JPH05180960A - Delay-time measuring apparatus - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy of a delay-time measuring apparatus for measuring a delay time by switching the amount of attenuation in response to the input level of a received signal. CONSTITUTION:A transmitting signal (a) outputted from a transmitting-signal generating circuit 1 is used. Thus, the difference in delay times caused by the difference in attenuation amounts of a digital-controlled attenuator 3 is measured before hand in response to the attenuation amount with a phase-difference measuring circuit 4 and a microcomputer 5. The difference is stored in a memory circuit 6. The delay time, which is measured by using the received signal (b) from an external circuit, is corrected by the time difference stored in the memory circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data delay time measuring device, and more particularly to a delay time measuring device for automatically correcting the delay time in its own device.

[0002]

2. Description of the Related Art A conventional delay time measuring device controls the amount of attenuation of an attenuator in order to keep an input signal level internally when measuring a delay time caused by passing through a circuit outside the device. The internal device delay time is measured in advance, and the internal device delay time is subtracted from the delay time measurement value via the external circuit to obtain the external circuit delay time. Here, when measuring the delay time in the device itself, the attenuator is used with a fixed amount of attenuation.

[0003]

Therefore, in the conventional delay time measuring device, the change in the delay time in the device itself when the amount of attenuation is changed in order to keep the input signal level of the external circuit constant is measured. There is a problem that it is difficult to measure the delay time with high accuracy because the value is not corrected. An object of the present invention is to provide a delay time measuring device that can measure the delay time with high accuracy.

[0004]

The present invention has means for previously measuring the difference in delay time due to the difference in the attenuation amount of the attenuator, which is switched according to the input level of the received signal, in correspondence with the attenuation amount. , Corrects the measurement delay time according to the amount of attenuation during measurement.

[0005]

[Function] By correcting the difference in delay time with respect to the difference in attenuation amount measured in advance, by correcting the measurement delay time according to the attenuation amount at the time of measurement, it is possible to correct the change in the delay time in the device itself due to the change in the attenuation amount. it can.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the device of the present invention. The signal generated from the transmission signal generating circuit 1 is turned back in the device by setting the input signal changeover switch 2 to the CAL side, and is input to the phase difference measuring circuit 4 via the digital control attenuator 3. In the phase difference measuring circuit 4,
The phase difference between the signal from the transmission signal generation circuit 1 and the in-house folded reception signal from the digital control attenuator 3 is measured. The microcomputer 5 outputs a control signal to the digital control attenuator 3, inputs the phase difference data measured by the phase difference measuring circuit 4 while changing the amount of attenuation, and stores it as a delay time in its own device corresponding to the amount of attenuation. It is stored in the circuit 6.

Next, the input signal changeover switch 2 is set to OPR.
By setting it to the side, the delay time due to passing through a circuit outside the device is measured. At this time, the microcomputer 5 automatically controls the attenuation amount of the digital control attenuator 3 according to the input level of the received signal. The amount of attenuation at this time is held by the microcomputer 5, and the loopback delay time in the own device corresponding to the amount of attenuation is subtracted from the delay time measurement value via the external circuit to calculate the delay time of the external circuit.

[0008]

As described above, according to the present invention, since it is possible to correct the change in the delay time in the device itself due to the change in the attenuation amount of the attenuator for adjusting the input level of the received signal, the delay time with high precision can be obtained. Has the effect of enabling measurement of.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

[Explanation of symbols]

 1 Transmission signal generation circuit 2 Input signal changeover switch 3 Digital control attenuator 4 Phase difference measurement circuit 5 Microcomputer 6 Storage circuit

Claims (1)

[Claims] 1. A delay time measuring device for measuring a phase difference between a transmission signal and a reception signal having the same frequency as the transmission signal to measure a delay time between transmission and reception, which corresponds to an input level of the reception signal. It has a means to measure beforehand the difference in delay time due to the difference in the attenuation amount (attenuation amount) of the attenuator that is switched in accordance with the attenuation amount, and is configured to correct the measurement delay time according to the attenuation amount during measurement. A delay time measuring device characterized by the above.