SU1415457A1 - Demodulator of signals with relative phase modulation - Google Patents

Abstract

The invention relates to communication technology and can be used in systems for transmitting digital information with relative FM in channels with interruptions, as well as via telecontrol channels. The purpose of the invention is to improve noise immunity. The demodulator contains phase demodulators 1, 2, 3, source 4 of the reference signal, delay blocks 5, 6, 7, three comparison blocks 8, 9, 11, decoder 13. The comparison block is entered. 10, a key (K) 12, decoders 14, 15, an element OR 16, a waiting multivibrator (LM) 17. In each communication session, a check is carried out for compliance with the code of two signals at once: maximum and second in size. In the event that the input signal of one of the decoders 13-15 coincides with the code of the beginning of the message, the corresponding decoder generates a match signal CC at the output. The OS (high potential) that occurred during the session at the output of one of the decoders 13-15, through the element OR 16, enters the launch of the LM 17, which generates a pulse arriving at the control input K 12. This pulse, the duration of which is equal to the transmission time of all information symbols of the packet, ensures the passage of information symbols from the output of the comparison block 1 1 to the output of the demodulator. one . with (L

Description

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The invention relates to communication technology and can be used in digital information transfer systems with relative phase shift in interrupt channels, as well as via remote control channels when commands are sent to an object during short sessions.

The purpose of the invention is to improve noise immunity.

The drawing shows a structural electrical circuit of the proposed device.

The demodulator contains the first phase demodulator 1, the second and third phase demodulators 2 and 3, the source 4 of the reference signal, delay blocks 5–7, the first, second, fourth and third blocks 8–11 comparisons, the key 12 first, the second and the third decoder 13-15, the element OR 16 and the waiting multivibrator 7,

The demodulator works as follows.

In each session (packet), a signal is transmitted with respect to phase modulation (), consisting of the start code of the message (start group) and information symbols transmitted after this code. The input signal is fed to the first inputs of phase demodulators 1-3 of the first, second and third channels, the second inputs of which receive reference signals of source 4, which have different initial phases (O 60 ° and 120 °) after passing through 5-7 delay blocks. In short sessions (ten symbols), the initial phase of the carrier of the SNR signal during one packet can be considered almost unchanged. So, for example, with the transmitter frequency instability ut,, the Mbps transmission rate, the volume of a packet of symbols, and the carrier frequency of 1 GHz, the departures of the initial carrier phase do not exceed 4 °. From packet to packet, the initial carrier phase may take on random values.

Therefore, the magnitudes of the signals at the output of the phase demodulators 1-3 of the first, second and third channels, determined by the magnitude of the projection of the vector of the input signal to the corresponding vector of the reference signal, are almost unchanged during one packet (communication session). Maximum

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the signal will be at the output of that phase demodulator, the phase of the reference signal of which is closest to the 1st phase of the input signal. From packet to packet, the relative position of the vector of the input signal and the vectors of the reference signals, and hence the output signals of phase demodulators 1-3, can vary. Therefore, the selection of the maximum of the channel demodulator output signals should be made in each session.

Three differences in magnitude of the signal from the output of phase demodulators 1-3 are fed to the inputs of blocks 8-10 comparison in pairs. In block 8, the comparison compares and selects the largest of the output signals of the phase demodulator 1 of the first channel and the phase demodulator 2 of the second channel. In block 9 comparison, the comparison and selection of the largest of the output signals of the phase demodulator 2 of the second channel and the phase demodulator 3 of the third channel occurs. Similarly, in the comparison unit 10, the largest of the output signals of the phase channel 1 demodulator 1 and the phase channel 3 demodulator 3 is compared and selected. Each of the blocks 8-10 comparison, choosing the largest of the two signals acting at its input, thereby eliminating the smallest. Therefore, in each session of the output signals of the channel phase demodulators 1-3, the comparison blocks 8-10 together select the two largest signals (maximum and second largest). In this case, the output of two of the comparison blocks 8-10 will be the maximum signal, and the output of the remaining 8-10 comparison blocks will be the second largest. Comparison unit II, which receives signals from the outputs of the comparison units 8 and 9, compares these signals and selects the maximum one, which then goes to the information input of the key 12. Simultaneously, the signals from the outputs of the comparison units 8-10 go to the decoder inputs 13-15, respectively. which check these signals for compliance with the code. Thus, in each session, a check is made for compliance with the code Vdecoding) of two signals at once: the maximum and the second largest. If there is a match, input 14

signal of one of the depotfrarators 13–13 with the code of the beginning of the message to the corresponding decoder generates a coincidence signal (high potential) at the output. In other cases (in the pauses between: waiting for communication sessions and when transmitting an arbitrary code), the output of all decoders 13-15 is no match signal (low potential acts).

The coincidence signal that occurred during the communication session at the output of one of the decoders 13-15, through the element OR 16, enters the launch of the waiting multivibrator 17, which forms a pulse arriving at the control input of the key 12. This and the mic, p, and step which is equal to the transmission time of all information symbols of the packet, unlocks key 12, ensuring the passage of information symbols from the output of the comparison unit 11 to the output of the demodulator. At the same time, there is a waiting cartoon for the pulse formation time; vibrator 17 remains insensitive to repeated trigger pulses.

Claims (1)

Invention Formula The demodulator of signals with relative phase modulation, containing the first decoder, three phase units modulators, the first inputs of which are the input of a demodulator of signals with relative phase modulation, the second inputs are connected to the output of the source of the reference signal through the corresponding delay blocks, the outputs of the first and third phase demodulators are connected to the inputs of the first Comparison unit, the outputs of the second and The third phase demodulators are connected to the inputs of the second comparison unit, the outputs of the first and second comparison units are connected to the inputs of the third comparison unit, characterized in that, in order to improve the noise immunity, the second, third descramblers, element OR, waiting a multivibrator and a switch, with the outputs of the first and third phase demodulators being connected to the fourth block comparison input, the outputs of the first, second and fourth comparison blocks respectively, through the second, first 1 third decoders are connected to the input of an ICh element, the output of which is connected to the first input of the key via the waiting multivibrator, the second input of the second one is connected to the output of the third b. This is a comparison, and the output is the output of a demodulator of signals with relative phase modulation.