RU2178952C1 - System for transmitting and receiving modulated signals over power supply mains - Google Patents

Abstract

FIELD: radio engineering and electric communications. SUBSTANCE: system has transmitting section incorporating at least modulator, carrier generator connected to modulator, and output channel-interface unit; receiving section including at least series-connected input channel-interface unit, line circuit, and signal discriminator, carrier generator connected to line circuit and/or to signal discriminator. Each carrier generator is made in the form of synchronized oscillator whose synchronizing input is connected to matching-unit output; inputs of matching units are used for connection to power supply mains; synchronized oscillators are tuned to frequency of mF, where F is frequency of power supply mains; m is harmonic chosen between 10 and 20 000. EFFECT: enhanced noise immunity. 2 dwg

Description

 The present invention relates to radio engineering and telecommunications, and in particular to systems for transmitting and receiving information and, in particular, to systems for transmitting and receiving both low-speed and high-speed information on distribution power supply networks used as a communication channel.

BACKGROUND OF THE PRIOR ART
A device for receiving and transmitting a frequency-manipulated signal (see SGS-THOMSON MICROELECTRONICS, HOME AUTOMATION MODEM, ST7537HS1, June 1995) containing a frequency manipulator in the transmitting part and a demodulator in the receiving part is known frequency-manipulated signal, the carrier frequency for which is synthesized from the frequency of a crystal oscillator. Since an autonomous crystal oscillator is used, the modem noise immunity is relatively low, since it is affected by both background noise and noise in the form of harmonics of the power supply network, which are shifted in frequency due to instability relative to the carrier frequency.

 Known systems for receiving and transmitting signals, for example, with manipulated signals that have increased noise immunity, in relation to the above (see, for example, Foreign Radio Electronics, 4, 1988, pp. 16-37, Pestryakov V. B. and others. " Continuous phase discrete signals: theory and practice "). The system comprises a transmitting part including at least a manipulator and a carrier frequency driver connected to the manipulator. The system also includes a receiving part, which includes at least a signal demodulator and a carrier frequency driver connected to the signal demodulator. However, these systems are mainly intended for use in space-based data lines and ground-based systems of mobile radiotelephony and when used to transmit information via the power supply network, their noise immunity will also be relatively low due to the above, although higher than in the previous one.

SUMMARY OF THE INVENTION
The invention is directed to the creation of such equipment, which would improve the noise immunity of information transmission.

 This increase in noise immunity is solved due to the fact that the system for transmitting and receiving modulated signals over the power supply network contains transmitting and receiving parts. The transmitting part includes at least a modulator, a carrier frequency oscillator connected to the modulator, and an output channel interface unit. The receiving part includes at least a serially connected input interface unit with a channel, a linear path and a signal discriminator, as well as a carrier frequency oscillator, connected to the linear path and / or to the signal discriminator. Each carrier frequency oscillator is designed as a synchronized oscillation source, the synchronization input of which is connected to the output of the matching unit. The inputs of the matching blocks are inputs for connecting to the power supply network, and the synchronized oscillation sources are tuned to the frequency mF, where F is the frequency of the power supply network, m is its harmonic, selected in the range from 10 to 20,000.

 In addition, the synchronized oscillation source is made in the form of a phase-locked loop, which contains a tunable oscillator connected to a ring, a frequency divider with a variable division coefficient, a phase detector and a loop filter, the reference input of the phase detector is a synchronization input.

 The line path also includes a filter that suppresses frequency harmonics of the power supply network.

 Moreover, the transmitting and receiving parts are blanked out between the voltage transitions of the power supply network through zero, mainly at time intervals located near the extremes of the mains voltage.

List of figures
In FIG. 1 shows an embodiment of a transmitting part of a system for transmitting and receiving modulated signals over a power supply network when a manipulator signal is used as a modulator.

 In FIG. 2 shows an embodiment of the receiving part of a system for transmitting and receiving modulated, for example, manipulated signals over a power supply network.

In FIG. 1 and 2 are presented:
1 - manipulator;
2 - synchronized oscillation source;
3 - output block interface with the channel;
4 - power supply network;
5 - tunable generator;
6 - frequency divider with a variable division ratio;
7 - phase detector;
8 - loop filter;
9 - matching unit;
10 - amplifier;
11 - attenuator;
12 - band-pass filter;
13 - digital-to-analog converter;
14 - input block interface with the channel;
15 - linear path;
16 - block transfer spectrum;
17 - signal discriminator;
18 is a synchronized source of oscillation;
19 - tunable generator;
20 - frequency divider with a variable division ratio;
21 - phase detector;
22 - loop filter;
23 - matching unit;
24 is a filter that performs harmonics suppression;
25 - band-pass filter;
26 - analog-to-digital Converter.

Information confirming the possibility of carrying out the invention
The possibility of carrying out the invention is confirmed by the following description of the operation of a system for transmitting and receiving modulated signals over a power supply network, in the case of using manipulated signals.

