JPS61295733A - Transmission system for high frequency synchronizing signal - Google Patents

Abstract

PURPOSE:To transmit precisely a synchronizing signal at any time by providing an electrooptic signal converter to a transmission part side and an optoelectric signal converter and a PLL circuit to a reception part, and using an optical fiber cable as a cable. CONSTITUTION:A high frequency signal outputted from an oscillator 3 is passed through a frequency divider 4 and applied to respective synchronizing signal output parts as a transmission synchronizing signal Tx and a reception synchronizing signal Rx and then converted into light pulse signals, which are outputted. Those light pulse signals are inputted to a synchronizing signal input part 7 through the optical fiber cable 6 and converted into electric signals, which are outputted to the PLL circuit. Said signal output is passed through a phase detector 81, an integrator 82, and a VCO 83 and transmitted at a frequency corresponding to its voltage, and the signal is inputted to the phase detector 81 as a reference signal and also outputted to the pulse generator 21 of an antenna unit 2 as the transmission synchronizing signal Tx.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a high frequency synchronization signal transmission method, and more specifically, in a device having a transmitting section and a receiving section connected by a cable, A high-frequency synchronizing signal transmission method that allows highly accurate synchronizing signal transmission to the receiving section % <Prior art> As described above, the device for transmitting high-frequency synchronizing signals from the transmitting section to the receiving section is as follows. For example, there are so-called underground radar systems used for shallow underground exploration.

In a typical underground radar system, an antenna unit equipped with an electromagnetic wave transmitting means and an electromagnetic wave receiving means is connected to the radar system main body by a coaxial cable, and a frequency of 5 Q K11Z, pulse is transmitted from the radar system main body to the antenna unit via the coaxial cable. Width 3~10ns
It transmits a synchronous signal of about The antenna unit l~ side uses the received synchronization signal as 1~suga, and at the input timing of the synchronization signal, the rise time of 1n is transmitted from the electromagnetic wave transmitting means.
It emits an extremely short electromagnetic wave pulse into the ground with a sharp rise characteristic of about 1.5 seconds. On the other hand, the electromagnetic wave pulse reflected from underground or the electromagnetic wave pulse transmitted through the ground is received by an electromagnetic wave receiving means, and a synchronization signal is used → The high-frequency electromagnetic wave pulse signal received by the non-pulling method is converted into a low-frequency signal that is easy to handle. is being converted and played.

<Problems to be Solved by the Invention> By the way, the underground radar system as described above has a drawback in that a part of the electromagnetic waves radiated from the antenna unit may mix into the coaxial cable depending on the conditions. As a result, these unnecessary signals are mixed into the synchronization signal transmitted to the antenna unit, causing inconveniences such as the timing of electromagnetic wave radiation from the antenna unit being shifted and the received signal not being able to be accurately reproduced using the sampling method. occurs. In particular, a so-called boreball is a system in which an electromagnetic wave transmitting means (transmitting probe) and a receiving means (receiving probe) are installed in separate polling holes, and the receiving probe receives electromagnetic wave pulses transmitted from the transmitting probe through the ground. In the case of an underground radar system, electromagnetic wave pulses are easily attached to cables, especially cables on the transmission probe side, and therefore have a particularly large influence on transmission synchronization signals, increasing the degree of the above-mentioned inconvenience.

In order to eliminate such inconveniences, it may be possible to eliminate the influence of electromagnetic waves as described above by using an optical fiber cable instead of the coaxial cable and adopting a system in which synchronous signal transmission is performed by optical signals. However, in this case, fluctuations occur in the optical signal due to the effects of bending of the optical fiber cable due to external pressure, expansion and contraction due to temperature changes, multiple reflections in the transmission line, wavelength selective absorption, etc., and its phase and amplitude fluctuate. Therefore, the synchronization signal transmitted to the antenna units 1~ has a lot of jitter, and therefore the synchronization signal cannot be transmitted with high precision.

<Means for Resolving Ties> The high frequency synchronization signal transmission method of the present invention is such that when transmitting a high frequency synchronization signal from a transmitting section to a receiving section connected to the transmitting section via a cable, the transmitting section side An electric-to-optical signal converter is provided on the receiver side, and an optical-to-electrical signal converter and P are provided on the receiver side.
In addition to providing an LL circuit, an optical fiber cable is used as the cable, and the above-mentioned high frequency synchronization signal is converted into an optical signal by an electric-to-optical signal converter, transmitted to the receiving section by the optical fiber cable, and converted into an electric signal by the optical-to-electrical signal converter. The gist is that after conversion, the signal is input to the receiving section via the PLL circuit. - Function> By using the above means, fluctuations in the reception synchronization signal due to fluctuations in the optical signal that occur in the optical fiber cable before reaching the receiving section are absorbed by the PLL circuit, so that The synchronization signal can always be transmitted with extremely high accuracy.

<Example> Figure 2 shows antenna unit 1 installed in an underground radar system.
~ and the related parts of the radar system body,
The radar module section 1 in the radar system main body is composed of a scan generator 11, a scan controller 12, a cable driver 13, an AGC amplifier 14, and a TVG amplifier 15, and also includes an antenna unit!
2 is composed of a pulse generator 21, a transmitting antenna 22, a receiving antenna 23, and a sampling circuit 24. Their functions and operations are as follows. first,
The scan generator 11 and scan controller 12 generate transmission synchronization signals, reception synchronization signals, limp ring synchronization signals, and other timing signals used in signal processing, and the cable driver 13 generates transmission synchronization signals, reception synchronization signals, sampling synchronization signals, etc. The signal is amplified and output to the antenna unit 2 via a cable. this house,
The transmission synchronization signal is input to the pulse generator 21, and an electromagnetic wave pulse is radiated underground from the transmission antenna 22 at the input timing of the transmission synchronization signal. The electromagnetic wave pulse from underground or the electromagnetic wave pulse transmitted through the ground is received by the receiving antenna 23 and sent to the limp ring circuit 2.
4, and after being converted into a low frequency signal by a sampling method, it is output to the AGC amplifier 14 of the radar module section 1.
, the signal is outputted to the data processing section via the TVG amplifier 15. The AGC amplifier 14 amplifies the input signal with a gain inversely proportional to its amplitude and outputs the amplified signal.
5 gradually increases the gain of the input signal over time and outputs it.

