SU824401A1 - Frequency band shifting device - Google Patents

Description

(54) FREQUENCY SHIFT DEVICE

I

The invention relates to radio engineering and can be used to shift a signal's frequency band, in signal processing systems.

A bandwidth shifter is known, comprising a series-connected sawtooth pulse generator, an adder and a threshold element, while the other input of the adder is an input of the device 1.

However, the known device has low accuracy.

The purpose of the invention is to improve the accuracy,

The delivery target is achieved in that the adder and the threshold element are connected in series to a frequency band shifter comprising a sawtooth pulse generator connected in series, another adder input being the device input, a subtractor inputted, the inputs of which are respectively connected to the output of the adder and the output of the threshold element and the output is the output of the device.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - stress diagrams.

The device of the shift of the frequency band contains the generator 1 sawtooth pulses, the adder 2, the threshold element 3, the subtractor 4.

The device bandwidth operates as follows.

The first input of the adder 2 receives the phase signal of the amplitude Е Е, and having changed in time, it repeatedly reaches its maximum value

) o-at- - (t) tmodEi,

where is the phase of the signal at the beginning of the dimensional

interval;

-I. -the rate of change of phase at the beginning of the measuring interval; I. — first derivative of the rate of phase change; .8, (t) - phase fluctuation.

To the second input of the adder receive sawtooth pulses from the generator 1, the amplitude of which ET E is equal to the amplitude of the phase signal, and the rate of change of the front is equal to the value of Ar. where I is the circular frequency of oscillations of the generator 1. The dependence of the signal of the generator 1 on time is described by the mathematical expression frCt) H r-ftpt modEI,

where "fr- initial / phase of oscillation of the signal of the local oscillator, O; vpj.E.

At the output of the adder, a signal P (t) is formed, equal to the sum of the input signals (Fig. 2), which is fed to threshold element 3 and to subtractor 4.- Threshold element 3 generates positive square-wave pulses fn (i) with amplitude E, front the front of which is formed each time at the moment when the level E is reached, and the pulse duration is equal to the time during which it remains greater than or equal to the value. The sequence of received pulses from the output of the threshold device is fed to the second input of the subtractor, the output of which by subtraction produces the output signal p (t), the rate of change of which SZp I + derivative of velocity L and the initial phase at p, O remain initial.

The phase signal is shifted by a device made according to the proposed scheme on standard elements of digital technology. The double conversion, i.e., the conversion of the signal Ep (t) to the original frequency, shows a high accuracy of matching the resulting resultant signal with the original in all its parameters Et,), L.L.

The digital representation of the phase signal is widely used in practice, the implementation of the device on the elements of digital technology is not difficult at ensuring high accuracy of conversions and does not require additional costs for working out the circuits.

Claims (1)

1. USSR author's certificate No. 224657, cl. H 03 D 7/00, 07.07.67 (prototype). FIG. one