 The transmitted signals, for example data, are fed to the input of the transmitting part of the system, namely, to the input of the manipulator 1, in which they manipulate the carrier signal from the synchronized oscillation source 2. The carrier signal can be manipulated using one of the parameters, for example, in amplitude, frequency or phase, or several simultaneously, known in the prior art methods on this issue, including using quadrature (as shown in dashed line in Fig. 1). As a result of the manipulation at the output of the manipulator 1, both a narrow-band and a wide-band spectrum can be formed depending on the selected manipulation parameters. This spectrum can be placed symmetrically with respect to the carrier oscillation frequency, equal to mF, where F is the frequency of the power supply network, m is the harmonic number of the frequency of the power supply network, selected in the range from 10 to 20,000. The generated manipulated signal of the required level through the output interface unit with channel 3 enters the power network 4. The synchronized oscillation source 2 can be made in a variety of ways, but mainly in the form of a phase-locked loop, which contains connected tunable oscillator 5, a frequency divider 6 with a variable division coefficient, a phase detector 7 and a loop filter 8, the reference input of the phase detector 7 is a synchronization input of a synchronized oscillation source 2. The reference input of the phase detector 7 is connected to the output of the matching unit 9, at the input of which the voltage of the power supply network is supplied. The frequency of the tunable generator 5, divided by m times the frequency divider 6, is compared in the phase detector 7 with the frequency of the voltage of the power supply network 4, the amplitude of which is set by the matching unit 9. If there is a mismatch between the frequency of the tunable generator 5 and the mth harmonic of the frequency of the power supply network 4 at the output of the phase detector 7, an error signal is generated, which through the loop filter 8 acts on the tunable generator 5, tuning it to the frequency of the mth harmonic of the frequency of the power network power supply 4. Thus, due to the synchronization through the matching unit 9 of the synchronized oscillation source 2, made, for example, in the form of a phase-locked loop, the spectrum of the manipulated signal at the output of the manipulator 1 is always located at the frequency of the mth harmonic and, for example, narrow-band spectrum between m-1 and m + 1 harmonics, and for broadband - between m-1000 and m + 1000 harmonics.

 If the power of the manipulated signal at the output of the manipulator 1, which is determined by its specific implementation, is sufficient to transmit signals at a given distance, then the output of the manipulator 1 is directly connected to the input of the output interface unit with channel 3, the output of which is the output of the transmitting part for connecting to the power supply network 4 . If the power of the manipulated signal at the output of the manipulator 1 is insufficient, then in series between its output and the input of the output unit of the interface with channel 3 coupled amplifier 10 and attenuator 11, by which the output power can be adjusted. To reduce spurious components in the output signal between the output of the manipulator 1 and the input of the output unit of the interface with the channel 3, a band-pass filter 12 can also be included. If the manipulator 1 is digitally executed, the digital-to-analog converter 13 is turned on at its output. The indicated blocks can be any.

 The receiving part works as follows. The manipulated signal transmitted through the power supply network 4 at a frequency equal to mF, through the input interface unit with channel 14 is fed to the input of the linear path 15, in which it is converted in level and spectrum, i.e., the amplification and / or transfer of the spectrum to intermediate frequency, including, mainly, to zero, and / or filtering. The converted signal, for example, using the spectrum transfer unit 16, is then fed to a signal discriminator 17, at the output of which data signals are generated. A synchronized oscillation source 18 is used to transfer the spectrum in the linear path 15 and / or to detect it in the discriminator 17 of the signals 18. This source can be made in various ways, but mainly in the form of a phase-locked loop (PLL). Advantageously, the PLL circuit includes a tunable oscillator 19 connected in a ring, a frequency divider 20 with a variable division coefficient, a phase detector 21 and a loop filter 22. The reference input of the phase detector 21 is a synchronization input of a synchronized oscillation source 18. The reference input of the phase detector 21 is connected to the output of the block coordination 23, the input of which is supplied the voltage of the power supply network 4. The frequency of the tunable generator 19, divided m times by the frequency divider 20, is compared in the phase detector 21 the voltage frequency of the power supply network 4, the amplitude of which is set by the matching unit 23. If there is a mismatch between the frequency of the tunable generator 19 and the mth harmonic of the frequency of the power supply network 4, an error signal is generated at the output of the phase detector 21, which acts on the tunable generator through the loop filter 22 19, tuning it to the frequency of the mth harmonic of the frequency of the power supply network 4.

Thus, due to synchronization through the matching unit 23 of the synchronized oscillation source 18, made, for example, in the form of a phase-locked loop, its output signal is “tied” to the frequency harmonic of the voltage of the power supply network 4. Therefore, if it is used in linear path 15 for spectrum transfer, the spectrum transfer will be carried out at zero frequency. Usually, the spectrum is transferred to the zero frequency using two quadrature channels, each of which includes a series-connected multiplier and a low-pass filter (see, for example, V. I. Korzhik and others. "Calculation of noise immunity of discrete message transmission systems", M. , Radio and Communications, 1982, p. 59), using either the additional (quadrature) output of the synchronized oscillation source 18 (shown by a dotted line), or a phase shifter 90 ^{° is} switched on at one of the inputs of one multiplier.

