JP2953507B2 - Transmission line amplitude characteristic measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for measuring the amplitude characteristic of a transmission line, and more particularly to a far-end measurement system for measuring the amplitude characteristic of a transmission line.

[0002]

2. Description of the Related Art Generally, when measuring the amplitude characteristic of a transmission line, a multi-burst signal with a synchronization signal is transmitted from the transmission side to the transmission line as a test signal. Then, the receiving side receives the synchronization signal, determines the gate position of the multi-burst according to the synchronization signal, extracts a necessary signal, and measures the amplitude.

In general, a pulse signal is used as a synchronization signal to be superimposed on a multiburst signal on the transmission side, and a gate signal is obtained by obtaining a reference timing from a predetermined threshold value of a pulse signal waveform. The gate position is determined according to the gate signal.

[0004]

As described above, in the conventional transmission line amplitude characteristic measuring apparatus, a pulse signal is used as a synchronization signal to be superimposed on a multi-burst signal on the transmitting side. Is affected by the amplitude characteristics of the transmission path to be measured. That is, the pulse signal waveform is deformed (distorted) depending on the amplitude characteristic of the transmission path to be measured.

On the other hand, as described above, when obtaining a gate signal, a reference timing is obtained from a predetermined threshold value of a deformed (distorted) pulse signal waveform, and a gate signal is generated in accordance with the reference timing. Therefore, there is a problem that the accuracy of the time axis when determining the gate position is deteriorated.

That is, the conventional transmission line amplitude characteristic measuring apparatus has a problem that a gate signal that extracts a single signal from a multiburst signal cannot be accurately reproduced.

An object of the present invention is to provide a transmission line amplitude characteristic measuring apparatus capable of accurately reproducing a gate signal that extracts a single signal from a multiburst signal.

[0008]

According to the present invention, the internal time reference of the GPS satellite is used as gate time information in order to improve the accuracy of timing reproduction at the receiving end. This provides accurate reference species in number and accurate time timing at the transmit and receive points.

That is, according to the present invention, there is provided a measuring apparatus for measuring the amplitude distortion characteristic of a transmission line, which receives a GPS signal from a GPS satellite and outputs a demodulation reference signal on the transmitting side in accordance with the GPS signal. GPS receiving means, receiving-side GPS receiving means for receiving the GPS signal from the GPS satellite and outputting a receiving-side demodulation reference signal in accordance with the GPS signal;
Multi-burst signal generating means for transmitting to the transmission path a multi-burst signal in which a plurality of signals are superimposed according to the transmission-side demodulation reference signal; and receiving the multi-bust signal via the transmission path, A transmission line amplitude characteristic measuring device, comprising: a measuring unit that generates a gate signal in accordance with the signal, extracts the signal from the multi-bust signal based on the gate signal, and measures the amplitude of the transmission line. can get.

The GPS signal includes a reference frequency and the G signal.
The multi-burst signal generation means includes a phase-locked oscillator for generating a transmission-side timing signal synchronized with the transmission-side demodulation reference signal, and a transmission-side timing. A multi-burst generator that operates in response to a signal and transmits the multi-burst signal. The multi-burst generator generates the plurality of signals in synchronization with the reference frequency based on the transmission-side timing signal, and sequentially transmits the plurality of signals in accordance with the reference time to generate the multi-burst signal. And

On the other hand, the measuring means generates a time timing signal for extracting the individual signals of the multiburst signal in accordance with the demodulation reference signal on the receiving side, and uses the time timing signal as the gate signal.

As described above, on the transmitting side, a plurality of signals (for example, sine wave signals) synchronized with the reference frequency obtained from the GPS signal are generated, and these signals are transmitted for each reference time obtained from the GPS. , Generate the required multiburst signal.

The receiving end obtains a gate signal based on a time reference detected from the GPS signal, and then extracts a necessary signal based on the gate signal. Then, the amplitude of the extracted signal is measured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, a transmission line amplitude measuring system according to the present invention comprises a GPS receiving antennas 1 and 8, GPS receivers 2 and 9, a phase locked oscillator 3, a multiburst generator 4, and an amplitude measuring device 10. , And the illustrated transmission line amplitude measurement system is connected to the transmission system.

The transmission system includes an analog transmission device 5 and an analog reception device 7. The analog transmission device 5 and the analog reception device 7 are connected by a transmission line 6. When measuring the specific amplitude of the transmission path 6,
The multi-burst generator 4 is connected to the analog transmitter 5 and the analog receiver 7 has an amplitude measuring device 1.
0 is connected.

The GPS receiving antennas 1 and 8 receive GPS signals from GPS satellites (not shown) and provide GPS signals to the transmitting and receiving GPS receivers 2 and 9, respectively. Then, the GPS receivers 2 and 9 demodulate the GPS signals to obtain a transmission-side demodulation reference signal and a reception-side demodulation reference signal, respectively. Specifically, a GPS satellite is provided with a highly stable clock, and the GPS signal includes time information based on the highly stable clock (internal clock). Therefore, the transmission-side demodulation reference signal and the reception-side demodulation reference signal are respectively GPS
It is synchronized with the satellite's internal clock.

