Device for transmitting frequency-shift keyed signals

 

(57) Abstract:

Usage: in radio engineering. The inventive device comprises a generator 1 clock frequency dividers 2,8,9 frequency generator 3 numeric sequence, a binary switch 4, the generator 5 of the Walsh function, the key 6, the source 7 DC voltage, multiplier products 10, 14, the inverter 11, the control delay line 12, the switch 13. 1 table, 4 Il.

The invention relates to electrical engineering and can be used in radio communication, radar, radio telemetry, radio control for forming a frequency-shift keyed signals.

A device for transmitting frequency-shift keyed signals,comprising a generator of clock frequency, a frequency divider, the clock frequency, the frequency divider, the numerical sequence generator, a binary switch. the function generator Walsh, a key circuit and the constant voltage source [1].

However, the known device has a low data transmission rate in a given channel bandwidth.

The closest in technical essence to the invention is a device for transmitting frequency-shift keyed signals containing the aqueous voltage, a second frequency divider, a third frequency divider, multiplier and a controlled inverter, and the output clock frequency is connected to the input of the first frequency divider, the first information input binary switch and a clock generator input numeric sequence, the output of which is connected with the control input of the binary switch, the output of the first frequency divider is connected to a second information input binary switch, the output of which is connected to a clock input of the function generator Walsh, the inputs of the second and third frequency dividers connected to the output of the binary switch, and outputs respectively to the first and second inputs of the multiplier, the output of which is connected to the output of the function generator Walsh, the output of the controlled inverter connected to a second input key, the first input connected to the output of the constant voltage source, the output key is the output of the device [2].

However, the known device has a low data transmission rate in a given channel bandwidth.

The aim of the invention is to increase the speed of information transmission in a given channel bandwidth.

The objective is achieved by the sequences, binary switch, the function generator Walsh, a key source of continuous voltage, the third frequency divider, the first multiplier and a controlled inverter, and the output clock frequency is connected to the input of the first frequency divider, the first information input binary switch and a clock generator input numeric sequence, the output of which is connected with the control input of the binary switch, the output of the first frequency divider is connected to a second information input binary switch, the output of which is connected to a clock input of the function generator Walsh, the inputs of the second and third frequency dividers connected to the output of the binary switch, and outputs respectively to the first and second inputs of the first multiplier, the output of which is connected with the control input of the control inverter, an information input connected to the output of the function generator Walsh, the first input key is connected to the output of the constant voltage source, the output key is the output of the device, entered controlled delay line, the switch and the second multiplier and the output of the second frequency divider connected to the first input of the switch and information input controlled output of controllable delay line connected to the second input of the switch, the output of the switch is connected to the first input of the second multiplier, the second input is connected to the output of the controlled inverter, and the output of the second multiplier connected to the second input of the key.

In Fig.1 ppedstavlene structura diagram of the device for transmitting frequency-shift keyed signals; Fig.2 is a timing diagram illustrating the process of forming the output signal S1(6,) in the proposed device, and Fig.3 - the appearance of signals at the output predlagaemogo device.

The device comprises a generator 1 clock frequency, the first frequency divisor of 2, the generator 3 numeric sequence, a binary switch 4, the generator 5 of the Walsh function, the key 6, the source 7 of constant voltage, a second divider 8 frequency, the third divider 9 frequency, the first multiplier 10, a controlled inverter 11, controlled delay line 12, a switch 13, a second multiplier 14.

Device for transmitting frequency-shift keyed signals is as follows.

Generator 3 numeric sequence forms (Fig.2B) the information symbols of "1" or "0" to be transferred. Binary switch 4 controlled numerical sequence from the output of the generator 3 Chiyoda divider 2 frequency (Fig.2B), having a division factor equal to two. If the control input binary switch 4 receives "1", then it skips to the clock input of the generator 5 of the Walsh function signal clock frequency, and if the control input is a binary commutator 4 goes to "0" then it skips to the clock input of the generator 5 of the Walsh function signal from the output of the divider 2 frequency. Thus, when the transfer informatsioonogo symbol "1" at the output of the function generator Walsh (Fig.2 d) are formed in the two periods of the Walsh function for the time T, and when the transmission information symbol is "0" at the output of the generator 5 of the Walsh function is formed by one period of the Walsh function for the time T (where T is the duration of "1" or "0").

The pulses from the output of the binary switch 4 (Fig.2 g) are provided to the inputs of the second and third dividers 8 and 9 frequency. Since the division ratio of the divider 9 frequency equal to 2n-1then during the first half period of the formation of Walsh functions at the output of the divider 9 (Fig.2ZH) frequency formed "1", and during the second half period is "0". The division factor of the divider 8 frequency equal to two, resulting in the period of formation of the Walsh functions at the output of divider 8 frequency (Fig.2E) is formed by a sequence of "1" iitala 10 (Fig.2H) is formed "1" only during the first half of the Walsh function in the moments of the formation of the odd-numbered elements of the Walsh functions.

In case of "0" on uplause the input of the control of the inverter 11 is the inverse of the function items Walsh, arriving at its Informatsionnyi entrance, and in the presence of a "1" at the control input of the controlled inverter 11 inverts elements is not carried out. Thus, during the formation period of the Walsh function output controlled invetor 11 (Fig.2) is formed, the signal S (i) , the form of which differs from the waveform Walsh Wal (i,).