 In angular manipulation, a phase discriminator can be used as discriminator 17 and in this case its reference input is connected to the output of the synchronized oscillation source 18 (shown by a dotted line if spectrum transfer is not performed in the linear path 15). If the spectrum is transferred to the intermediate frequency in the linear path 15, then the reference input of the discriminator 17 can either be combined with the reference input of the linear path 15 or connected to the output of a different frequency of the synchronized oscillation source 18. With this use of the synchronized oscillation source 18, the linear the working area of the discriminator 17. If the spectrum is transferred to the zero frequency in the linear path 15, the reference input of the discriminator 17 may not be connected to the output synchronously of the oscillation source 18, while the discriminator 17 can use the in-phase and quadrature (dashed line) outputs of the linear path 15.

 Since the voltage frequency of the power supply network 4 has instability, due to the phase-locked loop, the frequency of the carrier oscillation of the transmitting part, that is, the frequency from the tunable generator 5, becomes "floating". The frequency of the synchronized oscillation source 18 also becomes “floating”, which creates coherence during reception and, therefore, reduces the influence of interference caused by electrical equipment connected to the power supply network 4, while the interference frequencies are fixed — harmonics of the mains voltage, which can then be easily rejected . Thus, the specified technical result is achieved - increasing the noise immunity of the system.

 To further increase the noise immunity, a filter 24 can be included in the linear path 15, for example, at the input or output, which suppresses the harmonics of the frequency of the power supply network 4, made, for example, in the form of a synchronous notch comb filter (see, for example, L. E Leichter, “Calculation of comb filters”, M. “Sov. Radio” 1972, chapter 1) or adaptive compensator (see, for example, J. D. Shirman, “Resolution and compression of signals”, M. “Sov. Radio” 1974, 283-288, B. Widrow, S. Stearns "Adaptive signal processing", M., "Radio and communications", 1989, 288-29 9). For the operation of such filters, the frequency of the synchronized oscillation source 18 is used as a reference signal.

 If at the reception the signal processing is carried out in digital form, then the band-pass filter 25 and the analog-to-digital converter 26 should be sequentially included in the linear path 15.

 To increase the noise immunity, blanking of the transmitting and receiving parts in the intervals between the voltage transitions of the power supply network 4 through zero can also be used, mainly at time intervals located near the extremes of the mains voltage. For blanking, mainly keys are used that are included in the transmission and reception path practically anywhere, controlled by a pulse shaper, for example, a comparator, the input of which is connected either to the power supply network 4 or to the additional output of the synchronized oscillation source 18 (not shown) . The key functions can be assigned to almost any stage of the transmitting and receiving parts by supplying pulses from the specified pulse former as a blocking voltage to this stage.

 Matching blocks 9 and 23 can be made in the form of an attenuator, comparator, amplitude limiter, transformer, etc.

 The interface blocks with the channel 3 and 14 can be made, for example, in the form of a transformer, performing galvanic isolation from the power supply network 4, and a high-pass filter.

 If necessary, the organization of two-way data transmission can be applied to the second set of system. The transmitting part is provided with a receiving part, and the receiving part is supplied with a transmitting one, and, in addition, the return channel is tuned to the frequency nF, where the nth harmonic is selected in the same range as m. In simplex mode, m and n can be equal. In two-way transmission, the interface blocks with channel 3 and 14 can be combined and have one input, one output, and one input-output.

 For specialists in this field and other areas when reading this description will be clear other possible modifications of this invention. Such modifications may include other features known in the prior art, but not changing the essence of the invention, for example, appropriate modulation must be used for transmitting analog signals, i.e., the transmitting part uses, for example, a frequency modulator, and the receiving part uses a frequency modulator signal discriminator. The above-described variant of the system does not exhaust all their diversity, which can be implemented in accordance with the following claims.

Claims (4)

 1. A system for transmitting and receiving modulated signals over a power supply network, comprising a transmitting part including at least a modulator, a carrier frequency oscillator coupled to the modulator, and a channel output coupler, and a receiving part including, at least, a channel interface input block, a linear path and a signal discriminator, and a carrier frequency oscillator connected to the linear path and / or to the signal discriminator in series, characterized in that each carrier frequency oscillator is made in the form of a synchronized oscillation source, the synchronization input of which is connected to the output of the matching unit, while the inputs of matching units are inputs for connecting to the power supply network, and the synchronized sources of oscillation are tuned to the frequency mF, where F is the frequency of the power network power supply, m - its harmonic, selected in the range of 10 - 20,000.  2. The system for transmitting and receiving modulated signals over the power supply network according to claim 1, characterized in that the synchronized oscillation source is made in the form of a phase-locked loop containing a tunable oscillator connected in a ring, a frequency divider with a variable division coefficient, a phase detector and a loop filter The reference input of the phase detector is a synchronization input.  3. The system for transmitting and receiving modulated signals over a power supply network according to claim 1, characterized in that the linear path includes a filter that suppresses frequency harmonics of the power supply network.  4. The system for transmitting and receiving modulated signals over a power supply network according to claim 1, characterized in that the transmitting and receiving parts are blanked out between the voltage transitions of the power supply network through zero mainly at time intervals located near the extrema of the voltage supply.

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