JPS58129377A - Doppler aid system - Google Patents

Abstract

PURPOSE:To enable a highly accurate measurement with a simple circuitry by correcting dynamic phase errors of a distance measuring signal track PPL with a handy digital circuit. CONSTITUTION:An input distance measuring signal is inputted into a phase detector 4, an output of which is inputted into a voltage-frequency transducer 7 passing through a loop filter 5 and converted to a pulse train with the rate proportional to the output of the loop filter 5. The output of the voltage-frequency transducer 7 and the output of an incremental range generation circuit 8 are added and inputted into a digital phase control circuit 9. The signal is inputted into the local side of the phase detector 4 to compose a PLL. A signal having Doppler information and a reference frequency signal are inputted into said incremental range generation circuit 8 to perform a slip detection of the two signals. Based on it, conversion factors of the input and output are setted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Doppler needling method of a range subcarrier tracking PLL used in a system for measuring the rate of change in distance of a body #j based on Doppler information detected from a body #j.

FIG. 1 is a diagram showing an example of the configuration of a range subcarrier tracking PLL that shows a conventional dot planar needle system.

Conventionally, a method as shown in FIG. 1 has been used as a method for reducing the tracking loop stress of a range signal using a Doppler signal.

In Figure 1, 1 is a synthesizer, 2 is a mixer, 3 is a narrowband filter, 4 is a phase detector, 6 is a loop filter, 6 is a voltage controlled oscillator, fno is the subcarrier frequency, and fo (80) is the subcarrier frequency. Doppler shift equivalent to carrier frequency, fm.

fB, N indicate arbitrary frequencies and numbers.

In this method, a signal having Doppler information is converted by a synthesizer IK into a signal corresponding to a range subcarrier frequency. Further, the mixer 2 mixes this signal with the input ranging signal, thereby stabilizing the input subcarrier frequency. After removing the Doppler shift of the input ranging signal, the O/N is improved by the narrowband filter 3,
Tracking is performed by the subsequent PLL.

However, this method has the following problems: 1) If Doppler information cannot be obtained, the frequency input to the narrowband filter 3 will fluctuate, and this will increase the rounding distance fixation error in which the phase of the range subcarrier shifts from k.
In addition, 2) when switching the range subcarrier frequency input to the mixer 2, the synthesis of frequencies to be mixed in order to eliminate the top 2 deviation becomes complicated. There was a drawback.

The purpose of the present invention is to reduce the dynamic error of the loop and thereby eliminate the above-mentioned drawbacks.

It is said that the circuit configuration is 1 and provides a dots planar needle system suitable for multi-frequency range subcarriers.
be.

In order to achieve the above object, the Doppler needling method according to the present invention includes a loop filter, a voltage frequency converter that converts the output of the loop filter into a pulse train with a rate proportional to the output, and a Doppler converted frequency and a reference frequency as inputs. A circuit that generates an l pulse for a Topppler deviation, a digital phase control circuit for a pulse train that is the sum of the circuit and the converter output, and a digital phase control circuit that generates a pulse train for a Topppler deviation of the digital phase control circuit output and a Doppler deviation. and a phase detector which generates an output corresponding to the phase difference of the included nub carrier frequencies and whose output is input to the loop filter.

The system of the present invention will be explained in more detail below with reference to the drawings.

The first part is a block diagram showing an embodiment of the method of the present invention. In the figure, 4 is a phase detector, S is a loop filter, 7 is a voltage frequency converter, 8 is an incremental range generation circuit, and 5 is a digital phase control circuit.

The input ranging signal is input to the phase detector 4.

Since the signal input to the phase detector 4 contains a lot of noise, the phase detector used here has a sufficiently large dynamic range.

The output of the phase detector 4 is inputted to the voltage frequency converter through the loop filter 2, where it is converted into a pulse sequence with a rate proportional to the output of the loop filter 2. This circuit receives information (same as the information inputted to the synthesizer IK in FIG. 1) and uses a digital calculation circuit to generate one pulse each time the target moves a certain distance.

The output of the voltage frequency converter 7 and the output of the incremental range generation circuit 8 are added and then input to the digital phase control circuit 9. This signal (rectangular wave) is input to the local side of the phase detector 4 to form a PLL.

The input of the incremental range generation circuit, which occupies the main part of this method, is a signal having Doppler information,
A reference frequency signal with no Doppler applied is input 1. An IA pulse occurs when a slip of these two signals is detected and a constant value is added to a register each time one slip occurs, and an overflow of this is detected. Appropriate the addition value of Jin and the full scale value of the register! ! By selecting &, input and output conversion coefficients can be freely set.

Since the system of the present invention is configured as explained above, it is possible to correct the dynamic phase error of the range signal tracking PLL using a 4° digital circuit without using a complicated frequency conversion link. Become. Furthermore, even if the frequency of the field distance napcarrier signal and the format of the input Doppler information signal change, it is relatively possible to deal with JIK.

Furthermore, since the control of the dot planar needle is configured digitally, jitter errors and the like are less likely to occur, which is advantageous in constructing a highly accurate distance measuring device.

[Brief explanation of the drawings] IEIII is a block diagram of the conventional dotsplanade system,
FIG. 2 is a circuit block diagram showing an embodiment of the doppler needling system according to the present invention. l...Synthesizer, 2...Mixer. 3... Narrow band filter, 4... Phase detector. 6... Voltage controlled oscillator. 7...Voltage frequency converter. $...Incremental range generation circuit. 9...Digital 7 AIDS control circuit patent applicant Hisashi Inoro, patent attorney representing NEC Corporation

Claims (1)

[Claims] a loop filter, a voltage frequency converter that converts the output of the loop filter into a Norms train with a rate proportional to the output, and a voltage frequency converter that inputs the Doppler conversion frequency and the reference frequency, A circuit that generates a pulse, a digital 7 aids control circuit of a pulse train that is the sum of the circuit and the converter output, and a phase difference between the output of the digital phase control circuit and a subcarrier frequency including Doppler shift. A dots planar needle system comprising a phase detector that generates an output and uses the output as the input of the loop filter.