SU1322169A1 - Digital instantaneous frequency meter - Google Patents

Abstract

The invention relates to a measurement technique and serves to simplify the frequency meter. The device contains a generator 1 of the reference frequency, multipliers 2 and 3, and a counter 4. Introducing the (n + 1) -th bit into counter A and its functional connection with the elements of the device allows the code N,. Taken from the control inputs of one of the multipliers. 2 or 3 at time t, which satisfies the condition t, t, be inversely proportional to the period tu, and therefore, directly proportional to the selected frequency f 2 ill. G 2 cl G S ee ee 05 WITH Figure 1

Description

113

The invention relates to a measurement technique (in particular, to frequency measurement devices, and can be used to monitor, record and measure frequency in cases where high demands are placed on the accuracy and speed of a frequency meter, for example, E

The aim of the invention is to simplify frequency counters.

On figi presents the block diagram of the device; in fig. 2 - time diagrams that show the operation of the device.

The device consists of sequentially connected oscillator I reference frequency (GFC), multipliers 2 and 3 and counter 4, and the control inputs of multipliers 2 and 3 from the first through (n-1) -th digit are connected to the corresponding bits of counter 4 a The nth bits are the (n − 1) th bits of counter 4, the output of multiplier 3 is connected to the subtracting input C of counter 4, the installation input S of which is the device input.

The device works as follows.

At the beginning of each period of the input part, a short pulse arrives at the installation input S of the counter 4 and transfers it to the unit state j, after which the counter 4 is spiked by the pulses of the frequency coming from the output of the multiplier 3 to the counting input of the deducting counter 4

In accordance with the principle of operation of binary multipliers for the frequency fj value, it is possible to write the ratio

N,

„2 where Nj is the current value of the number in

binary code at the inputs of the multipliers;

fg - the value of the reference frequency | n is the number of bits of each of the multipliers. Since the high (p-e) bits of multipliers 2 and 3 are connected to the (n + 1) -th bit of counter 4, after some time t, after the beginning of the write-off from counter 4 at all control inputs multipliers 2 and 3, the All Foods code reappears. This happens when at all

92

the discharge of counter 4, except for discharge n, will be ones, and on the nth discharge of de zero, i.e. counter 4 is charged

2 to number -X-,

When iz eksteks doptseni x counter 4 can be considered as an integrating element for the input frequency. Then you can write the following expression for the frequency f depending on the number on the discharge outputs of counter 4 (Nj.):

f -dNe h dt

or, taking into account (), at change 2

la N. from 2 To (i.e. code of two J "

the higher bits of counter 4 remain unchanged) and N, Nu

 - G 0 l (J IG - J Fb 2)

After integrating expression (2), the following is obtained:

2

  -

 fc

 1G

or

(3)

. Let some time t ,,, and t (, it -u 2t, correspond to some number Nq at the control inputs of multipliers 2 and 3, Then, integrating expression (2) with the limits of integration t from tg to t and N from 2 to NU , taking into account the fact that in this case Ng N,., receive

.4and

(four)

R

2

(at t 2t, Nj, ---).

At time 2t, the nth setting and resetting of the (n + 1) th bits of counter 4 takes place. At the same time, as in the other calculation step, the number Nq at the control inputs of multipliers 2 and 3 is changed by one. And in this case the condition N, NM remains valid in view of the fact that in a further change occurs only in millions of bits of codes. Np and N ,, as described. Therefore, for any t 2to expression (2) is valid with the limits of integration t from

2t "to t.

and N from

to some N

R

given that

l, P1-1

2t.

2,

get

.gp

"S fO

(five)

It is seen that expressions (4) and (5) are identical, although they are defined for different integration intervals. Thus, the code Nj, which can be removed from the control of the inputs of one of the multiply-} 5

moment tu,. satisfying us--t,, is inversely proportional to love

flax period t, and therefore, directly proportional to the measured frequency f..20

Thus, the frequency meter is simplified while maintaining high

3221694

values of all metrological characteristics.

Claims (1)

Invention Formula An instantaneous digital frequency meter containing a series-connected reference frequency generator, the first and second multipliers and a counter, whose bit outputs from the first to (n-1) -th are connected to the corresponding control inputs of the first and second multipliers} with the output of the second multiplier connected to a subtracting input of the counter, characterized in that, with a simplification, the input introduces (pI) -th bit, the output of which is connected to the nth control inputs of both multipliers, and the installation input of the counter to 1 is the input of the device Twa, Phie.g Compiled N.Fyodorov Editor I.Nikolaychuk Tehred L.Oliynyk Proofreader L.Patay Order 2858/40 Circulation 730 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4