The output signal of the second divider 8 frequency supplied to the information input of controllable delay line 12. When it arrives at the control input line 12 delay "1" output from the generator 3 numeric sequence in lines 12 delay is the delay of the signal by the value of t equal to the duration element of the Walsh function in the formation of two periods of Walsh functions over time So When it arrives at the control input line 12 delay is the delay of the signal by the value of 2t, the same length as the element of the Walsh function in the formation of one period of the Walsh functions over time So

The control switch 13 is carried out prior to the operation of the device for transmitting frequency-shift keyed signals. This Moreta.

If the output of the controlled inverter 11 is formed, the signal S(i) with sequence number 0, ...,2n-1-1, prior to the operation of the device, the operator sets the switch to the left (first) position (i.e., performs output switching switch 13 with his first entrance, in other words, connects the first input of the multiplier 14 with the output of divider 8 frequency).

If the output of the controlled inverter 11 is formed signal S(i,) with sequence number 2n-1,...,2n-1, prior to the operation of the device, the operator sets the switch in the right (second) position (i.e., performs output switching switch 13 to its second input, in other words, connects the first input of the multiplier 14 with the output of controllable delay line 12). In Fig. 1, the switch 13 is set as described in the second case.

If the output of the controlled inverter 11 is formed, the signal S(i) with sequence number 0,...2n-1-1 (for example, for N = 8 the signal from one of the sequence numbers 0, 1, 2, 3), before the beginning of operation the output of the switch 13 is switched to its first input. As a result, the pulses from the output of divider 8 frequency (Fig.2E) are fed to the first input of the multiplier 14, the output of which four output controlled inverter 11 is formed, the signal S(i) with sequence number 2n-1,...2n-1 (for example, for N = 8 the signal from one of the sequence numbers 4, 5, 6, 7), before beginning the work and the output of the switch 13 is switched to its second input. As a result, the pulses from the output of delay line 12 (Fig.2i) are fed to the first input of the multiplier 14, the output of which form only even-numbered pulses of the signal S(i) supplied to the second input of the multiplier 14.

As a result, the output of multiplier 14 is formed, the signal S'(i,) at the input of key circuit 6, the output of which is an output device. Source 7 DC voltage and the 6 key functions of the amplifier signal S'(i,) to the level required for radiation.

In the diagrams of Fig.2 shows the temporal state of the outputs of the generator 1 clock frequency (a), the generator 3 numeric sequence (b), the divisor 2, frequency (), binary switch 4 (d) of the generator 5 of the Walsh function, on which a signal is generated Wal (6,) (d), the divider 8 frequency (f), divider 9 frequency (W), multiplier 10 (C), the output controlled inverter 11, which is formed by the signal S(6,) (and), controlled line 12 delay (s) multiplier 14, which is formed by the output signal S'(6,) ().

In Fig.3 shows the shape of the signals S, if the modulating signal is the same for all signals of the two devices.

It is known that the transmission rate information and the length of the binary symbol T be the transmission, connected by the relation

R = 1/T (1) (cm. Varakin L. E. Theory of systems of signals. M: Soviet radio, 1978, S. 54, the ratio of 2.12). The duration of the binary symbol T in the proposed device is equal to the period of the Walsh functions (in the case of transfer "0") or two periods of Walsh functions (in the case of transfer "1"). However, when a given channel bandwidth, the duration T is determined by the spectral width of the modulated signal

WeffWchannel, (2) where W is channel - sadana the channel bandwidth. The less effective spectral width of the modulated signal, the in less time T can be transmitted in a given channel bandwidth, therefore, the higher the speed of information transmission.

System output signals generated by the proposed device, and system output signals generated by the prototype is orthogonal, it is easily seen by multiplying two signals included in one system. If all of the spectra of the signals within the system are of the same width and the signals; F - width of the spectrum of a single signal). When different widths of spectra Fsist= Fmax- maximum width of the spectrum (see Varakin L. E. Theory of systems of signals. - M.: Soviet radio, 1978, S. 11).

In the device, taken as a prototype, forming output signals S (i ). It is known that the more blocks the signal (block - a sequence of identical elements), the more efficient signal spectrum width Weff(see Varakin L. E. Theory of systems of signals. - M.: Soviet radio, Moscow (1978). S. 208). The output signals generated prototipo have the number of blocks

= or = , and the maximum effective width of the spectrum of the output signal with regard to = is determined according to the expression

Weff= (3) where t is the duration element signal; - number of blocks; N is the number of elements.

In the proposed device, all output signals S'(i) have the same number of blocks

= (4) and the maximum effective width of the spectrum of the output signal determines by the ratio (3) subject to = (Fig.4).

Taking into account relations(1), (3), (4) were calculated transmission rate of the analog prototype and offer the device at a fixed channel bandwidth and rasledovanie proposed device for transmitting frequency-shift keyed signals makes it possible to increase the speed of information transmission in a given channel bandwidth in 1.19 times for N = 4, 1.09 times for N = 8 and so on

DEVICE FOR TRANSMITTING FREQUENCY-shift keyed SIGNAL containing the clock frequency, the output of which is connected to the inputs of the first frequency divider and oscillator numerical sequence and the first information input binary switch, the second information input connected to the output of the first frequency divider, the output of the generator numeric sequence is connected with the control input of the binary switch, the output of which is connected to the input of function generator Walsh, second and third frequency dividers, the outputs of the latter are connected to the corresponding inputs of the first multiplier, the output of which is connected with the control input of the control inverter, an information input connected to the output of the function generator Walsh, and the constant voltage source, the output of which is connected to the first input key whose output is the output of the device, characterized in that it introduced serially connected controllable delay line, the switch and the second multiplier and the output of the first frequency divider is connected to the information input of controllable delay line and the other input of the switch, you is ljuca, the control input of controllable delay line is connected to the generator output numeric sequence.

 

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