SU830251A1 - Device for detecting signals and measuring their parameters - Google Patents

Description

The invention relates to a frequency meter and frequency spectrum analyzers and can be used to detect several signals with an unknown frequency and amplitude against a background of noise, to measure their frequency and amplitude. A device is known that represents a spectrum analyzer of a serial action with time compression and contains a frequency-modulated local oscillator, an analog storage device, a mixer, and an analysis filter. The disadvantage of the device is low accuracy due to the use of a memory device and an analysis filter made in analog form. A device for detecting a signal and determining its frequency is known, comprising a band-pass filter, an analog digital converter, a low-pass filter, random access memory, the first and second square squaring blocks, the outputs that are connected to the memory and processing unit through an adder, and chronizato, the first output of which is connected to the clock input of the operative storage device, the second output to the memory and processing unit. However, the impossibility of simultaneously detecting several signals with different amplitudes due to the use of an analog-digital converter in the form of a quantizer on two levels and a random access memory in the form of a shift register reduces the reliability of the device. The purpose of the invention is to increase the reliability of the device. To achieve this goal, a device containing a band-pass filter, an analog-to-digital converter, a low-pass filter, an online storage unit, the first and second. the squaring blocks, the outputs of which through the adder are connected to the memory and processing unit, and the chronizer, the first output of which is connected to the clock VU of the random access memory, and the second output to the memory and processing unit, introduced the phase code generator, code converters phases in real and. imaginary components of the local oscillator signal, the first and second multipliers, an additional low-pass filter, an additional operational storage unit, a permanent storage unit, a multiplier of complex signals, the first and second drives, the output of the bandpass filter connected to the analog-to-digital converter, the output of which is connected with the first inputs of the first and second multipliers, the third output of the chronizer is connected to the generator of the phase code, the output of which is through the transform. The converter of the phase code to the real component of the local oscillator signal is connected to the second input of the first multiplier, the output of which is connected to the operational storage unit through a low-pass filter, and through the converter of the phase code to the imaginary component of the signal of the local oscillator is connected to the second input of the second multiplier, whose output an additional low-pass filter is connected to an additional operational storage unit, the clock input of which is connected to the chroniser, the output of the permanent storage unit with Uniform multiplier with complex signals, second inputs connected to the outputs of operational and additional RAM blocks, and outputs via the first and second drives to the first and second upmixing unit in kvsschrat.

FIG. 1 shows a block diagram of the device in FIG. 2 — a frequency-time diagram of its operation.

The device contains (FIG. 1) a band-pass filter 1, an analog-to-digital converter (ADC) 2, a low-pass filter 3, a random access memory unit 4, a first and second square blocks 5 and 6, an adder 7, a memory and processing block 8 , chronizer 9, phase code generator 10, converting the phase code to real imaginary 12 components of the local oscillator signal, first and second multipliers 13 and 14, additional operational storage unit 16, permanent storage unit 17 multiplier 18 complex signals first and second drives 19 and 20, When e The volume of the band-pass filter 1 is connected to the A / D converter 2, which is connected to multipliers 13 and 14. Phase code generator 10 through Ne converters 12 phase codes to the real and imaginary components of the local oscillator signal; also connected to multipliers, i Multipliers through digital filter 3 and 15 are connected to operational storage units 4 and 16. Random access memory devices are connected to multiplier 18 complex signals, to which the permanent storage unit 17 is connected. Multiplier of complex signals. connected to storage device mi 19 and 20, KO tory through blocks 5 and 6 of construction

square connected to the adder 7. The adder is connected to the block 8 memory and processing. The timing device 9 is connected to a phase code generator 10, a random access memory unit 16 and a memory and processing unit 8.

The device works as follows.