FIG. 1 shows an embodiment in which the transmission method of the present invention is applied to the case where the transmission synchronization signal is transmitted from the radar module section 1 described above to the antenna units i to 2, and the operation thereof will be explained below. .

First, 10
The high frequency signal of 00 Hz is divided into 100 Hz by frequency divider 4.
After the frequency is divided into the transmission synchronization signal Tx and the reception synchronization signal R
X is injected into each synchronization signal output. That is, to explain the transmission synchronization signal side, the transmission synchronization signal Tx is input to the transmission synchronization signal output section 5, differentiated by the capacitor C1 in the figure, resistor R1, and injected into the bases of transistors Q1 to 1. . Transistor Q1 operates in the avalanche mode switching operating region, and the charge charged in capacitor C2 flows through the primary winding of lance T1 at an extremely high speed.

The voltage generated in the secondary winding of the transformer T1 is injected into the base of the transistor Q2, which also operates in the avalanche mode switching region, and the charge charged in the capacitor C3 is extremely fast. The light flows into the laser diode D1, and the laser diode DT outputs an optical pulse signal with a very fast rise time.

This optical pulse signal is input to a transmission synchronization signal input section 7 provided on the antenna units 1-2 through an optical fiber cable 6 connected between the radar module section 1 and the antenna units 1-2.

The optical pulse signal inputted to the transmitting signal input section 7 is injected into the first avalanche eff diode D2, and the first avalanche eff diode D2 performs ON and OFF operations at extremely high speed above a certain input light level. Due to the OFF operation, the electric charge of the capacitor C5 connected to the collector side of the avalanche type transistors Q1 to Q3 flows at an extremely high speed to the primary windings of the transistors T2, and from the secondary windings of the transistors T2 to PLL circuit. A signal is output to 8.

The PLL circuit 8 is composed of a phase detector 81, an integrator 82 such as a Miller integration circuit, and a VCO 83, and the above signal output is input to one input terminal of the phase detector 81.

The output signal of the VCO 83 (transmission synchronization signal TX) is input to the other terminal of the phase detector 81, and the phase detector 81 detects the phase difference between these two signals and outputs the signal to the integrator 82.
The integrator 82 outputs a voltage corresponding to this phase difference to VC.
The voltage is output to O83, and VC083 transmits and outputs a signal at a frequency corresponding to the voltage. The output signal of this VC○ 83 is input as a reference signal to the phase detector 81 as described above, and is also output as a transmission synchronization signal TX to the pulse generator 21 of the antenna units 1 and 2.

Incidentally, even if a low-pass filter is used in place of the integrator 82 in the PLL circuit 8, almost the same operation can be performed, and a highly accurate transmission synchronization signal Tx can be obtained. However, in a PIL circuit using a low-pass filter, if the signal from the phase detector 81 to the low-pass filter is interrupted due to the influence of jitter in the optical signal, the input voltage of the VCO 83 decreases, and in this case, the input voltage of the VCO 83 decreases. It becomes impossible to reproduce and transmit × with high precision. On the other hand, when the integrator 82 such as a Miller integrator circuit is used as in the embodiment, even if the input signal is interrupted, the integrator 82 maintains the voltage immediately before the signal interruption for a long time, and the integrator 82 maintains the voltage immediately before the signal interruption, and transmits data under any conditions. A synchronization signal can be generated and transmitted with high precision.

<Effects of the Invention> According to the high frequency synchronous signal transmission method of the present invention configured as described above, an optical fiber cable is used as a cable connecting the transmitting section and the receiving section. In addition to eliminating the influence of electromagnetic pulses on the synchronization signal, by providing a PLL circuit in the receiving section, it is possible to reliably remove jitter components generated in the optical fiber cable.
As a result, it is possible to always accurately transmit the synchronization signal from the transmitter to the receiver.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the main parts of an embodiment in which the present invention is applied to an underground radar system, and FIG. 2 is an explanatory diagram showing an antenna unit and its related parts in the underground radar system. DESCRIPTION OF SYMBOLS 1...Radar module part, 2...Antenna unit, 5...Transmission synchronization signal output part, 6...Optical fiber cable, 7...Transmission synchronization signal input part, 8...P
LL circuit, 81... phase detector, 82... integrator,
83...VCO.

Claims (1)

[Claims] 1. In transmitting a high frequency synchronization signal from the transmitter to the receiver connected via a cable, an electrical-to-optical signal converter is provided on the transmitter side, and an optical signal converter is provided on the receiver side. - An electric signal signal converter and a PLL circuit are provided, and an optical fiber cable is used as the cable, and the high frequency synchronization signal is converted into an optical signal by the electric-optical signal converter, and transmitted to the receiving section by the optical fiber cable. A transmission system for a high frequency synchronizing signal, characterized in that the signal is converted into an electrical signal by the optical-electrical signal converter and then input to the receiving section via the PLL circuit. 2. The PLL circuit has a phase detector, a Miller integration circuit, and a VC
The transmission system according to claim 1, characterized in that the transmission system comprises O.