SU855519A1 - Method of measuring frequency of random narrow-band signal - Google Patents

Description

(54) METHOD OF MEASURING THE FREQUENCY OF A RANDOM NARROWBAND SIGNAL The invention relates to a radar technique and can be used in measuring the velocity vector of moving objects. There is a method of measuring the frequency of a random narrowband signal by forming a pulse sequence in accordance with the magnitude and sign of the difference between the frequency of the input signal and the signal of the controlled local oscillator followed by the integration of this pulse sequence Cl. The disadvantage of this method is the large amount of functional yields, which increases the likelihood of a tracking failure when the signal is heterodyne controlled with a high frequency average frequency. The purpose of the invention is to reduce the fluctuation errors in measuring the frequency of a random narrowband signal. The goal is achieved by the fact that in the method of measuring the frequency of a random narrowband signal by forming a pulse sequence in accordance with the magnitude and sign of the frequency difference between the input signal and the controlled local oscillator, then the number of changes in the sign of the frequency difference of the input signal is recorded; and the signal of the controlled local oscillator, characterized by the number of pulses of no more than two in a series of one sign, compare this number with the threshold value and the measured frequency of the signal is read at the moment of its equality or when the threshold is exceeded. FIG. 1 shows a functional diagram of a device for measuring the frequency of a random narrowband signal implementing the proposed method in FIG. 2 is a functional diagram of one of the possible reattings of the block for analyzing changes in the sign of the frequency difference in FIG. 3 - time diagrams of signals that explain the operation of the block for analyzing the sign of the frequency difference for m 1, where go is the number of pulses in a series of one detuning sign. A device for measuring the frequency of a random narrow-band signal with. Holds ring-connected forms of a 1-pulse sequence, 1 integrator 2 to a controlled local oscillator 3. Outputs 4 and 5 of the driver I

the pulse sequence is connected to the inputs of the frequency difference reversal analysis block 6, the output 7 of which is connected to the control input of the key 8, the other input of which is connected to the output of the integrator 2. The output of the key 8 is the output of the device.

A device for measuring the frequency of a random narrowband signal operates as follows.

A narrowband random signal, whose frequency is to be measured, is fed to the first input of the pulse shaper 1, its control signal is sent to its second input 3. At one of outputs 4 or 5 of the shaper pulse shaper, an error signal appears in the form of pulses, whose frequency is proportional to the difference between the frequency of the input signal and the signal of the controlled local oscillator 3. In this case, the voltage at the output of the integrator 2 begins to change so that the frequency of the controlled r The local interface is closer to the frequency of the input signal. When these frequencies become close, the pulses at the outputs 4 and 5 of the generator 1 of the pulse sequence begin to alternate, and the number of pulses in a series of one detuning sign is variable. The pulses from the outputs 4 and 5 of the pulse sequence generator are also fed to the inputs of the frequency difference sign analyzer b block, which is analyzed by the pulse series accompanying the sign reversal of the difference of the compared frequencies, i Once the frequency difference sign analyzer block 6 has changed the sign of the frequency difference, characterized pulses in a series, for example, with m 1, one pulse, at its output 7, a control voltage appears, which opens the key 8. At this, the output voltage of the integrator 2 is supplied the output of the device as a reference is measured by the frequency of the input random signal. As soon as the number of pulses in a series of one, the detuning sign exceeds m, where m in this case is equal to one, the supply of control voltage opening key 8 from output 7 of block b of the analysis of changes in the sign of the frequency difference stops. In this case, the switch 8 is closed, and the supply of voltage from the output of the integrator 2 to the output of the device also stops. Shown in FIG. The second embodiment of the variable analysis block. The sign of the frequency difference contains the first element OR 9, the counter 10, the puller subtractor 11, the second element OR 12. In turn, the counter 10 has two triggers.

13 and 14. At the same time, the first and second inputs of the first element OR 9 and the pulse subtraction stage 11 are interconnected and connected to the outputs 4 and 5 of the pulse sequencer 1, the output of the first element OR 9 is connected to the counting input of the first trigger 13 of the counter 10, and The first and second outputs of the subtraction cascade 11 are connected to the first and second inputs of the second element OR 12 whose output is connected to the installation input of the counter 10. The output of the first trigger 13 is connected to the input of the second trigger 14 in such a way that the output pulse the second trigger 13, the second trigger 14 is set to a state of logical one.

Block analysis of the change of the sign of the frequency difference works as follows.

When more than one pulse appears at the input 4 or 5 (for m 1), then, starting with the second pulse in the count (Fig. Za and Zb), the sequence of pulses appears at the outputs of the pulse-subtraction stage 11, holding through the second element OR 12, the counter 10 is in the state of logical zero (Fig. 3g). If the number of pulses in a series does not exceed one, then the signal for setting a logical zero at the input of counter 10 is absent (Fig. 3g), since alternating successive input pulses are subtracted in the pulse subtraction cascade 11. However, the input pulses through the first element OR 9 arrive at the input of the first trigger 13, and the counter 10 begins to fill. With the second pulse from the output of the element OR 9, the trigger 14 is set to the state of the logical unit, and at its output a control signal appears, opening the key 8 (Fig. 3). The first, followed by a change in the sign of the frequency difference, followed by a series exceeding one pulse, through a cascade 11 of pulse subtraction and a logical element OR 12 sets the counter 10 to the logical zero state. If necessary, the allowable number of pulses in a series of one sign of the setting can be increased by one if, in series with the pulse subtraction stage 11, one more such stage is added. The threshold number m can be increased by adding another counting trigger to the counter 10.

The use of the invention allows to reduce fluctuation errors in measuring the frequency of a random narrowband signal and to reduce the likelihood of tracking failure with a changing average frequency of the input signal.

Claims (1)

1. USSR author's certificate 474756, cl. G 01 R 23/00, 08.03. eleven P AND four W / 12