CN103308930A - Pseudo-range precision measurement method of satellite navigation signal simulator - Google Patents

Abstract

The invention provides a satellite navigation signal simulator pseudo-range precision measurement method, which can meet the measurement requirements of any pseudo-range value range, has high measurement accuracy, and satisfies the calibration and verification requirements of the satellite navigation signal simulator pseudo-range precision index. The measurement method of the present invention is that the satellite navigation signal simulator is set to output a radio frequency simulation signal whose pseudo-range nominal value is p, the measurement of the pseudo-range p is converted into the measurement of the delay time corresponding to the pseudo-range p, and the time measurement It is decomposed into the measurement of the whole cycle part and the measurement of the fractional part. The measurement of the whole cycle part refers to counting the number of whole cycles of the time delay of the radio frequency simulation signal from the starting point of the pseudorange with the periodic calibration signal and measuring the calibration signal. Period, the measurement of the fractional part refers to the part of the time interval in which the delay time of the starting point of the pseudo-range of the RF simulation signal is less than one cycle of the calibration signal.

Description

Measurement Method of Pseudorange Accuracy of Satellite Navigation Signal Simulator

technical field

The invention relates to the technical field of satellite navigation, in particular to a method for measuring pseudorange accuracy of a satellite navigation signal simulator.

Background technique

Satellite navigation technology is a technology based on Global Navigation Satellite System (GNSS, Global Navigation Satellite System) to provide users with location, navigation and time services. It has been widely used in military and civilian fields. Users obtain related services based on satellite navigation user equipment, such as chips, modules and terminal products.

In the process of development, inspection and testing of satellite navigation user equipment, it is necessary to be able to customize navigation signals under different satellite constellations, error models, user trajectories, signal power, etc., to verify or test whether the technical indicators of the product meet the relevant requirements, so , manufacturers and testing organizations of satellite navigation user equipment widely use satellite navigation signal simulators to generate navigation simulation signals on demand.

Pseudorange is the original observation quantity for satellite navigation user equipment to calculate the position, and it is also the key simulation data generated by the satellite navigation signal simulator. The error of the simulated pseudorange by the simulator is directly related to the reliability of the detection results of the receiver under inspection. At present, the measurement method of the pseudo-range accuracy index of the satellite navigation signal simulator is: through the time-domain analysis of the RF simulation signal output by the simulator in a specific simulation scenario (the nominal value of the pseudo-range is zero), identify the origin of the pseudo-range signal Start point and measure its delay on the time axis (simulating the transmission delay of satellite signals), and measure the delay time, and then multiply it by the speed of light to convert it into a pseudo-range value. The limitations of this method are as follows:

1. Judging the starting point of the pseudo-range signal by the displayed waveform of the time-domain analysis instrument (such as an oscilloscope), which can be identified for some signals, such as the Beidou regional navigation analog signal, with the Barker code flip point as its feature point, and for Other types of navigation signals are less or less recognizable, so this measurement only works with certain types of simulators.

2. Due to the dual constraints of the time interval measurement accuracy index of the time-domain analysis instrument and the longest sampling time index that meets the measurement accuracy, this measurement method can only measure the error of the pseudo-range zero value or a small pseudo-range value, but cannot measure Error for any pseudorange. For example: the pseudo-range accuracy index of the simulator is 0.05m, and the conversion to transmission time is about 167ps (that is, the time required for the electromagnetic signal to propagate the distance at the speed of light). In order to meet the calibration requirements of this index, the time interval measurement of the time domain analysis instrument The accuracy must be able to reach 167ps, and if more stringent verification requirements are to be met, it needs to reach the order of 55ps. High-end oscilloscopes can already meet the measurement accuracy requirements within a certain maximum acquisition time (generally at the highest real-time sampling rate), such as 2.5ms. However, this acquisition time cannot meet the measurement requirements of the pseudorange output value range of at least 20000km (converted into a transmission delay time of about 67ms).

Contents of the invention

According to the defects in the prior art, the present invention provides a method for measuring the pseudorange accuracy of a satellite navigation signal simulator, which can meet the measurement requirements of any pseudorange value range, has high measurement accuracy, and satisfies the pseudorange accuracy of a satellite navigation signal simulator. Calibration and verification requirements for accuracy indicators.

