JPS5925407B2 - Pulse number counting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for counting the number of pulses in a pulse train recorded on a sequential access type recording device using a recording medium such as a magnetic tape, and more specifically relates to a device for counting the number of pulses in a pulse train recorded on a sequential access type recording device using a recording medium such as a magnetic tape. It is an object of the present invention to provide an improved pulse number counting device that counts the number of pulses in a pulse train in accordance with the moving speed of a medium.

Conventionally, when reading a pulse train recorded on a recording medium, such as a magnetic tape, the pulse width or pulse interval changes due to fluctuations in the reading speed caused by speed fluctuations in the rotation system at startup or when the tape is running. There is a drawback that it does.

In particular, the readout speed fluctuates significantly at startup, and pulse train readout is rarely prohibited until a constant speed is reached. The present invention measures the pulse width and pulse interval using a reference pulse and a divided pulse obtained by dividing the reference pulse at a ratio corresponding to the ratio of the pulse width to the pulse interval, and measures the number of reference pulses and the number of divided pulses that are counted. This method attempts to eliminate the drawbacks of the conventional example described above by determining the relative ratio of pulse width and pulse interval using It is.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings. Figure 1 is part of a time chart of a pulse train read from a magnetic tape, which is a sequential recording device.
A indicates the time of startup, and B indicates the time of normal running.

FIG. 2 is a time chart of the reference pulse, where C represents the reference pulse and D represents the frequency division pulse. FIG. 3 is a block diagram of one embodiment of the present invention.

In the figure, 1 is a reference pulse generator, and 2 is a frequency divider for dividing the reference pulse by (-+α, where α is the correction number) corresponding to the ratio of the pulse width (n) of the pulse train to the pulse interval... It is.

4 is a pulse interval measuring circuit which is a third counting means for counting the number of divided pulses from the frequency divider 2 which is proportional to the pulse interval of the pulse train, and 5 is a reference pulse generator 1 which is proportional to the pulse width of the pulse train. the second to count the number of reference pulses from
3, a pulse detection circuit for resetting the pulse interval measuring circuit 4 and the pulse width measuring circuit 5 at the leading edge of each pulse of the pulse train; 6, a pulse detecting circuit for resetting the pulse interval measuring circuit 4 and the pulse width measuring circuit 5; Spear 1 circuit 4, a comparison circuit that compares the number of frequency-divided pulses counted by the pulse width measurement circuit 5 and the reference number of pulses, and 7 a pulse that determines whether the number of pulses in the pulse train can be counted based on the output signal of the comparison circuit 6. The counting control circuit 8 is a pulse counter which is a first counting means for counting the number of pulses of the pulse train based on the output signal of the pulse counting control circuit 7.

In addition, numbers 9, 10, and 11 in the illustration are AND gate circuits, and 12
is an inverter. FIG. 4 is a time chart of pulse width and pulse interval measurements for a pulse train, where E is a pulse train read out from a sequential storage device;
F is a reference pulse train that is input to the pulse width measuring circuit 5 in FIG. 3, and G is a frequency-divided pulse train that is input to the pulse interval meter side circuit 4 in FIG.

The pulse number detection operation of the embodiment shown in FIG. 3 will be described below.

When a pulse train is read out from a sequential recording device, the pulse width measuring circuit 5 and the pulse interval measuring circuit 4 are respectively set at the leading edge of each pulse by the pulse detection circuit 3, and the pulse counter 8 is incremented by 1. Ru. The reference pulse output from the reference pulse generator 1 is input to the pulse width measuring circuit 5 for each pulse width period of the pulse train. On the other hand, the frequency-divided pulses output from the frequency divider 2 are input to the period pulse interval measuring circuit 4 for each pulse interval of the pulse train.

In this embodiment, the ratio of the pulse width to the pulse interval is 1:3, and the frequency-divided pulse is obtained by dividing the reference pulse in 4 bases. This takes into consideration the error when counting the reference pulse or frequency-divided pulse by the pulse width measuring circuit 5 and the pulse interval measuring circuit 4, respectively. The reference pulse number N counted by the pulse width measuring circuit 5 and the frequency-divided pulse number M counted by the pulse interval measuring circuit 4 are compared in the comparison circuit 6, and N≧
As long as M, each pulse of the pulse train is counted by the pulse counter 8.
is counted. However, if the output of the comparison circuit 6 is N<M, the pulse counting control circuit 7 outputs a signal to the pulse counter 8 that prohibits counting of the number of pulses of the pulse train. Even if the pulse width and pulse interval of the pulse train read from the recording device vary, if the ratio of the pulse width to the pulse interval is within a predetermined range, N≧M, and N<M means that the pulse train has ended. This is the case immediately after the pulse train has passed, or when some pulses are missing in the pulse train. The output information of the pulse counter 8 at the time when the count prohibition signal is generated from the pulse count control circuit 7 represents the number of pulses of the pulse train. FIG. 5 is a block diagram showing another embodiment of the present invention. In this case, 4, 5, and 6 used in FIG. 3 are constructed by an up-down counter 13, and the same effect can be obtained by doing so. As is clear from the above description, according to the present invention, the pulse width and pulse interval of a pulse train read out from a sequential recording device are determined by a reference pulse and a frequency division corresponding to a predetermined ratio of the pulse width and pulse interval. Since each pulse is counted and compared, even if the pulse width and pulse interval vary within the pulse train, as long as the ratio of pulse width to pulse interval is within a predetermined range,
It is possible to accurately count the number of pulses in the pulse train, especially when counting the number of pulses in the pulse train by following speed fluctuations at startup or when the tape is running, such as in a recording device using magnetic tape. This is extremely effective.

[Brief explanation of the drawing]

Figure 1 A and B are time charts of the data pulse train, Figure 2
Figures C and D are time charts of a reference pulse train; Figure 3 is a block diagram of an embodiment of the present invention; Figures 4E, F, and G are time charts of a pulse train for measuring pulse widths and pulse intervals; FIG. 5 is a block diagram of another embodiment of the present invention. 1... Reference pulse generator, 2... Frequency divider, 3... Pulse detection circuit, 4... Pulse interval measurement circuit, 5... ...Pulse width measurement circuit,
6... Comparison circuit, 7... ...Pulse counting control circuit, 8...Pulse counter, 13...
・Up-down counter.

Claims (1)

[Claims] 1. In a sequential access type recording device that records a pulse train, a first counting means for counting the number of pulses in the pulse train, a reference pulse generating means for generating a reference pulse, and a ratio of the recorded pulse width to the pulse interval. A frequency dividing means for dividing the frequency of the reference pulse at a corresponding ratio, a second counting means for counting the number of reference pulses proportional to the pulse width, and a third counting means for counting the number of divided pulses proportional to the pulse interval. and comparison means for comparing the reference pulse number (N) corresponding to the pulse width counted by the second and third counting means and the frequency-divided pulse number (M) corresponding to the pulse interval; According to the results, if N≧M, continue counting the number of pulses in the recorded pulse train;
A pulse number counting device comprising a control means for stopping counting of pulse numbers, and configured to count the number of pulses by following fluctuations in reading out a recorded pulse train.