JPH02200022A - Tone signal measuring circuit - Google Patents

Abstract

PURPOSE:To decrease the effect of the jitters of a tone signal by making a frequency changing point into a reference for a frequency measuring time, preventing a part near the changing point of the tone signal from being measured, and averaging the signal by means of the counted value of the input signal. CONSTITUTION:A gate signal generator 1 controls the gates of counters 4 and 5 to compare an input signal at every cycle. A counter 2 measures how many cycles of the input signals 11 are inputted in the counting period of a counter 6. The time to measure the tone signal is decided with the changing point of the frequencies as the reference, the measurement of the tone signal is started when the tone signal is stabilized from the changing point of the frequencies, and the signal is measured up to the next changing point of the tone frequencies. Further a function to cancel the jitters of the input frequencies is added to a circuit to search for the frequency changing point. In addition, the measurement of the tone signal is averaged by the counted values of the input signal and a reference clock, and thus the measured value is obtained. Thus the effect of the jitters of the tone signal can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention In wireless communications, signals such as five tones and three tones are used as selective calling signals. This tone signal brings the receiving side into a receiving state by sequentially generating a plurality of arbitrary frequencies.

Next, an example of a tone signal will be explained with reference to FIG.

In FIG. 6, f0 to f are 1-on signals, T1 to T.

is the generation time of each of the tone signals f1 to f.

The present invention relates to a circuit that compares successive 1.--on signals every cycle and measures the time until the change point of the 1.--on signal in terms of a reference clock.

(b) Prior Art and Problems Next, the configuration of the prior art will be explained with reference to FIGS. 10 and 11.

Figure 10 is a configuration diagram when the gates are divided by emission time, and Figure 11 is a configuration diagram when the gates are synchronized with the measurement tone signal and the frequency is measured using another reference clock and the measurement tone signal. be.

In the method of synchronizing the gate time of the counter with the generation time of the tone signal, the time T1 to T in FIG.

is generally on the order of several tens of milliseconds, and the measured) signals f1 to f are on the order of several hundred Hz to several kI-1z, which causes the following problems.

The first problem is that if the times T1 to T deviate from the specified values or are not uniform, accurate values cannot be obtained as shown in FIG.

In FIG. 7, T1 and T2 are the specified generation times of the tone signals, and Tll and TI2 are the actual generation times of the tone signals.

Even if the gate time of time T1 is synchronized with the generation of tone signal f, the generation time of tone signal f becomes longer as at time T, and the generation time of tone signal f2 deviates from the specified time. In this case, the clock frequency at the gate time of time T2, that is, the count value of the counter is l・−
(The frequency of signal f2 is not necessarily measured.)

Also, T has no tone signal. When a time like this occurs, the accuracy of the measurement frequency cannot be improved as this time T0 becomes longer.

The second problem is that with the method of measuring the tone signal with a period counter at each time between times T and T5 in Fig. 6, it is necessary to measure the number of periods in order to eliminate jitter in the input signal. However, it is limited by the error in time T, ~T, and the size of the tone signal, as shown below.

As shown in FIG. 8, due to the error in the occurrence time, the time T,
In the period of -1, tone signals f, -, -f are included, which affects the tone signal itself for taking the average value.

In order to avoid this, 1.
If only the -on signal f7-1 is measured, there will be less data from which to take the average value, and the influence of jitter will be greater.

Time T0 occurs at the change point of the tone signal, and the value determined by the period counter becomes unstable during time T0, so 1
・-on signal f, ・f affects the measured value of nil.

There is also a method of acquiring all the data of the input signal every cycle and making a statistical judgment, but the amount of data becomes large and
It's not realistic.

(C) Purpose of the Invention The purpose of the present invention is to solve the problems of the prior art by the following means.

In order to eliminate the influence of the difference in the generation time of the 1.-- signal, the frequency measurement time is based on the frequency change point.

Since the tone signal is unstable near the change point, this section is not measured.

During the measurement time, the input signal is averaged by the count number in order to reduce the influence of jitter on the 1.--on signal.

(d) Examples of the invention Next, a block diagram of an embodiment according to the present invention is shown in FIG.

In FIG. 1, 1 is a gate signal generator, 2 is a counter, 3 is a reference clock generator, 4 to 6 are counters, 7 is a jitter cancellation circuit, 8 is a data comparator, 9 is a counter controller,
10 is a data calculator.

A gate signal generator 1 controls the gates of counters 4 and 5 for comparing input signals 11 every cycle.

Counter 2 receives input signal 1 during the count period of counter 6.
Measure how many cycles 1 enters.

The reference clock generator 3 supplies clocks to counters other than the counter 2 with a 10 MHz reference clock.

The counter 4 measures the time of one odd-numbered cycle of the input signal 11.

In other words, the number of clocks of the reference clock generator 3 while it is opened by the gate signal is counted.

The counter 5 measures the time of one even-numbered cycle of the input signal 11. The operation of counter 5 is the same as counter 4.

