RU2236754C2 - Method and device for telemetering data transfer using time-and-frequency-division multiplexed radio channel and analog-to-digital method for carrier conversion - Google Patents

Abstract

FIELD: radio-metering systems; data transfer using time-and-frequency-division multiplexed radio channel.

SUBSTANCE: data transfer is effected in several concurrent streams with time division of channel being made in each stream at clock frequency with on-off time ratio O = 2, each stream being separated from adjacent one with respect to carrier by frequency interval equal to F_cl like n and shifted in time through half the time step.

EFFECT: enhanced throughput of radio channel in restricted frequency band while retaining energy potential of radio line.

3 cl, 7 dwg

Description

The invention relates to radio telemetry systems, in particular to methods for transmitting information with time-frequency compression of a radio channel.

A known method of transmitting telemetric information with a frequency division of channels (1). Moreover, each of the N information sources (for example, telemetry sensor) is allocated a specific frequency band Δ f _k . The total frequency band will be Δ f _rev = Σ Δ f _k , where k = (1 ... N) is the number of system channels.

The disadvantage of this method is the limited number of channels and a sharp increase in the required radio frequency band with an increase in the number of system channels.

A known method of transmitting information with pseudo-random tuning of the operating frequency in a wide frequency band that exceeds the band necessary for transmitting useful information (4). The number of tunable frequencies and the order of their alternation in time and frequency band is determined by random codes. In this way, due to the expansion of the frequency band occupied by the signal on the air, the useful signal is provided when the signal-to-noise ratio is many times smaller than unity.

However, this method of signal transmission cannot be applied in telemetry, because its implementation would require the use of an unreasonably large frequency band on the air.

A device is known for transmitting information through two parallel channels, in each of which information from the sensors is transmitted alternately, i.e. time division (2). comprising a filter, a reference generator, a multiplier, first and second amplifiers, first and second power amplifiers, a first controlled generator, a mixer, the first input of which is connected to the first output of the second controlled generator.

The closest in technical essence to the claimed device is a device for transmitting information through two parallel channels (3), containing a reference oscillator, two phase detectors, two controlled generators, two power amplifiers.

However, the known technical solution does not allow to increase the amount of information transmitted by increasing N times the number of information streams transmitted in the radio channel while simultaneously compressing the frequency spectrum on the air and keeping the radio line energy constant.

The expected technical effect of the method and device for transmitting information with time-frequency channel multiplexing is to increase the bandwidth of the radio channel in a limited frequency band while maintaining the energy potential of the radio line.

This goal is achieved by the fact that the information is transmitted over several synchronously radiated with a duty cycle of Q = 2 radio streams spaced from each other along the carrier frequency by a certain frequency interval.

For this, in the method of transmitting information with time-frequency multiplexing of the radio channel and the analog-digital method of modulating the carrier frequency, the information is transmitted in N (where N = 2, 4, 8 ...) synchronous streams, in each of which at the clock frequency F _so channels are separated in time with a duty cycle of Q = 2, and each stream is separated from the adjacent carrier frequency by the frequency interval Δ f _p = F _so · n (where n = 5, 7 ...) and is half shifted in time tact

In addition, in order to narrow the spectrum of radio frequencies occupied by several on-board devices on air, the operation of these on-board devices is synchronized by the signals of the master oscillator of one of them, while the first information stream of the synchronized on-board device is carried in frequency from the last information stream of the synchronizing on-board device to the frequency interval Δ f _p = F _so · n (where n = 5, 7 ...) and shift in time by half a clock

