CZ12271U1 - Circuit arrangement of synchronous repeater with external modulation - Google Patents

Description

Technical field

The technical solution relates to the connection of a synchronous repeater with external modulation, used mainly to cover the area with terrestrially solved distribution of nationwide television programs.

Background Art

The current state of the art available to radiocommunication service providers does not allow to satisfy the current needs of TV and BC operators in their entirety without the total reorganization of the respective frequency allocations. However, such a solution is not yet possible for many serious reasons.

As an ideal solution to the current lack of free frequencies for TV and BC operators, the digitization of television and radio signals appears. This modern system, which allows, for example, to broadcast up to five TV programs on a single TV channel, is already operated to a limited extent. However, the high financial costs involved in building it are hampering the desired expansion, as a new network of digital transmitters, including the relevant distribution network, is needed. In this case, it should also be borne in mind that the vast majority of existing receivers are not compatible with digital data transmission.

A compromise solution to meet the current demands of TV and BC operators seems to be even greater concentration of the existing television and radio network. However, there is a real risk that overlapping networks will overlap in a too dense network of transmitters, with end users being negatively affected. To avoid this, it is necessary to replace or modify the excitation stages of the existing transmitters, which is again technically demanding and expensive.

The essence of the technical solution

The above drawbacks are largely eliminated by the involvement of a repeater with external modulation, the output of the primary antenna receiving antenna being coupled to the filter input of the phasing element, the output of which is connected to the input of the input mixer whose input / output is bidirectionally connected the input / output of the audio / video modifier, the output of which is connected to the input of the output mixer, the output of which is connected to the input of the power amplifier, the output of which is coupled to the input of the selective channel LC filter, the output of which is coupled to the input of the broadcasting system, that the output of the auxiliary oscillator is coupled to the second input of the output mixer and the second output of the output mixer is coupled to the second input of the filter with the phasing element, wherein the other input of the audio / video modulator is coupled to an external modulation signal source.

The advantages of wiring consist in allowing smaller localities to be covered by the signal of new TV stations which, due to the current lack of free frequencies, cannot be distributed to end users by known and available technical means, eg by building additional retransmission points. The wiring according to the present invention will be functional even if the primary transmitter signal fails, which may be advantageous for providing local transmission in the event of major environmental disasters. Another advantage is the ability to chain several levels of cascade without loss of image quality.

Exemplary embodiments

The wiring diagram shown in the drawing has both a receiving antenna and a primary signal. The primary signal is supplied to a filter 2 with a phasing element, the output of which is connected to the input of the mixer 3 with an intermediate frequency product 38.9 or 38.0 MHz. Ve

The signal is converted to an intermediate frequency of 38.9 or 38.0 MHz after the conversion with the auxiliary oscillator 4 by the input mixing 3. The input mixer 3 is bi-directionally coupled to the video / audio modulator 5 to synchronize the carrier image to the input relic frequency. From the video / audio modulator 5, the signal is fed to the output mixer 6, where after the conversion with the opposite sign than that realized in the input mixer 3, when using an identical auxiliary oscillator 4, the signal is converted back to the original frequency. From the output mixer 6, the signal is fed to the end power amplifier 7. From the output power amplifier 7, the signal is fed to a selective channel LC filter 8, the output of which is provided with an impedance matching tap for connecting the transmitter system 9. The output of the auxiliary oscillator 4 is coupled to the second input the output mixer 6 and the second output mixer output 6 is coupled to the second filter of the phase cell filter 2. A further input of the audio / video modulator 5 is coupled to an external modulation signal source 10.

Industrial usability t *

The connection of the synchronous repeater with external modulation can be used especially for covering the area with terrestrially solved distribution of nationwide television signals.

Claims (1)

PROTECTION REQUIREMENTS Connection of a synchronous repeater with external modulation, in particular to cover the territory by a sterrestrial distribution of nationwide television programs, characterized in that the output of the receiving antenna (1) of the primary signal is connected to the input of the filter (2) an input mixer input (3) whose input / output is bi-directionally coupled to an audio / video modulator input / output (5) whose output is coupled to an input mixer input (6) whose output is coupled to an output power amplifier (7) whose output is coupled to the input of a selective channel LC filter (8), the output of which is coupled to the input of the broadcast system (9), the output of the auxiliary oscillator (4) being coupled to the second input of the output mixer (6) and the output mixer (6) is coupled to the second input of the phasing element filter (2), wherein the other audio / video modulator input (5) is coupled to an external modulation signal source (10).