Takeda Riken Kogyo Kabushiki Kaisha

Takeda Riken Co., Ltd.

Shoji Niki

Toshiro Takahashi

Yohei Hirakoso

Yuji Yoshino

A synchronizing gate signal is generated in synchronism with an input signal or a clock signal, and first and second gates are opened by the synchronizing gate signal. The input signal having passed through the first gate is counted by a first counter circuit, and the clock signal having passed through the second gate is frequency-divided by a divide-by-10.sup.n frequency divider. An output from the frequency divider is counted by a second counter means. The synchronizing gate signal is generated under the control of a control circuit, and is prevented from being generated when the output from the frequency divider is applied to the control circuit. The n in the frequency-division ratio 1/10.sup.n of the frequency divider and a maximum count P of a third counter circuit are determined from a count of the third counter circuit, a preset measurement accuracy, and a period of the clock signal at the time one output is produced from the frequency divider, the n being set in the frequency divider. The control circuit is caused to generate the synchronizing gate signal. When the output from the frequency divider is obtained, the count is picked up from the first counter circuit and the synchronizing gate signal is generated again in a repetitive process. Each time the output from the frequency divider is obtained, an average frequency is calculated from the counts of the first counter circuit and the second counter circuit. Until the count of the second counter circuit reaches P, a display indicates that a displayed average frequency has the preset measurement accuracy.

Device for measuring average frequencies

A signal detector identifies a desired frequency component having the greatest amplitude in an input signal containing other frequency components of smaller amplitude such as spurious noise, etc. This allows measuring for instance the frequency of the desired frequency component. The envelope of an intermediate frequency signal corresponding to the desired frequency component is set to be above a desired level in a single sweep of a local oscillator by comparing the envelope with a predetermined value for controlling the attenuation of the input signal. After the attenuation is thusly set, only the desired frequency component has an envelope larger than the predetermined value, so that the desired frequency component is easily identified thereby in the next sweep.

Signal detector

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.

Average frequency measuring apparatus

An input signal frequency and the output from a local oscillator are applied to a frequency converter to derive therefrom intermediate-frequency signals of frequencies corresponding to the differences between the input signal frequency and the output frequency of the local oscillator and between the former and harmonic frequencies of the latter. The intermediate-frequency signals are amplified by an amplifier, and the output freqeuncy of the amplifier and the oscillation frequency of the local oscillator are simultaneously measured twice. From intermediate frequencies F.sub.i1 and F.sub.i2 and the local oscillation frequencies F.sub.1 and F.sub.2 thus measured, the following calculation is made: ##EQU1## where .alpha. is zero or a decimal. At the same time, it is detected which one of the intermediate frequencies F.sub.i1 and F.sub.i2 is larger, and from the result of this determination, the above-mentioned N, the local oscillation frequency and the intermediate frequency corresponding thereto, the input signal frequency is calculated.

Frequency measuring apparatus

An input signal from an antenna is level-adjusted by a first level adjuster and then frequency-converted by a frequency converter. The frequency-converted signal is further level-adjusted by a second level adjuster and then detected by a detector, and the detected output is displayed on a first display. A control signal for controlling the frequency of a local oscillation signal of a local oscillator, which is applied to the frequency converter, is adjusted to select the input signal to be measured. The control signal is applied to a compensating signal generator to derive therefrom a compensating signal for compensating for the frequency characteristic of the antenna. The compensating signal, a first set signal representing the set value of the first level adjuster, and a second set signal representing the set value of the second level adjuster are added together. The added output is applied to a second display to indicate the antenna input value provided at the time when the first display indicates a reference level of the first display, thus measuring the electric field intensity of the input electric wave.

Electric field intensity measuring apparatus

The rise of an intermittently incoming pulse modulated wave is detected to open a gate circuit by the detected output to supply therethrough a clock pulse of a frequency higher than the carrier frequency of the incoming pulse modulated wave to a counter and a pulse decay detector for counting with the former and resetting the latter every carrier cycle of the pulse modulated wave. While the pulse modulated wave continue, the pulse decay detector is repeatedly reset to be prevented from overflowing. Upon interruption of the pulse modulated wave, the pulse decay detector overflows to provide an output after the elapse of predetermined time selected to be longer than one carrier cycle. By the overflow signal, the gate circuit is closed to stop the counting operation of the counter and the numerical value corresponding to the predetermined time is subtracted from the count value of the counter, thereby obtaining the pulse width of the pulse modulated wave. Further, a second counter is provided for counting the carrier cycle of the pulse modulated wave and its carrier frequency is also measured from the count value of the second counter and the pulse width.

Pulse modulated wave measuring device

An input signal and a local oscillator signal are supplied to a harmonic mixer. The local oscillator signal is swept over a frequency range. The output from the harmonic mixer is supplied to an intermediate frequency filter having a preselected frequency response, which provides an output signal when the difference formed by subtracting one of the input signal frequency and one harmonic frequency of the local oscillator signal from the other is equal to the intermediate frequency or when the difference formed by subtracting the other frequency from said one frequency is equal to the intermediate frequency as the local oscillator frequency is swept. By choosing a time interval between the times when the pair of intermediate frequency output signals are obtained, the order of that harmonic of the local oscillator signal with which the intermediate frequency output signal is obtained is determined depending on the frequency of the input signal. Thus, with a chosen time interval, when the frequency sweep of the local oscillator signal is interrupted with the later occurring one of the pair of the intermediate frequency output signals, the frequency of the local oscillator permits, together with the order of selected harmonic which corresponds to the chosen time interval and the direction of the frequency sweep, the frequency of the input signal to be determined. By using a definite time interval between the pair of intermediate frequency signals obtained and adjusting the rate of the frequency sweep, the order of the harmonic which is effective to obtain the intermediate frequency signals can be varied.

Growing community of inventors

Saitama, Japan

Shoji Niki