The counter 6 determines the time during which the tone signal is being measured.

In other words, the clock of the reference clock generator 3 is cycled.

The jitter canceling circuit 7 receives from the data calculator 10 the number of counts of the reference clock generator 3 that corresponds to the time difference of the one with the shortest one-cycle time difference among the group of applied l·-n signals. It is determined that the count difference less than the given counter l~difference is due to the jitter of the input signal 11, and the data sent to the data comparator 8 is shared with the lower bits of the counter 4 or counter 5 to make the same data This is a circuit that sends

The number of lower bits of data to be shared depends on the frequency of the given tone signal.

The data ratio P2 unit 8 compares whether the odd-numbered and even-numbered cycles that have passed through the counters 4 and 5 and the jitter cancellation circuit 7 have changed.

The counter controller receives the change point data of the input signal 11 from the output data of the data comparator 8, controls the counters 2 and 6, and sends the frequency data to be measured to the data calculator 10.

The data calculator 10 calculates the generated tone frequency and generation time from the data of the counters 2 and 6.

Next, the operation of the first answering section will be explained.

When the input signal 11 enters the gate signal generator 1, the gate signal generator 1 alternately sends gate signals equal to the period of the input signal 11 to the counter 4 and the counter 5.

Counter 4 and counter 5 count the number of reference clocks only in the period of the applied gate signal.

Further, the counters 4 and 5 send data to the jitter canceling circuit 7 every cycle of the input signal 11.

The jitter canceling circuit 7 sends to the data comparator 8 data that has been canceled by a count corresponding to the difference in cycle time below the given tone frequency.

The data comparator 8 compares the counts of the reference clock corresponding to two successive cycle times that are sent, and if the data is changing, it is assumed that the frequency has changed and sends the signal to the counter controller 9.

When the counter controller 9 receives a signal indicating that the frequency has changed, it stops the counters 2 and 6 and sends the data of the counters 2 and 6 from the point of frequency change to the point of change to the data calculator 10.

A data calculator 10 receives data from the counters 2 and 6 and calculates the generation time of each tone and the frequency during that time.

Next, the operation of the counter controller 9 will be explained with reference to FIG.

In the measurement of the input signal 11, the counter controller 9 operates the counters 2 and 6 for a certain period of time T, because there are many cases in which there is no signal near the frequency change point fe or the frequency is unstable. stop.

Next, the timing diagram of FIG. 1 is shown in FIG. 3.

FIG. 3A is a waveform diagram of the input signal 11, and FIG. 3B is an explanatory diagram of the operating states of the counters 4 and 5 corresponding to FIG. 3A.

The shaded area in FIG. 3A is the operation section of the counter 4,
The blank areas are the operation divisions of the counter 5.

In FIG. 3A, when the frequency change point fc is determined, the counter 4 or 5 does not measure for a certain period of time T8.

In FIG. 3, the frequency up to point M, one period before the frequency change point fc, is measured by counters 4 and 5, and the frequency fm-1
The frequency measurement time for frequency f is Tsi, and the frequency measurement time for frequency f is Tm2.

Next, an example of the measured values according to FIG. 1 will be shown.

If the count number of the counter 2 is 01, the count number of the counter 6 is 04, and the frequency of the reference clock is fc, the frequency f and the generation time T of the generated tone are calculated by the following equation.

f" (C1/C4)

Next, frequency jitter will be explained with reference to FIG.

When measuring a signal of a constant frequency with a counter (particularly in the case of a periodic counter), the rising level of the input signal 11 crosses the threshold of the circuit that creates the gate, making it unstable due to noise and the like. For this reason, as shown in FIG. 4, the lower digits of the frequency in each cycle vary.

Since the frequency jitter above -R is small, it is quite small compared to the frequency difference between the given tone signals.

For example, the CCIR 1.-on is as follows.

No, Frequency Time of one cycle Number of counts (Il
z) ()t s ) (10HIlz standard) 1 1124, G 889 88
904 1358 736 73GO
51446G92 692 (161540G4
9 G4'JO71040GIO61 (10 918GO5385380 1193010γ5 10750 In this case, calculate the frequency 1 0 M r (z reference count number is at least frequency No, 10 and No, 2 as 12
There is a difference of 80 counts, and although the order of the jitter described above depends on the input circuit and the measurement frequency, at the frequency used for the 1-tone signal, it is on the order of a sufficiently smaller value than these count differences.

Therefore, as shown in FIG. 5, frequency fluctuations (considered to be jitter) in which the frequency difference of the applied I--on signal is smaller than the smallest one (as a reference count difference) are canceled out.

Data 4A and 5A are binary data, and the number of pins is determined by the lower limit of the measurement frequency.

Assuming that the standard is 10 MHz, 12 bits is usually sufficient at about 300 Hz.

Next, the operation of the jitter cancellation circuit 7 will be explained with reference to FIG.

Although the setting method will be described later, the cancellation data of the n-th bit is set in advance.

