SU1078582A1 - Device for generating carrier frequencies - Google Patents

Abstract

A DEVICE FOR GENERATING CARRYING FREQUENCIES, containing a series-connected master oscillator, a frequency multiplier, a binary counter and a block of permanent memory, as well as a band of bandwidth; That, in order to increase the spectrum purity of the generated oscillations, a sequentially connected inverter and a buffer register are entered into it, the information inputs of which are connected to the corresponding outputs of the fixed memory unit, and the inputs of the bandpass filter unit are connected to the corresponding outputs of the buffer register.

Description

The invention relates to telecommunications and can be used to generate a frequency grid in the equipment channel conversion of transmission systems with frequency multiplexing.

A device for generating carrier frequencies is known, comprising a serially connected master oscillator, a pulse shaper, and a carrier bandpass filter block [1J. 10

However, the known device for generating carrier frequencies has insufficient noise immunity due to the use for the formation of pulses with high carrier frequency 15 of the frequency uncertainty of primary ^- which creates a large phase noise.

The closest technical essence to the proposed one is a device for generating carrier frequencies, which contains a serially connected master oscillator, a frequency multiplier, a binary counter and a permanent memory unit, as well as a bandpass filter unit [2]. “

However, the spectrum of the generated oscillations of this device for generating carrier frequencies is also not clean enough due to the presence of spurious conversion products.

The purpose of the invention is to increase the purity of the spectrum of the generated oscillations. ! This goal is achieved by the fact that in the device for generating running frequencies, containing a serially connected master oscillator, a frequency multiplier, a binary counter and a permanent memory unit, as well as a bandpass filter unit, a serially connected inverter and a buffer register are introduced, the information inputs of which are connected to the corresponding outputs of the read-only memory block, and the inputs of the band-pass filter block are connected to the corresponding outputs of the buffer register. The drawing shows a structural electrical diagram of a device for generating a carrier frequency device., For generating non-carrier frequencies 50 contains a master oscillator 1, frequency multiplier 2, binary counter 3, read only memory block 4, buffer register 5, block 6 filter and inverter 7. '

A device for generating carrier frequencies operates as follows.

The signal from the master oscillator 1 is fed to a multiplier 2, at the output of which the signal frequency is determined by the largest common divider of the generated frequencies and the number of layers that can be recorded in the BPP 4. The bit depth of the layers recorded by the BPP 4 is equal to the number of generated carrier frequencies. Each digit contains information in the form of a sequence of ones and zeros, with the units corresponding, for example, to the positive half-wave of the generated carrier frequency, and the zeros to the negative half-wave. For the best noise immunity, the error in determining the need for zero or one does not exceed half the period of the clock frequency supplied from the multiplier 2. The signal from the multiplier 2 in the form of clock pulses is fed to the binary counter 3 addresses, the full counting cycle of which is equal to the number of layers recorded in the BPP 4. From the binary counter of chic 3, address codes of memory cells of BPP 4 are sequentially delivered to the address inputs of the BPP 4. At the outputs, in accordance with the information recorded in the memory cells, signals are generated that are fed to the information inputs of the buffer register 5. Further, the signals are in the form of pulse sequences, whose frequencies are equal to the frequency of the corresponding carrier, with a duty cycle close to two, from each output of the buffer register 5 are supplied to the corresponding inputs of the filters of block b bandpass filters, the outputs of which are allocated the necessary carrier frequencies.

An increase in the purity of the spectrum of generated oscillations is achieved due to the fact that at the outputs of the entered buffer register 5, signals with a high level of the corresponding carrier frequency are formed. In addition, the introduction of the inverter reduces the noise level in the carrier frequency signals by delaying the write clock signal in the buffer register 5 by the time required to read data from the BPP.

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Claims (1)

A DEVICE FOR GENERATING CARRIER FREQUENCIES, which contains a serially connected master oscillator, a frequency multiplier, a binary counter and a constant memory unit, as well as a bandpass filter unit, which are included in order to increase the purity of the spectrum of generated oscillations a series-connected inverter and a buffer register, the information inputs of which are connected to the corresponding outputs of the read-only memory block, and the inputs of the band-pass filter unit are connected to the corresponding outputs of the buffer register a.