Technical scheme of the present invention is:

A satellite navigation signal simulator pseudo-range accuracy measurement method, characterized in that, the satellite navigation signal simulator is set to output a radio frequency simulation signal whose pseudo-range nominal value is p, and the measurement of the pseudo-range p is converted into corresponding to the pseudo-range p The measurement of the delay time, the time measurement is decomposed into the measurement of the whole cycle part and the measurement of the fractional part, and the measurement of the whole cycle part refers to using the periodic calibration signal to the radio frequency simulation signal from the pseudorange starting point in time The delay of the delay carries out the counting of the whole cycle number and the period of the calibration signal, and the measurement of the fractional part refers to the time interval part in which the delay time of the radio frequency simulation signal pseudo-range starting point is less than one cycle of the calibration signal; thus the simulator output pseudo The actual measured value p' from the nominal value p is:

p′=c×(NT+d) (1)

in:

p' - the actual measured value of the pseudorange output by the simulator

c - the speed of propagation of electromagnetic waves in a vacuum

N - the number of whole cycles of the calibration signal, N starts counting from 0

T - calibration signal period

d - the fractional part of the delay time, that is, the time interval part of the delay time that is less than one calibration signal period; then the error Δp of the pseudorange output by the simulator is:

Δp=p-p' (2).

In the radio frequency simulation signal output by the simulator, any easily identifiable characteristic mark is added at the starting point of the pseudo-range, and the characteristic mark can be recognized by the time-domain analysis instrument used for time interval measurement.

The periodic calibration signal is output synchronously with the radio frequency simulation signal, and the period of the periodic calibration signal is not greater than the longest sampling time of the time-domain analysis instrument under the condition that the pseudo-range accuracy measurement requirements of the simulator are met.

The periodic calibration signal is simultaneously used as an external trigger signal of the time-domain analysis instrument, and the N-1th periodic signal of the periodic calibration signal has the characteristics of being able to trigger the time-domain analysis instrument, wherein N is the entire period of the calibration signal The number is calculated by the simulator according to formula (1).

The periodic calibration signal is a calibration pulse signal, and the high level of the raised N-1th pulse signal is used to trigger the time-domain analysis instrument, where N is the number of whole cycles of the calibration pulse, which is determined by the simulator according to the formula ( 1) Calculated.

Technical effect of the present invention:

The method for measuring pseudorange accuracy of a satellite navigation signal simulator provided by the invention can meet the measurement requirements of any pseudorange value range, has high measurement accuracy, and meets the calibration and verification requirements of the pseudorange accuracy index of a satellite navigation signal simulator .

By the measurement method of the present invention, the traceability of the simulator pseudo-range value can be realized: 1. for the simulator capable of outputting the required radio frequency simulation signal and the periodic calibration signal of the measurement method of the present invention, the described The measurement method is calibrated to realize the traceability from the pseudo-range value to the time-frequency parameter. 2. For the simulator that can not output the required radio frequency simulation signal and the periodic calibration signal of the measuring method of the present invention, can at first use the used calibrated simulator of the inventive method to the satellite navigation receiver of the stable performance of high precision Calibrate, and then use the receiver to calibrate other general-purpose simulators to realize the traceability of various satellite navigation signal simulator pseudo-range values to time-frequency parameters.

Description of drawings

Fig. 1 is a schematic diagram for implementing the measurement method of the present invention.

Fig. 2 is a schematic diagram of waveforms of a radio frequency simulation signal and a periodic calibration signal for implementing the measurement method of the present invention.

Detailed ways

Embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings.

A satellite navigation signal simulator pseudo-range accuracy measurement method, the satellite navigation signal simulator is set to output a radio frequency simulation signal whose pseudo-range nominal value is p, and the measurement of the pseudo-range p is converted into the delay time corresponding to the pseudo-range p Measurement, decomposing the time measurement into the measurement of the whole cycle part and the measurement of the fractional part, the measurement of the whole cycle part refers to using the periodic calibration signal to adjust the time delay of the radio frequency simulation signal from the pseudo-range starting point Count the number of cycles and measure the period of the calibration signal. The measurement of the fractional part refers to the time interval part of the delay time of the starting point of the pseudo-range of the measurement radio frequency simulation signal less than one cycle of the calibration signal, thus obtaining the nominal value of the pseudo-range output by the simulator The actual measured value p' of p is:

p′=c×(NT+d) (1)

in:

p' - the actual measured value of the pseudorange output by the simulator

c - the speed of propagation of electromagnetic waves in a vacuum

N - the number of whole cycles of the calibration signal, N starts counting from 0

T - calibration signal period

d - the fractional part of the delay time, that is, the time interval part of the delay time that is less than one calibration signal cycle;

Then the error Δp of the pseudorange output by the simulator is:

Δp=p-p' (2).