The signal from the output of the bandpass filter 1, the bandwidth of which. is converted into digital form using an ADC 2. With this conversion, the spectra multiply around the sampling frequency and its harmonics, including around zero frequency. In the band near the zero frequency (Fig. 2), the signal in the general case can be written as S (t) A (t) cos (Wct, where t is discrete time points with a period; ff is the sampling frequency of the signal in the ADC.: Generator 10 the phase code gives the numbers that are the phase values as a quadratic time function Ч (t) 44 tjTo corresponds to the linear variation of the frequency si (tj L (.-- t / T. Function 4 (t) is periodic with a period T. Transducers and 12 phase codes form at the output the real Spn (t) cosf (t) and imaginary) sin4, (t) components of the complex signal of the local oscillator S (t) S, g (t) +), which multiply It is the signal S (t) in the multiplier 13 and 14. The result of this operation can be written as

- s (:). l-A (t) e-H. (t)).

: .s ((t).

Digital filters 3 and 15 of the lower frequencies with a bandwidth of diCs each separate the real and imaginary components of the complex signal of the difference frequency S (t). A useful signal at the outputs of the filters is present for the time T, when the difference frequency is in the interval (HLM). Band 4tS) n4 The lifetime of the signal T is delayed relative to the beginning of the period by 1; (W. —Ald4) / t {u) (. —And) 4) / Wp, which depends on the frequency value. (A; input signal By the delay is determined by the frequency i.

At the output of digital low-pass filters, a pulse is formed, the frequencies within which vary linearly (chirp - pulse). If we transfer the time reference to f (Fig. 2), then the useful signal at the filter outputs can be written as

S (V) .AtB-% A (t-4),

where t -t-tr.

The sampling period of the signal at the filter outputs is chosen from the ty. L / AU. Over time, TH is formed. N. values of the output signal

 Under this condition

those. t

9

, s) A (w) e M4C -irtA (r ,, (- T).

The real and imaginary components of the signal S (p) are recorded in two operational storage units 4 and 16 connected through a multiplier 18 of complex signals, to the other input of which a complex signal is received from a constant interrupting unit 17, with two accumulators 19 and 20, These blocks form a digital matched filter with a chirp pulse appearing at the outputs of digital lower filters often, the filter impulse response is written in a persistent storage device and has the form

. h (v). Matched filter calculates convolution

- 1) - il5nr, sV) (v - n) (,

   .

which is essentially the spectrum of the signal A (p). Blocks 5 and 6 squaring and adder 7 are designed to allocate the power of the spectral components A (p),

Under the action of several signals at the device input with different frequencies and amplitudes, the values of squares of their amplitudes will be consistently obtained at its output. These numbers enter block 8 of memory and processing. Here they are compared with the threshold and between themselves, the signals are detected and their amplitudes are measured. The time of the occurrence of these numbers from the beginning of the period T determines the frequency of the signals. The time stamps are sent to the memory and processing unit from the chronizer 9.

Claims (1)

Formula of gain A device for detecting signals and measuring their parameters, comprising a bandpass filter, an analog-to-digital converter, a low-pass filter, an operational storage unit, the first and second squaring blocks, the outputs of which are connected to the memory and processing unit through the adder, and the timing unit, the first output which is connected to the clock input of the operative storage unit, the second output to the memory and processing unit, which is e0 so that, in order to increase the reliability of the device, a phase code generator is introduced into it, verters code phase in the real and imaginary components of the heterodyne signal, 5 the first and second multipliers, an additional low-pass filter, an additional operational storage unit, a permanent storage unit, a multiplier of complex signals, 0 the first and second drives, and the output of the bandpass filter is connected to an analog-to-digital converter, the output of which is connected to the first inputs of the first and second multiplications, l, the third output of the chronizer is connected to the generator of the phase code, the output of which is through the converter of the phase code to real moiety. the signal of the local oscillator is connected to the second input of the first multiplier, the output 0 which is connected to the operational unit through a lowpass filter, and through the converter of the phase to the imaginary component of the signal of the local oscillator is connected to the second input of the second multiplier, the output of which is connected to the additional operational memory through an additional lowpass filter, the clock input of which is connected to the memory, the output of the permanent storage unit is connected with a multiplier of complex signals, the second inputs of which are connected to the operational and additional memory outputs th blocks, and the outputs - through the first 5 and the second drives with the first and second block squaring.