In addition, in a device for implementing a method of transmitting information with time-frequency multiplexing of a radio channel and an analog-to-digital method of modulating a carrier frequency, comprising a reference carrier frequency generator (19), first and second controlled generators (17, 18), first and second power amplifiers (20,21), the first frequency modulator (13), the first and second phase detectors (15, 16), the inputs 2 of which are connected to the first outputs of the controlled generators (17, 18), the outputs 2 of which are connected to the inputs of the power amplifiers (20, 21), input 3 of the first phase detector the ora (15) is connected to the first output of the reference carrier frequency generator (19), the input of the first controlled generator (17) is connected to the output of the first frequency modulator (13), the power adder (22), the second frequency modulator (14), the first and second frequency “stand” shapers (11, 12), first and second adders (9, 10), four switches (5, 6, 7, 8), a divider (2), a marker pulse shaper (3), a key (4), a clock generator (1), the antiphase outputs 1 and 2 of which are connected in pairs with the inputs of the switches (5, 6 and 7, 8), as well as with inputs of the 1 form rovateley frequency "cradle" (11, 12); the outputs of the switches (5, 6) are connected to the first adder (9), and the switches (7, 8) to the second adder (10); output 3 of the first adder (9) is connected to input 1 of the first frequency modulator (13) and input 2 of the key (4); the output 3 of the second adder (10) is connected to the input 1 of the second frequency modulator (14), and the outputs 3, 4 of the key (4) with the inputs of 1 phase detectors (15, 16), the outputs of the phase detectors (15, 16) are connected to inputs 2 frequency modulators (13, 14), the input 3 of the second phase detector (16) is connected to the second output of the reference carrier frequency generator (19), the output of the clock generator (1) is connected through the divider (2) to the input of the marker pulse shaper (3), the output of which is connected to the input 1 of the key (4); the outputs of the frequency “stand” shapers (11, 12) are connected to the inputs of 3 frequency modulators (13, 14); the output of the second modulator (14) is connected to the input of the second controlled generator (18), the outputs of the power amplifiers (20, 21) are connected to the inputs of the power adder (22).

Figure 1 shows the structure of the video and radio signal of a single-threaded telemetry system used to form a multi-threaded signal.

Figure 2 shows the structure of a four-stream radio signal.

Figure 3 shows the spectra of two synchronously operating four-line onboard telemetry devices.

Figure 4 shows a block diagram of a device for generating and transmitting a four-stream radio signal.

Figure 1 presents:

a) video pulses at the input of the frequency modulator of a single-threaded transmitter;

b) pulses that lock the output stage of the transmitter and provide the emission of signals on the air with a duty cycle of Q = 2;

c) radio pulses at the output of the transmitter.

-ЧМ), где АИМ - амплитудно-импульсная модуляция, КИМ - кодоимпульсная модуляция. При формировании многопоточного сигнала метод модуляции несущей каждого потока сохраняется прежним.In a single-threaded transmitter, the measurement information is transmitted by the frequency modulation (FM) method of the carrier frequency in analog or digital form (modulation is used

-FM), where AIM is pulse-amplitude modulation, KIM is pulse-code modulation. When generating a multi-threaded signal, the carrier modulation method of each stream remains the same.

When switching to a two-stream radio line (doubling the information content of the system), a second stream operating at the same clock frequency F _so that the first stream is placed in pauses of a single-stream radio line (Fig. 1). To ensure the reception of these streams without interference, the carrier frequencies of both streams are distributed over the frequency interval Δ f _p = F _so · n (n = 5, 7 ... an odd integer determined experimentally from the minimum allowable interference between the streams at the minimum frequency separation).

, и по несущей частоте на частотный интервал Δ f_р=F_так· n (где n=5, 7). Потоки 1 и 3 излучаются одновременно, но частотный разнос между ними увеличен в 2 раза: Δ f_р=2F_так· n; также одновременно и с таким же частотным разносом излучаются потоки 2 и 4. Переход одного потока к другому осуществляется без разрыва фазы несущего колебания, что снижает уровень побочных составляющих спектра радиосигнала. Этому же способствуют и кратность частотного разноса Δ f_р тактовой частоте F_так. Передатчик излучает радиосигналы в эфир непрерывно со скважностью Q=1.When moving to a four-stream radio line (four times increase in information content compared to a single-stream radio line), the formation of the total four-stream radio signal is carried out from two synchronous two-stream signals (figure 2); in this case, all streams are synchronized from one clock generator operating at a frequency F _so ; the second stream is placed in the pauses of the first stream, the third stream is in the pauses of the second, the fourth is in the pauses of the third; streams 1 and 2, 2 and 3, 3 and 4 are separated in time by an interval

, and the carrier frequency per frequency interval Δ f _p = F _so · n (where n = 5, 7). Streams 1 and 3 are emitted simultaneously, but the frequency spacing between them is increased 2 times: Δ f _p = 2F _so · n; also at the same time with the same frequency separation, streams 2 and 4 are emitted. The transition of one stream to another is carried out without breaking the phase of the carrier wave, which reduces the level of side components of the spectrum of the radio signal. This also contributes to the frequency spacing Δ f _{p the} clock frequency F _so . The transmitter emits radio signals on the air continuously with a duty cycle of Q = 1.