For realizing above-mentioned measurement method, periodic calibration signal and radio frequency simulation signal of the present invention's structure are as follows:

1. The RF simulation signal output by the simulator is used to identify the starting point of the pseudorange to measure the time delay corresponding to any pseudorange value. Add any easily identifiable characteristic mark, such as a spike signal, at the starting point of the pseudo-range signal, so that the point can be accurately identified on the time-domain analysis instrument.

2. The periodic calibration signal is output by the simulator or the periodic calibration signal generator, and is used to count the whole number of cycles for the delay time corresponding to any pseudorange value. The calibration signal is output synchronously with the RF simulation signal, and its period is not greater than the longest sampling time of the time-domain analysis instrument under the condition that the simulator pseudo-range accuracy measurement is met (generally at the highest sampling rate). For example, the pseudo-range accuracy index of the simulator is 0.05m. To meet its calibration requirements, the time measurement accuracy of the time-domain analysis instrument needs to reach at least 167ps. Assume that for a certain type of time-domain analysis instrument, the longest sampling time that meets the accuracy requirements is 2.5ms, it is required that the period T of the calibration signal is not greater than 2.5ms.

3. The periodic calibration signal is also used as an external trigger signal for the time-domain analysis instrument. The N-1th periodic signal of the periodic calibration signal has the characteristics that can trigger the time-domain analysis instrument, such as raising the height of the N-1th periodic signal. level, where N is the number of full cycles of the calibration signal. For any pseudorange nominal value p to be measured, the simulator calculates N according to formula (1). When outputting the pseudorange signal of this value, the calibration signal is synchronously output to trigger the time-domain analysis instrument.

As shown in FIG. 1 , it is a schematic diagram of an embodiment implementing the measuring method of the present invention. In this embodiment, the satellite navigation signal simulator outputs a radio frequency simulation signal with a nominal pseudorange value p, and simultaneously the simulator outputs a periodic calibration pulse signal synchronously. The time domain analysis instrument used for time interval measurement is an oscilloscope, and the frequency counter is used to count the whole number of cycles of the calibration signal and measure the period of the calibration signal. The output terminal of the RF simulation signal (referred to as "RF output" in Figure 1) is connected to the first channel of the oscilloscope, and the output terminal of the calibration pulse signal (referred to as "calibration signal output" in Figure 1) is connected to the second channel of the oscilloscope and the external port of the oscilloscope. Trigger the port, and the output terminal of the calibration pulse signal is also connected to the frequency counter; wherein, the output radio frequency simulation signal includes a characteristic mark that can be recognized by the time domain analysis instrument used for time interval measurement on the pseudorange starting point, and the output The period of the calibration pulse signal is not greater than the longest sampling time of the time-domain analysis instrument under the condition that the pseudo-range accuracy measurement requirements of the simulator are met, and the high level of the N-1th pulse of the calibration pulse signal is raised as the pulse signal of the oscilloscope The external trigger signal, where N is the whole cycle number of the calibration pulse.

Fig. 2 is a schematic waveform diagram of a radio frequency simulation signal and a calibration pulse signal output by a simulator implementing the measurement method of the present invention. Among them, the RF simulation signal is represented by a sine wave, and the actual modulation waveform is not drawn (the actual modulation waveform does not show periodicity). The output radio frequency simulation signal is added with a peak at the starting point of the pseudo-range as a characteristic mark, and the high level of the N-1th pulse of the output calibration pulse signal is raised as the external trigger signal of the oscilloscope.

The measurement steps are as follows:

1. Connect the tested simulator, oscilloscope and frequency counter according to Figure 1. The output terminal of the RF simulation signal is connected to channel 1 of the oscilloscope; the output terminal of the calibration pulse signal is connected to channel 2 of the oscilloscope, and at the same time connected to the external trigger input port of the oscilloscope; the calibration pulse The output end of the signal is connected to the input end of the frequency counter.

