Average frequency measuring apparatus
First Claim
1. An apparatus for measuring the average frequency of an input signal with a predetermined desired accuracy R, said apparatus comprising:
- clock generating means for generating a clock signal having a period t0 ;
auxiliary gate signal generating means for generating auxiliary gate signals in response to an input thereto, for roughly determining the times for said measuring of said average frequency;
a gate signal generator for converting the auxiliary gate signals from the auxiliary gate generating means into synchronized gate signals synchronized in a predetermined manner with a predetermined one of said clock signal and said input signal;
a first gate controlled by the synchronized gate signals to pass said input signal while the first gate is open;
a second gate controlled by the synchronized gate signals to pass the clock signals from the clock generating means while the second gate is open;
a first counter connected to the first gate, for counting the number F of the input signals passed by the first gate;
a second counter connected to the output side of the second gate, for counting the number T of the clock signals passed by the second gate;
a third counter connected to the output of the gate signal generator, for counting the number N of the synchronized gate signals output therefrom during the counting of said first and second counters;
measurement accuracy setting means for setting said desired accuracy R of the average frequency measuring;
minimum counting time calculating means connected to the second and third counters and to the measurement accuracy setting means, for calculating a minimum counting time corresponding to said accuracy R and the numbers T and N;
counting end detecting means for detecting that the time for which the first, second and third counters perform their counting operation exceeds the minimum counting time calculated by the minimum counting time calculating means and for providing a respective output;
control means for stopping the generation of the synchronized gate signals from the gate signal generator according to said output from the counting end detecting means; and
frequency calculating means connected to said first and second counters for calculating the average frequency of the input signals with at least said desired accuracy, as ##EQU15##
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Accused Products
Abstract
An average frequency measuring apparatus in which auxiliary gate signals are converted into synchronized gate signals synchronized with either input signals or clock signals; first and second gates are opened by the synchronized gate signals; the input signals and the clock signals having passed through the first and second gates are counted by first and second counters, respectively; and the frequency of the input signals is calculated from the count values of the first and second counters for a plurality of occurrences of the synchronized gate signal. A third counter is provided for counting the number of the synchronized gate signals, and a minimum counting time is calculated by calculating means from the count values of the third and second counters and the set measurement accuracy. When it is detected from the count value of the second or third counter that the actual counting time has been exceeded, measurement is stopped, thereby obtaining measured results of accuracy at least higher than the set measurement accuracy.
11 Citations
24 Claims
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1. An apparatus for measuring the average frequency of an input signal with a predetermined desired accuracy R, said apparatus comprising:
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clock generating means for generating a clock signal having a period t0 ; auxiliary gate signal generating means for generating auxiliary gate signals in response to an input thereto, for roughly determining the times for said measuring of said average frequency; a gate signal generator for converting the auxiliary gate signals from the auxiliary gate generating means into synchronized gate signals synchronized in a predetermined manner with a predetermined one of said clock signal and said input signal; a first gate controlled by the synchronized gate signals to pass said input signal while the first gate is open; a second gate controlled by the synchronized gate signals to pass the clock signals from the clock generating means while the second gate is open; a first counter connected to the first gate, for counting the number F of the input signals passed by the first gate; a second counter connected to the output side of the second gate, for counting the number T of the clock signals passed by the second gate; a third counter connected to the output of the gate signal generator, for counting the number N of the synchronized gate signals output therefrom during the counting of said first and second counters; measurement accuracy setting means for setting said desired accuracy R of the average frequency measuring; minimum counting time calculating means connected to the second and third counters and to the measurement accuracy setting means, for calculating a minimum counting time corresponding to said accuracy R and the numbers T and N; counting end detecting means for detecting that the time for which the first, second and third counters perform their counting operation exceeds the minimum counting time calculated by the minimum counting time calculating means and for providing a respective output; control means for stopping the generation of the synchronized gate signals from the gate signal generator according to said output from the counting end detecting means; and frequency calculating means connected to said first and second counters for calculating the average frequency of the input signals with at least said desired accuracy, as ##EQU15## - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 24)
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15. An apparatus for measuring the average value of a series of frequency measurements of an input signal, said apparatus comprising:
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clock generating means comprising a random signal generator for generating a random signal of randomly varying level, a voltage controlled oscillator, a phase comparator for phase comparing a signal corresponding to the output from the voltage controlled oscillator and a reference signal, and an analog adder for adding the output from the phase comparator and the random signal to supply the added output as a control signal to the voltage controlled oscillator, the output from the voltage controlled oscillator being used as a clock signal and having an average period t0 ; auxiliary gate signal generating means for generating auxiliary gate signals in response to an input thereto for roughly determining a counting time for each said measurement; a gate signal generator for converting said auxiliary gate signals from the auxiliary gate signal generating means into synchronized gate signals synchronized with a predetermined one of said clock signal from the clock generating means and said input signal; a first gate connected to the output of the gate signal generator, for being controlled by the synchronized gate signals therefrom to pass said signal during each said measurement; a second gate connected to the output of the gate signal generator, for being controlled by the synchronized gate signal therefrom to pass the clock signal from the clock generating means during each said measurement; a first counter connected to the output of the first gate, for counting as the number F the input signal passing through the first gate for said series of measurements; a second counter connected to the output side of the second gate, for counting as the numbe T the clock signal passing through the second gate for said series of measurements; and frequency calculating means for calculating the average frequency of the input signal, according to ##EQU21## from the values f and T of the first and second counters, respectively. - View Dependent Claims (22)
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23. An apparatus for providing the average of a series of measurements of the frequency of an input signal, said apparatus comprising:
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a phase lock loop including a phase detector; a local oscillator the frequency of which is stabilized by the phase lock loop; a frequency converter for frequency converting the input signal using the output from the local oscillator as a local signal; means for generating a gate signal corresponding to each of said series of measurements; a gate supplied with a signal corresponding to the output from the frequency converter and said gate signals, said gate being opened and closed by said gate signals corresponding to said measurements; a random signal generator for generating a random signal of randomly vaying level for each said measurement; an adder for superimposing a respective output from the random signal generator on the output from said phase detector in the phase lock loop for each said measurement; and averaging and counting means for counting the output from the gate for each said measurement and averaging the count value for a plurality of said gate signals corresponding to said series of measurements.
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Specification