SU892337A1 - Analog-digital dispersion spectrum analyzer - Google Patents

Description

one

The invention relates to a radio measuring technique and can be used in the analysis of radio transmission spectra and a panoramic radio receiver.

The closest in technical essence to the proposed invention is a dispersion spectrum analyzer, which contains serially connected broadband path, first mixer, dispersive delay line, amplitude detector and indicator, as well as a sawtooth generator, second mixer, first and second frequency modulated heterodyne, line delays, two keys and a synchronizer.

To increase the speed of analysis, the circuit of the known device includes two signal processing paths, each of which consists of a mixer and a frequency-modulated local oscillator, with the heterodyne paths being rebuilt with a shift of TQ / 2. Here TQ is the period of analysis. With such an inclusion, all spectral components in the anyshiz band affect the input of the dispersive delay line simultaneously, and are processed according to the principle of a sequential method. it

allows you to search for loss of information about the signal and achieve maximum use of the quality of the delay line. one .

However, to ensure high accuracy of the analysis (high, for example, in units, tenths and hundredths of a hertz frequency resolution), the known device allows.

10 This is hampered by the difficulty or impossibility of the realization of analog dispersive delay lines with a range of delays from units to tens of seconds.

15

The purpose of the invention. Improving the accuracy of the analysis.

The goal is achieved due to the fact that the analog-digital dispersion spectrum analyzer,

20 containing an input broadband unit connected to the inputs of two mixers, the second inputs of which are connected to the corresponding outputs of two frequency modulated heteroins, the input of one of which is connected to the output of the sawtooth generator directly, and the input of the other through a delay line, as well as a synchronizer which inputs are connected to the generator output

sawtooth voltage and to the output of the delay line, and the output is connected to the indicator input, additionally introduced a read switch and serially connected analog combiner, band-pass filter, voltage converter to code, write switch, random access memory, digital adder and code to voltage converter The output is connected to the second input of the indicator, while the inputs of the analog adder are connected to the outputs of both mixers, and the read switch is connected between the second output synchronized and a second input of the operational Memory Devices.

The write and read switches T the on-line memory and the adder are a digital dispersion delay line and can be implemented as a microprocessor or modeled on a computer

The drawing shows a structural diagram of an analog-digital spectrum analyzer.

Analog-digital dispersion spectrum analyzer contains serially connected: broadband path 1 first mixer 2, analog adder 3, band-pass filter 4, voltage-to-voltage converter 5, write b switch, random access memory 7, digital adder 8, code to 9 converter voltage and indicator 10, as well as a sawtooth voltage generator 11, connected via the first frequency-modulated local oscillator 12 to the second input of the first mixer 2 and through the delay line 13 and the second frequency-modulated het Source 14 to the second input of the second mixer 15, which is connected between the output of the wideband tract 1 and the second 9FOROD of the analog adder 3, and between the output of the generator 11 pi. and the indicator input of the synchronizer 16, the second input of which is connected to the output of the delay line 13, and the second output through the switch 17 of the readout is connected to the second input of the random access memory 7.

Analog-digital dispersion spectrum analyzer works as follows.

Frequency modulated local oscillators 12 and 14 operate with a phase shift of half a period of To / 2. As a result, a continuous signal is applied to the input of the digital dispersion delay line, if it is located at any point of the analysis band. The limitation of linear-frequency-modulated radio pulses (LCRM) over time and frequency is performed by band-pass filter 4. Therefore, the duration of all LCHMRIs is identical. But the spectral components affect the input of the digital dispersion delay line at different or overlapping time intervals (. By virtue of the principle of a consistent analysis method).

The voltage transformer 5 into the code is sampled by the Kotelnikov theorem and converted into a digital form. The sampling interval is T l / 2uF (Here, dR is the deviation of the LMNI). The size of the code patterns representing the samples in digital form is determined by the required conversion accuracy. The code combinations through the recording switch 6 are sequentially entered into the operational storage device 7. In the interval T, N Td / T of 2DR TCI samples must be entered. The input of code digits continues until the end of the TO analysis period, but since t T, the values of the code combinations and their bitwise addition are output by means of the read switch 17

The input of the code combinations is line by line, the addition is performed on the columns of the matrix of the operational storage device. In addition, always involves N code combinations. The resulting code combination is the response of the digital dispersion delay line at time t T. To form the next sample, the code combination recorded in the random access memory 7 is excluded from the previously obtained amount and includes the (L + 1) code combination. For the formation of the third reading, the second is additionally excluded, and the code combination (L + 2) is included, etc. Code combinations from the N number to 2 N participate in the initialization of the N-ro count. The first analysis period is over.

In the second analysis period, the first sample of the response of the digital dispersion delay line is formed from the code combinations with the number from (N + 1 to 2 N and the updated combination is added to them with the number 1. Then the process is repeated throughout.

The digital response as well as the analog dispersive delay line represents the spectral density of the signal. To form it, it is necessary to perform Nk elementary operations of logical addition and N-k subtraction operations during T., moreover, k is the size of code combinations. Tat CIM way, the speed requirements of the microprocessor or computer are significantly reduced in comparison with the FFT algorithm. The reduction is achieved by performing multiplication of the signal with a basis of analog frequency modulated local oscillator and a panoramic mixer. The deviation of the characteristics of analog circuits from those required can always be taken into account by means of a synchronizer of corrections of the addition algorithm. Important is the fact that for a given analysis bandwidth, the speed requirements are lower, the greater the T, and hence the accuracy of the analysis.

Claims (1)

1. USSR author's certificate No. 490034, cl. G 01 R 23/16, 1975.