2. The simulator runs the test simulation scene with the nominal pseudo-range value p. p can be set arbitrarily within the output range of the pseudo-range value supported by the simulator. The simulator outputs the calibration pulse signal and the RF simulation signal synchronously. For pulse signals, the simulator needs to calculate the number of full cycles N according to formula (1), and raise the high level of the N-1th pulse to trigger the oscilloscope.

3. After the oscilloscope is triggered, channel 1 displays the waveform of the fractional part of the stable RF output signal, and channel 2 displays the waveform of the Nth pulse of the stable calibration pulse signal. Use the oscilloscope to measure the rising edge of the Nth calibration pulse. The measured value of the fractional part d in the formula (1) can be obtained by simulating the time interval between the starting points of the pseudo-range of the signal.

4. Use a frequency counter to measure the period and number of pulses of the calibration pulse signal, and obtain the measured values of the calibration pulse period T and the number of calibration pulses N in formula (1).

5. According to formula (1), calculate the actual measured value p′ of the nominal value p of the pseudorange output by the simulator, and calculate the error Δp of the pseudorange output by the simulator according to formula (2).

It should be pointed out that the specific embodiments described above can enable those skilled in the art to understand the invention more comprehensively, but do not limit the invention in any way. Therefore, although the description and examples have described the invention in detail, those skilled in the art should understand that the invention can still be modified or equivalently replaced; and all technologies that do not depart from the spirit and scope of the invention The scheme and its improvement are all included in the protection scope of the invention patent.

Claims (5)

1. a satellite navigation signal simulator pseudo-range accuracy measurement method is characterized in that, the radio frequency simulation signal that the satellite navigation signal simulator output pseudo-range nominal value is p is set, and p is the value in the output range of the simulator pseudo-range value Any value, the measurement of the pseudorange p is converted into the measurement of the delay time corresponding to the pseudorange p, and the time measurement is decomposed into the measurement of the whole period part and the measurement of the fractional part, and the measurement of the whole period part means Use the periodic calibration signal to count the entire cycle number of the radio frequency simulation signal from the time delay of the pseudo-range starting point and measure the period of the calibration signal. The measurement of the fractional part refers to the measurement of the delay time of the radio frequency simulation signal pseudo-range starting point The part of the time interval that is less than one cycle of the calibration signal, thus the actual measured value p' of the nominal value p of the pseudorange output by the simulator is: p′=c×(NT+d) (1) in: p' - the actual measured value of the pseudorange output by the simulator c - the speed of propagation of electromagnetic waves in a vacuum N - the number of whole cycles of the calibration signal, N starts counting from 0 T - calibration signal period d - the fractional part of the delay time, that is, the time interval part of the delay time that is less than one calibration signal cycle; Then the error Δp of the pseudorange output by the simulator is: Δp=p-p' (2). 2. satellite navigation signal simulator pseudo-range accuracy measurement method according to claim 1, is characterized in that, the radio frequency simulation signal of described simulator output, adds any easy-to-recognize feature mark at pseudo-range starting point position, described Signatures can be identified by time domain analysis instruments for time interval measurements. 3. satellite navigation signal simulator pseudo-range accuracy measurement method according to claim 1, is characterized in that, described periodic calibration signal and described radio frequency simulation signal synchronous output, the cycle of described periodic calibration signal is not greater than time The maximum sampling time of the domain analysis instrument under the condition that the pseudorange accuracy measurement requirements of the simulator are met. 4. satellite navigation signal simulator pseudo-range accuracy measurement method according to claim 3, is characterized in that, described periodic calibration signal is used as the external trigger signal of time-domain analysis instrument simultaneously, the first of described periodic calibration signal N-1 periodic signals have the characteristics that can trigger the time-domain analysis instrument, where N is the whole cycle number of the calibration signal, which is calculated by the simulator according to formula (1). 5. satellite navigation signal simulator pseudo-range accuracy measurement method according to claim 4, is characterized in that, described periodic calibration signal is calibration pulse signal, the high level of the N-1th pulse signal that will raise It is used to trigger the time-domain analysis instrument, where N is the whole cycle number of the calibration pulse, which is calculated by the simulator according to the formula (1).

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