Figure 2 provides the placement of flows in the time-frequency plane; here: f _n1 , f _n2 , f _n3 , f _n4 - carrier frequencies of flows; Δ f _p is the frequency spacing between the streams; 2Δ f is the magnitude of the measuring scale of the flow; M - marker impulse.

When transmitting information with time-frequency compression of streams, the reception of signals of each stream is carried out by a separate receiving device, the bandwidth of which is optimized for the clock frequency of the stream. This ensures, with a constant transmitter power, maintaining the constant energy potential of the radio link, despite the increase in the information content of the system.

As a rule, when conducting telemetry on a test rocket, several onboard telemetry systems are installed that operate independently of each other.

In this case, to exclude the mutual influence of on-board devices, taking into account possible power transfers in the received signal, the carrier frequencies of the transmitters are carried on the frequency scale by the interval Δ f _p ≈ 25 · F _so

(см. фиг.3); этот порядок сохраняется при синхронизации третьего, четвертого и последующих бортовых устройств.To narrow the carrier frequency band occupied by several telemetry systems on the air, it is proposed to synchronize the on-board device switches from the clock generator of one of the on-board devices; the transmitter of the synchronized on-board device is tuned so that its first stream must stand (on the carrier frequency scale) from the frequency of the last stream of the synchronizing on-board device in the frequency interval Δ f _p = F _so · n (where n = 5, 7 ...) and shifted in time by half a beat

(see figure 3); this order is maintained during synchronization of the third, fourth and subsequent on-board devices.

The analysis shows that in the frequency band that provides operation without interference of two single-threaded non-synchronous airborne devices, it is possible to place two four-threaded, synchronously operating airborne devices and transmit three times as much information, which confirms the efficient use of the carrier frequency band for time-frequency radio channel multiplexing .

Figure 4 shows a block diagram of a device for generating and transmitting a four-stream radio signal for implementing a method for transmitting telemetric information with time-frequency compression of a radio channel.

A device for implementing the method comprises: a clock generator (1); frequency divider (2); marker pulse shaper (3); key (4); clock switches (5), (6), (7), (8); adders (9); (10); shapers of the frequency “stand” (11), (12); frequency modulators (13), (14); phase detectors (15), (16); controlled generators (17), (18); reference generator (19); power amplifiers (20), (21); power adder (22).

(половина такта), аналогично сдвинуты и потоки 3, 4 с выхода коммутаторов (7, 8). После сложения потоков 1, 2 в сумматоре (9) и потоков 3, 4 в сумматоре (10) потоки с удвоенной частотой 2F_так поступают на входы частотных модуляторов (13, 14), осуществляющих частотную модуляцию несущей частоты пропорционально напряжению, передаваемому по каналу системы в моменты его опроса коммутатором. На каждый частотный модулятор также поступают импульсы частоты F_так с выхода соответствующего формирователя частотной “подставки” (11, 12), обеспечивающие скачкообразное изменение частоты модулятора и раздвигающие по частоте потоки 1, 2, а также 3, 4 между собой на частотный разнос Δ f_p=F_так· n, при этом скачок частоты происходит без разрыва фазы несущего колебания. Кольцо фазовой подстройки частоты (ФАПЧ) блоки (13, 15, 17, 19) обеспечивает подстройку несущей частоты потока по уровню маркерного импульса, значение которого соответствует середине измерительной шкалы потока и номинальному значению несущей частоты излучаемого сигнала.The device operates as follows: four switches (5, 6, 7, 8) that carry out the collection of measurement information are synchronized from one clock generator (1) operating at a frequency F _{like this} . Synchronization is carried out in such a way that flows 1, 2 from the output of the switches (5, 6) are shifted between themselves temporarily

(half clock cycle), flows 3, 4 from the output of the switches are similarly shifted (7, 8). After addition of streams 1, 2 in the adder (9) and streams 3 and 4 in the adder (10) flows 2F twice the frequency _as applied to inputs of frequency modulators (13, 14), carrying out a frequency modulation of the carrier frequency is proportional to the voltage transmitted through the channel system at the moments of his interrogation by the switch. At each frequency modulator also receives pulses of frequency F _as output from the corresponding driver frequency "cradle" (11, 12), providing an abrupt change in the modulator frequency and Spreading frequency flows 1, 2, and 3, 4 to each other in the frequency spacing Δ f _p = F _so · n, while the frequency jump occurs without breaking the phase of the carrier oscillation. The phase-locked loop (PLL) blocks (13, 15, 17, 19) provide adjustment of the carrier frequency of the stream according to the level of the marker pulse, the value of which corresponds to the middle of the measuring scale of the stream and the nominal value of the carrier frequency of the emitted signal.

