SU828424A1 - Device for processing broad-band frequency-modulated signals - Google Patents

Description

one

The invention relates to a technique of electrical communication and may find application in communication systems using broadband signals with linear or linear-step frequency modulation operating in multipath channels.

A device for receiving time-frequency signals is known, comprising a linear path, a synchronization unit, a set of kinematic filters, amplitude detectors, low-pass filters, key elements, memory units, an adder, a decisive unit and devices for selecting and suppressing interference 1.

However, this device does not possess sufficiently high noise immunity due to the absence of separation and weighting of the beams of signals with linear or linear-step frequency modulation.

The aim of the invention is to improve noise immunity.

To do this, in a device for processing broadband signals with frequency modulation, containing a linear path, the output of which is connected to the input of a synchronization unit, two matched filters, each of which consists of L filter channels connected through a corresponding adder to the inputs of the decisive

block, and each filtering channel contains a switched bandpass filter, one of the inputs of which is connected to the first output of the synchronization unit, an amplitude detector, an integrator and a storage device, between the output of the linear path and the input of each matched filter are included multipliers, the other inputs of which

the reference generator is connected to other outputs of the synchronization unit, and in each filtering channel of matched filters between the output of the switched bandpass filter and the input of the amplitude detector a weighing unit is connected, the integrator and the memory are connected to the output of the amplitude detector, the other inputs of which are connected

with the first output of the sync block.

FIG. Figure 1 shows the structural electrical circuit of a device for processing frequency-modulated broadband signals; in fig. 2 - timing diagrams for the operation of the device.

The device contains a linear path 1, a synchronization unit 2, a matched filter 3, matched with the symbol “1, a matched filter 4, matched with

Claims (2)

the symbol "O, multipliers 5, reference oscillators 6. Each matched filter contains N filtering channels consisting of a switched band-pass filter 7, a weighing unit 8, an amplitude detector 9, an integrator 10 and a storage device 11 and connected to the inputs of the adder 12. Adders outputs matched filters 3 and 4 are connected to the inputs of decision block 13. It is known that for signals with linear or linear-step frequency modulation, the delay of received signals over time (after convolution) is converted to detuning in frequency with parameters that are uniquely determined by the amount of delay. Consider the processing of the signal corresponding to the symbol "I (here it is assumed that the signal" O differs from "1 by the average frequency, and the signal spectra do not overlap). FIG. 2a shows the frequency / g of the reference oscillator 6, shifted relative to the received frequency at the intermediate frequency fo, and the frequency of the received signals / s, and / s. , delayed relative to the reference (the first beam arrives at the moment it, the second - at the moment 4). The values of the signal delays uniquely determine their detuning in the receiver relative to the frequency / o: the first beam in the interval ti / 3 is upset (see Fig. 26) by the value: A fА /. / t D / 1-L C, J., where; D / C. the delay of the first beam, Afm - the maximum frequency separation of the FM signal; The T-duration of the element, at the moment of ts, the detuning abruptly changes, in the interval ta-tt is d /; .. (g-l4,) - d / „- for, for the second beam (see Fig. 2c) has in the interval DL A4. in the interval ts-tz: D / 2: (G-D4.) - -D / „- AL, where is the delay of the second beam. Thus, the signals of each beam are distinguished by an appropriate filter, the tuning of which and the moments of its change are unambiguously determined by the magnitude of the delay of the beam. With filters corresponding to all signal delays, we can separate the rays (similarly to the delays of the delay line), raise the intensity of each beam with any given averaging time, and then add energy with an appropriate weight. These operations are performed by the filtering channels. The operation of the integrator 10 and the storage device 11 is illustrated in FIG. 2 g, d n 2e, g for the first and second rays, respectively. The switching times ti and 4, as well as integrator 10 bits onto memory 11 ti to tz, are individual for each filtering channel (for each beam) and are determined by the synchronization unit 2. The voltage of all filtering channels proportional to the energy of the respective beams is read, their summation in the adder 12 n is applied to the decision block 13 simultaneously at time 4 The signal corresponding to the symbol "O" is processed in the same way. Thus, the processing of a broadband signal with frequency modulation provides high noise immunity. The invention of the Device for processing broadband signals with frequency modulation, contains a linear path, the output of which is connected to the input of the synchronization unit, two matched filters, each of which consists of N filtering channels connected through the corresponding adder to the inputs of the decision unit, and each filtering channel contains a switched bandpass filter, one of the inputs of which is connected to the first output of the synchronization unit, an amplitude detector, an integrator and a memory device, characterized in that then, in order to improve noise immunity, multipliers are included between the output of the linear path and the input of each matched filter, the other inputs of which are connected to other outputs of the synchronization unit through the corresponding reference oscillator, and on each filter channel of matched filters between the output of the switched bandpass filter and the amplitude detector input a weighing unit, with an integrator and a memory device connected in series to the output of the amplitude detector, the other inputs of which They are connected to the first output of the synchronization unit. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 333713, cl. H 04B 1/10, 1970 (prototype).