SU365660A1 - DIGITAL FREQUENCY METER WITH NONIUS INTERPOLATION - Google Patents

Description

I

The invention relates to the field of electrical measuring equipment and can be used to create precision digital frequency meters.

Known digital frequency meters with a vertex interface, containing an input shaper, a key, a counter, a time interval sensor, a selectable frequency period selector, and a set of circuits for evaluating each additional bit of the frequency to be converted, each of which consists of a pulse extender, a pulse shaper, a sleeper, a pattern, the matches, the key and the counter, are quite complex and require a separate block for each interpolation step.

In order to reduce the equipment volume, the proposed frequency meter is equipped with a switch and a scaling control device included in the feedback circuit of the scaling circuit, the first control input of which is connected to the output of the scaling circuit, and its second control input and control input of the switch are connected to the output of the comparison circuit the reference and vernier sequences, while the output of the code comparison circuit is connected via a conius key and a switch to the input of a vernier counters.

The drawing shows the block diagram of the described device.

The device contains a generator / reference frequency, a key 2 for synchronization of the measuring time interval with pulses of the measured frequency, a scaling circuit 3, a control device 4 for the scaling factor, a circuit 5 for comparing codes, but not a switch key 6, an input driver 7, a selector 6 for the period of the measured frequency, a key 9, the storage counter 10, the key 11, the U2-12 nopius counters by the number of interpolation stages, the counter 13, the commutator 14, and the comparison circuit 15 of the vernier and reference sequences. Frequency meter works as follows. The first pulse of the measured frequency / d-,

coming from the output of the imaging unit 7 opens the key 2. By dividing the exemplary frequency supplied through the public key 2 to the input of the circuit 3 of the circuit, the measuring time interval Г "is formed, during which the frequency pulses 11 through the key 11 go to the counter 13. The selector 8 selects the period Gd. the measured frequency n opens for this time the key 9 through which the pulses of the exemplary frequency pass the pa input

a memory counter 10, in which a code proportional to the period T ,, of the measured frequency is stored.

The end signal of the measurement time interval G ,, from the output of circuit 3 closes key 11, opens key 6, and through control device 4 sets the recalculation factor of the first decade of circuit 3 to nine. As the sample frequency arrives, the codes written in the non-rhythmic circuit .3 and the storage counter 10 are equal. At this moment, the signal from the output of circuit 5 compares codes 3 to zero and arrives at the inputs of switch 14 and comparison circuit 15. Then the process the filling and resetting of the recalculation scheme is repeated and a vernier sequence is formed, the repetition period of which at the expense of the conversion factor 9 is equal to 0.9 G. Pulses of the vernier sequence through the commutator 14 is fed to the input of the first vernier counter / 2. When the phases of the reference and the Vernier sequences coincide, the comparison circuit 15 is triggered and, acting on the switch 14, connects the pulses of the non-initial sequence to the input of the second vonius counter 12, setting the conversion factor to 0.99 simultaneously in control device 4. In this case, the repetition period of the pulses of the Vernier sequence is set with a given degree of accuracy equal to 0.99 T. In the future, the work is similar. Comparison of the reference and vernier sequences by changing the phase of following the pulses of the vernier sequence relative to the reference sequences eliminates the need to form a specific pulse duration of one of the sequences, which makes it possible to remove the pulse extender from the device circuit. In addition, the use of a single vernier sequence generator for all interpolation steps in combination with scaling circuit 3 and the device

Control 4, significantly reduces the amount of equipment.

Subject invention

Digital frequency meter with vernier interpolation, containing an exemplary frequency generator connected via the synchronization key of the measuring time interval with

pulses of measured frequency at the output of the input shaper to the scaling circuit, the outputs of which are connected to the inputs of the comparison circuit, the other inputs of which are connected to the outputs of the memory counter, and the input

the latter is connected via a selector key to the output of the synchronization key, while another input of the selector key is connected via the selector to the output of the input driver, the vernac key whose input is connected to the output of the comparison circuit, and the output to the code input of the scaling circuit and the input of the sequence comparison circuit, the main counter connected through the main key with the output of the input driver and the output of the scaling circuit, and vernier counters according to the number of interpolation stages, characterized in that, in order to reduce the volume equipment, it is equipped with a switchboard and a scaling control device included in the feedback circuit of the scaling circuit, the first control input of which is connected to the output of the scaling circuit, and its second control input and control input of the switch are connected to the output of the reference and vernier comparison circuit sequences, while the output of the comparison circuit codes through the vernier key and the switch is connected to the input of the vernier counters.