The data to the data comparator 8 from the 11th pins 1 to 1 of the counter 5 is transferred to the counter 4 by the cancellation data from the nth pins.
In some cases, the n-th bit data of the counter 5 goes, and in other cases, the n-th bit data of the counter 5 goes.

When it is desired to cancel the n-th bit of the data of the counters 4 and 5, the n-th bit data of the counter 4 is inputted to the data comparator 8 of the n-th pin 1- of the counter 5.

The data of counters 4 and 5 is sent to the data comparator 8 in the above operation, so when a certain bit (usually a bit below a certain bit) is canceled, the data of counters 4 and 5 of that bit are sent to the data comparator 8. are the same, and the data comparator 8 determines that the data at those bits are the same.

The cancellation data of the n-th bit is set as follows.

Assume that one period of time in a given tone signal frequency group corresponds to the reference frequency N2072 minutes. N
When expressed in binary, if the m-th bits 1 to 1 are the bits I~ that differ between the closest values, then all data below the (m-1)th bit is set to be canceled.

The nth bits below the (m-1)th bit are considered to be the same.

Next, the operation of measuring one cycle before the change point will be explained.

It is checked every cycle of the input signal 11 whether the frequency changes from the output of the data comparator 8 which is a counter controller.

The counter 2 sends data every cycle to the data calculator 10 as data. That is, it is latch-up data.

The data calculator 10 stores the data sent every cycle until it receives a signal from the data comparator 8 indicating that the frequency has changed.

Figure 1 ends up acting like a garment.

First, the time to measure the 1-tone signal is measured based on the point of frequency change7, and after the tone signal has stabilized from the frequency change point, the measurement of the tone signal is started, and then the next 1-- Measure up to the point of change in frequency.

The measurement time is the time 'rK-1, TK, TK+ in Figure 9.
1, it is possible to measure only the tone signal that is occurring.

In other words, it does not depend on the deviation or uniformity of the occurrence time.

Second, the circuit that searches for frequency change points is provided with a function to eliminate jitter in the input frequency.

Frequencies such as a 5-tone signal usually include tens to hundreds of 1-
There is a spacing of 1 z, and there is jitter in the input frequency. - Since the frequency change of the tone signal is larger than the jitter of this input signal, the frequency change due to jitter is not determined to be a frequency change of the input signal.

Thirdly, the measurement of the l·-on signal is made by averaging the input signal count number and the reference clock count number to obtain a measurement value.

(e) Effects of the Invention According to this invention, the frequency measurement time is based on the frequency change point, so that measurement is not performed near the change point of the l-on signal, and the frequency measurement time is averaged by the input signal count I-number. Therefore, the influence of jitter on the 1--on signal can be reduced, and the influence of the lag in the generation time of the 1--on signal can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment according to the present invention, FIG. 2 is an explanatory diagram of the operation of the counter controller 9, FIG. 3 is a timing diagram of FIG. 1, FIG. 4 is an explanatory diagram of frequency jitter, and FIG. 5 is an illustration of the operation of the counter controller 9. is an explanatory diagram of the jitter cancellation circuit 7, FIGS. 6 to 8 are explanatory diagrams of tone signals, FIG. 9 is an explanatory diagram of measurement according to FIG. 1, and FIG.
1 and 11 are measurement circuit diagrams according to the prior art. 1...Gate signal generator, 2...Counter, 3...Reference clock generator, 4-6...
... Counter, 7... Jitter cancellation circuit,
8...Data comparator, 9...Counter controller, 10...Data calculator. Agent Patent Attorney Kinji Omata Diagram f. Figure between figure figure figure figure figure figure figure figure figure figure figure figure figure figure counter figure counter

Claims (1)

[Claims] 1. A gate signal generator (1) that receives an input signal (11) and outputs a gate signal synchronized with the input signal, and measures how many cycles the input signal (11) enters. 1st
a counter (2), a reference clock generator (3) that generates a reference clock, and a second counter that receives the gate signal and the reference clock and measures the time of one odd-numbered cycle of the input signal (11). (4), a third counter (5) that receives the gate signal and reference clock as input and measures the time of one even-numbered cycle of the input signal (11), and a fourth counter (6) that operates with the reference clock. ), a jitter cancellation circuit (7) which receives the output of the second counter (4) and the output of the third counter (5), and a jitter cancellation circuit (7) that receives the output of the odd and even numbers that have passed through the jitter cancellation circuit (7). A data comparator (8) that compares the period, and an input signal (11) from the output data of the data comparator (8).
A counter controller (9) receives the change point data and controls the gates of the first counter (2) and the fourth counter (6).
), and a data calculator (10) that calculates the tone frequency and occurrence time from the output data of the first counter (2) and the fourth counter (6), from among the group of given tone signals. A tone signal measuring circuit characterized in that a data calculator (10) sends information about how many counts of a reference clock the time difference of one period is the shortest to a jitter canceling circuit (1).