JPS5952590B2 - television signal relay equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a television signal relay device.

The so-called Gostar relay method, which amplifies and transmits the relay reception signal, is desired to be used from the viewpoint of simplifying equipment and making effective use of radio waves. There is a drawback that it is difficult to select a base station that provides sufficient D/U because the D/U of the relay wave is insufficient, giving rise to ghosts.

To reduce this interference, the difference between the relay reception frequency and transmission frequency should be set to 1/2fH, 2/3fH, 4/3fH, etc.
... (however, fH: horizontal synchronization frequency) etc., and when the ghost is converted to beat jima and displayed,
There is a relay method using a precision offset carrier that cancels out the interference using the eye's integral effect.

By the way, if we try to apply a relay system using precision offset carriers to the conventional relay equipment shown in Figure 1, the frequency accuracy of the transmitting station oscillator and the receiving station oscillator must be made extremely high as follows. The problem is that it is difficult to put it into practical use.

That is, in the configuration of the conventional relay device shown in FIG.
is the input terminal, 2 is the output terminal, 3 is the receive mixer, 4 is the IF
5 is a transmitting mixer, 6 is a power amplifier, 7-1 is a receiving station oscillator, 7-2 is a transmitting station oscillator, and relay reception signal F
R is converted into IF (intermediate frequency) signals F and F by the reception mixer 3 and amplified, and then converted into the offshore transmission signal FT by the transmission mixer 5, power amplified, and sent out from the output terminal 2. , the frequency of the receiving station oscillator 7-1 is f, (R),
If the frequency of the transmitting station oscillator 7-2 is fL(T), the frequency of the relay reception signal is fR, and the frequency of the relay transmission signal is f'T, then fT=fR+ (f, (T) - f, (R)) Then,
f,T includes errors between f,(T) and fL(R).

In other words, in order to obtain the highly accurate relay transmission signal required for the precision offset carrier method, in this conventional configuration,
The frequency accuracy of the receiving station oscillator 7-L and the transmitting station oscillator 7-2 must be maintained at a high level of accuracy, which is on the order of 10-L.
8 to 10-9, and it is almost impossible to configure it as a practical device.This invention was made in view of this point, and is a relay device that can perform relay transmission using the required precision offset carrier method with a simple configuration. It provides:

The details of this invention will be explained below using the figures.

FIG. 2 is a configuration diagram showing an embodiment of the present invention. In FIG. 2, the same reference numerals as in FIG. 2 indicate the same functions. 7-3 is a transmitting station oscillator that can control the frequency; 8
9 is a frequency mixer, 9 is a first frequency divider inserted as required, 10 is a phase detector, 11 is a second frequency divider inserted as required, 12 is an oscillator (frequency is F.

), 13 is a Lube filter. The output of the frequency mixer 8 is the difference between the frequency F, ω of the receiving station oscillator 7-1 and the frequency F, (1) of the transmitting station oscillator 7-3, which is divided by the first frequency divider 9. A phase detector 10 (with a frequency division ratio of m)
is applied to one input terminal of On the other hand, the output signal of the oscillator 12 is frequency-divided by the second frequency divider 11 (the division ratio is n) and input to the other input of the phase detector 10 [■■The phase detection output obtained in this way is The signal is applied to the frequency control terminal of the transmitting station oscillator via the loop filter 13.

As a result of the above, the following relationship among the frequency FL(1) of the transmitting station oscillator 7-3, the frequency F of the receiving station oscillator 7-1, the frequency F of the 2(R) oscillator FO, the relay receiving frequency FR, and the relay transmitting frequency FT is obtained. is automatically controlled so that it holds true. F, ω=FL(T)±m
/NfO fTOfRtm/NfO Now m/NfO is the frequency 1/NfO required by precision offset.
When set to 2fH, 2/3fH, 4/3fH, etc., relay broadcasting can be performed with precision offset, and interference such as ghosts and beads can be reduced.

By the way, the frequency accuracy required by the precision offset method is several cycles due to the difference in transmitting and receiving frequencies of the relay, but in the configuration according to the present invention, f1-FR=±m/NfO, and it depends only on the accuracy of the FO.

F as ko・deshi m/NfOflOKHZ. The frequency accuracy of oscillator 12 is on the order of 10-4.
It can be seen that this can be put to practical use with a simple crystal oscillator or the like.
As described above, according to the present invention, it is possible to provide a relay device using a precision offset method using an extremely simple oscillator.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional relay device, and FIG. 2 is a block diagram showing an embodiment of the relay device according to the present invention. In the figure, 1 is an input terminal, 2 is an output terminal, 3 is a reception mixer,
4 is an IF amplifier, 5 is a transmitter, 6 is a transmitter, and 7
11 is a receiving station oscillator, 7-2 is a transmitting station oscillator, 7-3 is a frequency controllable transmitting station oscillator, 8 is a frequency mixer, 9 is a first
10 is a phase detector, 11 is a second frequency divider, 1
2 is an oscillator, and 13 is a loop filter.

Claims (1)

[Claims] 1 Offset television that has a reception station oscillator and a transmission frequency generator, converts the received television signal to an intermediate frequency, amplifies it, converts this amplified output to a transmission frequency near the reception frequency, and transmits it. In the John signal relay device,
A frequency detection unit that detects the frequency difference between the receiving station oscillator and the transmitting station oscillator, and a phase detection unit that compares the phase (frequency) of the difference frequency signal output from this frequency detection unit and the oscillation signal output from the fixed oscillator. By controlling the local frequency of the receiving station oscillator or the transmitting station oscillator using the output voltage output from the phase detector, the frequency difference (phase difference) between the two local oscillators is set to a predetermined value. A television signal relay device characterized in that the offset frequency is set to .