The PLL-1 operation provides a binding of the carrier frequencies of streams 1, 2 to each other and to the frequency of the reference oscillator (19), the PLL-2 provides a binding of the carrier frequencies of flows 3, 4 to each other and to the carrier frequency of the stream 1, since the phase-locked PLL detector 2 (16) through the key (4), the marker pulse of the first stream arrives for tuning.

High-frequency signals from the outputs of controlled frequency generators (17, 18) after amplification in power in power amplifiers (20, 21) are added (22) and fed to the input of the on-board antenna.

Sources of information

1. Krassner G.N., Michaels J.V. Introduction to space communication systems., Chap. 7th ed. 1967.

2. British patent No. 1108564, H 4 L, 1968.

3. A.S. No. 938417, 1982.

4. Borisov V.I., Zinchuk V.M. Interference immunity of radio communication systems. M .: Radio and communications, 2000.

Claims (3)

1. A method of transmitting information with time-frequency compression of a radio channel and an analog-to-digital method of modulating the carrier frequency in on-board devices, characterized in that the information is transmitted from each on-board device in N (where N = 2, 4, 8 ...) synchronous flows, in each of which at the clock frequency F _{, the} channels are separated in time with a duty cycle of Q = 2, and each stream is spaced from the neighboring carrier frequency in the frequency interval Δ f p = F _so · n (where n = 5, 7 ...) and shifted in time by half a beat

2. The method of transmitting information according to claim 1, characterized in that to exclude the mutual influence of the on-board devices, the on-board devices are synchronized by the signals of one of them, while the first stream of the synchronized on-board device is carried on a frequency scale from the last stream of the synchronized on-board device to the frequency interval Δ fp = F _so · n, (where n = 5, 7 ...) and shift in time by half a clock

3. A device for implementing the method according to claim 1, comprising a reference carrier frequency generator (19), first and second controlled oscillators (17, 18), first and second power amplifiers (20, 21), a first frequency modulator (13), a first and the second phase detectors (15, 16), the inputs 2 of which are connected to the first outputs of the controlled generators (17, 18), the outputs 2 of which are connected to the inputs of the power amplifiers (20, 21), the input 3 of the first phase detector (15) is connected to the first the output of the reference carrier frequency generator (19), the input of the first controlled generator (17) is connected to the course of the first frequency modulator (13), characterized in that a power adder (22), a second frequency modulator (14), the first and second frequency “shaper” drivers (11, 12), the first and second adders (9, 10) are introduced into it ), four switches (5, 6, 7, 8) that carry out the collection of measurement information, a divider (2), a marker pulse shaper (3), a key (4), a clock generator (1), the antiphase outputs 1 and 2 of which are connected in pairs with the inputs of the switches (5, 7, and 6, 8), as well as with the inputs of 1 shapers of the frequency “stand” (11, 12); the outputs of the switches (5, 6) are connected to the first adder (9), and the switches (7, 8) to the second adder (10); output 3 of the first adder (9) is connected to input 1 of the first frequency modulator (13) and input 2 of the key (4); the output 3 of the second adder (10) is connected to the input 1 of the second frequency modulator (14), and the outputs 3,4 of the key (4) with the inputs of 1 phase detectors (15, 16), the outputs of the phase detectors (15, 16) are connected to inputs 2 frequency modulators (13, 14), the input 3 of the second phase detector (16) is connected to the second output of the reference carrier frequency generator (19), the output of the clock generator (1) is connected through the divider (2) to the input of the marker pulse shaper (3), the output of which is connected to the input 1 of the key (4); the outputs of the frequency “stand” shapers (11, 12) are connected to the inputs of 3 frequency modulators (13,14); the output of the second frequency modulator (14) is connected to the input of the second controlled generator (18), the outputs of the power amplifiers (20, 21) are connected to the inputs of the power adder (22).

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