section and used for pseudorange calculation. The pseudorange r is expressed as r(t-T), where C is the radio wave propagation speed, and the pseudorange r is given by the pseudorange r (relative speed)
is expressed as v-C(ω,/2π)/f.

The output Sa of the despreader 15 has a narrowed spectrum (reverse 44 (spread), but if they are not matched, it is not despread and becomes a signal with a wide spectrum.

The output of this despreader 15 is the carrier tracking loop 1
7 will be powered by humans.

This carrier tracking loop is composed of a digital filter using a digital signal processor, for example, and inputs the output Sa of the despreader 15 to a 1 multiplier 171 and a 0 multiplier 172, as shown in FIG. One of I and Q represents a cosine (COS) component of the input level, and the other represents a sine (sin) component of the input level. Each multiplier 171
, 172 are supplied with the oscillation output of a VCO (voltage controlled oscillator) 173 with a phase difference of 90° by a 90' phase controller 174, and each multiplier 171, 1
The multiplication result of 72 is a low pass filter (L P F) 1
75 and 176 to become an IQ signal, and after being mixed in a mixer 178, it is manually input to a carrier tracking loop filter 179. This carrier tracking loop filter 79 is designed so that the frequency bandwidth to be passed can be set at will according to the parameters set in the setting section 201 of the computer 20, and the signal passing through this loop filter 79 is set as the Doppler shift amount ω. ;I
The voltage is outputted to the computer 20 and inputted to the VCO circuit 173 as a control voltage.

This carrier tracking loop 170 input signal Sa is expressed as ±A cos(ω, t+ω, , where 100). A is a proportionality constant of received power, and θ is phase information.

1 multiplier 1711;: Assuming that a cos product t and a sin product t are supplied to the 0 multiplier 172, each output of the LPF 175゜176 is equal to (A/2) co
sφ±(A/2) sinφ, and the output of the mixer 178 is (A"/8) 5in2φ. Note that φ
represents ((ω2+ω,)-ω) t+θ.

The (2) output of the carrier tracking loop 17 is sent to the bit synchronization circuit 22, and phase information θ is extracted. Further, the I and Q outputs are squared by arithmetic units 18 and 19, respectively, and then input to the code tracking loop 21.

This code tracking loop 21 is configured by the software of the computer 20 in a τ dither system, and as shown schematically in FIG.
It is composed of a code start position specifying section 214.

First, input signal x2. Q2 is mixed in the mixing section 21+,
This determines the received power Ps.

This received power P8 is input to the code tracking loop filter 212. This code tracking loop filter 212 has a frequency bandwidth that can be adjusted by the parameters set in the setting section 202 of the computer 20, and its passing signal is supplied to the V CO2+3 as a control signal, and Control the oscillation frequency. The output signal of this VCO 213 is supplied to a code start position specifying section 214. The code start position specifying section 214 generates a position specifying signal according to the frequency of the human input signal, and as described above, this position specifying signal is supplied to the code generator 16 to specify the code generation position.

The operation of the computer 20 will be explained.

First, the I and Q signals are PN (Psendo-Random) included in the GPS satellite signals called Early and Late in the code tracking loop 21.
1. with No.1se) signal. It is detected at a timing slightly shifted from the -7j period. If these are respectively denoted by ()u+ ()L, the phase synchronization within the computer 20 is due to (1
” The calculation Q2)+!+(12Q2)E is performed.

For example, if a coordinate point (Early 1, Late 1) such as 1 shown in Fig. 4 is obtained, the above calculation result is the maximum, that is, φ8=
φ1, (Early 2, 1.
The coordinate point of ate 2) is obtained. At this time, a peak output proportional to the received power P is detected, assuming that it is synchronized with the PN code. On the other hand, the power Ps of the received signal is P
s − (12 + 0 2 ) E + (12
+Q 2 ) t, and after synchronization detection Ps
=A2/2. Therefore, the estimated value of the received power P5 may be estimated using the amount A-J, which is proportional to the received power, P. Tracking of the received signal within the computer 20 is performed using (12
+Q2)p, (12+Q2) The operation result of I is controlled to be O.

In the above configuration, in the present invention, in the start-up state in which signals from a satellite are captured, the carrier tracking loop 17 and the code tracking loop 21 are operated until the phase synchronization of the PN code is established and the GPS satellite signal is captured. Each loop filter 179
, 212 are set such that the frequency bandwidth of the signals is widened. This increases the signal acquisition speed. In a steady state where a signal from a satellite is captured and phase information θ is extracted, each loop filter 1 of the carrier tracking loop 17 and the code tracking loop 2I
Parameters are set so that the frequency bandwidth of at least one of 79 and 212 is narrow enough to prevent tracking. This improves the accuracy of the extracted phase information θ in a steady state, that is, the navigation accuracy.

Therefore, by setting parameters, the GPS receiver with the above configuration increases the signal acquisition speed during start-up to acquire signals from satellites, and in the steady state when signals from satellites are acquired and phase information is extracted. The navigation accuracy can be improved, and the performance of GPS satellite signal reception can be improved.

3 [Effects of the Invention] As described above, according to the present invention, the frequency bandwidth can be adjusted arbitrarily, allowing the user to freely set priorities for increasing acquisition speed and improving navigation accuracy. It is possible to provide a receiving device that can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a receiving device according to the present invention, FIG. 2 is a block diagram showing the configuration of a carrier tracking loop in the same embodiment, and FIG. 3 is a block diagram showing the configuration of a code tracking loop in the same embodiment. FIG. 4 is a characteristic diagram for explaining the τ dither h formula in the code tracking loop of the same embodiment. 11...Receiving antenna, 12...Mixer, 13...
・Local oscillator, 14... High band amplifier, 15... Despreader, 1B... Code generator, 17... Carrier tracking loop, 171, 172... I, Q multiplier, ]73 ...VCO. 174...90° phase controller, 175, 176...
・LPF. 178...Mixer, 179...Carrier tracking filter, 18.19...Arithmetic unit, 20...Subtraction machine, 201゜202...Setting) section, 21...Code tracking Loop, 211... Mixing section, 212... Code tracking loop filter, 2]3... VCo,
214...Code start position specification section.

Claims (1)

[Claims] A code capturing means that is supplied with a carrier signal modulated with code information and extracts the carrier signal by synchronizing with the internally generated code information, and an output signal of the code capturing means and tracking the frequency of this output signal. a carrier wave capturing means for extracting the carrier wave signal phase information by multiplying by a frequency signal of and setting means for setting a frequency bandwidth of 1 to be narrower than a frequency bandwidth before entering the steady state.