SU815900A1 - Code-to-harmonic signal frequency converter - Google Patents

Description

(54) HARMONIC SIGNAL CODE-FREQUENCY CONVERTER

keys to the input of the low-pass filter, and a clock generator, a frequency divider, a random number generator, a digital multiplying device, an adder, a counter, a reference element and an And element are entered, the clock generator output being connected by a counter of the counter, the first input of the And element and the frequency divider input The output of which is connected to the reset input of the counter, the second input of the accumulator and the input of the random number generator, the first output of which is connected to the first input of the comparison element, and the second output to the first digital input multiplies device, the second input of which is connected to the output of the frequency code register, and the output is connected to the first input of the adder, the second input of which is connected to the output of the accumulator, and the output is connected to the input of the sine calculator, the output of the counter is connected to the second input of the comparison element, the output of which is connected to the second input element And, the output of which is connected to the second input of the code-analogue converter.

The drawing shows a structural electrical converter circuit.

The converter contains a frequency code register 1, a drive 2, a sine calculator 3, a code-analog converter 4, a low-pass filter 5, a clock generator, a torus 6, a frequency div 7 frequency, a random number generator 8, a digital multiplier 9, an adder 10 , counter P, element 12 comparison, logical element AND 13.

The Converter operates as follows.

Register 1 is for recording and storing a frequency code. With a cycle equal to the period of the frequency at the output of the divider, this code is added to the contents of accumulator 2, forming a new value of the phase of the synthesized signal corresponding to the front of the clock pulse, which is forwarded by frequency divider 7. The same pulse is used to generate a new random number in the generator 8 of a random number and to zero the counter I. In the digital multiplier 9, the frequency code is multiplied by a random number, the result of multiplication is the increment of the synthesized signal phase for an integer random number of periods of the 6 Counter 11, code comparison element 12 and And 13 element form a write pulse in the code equivalent converter, delayed relative to the pulse at the output of frequency divider 7 by a random determination. ate emoe 8 random number generator, the number of cycles of the generator 6. The adder 10 calculates a phase value corresponding to the recording pulse edge in the sine calculator 3 is formed a digital amplitude value corresponding to this value of phase. In a code equivalent transducer, a digital amplitude value is converted to an analog signal filtered in a filter.

5 low frequencies to reduce harmonics.

Thus, in the considered code-frequency converter, pseudo-random modulation of the sampling clock frequency is performed, which has the effect of reducing the level of the discrete components of the side spectra in the range from 0 to the frequency of the clock generator 6, the limitations of which are imposed by the speed

digital circuits, rather than the speed of a multi-bit code-analog converter, which is an order of magnitude lower than the speed of digital circuits.

The use of pseudo-random frequency modulation in the code-frequency converter allows you to extend the tuning range of the synthesizer to higher frequencies and get more suppression of discrete parasitic components, which expands the range of applications

such synthesizers.

Claims (2)

1. Author's certificate of the USSR 5 No. 191894, cl. H 03 K 13/02, 1967. 2. Tyrney, Gold, Raider. Digital frequency synthesizer. - “Foreign Radioelectronics, 1972, No. 3, p. 60, fig. 4 (prototype).