At the transmitting end, the phase locked oscillator 3 generates a transmitting side timing signal in synchronization with the transmitting side demodulation reference signal. Then, the multi-burst generator 4 operates according to the transmission-side timing signal. That is, the multi-burst generator 4 transmits the multi-burst signal as a transmission test signal according to the transmission-side timing signal. Specifically, the multi-burst generator 4 generates a plurality of signals in synchronization with the reference frequency of the GPS signal based on the transmission-side timing signal, and sequentially transmits the plurality of signals in accordance with the reference time of the GPS signal. As a multi-burst signal.

FIG. 2A shows a form of the transmission test signal.
As shown in FIG. 2A, in the transmission test signal, sine wave signals of frequencies f1 to fn are multiplexed at times t1 to tn, respectively.

The transmission test signal is transmitted to the analog transmitting device 5.
Is transmitted to the transmission line 6 and received by the analog receiver 7. Then, it is provided to the amplitude measuring device 10 as a reception test signal.

On the other hand, as described above, the receiving-side demodulation reference signal is given from the receiving-side GPS receiver 9 to the amplitude measuring device 10, and the amplitude measuring device 10 transmits the multi-burst signal based on the receiving-side demodulation reference signal. The gate position of the signal (reception test signal) is determined.

For example, when measuring the amplitude of the signal at the frequency f1, the timing f shown in FIG.
One signal will be extracted. That is, a reception-side timing signal (gate signal T1 for f1) is generated according to the reception-side demodulation reference signal, and a signal of the frequency f1 is extracted.

It is to be noted that signals are similarly extracted from the signals after f2, the amplitude of each signal is measured, and the state of amplitude deterioration in the transmission system is measured.

[0024]

As described above, in the present invention, the timing signal is not transmitted to the transmission line, that is, the measurement waveform is distorted due to the transmission characteristics, and as a result, the measurement timing changes and the measurement accuracy changes. Therefore, there is an effect that the far-end measurement of the transmission path amplitude can be stably performed.
In addition, since the transmission path amplitude is measured in response to GPS signals from GPS satellites, the effect of being able to measure accurate far-end amplitude characteristics not only in Japan but also over the entire world, which is an extremely long distance. is there.

Further, according to the present invention, it is not necessary to consider the guard period of the synchronization signal and the like, so that not only the number of burst signals for measurement can be increased, but also the number of frequency measurement points can be increased.

Further, in the present invention, since a pulse-like synchronization signal having an energy component over a wide band is not used as the control synchronization signal, the saturation phenomenon of the transmission line due to the synchronization pulse can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a transmission line amplitude measuring apparatus according to the present invention.

2A and 2B are diagrams illustrating a relationship between a transmission test signal (multi-burst signal) and a gate signal, wherein FIG. 2A is a diagram illustrating a multi-burst signal, and FIG. 2B is a diagram illustrating a gate signal.

[Explanation of symbols]

 1,8 GPS receiving antenna 2,9 GPS receiver 3 Phase locked oscillator 4 Multiburst generator 5 Analog transmitting device 6 Transmission line 7 Analog receiving device 10 Amplitude measuring device

Claims (4)

(57) [Claims] 1. A measuring device for measuring an amplitude distortion characteristic of a transmission line, wherein the measuring device receives a GPS signal from a GPS satellite.
A transmitting side G that outputs a transmitting side demodulation reference signal according to the S signal
PS receiving means, receiving-side GPS receiving means for receiving the GPS signal from the GPS satellite and outputting a receiving-side demodulation reference signal according to the GPS signal, and superimposing a plurality of signals according to the transmitting-side demodulation reference signal Multi-burst signal generating means for transmitting the multi-burst signal to the transmission path, receiving the multi-bust signal via the transmission path, generating a gate signal in accordance with the receiving-side demodulation reference signal, and generating a gate signal based on the gate signal. Measuring means for extracting the signal from the multi-bust signal and measuring the amplitude of the transmission line. 2. The transmission line amplitude characteristic measuring apparatus according to claim 1, wherein the GPS signal includes a reference frequency and a reference time according to a high-stability clock in the GPS satellite, and the multi-burst. The signal generation means includes a phase-locked oscillator that generates a transmission-side timing signal synchronized with the transmission-side demodulation reference signal, and a multi-burst generator that operates according to the transmission-side timing signal and transmits the multi-burst signal. A transmission line amplitude characteristic measuring device characterized by the following. 3. The transmission line amplitude characteristic measuring device according to claim 2, wherein the multi-burst generator generates the plurality of signals in synchronization with the reference frequency based on the transmission-side timing signal. A transmission path amplitude characteristic measuring device, wherein the plurality of signals are sequentially transmitted in accordance with a reference time to form the multi-burst signal. 4. The transmission path amplitude characteristic measuring apparatus according to claim 3, wherein the measuring means generates a time timing signal for extracting an individual signal of the multi-burst signal in accordance with the receiving-side demodulation reference signal. A transmission path amplitude characteristic measuring device, wherein a time timing signal is used as the gate signal.