SU1620954A1 - Frequency-to-code converter - Google Patents

Abstract

The invention can be used in measuring the frequency of pulse sequences. The purpose of the invention is to improve the accuracy of frequency conversion to code. The goal is achieved by inputting a accumulating adder 7 into the frequency converter, the converter also contains a shaper 1 measurement interval, a generator 2 of the reference frequency, the first driver 3. pulses, a counter 4 pulses, the second driver 5 pulses, register 7. The essence of the invention is in the possibility of reducing the measurement error due to the difference between the nominal and real conversion functions. This is achieved by presenting the result code in the accumulating adder as the sum of the members of an arithmetic progression. 2 Il.

Description

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This invention relates to digital measurement technology and can be used in measuring the frequency of pulse sequences.

The purpose of the invention is to improve the accuracy of frequency conversion to code.

FIG. 1 shows a functional diagram of the frequency converter in the code; in fig. 2 - time diagrams of his work.

The frequency converter in the code contains (Fig. 1) a shaper 1 measurement interval, a generator 2 of the reference frequency, the first shaper 3 pulses, the counter 4 pulses, the second shaper 5 pulses, accumulating adder 6 and register 7.

In the frequency converter in the code, the first input of the measurement interval 1 generator, which is the device input, is connected to the counting input of the pulse counter 4, the control input of which is connected to the input of the first pulse generator 3 and the output of the measurement interval generator 1, the second input of which is connected to the generator output 2 reference frequency and the synchronization input accumulating adder 6, the reset input of which is connected to the reset input of the counter 4 pulses and the output of the second driver 5 pulses, the input of which is connected With the output of the first pulse shaper 3 and the recording entry of the register 7, the outputs of which are the device outputs, the information inputs of the register 7 are connected to the outputs of accumulating adder b, the first information input of which is connected to the signal of the logic unit level, the remaining information inputs of the accumulating adder 6 connected to the outputs of the counter 4 pulses.

FIG. 2 shows time diagrams explaining the operation of the frequency converter in the code: a is the signal of the initial frequency at the device input; b - signal at the output of the measurement interval imager; в - signal at the output of the reference frequency generator; g - diagram of changing the contents of the counter 4 pulses; d, e - diagrams of the formation of the result code in the accumulating adder 6.

The frequency converter in the code works as follows.

The shaper 1 of the measurement interval forms the time interval Ti (Fig. 26), the beginning of which coincides with the first pulse of the recorded frequency fx (Fig. 2a). A pulse counter 4 counts the number of pulses of a recorded frequency received during a time interval.

Ti, i.e. during the time interval Ti and S- the discharge code NI in the counter 4 pulses gradually increases with the arrival of each subsequent frequency pulse fx

(Fig. 2d). The information inputs of the accumulating adder 6 from the second to (5 + 1) -th are fed with the NI code, and the signal of the unit level is fed to the first information input. So the code

formed on the data information inputs, changes at the moments of arrival of pulses of frequency fx according to the law of arithmetic progression

15

1,3,5 (21-1), ... (1)

The synchronization input of the accumulating adder b receives impulses of the reference frequency f0 (Fig. 2c), the code value

the accumulating adder NCM gradually increases (Fig. 2d), and by the end of the measurement interval it is the resulting count N. At the end of the measurement interval Ti, the driver 3 generates a pulse rewriting the accumulated number N at the output of the P-bit of the bottom register 7. Then the pulse from the output of the imaging unit 5 leads to the zero state the counter of 4 pulses and the accumulator adder 6, thus preparing the device for the next measurement cycle.

The accumulation of the number N is the result of the summation of the values of the members of the row (1),

carried out on arrival of pulses of a constant reference frequency fo for NT entire periods Tx in the interval Ti and the part of the latter, which did not fit completely, period At (Fig. 26):

N +3 + 5 + ... + (2Mt-1) +

+ fo (2NT + 1) At, (2)

or taking into account the formula for the sum of the members of the arithmetic progression

N fоТхМт2 + f 0 (2 NT + 1) A t, (3)

Where

At Ti-MtTh Ti - 71. Tx

(four)

Solving equation (4) with respect to NT and substituting the result in equation (3), the latter leads to

TSfx

AT

T2i

).

(five)

where is TSfx

Ar t2.

(6)

5f is the measurement error due to the difference between the nominal and real conversion functions.

Claims (1)

Claims A frequency converter in a code comprising a serially connected measurement interval driver, the first and second pulse drivers, the output of the last of which is connected to the pulse counter reset input, the control input of which is connected to the output of the measurement interval driver, the first input of which is connected to the counter counting input pulses and is the input of the device, the second input of the measurement interval former is connected to the output of the reference frequency generator, the output of the first pulse generator connected to a register recording input, whose outputs are converter outputs, characterized in that, in order to increase the frequency conversion accuracy in the code, a accumulating adder is entered into it, the reset input of which is connected to the output of the second pulse forcing generator, and the synchronization input with output the reference frequency generator, the first information input - with a logic unit level signal, the remaining information inputs - with the outputs of the pulse counter, and the outputs - with the information inputs of the register.