SU1109933A1 - Frequency-shift keyer - Google Patents

Abstract

A FREQUENCY MANIPULATOR containing a series-connected reference oscillator of stable frequencies J / and a controlled frequency divider with a variable division factor, characterized in that, in order to spread the frequency range while increasing the accuracy of the generated signal, a balancing unit, a counter, a memory block and a digital-to-analog converter whose outputs are connected to the input of a balancing unit, the output of which is connected to one input of the digital-to-analog converter, to the other inputs of which yucheny outputs the memory block, the inputs of which are connected to the outputs of the counter, which is connected to the input of the controllable output frequency divider with variable division ratio.

Description

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Output The invention relates to a technique for transmitting discrete information over channels of a tonal part and can be used in multi-frequency systems for transmitting discrete information for multipositional frequency shift keying. A frequency manipulator is known that contains a carrier frequency generator, whose magnitude is determined by the p-resonance circuit with inductance and capacitance, and two circuit bridges designed to carry out frequency manipulation of the carrier frequency lj. However, this manipulator has a low accuracy of the generated signal. The closest technical solution to the proposed is a frequency manipulator containing serially connected reference oscillator of stable frequency and controlled frequency divider with variable division factor 2. However, the known frequency manipulator has a narrow frequency range and low accuracy of the generated signal. The purpose of the invention is to expand the frequency range while improving the accuracy of the generated signal. This goal is achieved by introducing a balancing unit, a counter, a memory unit and a digital-to-analog converter, the outputs of which are connected to the inputs of the balancing unit, into a frequency manipulator containing a serially connected reference generator of stable frequency and an adjustable frequency divider with variable division factor. the outlets of which are connected to one input of the cyanalog converter, to the other inputs of which are connected the outputs of the memory unit, the inputs of which are connected to the outputs of the counter, to the input of which under The output is an adjustable frequency divider with a variable division factor. The drawing shows the structures on the electrical circuit of the proposed manipulator. The frequency manipulator contains a stable frequency reference oscillator 1, a variable frequency controlled divider 2 with a variable division factor, a counter 3, a memory block 4, a digital-to-analog converter 5, a balancing block 6. Frequency manipulator works as follows. The controlled divider 2 performs frequency division of the stable frequency reference oscillator 1 in accordance with the binary code received at its inputs 1 ... n. The pulses from the output of the controlled divider 2 are fed to the input of counter 3, which generates the current sequence of all sinusoid addresses . The highest frequency of formation is chosen based on the speed of the selected elements. The current sequence of addresses from the output of counter 3 is fed to the inputs of memory block 4, where sequential sampling of sine codes is made, which are fed to the inputs of the analog to analog converter 5. From the outputs of digital to analog converter 5, there are unipolar anti-phase signals that are is converted by the balancing unit 6 into a two-pole symmetric sinusoidal signal. The accuracy of the approximation of the sinusoidal signal generated at the output of the digital-to-analog converter 5 is determined by the number of times, quantization intervals, and the number of approximation levels. In order to expand the generated frequency range, it is necessary that the non-linear distortions be minimal for the entire range of generated frequencies. When forming a sinusoidal signal in a discrete way, the amount of nonlinear distortion is determined by the number of quantization time intervals and the number of approximation levels of the sinusoidal signal. The longer the quantization time intervals and the approximation, the smaller the nonlinear distortion, the greater the range of frequencies generated. In the known frequency manipulator, the number of quantization time intervals and the number of approximation levels are defined as, where m is the number of states of the distributor. In the proposed frequency manipulator, the number of time slots 3 11099 quantization is defined as, where m is the number of states of counter 3, and the number of approximation levels of the sinusoid are as, where k is the number of binary steps of the digital-to-5 conversion of the analogue converter 5, quantization q t ... and the minimum approximation level IT mm. 2 where TGRO is the period of a sinusoidal signal; 34 Umax is the amplitude of the sinusoidal signal. Thus, the number of quantization time intervals and the number of approximation levels in the proposed frequency manipulator is much larger than in the known device with equal number of counters and distributor outputs, and hence nonlinear distortions are much smaller, which allows It does not extend the generated frequency range and significantly improve the accuracy of the generated signal.

Claims (1)

FREQUENCY MANIPULATOR, containing serially connected inputs of which are connected to the outputs of the counter, to the input of which the output of the controlled frequency divider is connected SU,. „1109933