KR20020067865A - The Variable Frequency Band Attenuator of Broadband Re-Broadcasting System to improve frequency selectivity. - Google Patents

Abstract

PURPOSE: A variable frequency band attenuator for improving frequency sensitivity of a broadband broadcasting relay apparatus is provided to extend a broadcasting relay region and improve quality of broadcasting by preventing re-transmission of spurious frequencies. CONSTITUTION: Broadcasting signals are distributed by using a distributor(2). A mixer(3) receives the broadcasting signals. An intermediate frequency is determined by a local signal generated from a frequency synthesizer(8). An intermediate frequency module(4) passes the broadcasting signals of a lower band and removes the broadcasting signals of an upper band by using a band pass filter. A mixer(6) outputs the broadcasting signals without spurious signals. The intermediate frequencies of the broadcasting signals inputted to a mixer(9) are determined by the local signal of a frequency synthesizer(13). An intermediate frequency module(10) passes the broadcasting signals of the upper band and removes the broadcasting signals of the lower band by using the band pass filter. A mixer(12) outputs the broadcasting signals without the spurious signals.

Description

The variable frequency band attenuator of broadband re-broadcasting system to improve frequency selectivity.

The present invention relates to a variable frequency band attenuator for improving frequency selectivity of a broadband broadcast repeater. More specifically, a variable frequency band attenuator for removing spurious frequencies in a broadcast band and transmitting desired broadcast signals in the broadcast band. to be.

In general, the broadband broadcast repeater receives and relays signals of the entire broadcast band, thereby amplifying and relaying spurious frequencies other than the broadcast signal in the broadcast band. Therefore, the presence of spurious frequencies of similar or higher level to the broadcast signal in the broadcast band affects the signal quality of the adjacent band. Therefore, in order to solve these problems in the existing broadcast relay device, a trap using a simple inductor (0) and a capacitor (1) has been used. The traps have band attenuation, but they affect wide bandwidth, low attenuation, and most importantly, adjacent frequencies, adversely affecting the quality of the broadcasted signals and limiting the repeater's coverage.

The purpose of the present invention is to prevent the retransmission of spurious frequencies other than the broadcast signal in the broadband broadcast repeater for solving the shadow area of the air broadcasting such as AM, FM, TV, to extend the range of broadcast relay, Variable frequency band attenuator for

Figure 1. TRAP for band attenuation of conventional broadcast repeater

Figure 2. Variable frequency band attenuator for improving the frequency selectivity of the broadband broadcast repeater according to the present invention.

According to the present invention, the broadcast signals entering the variable frequency band attenuator are distributed using the divider 2 and the broadcast signal is applied to the mixer 3. By the local signal from the frequency synthesizer 8, an intermediate frequency is determined. The intermediate frequency module 4 uses only a high performance bandpass filter (crystal, SAW, etc.) to pass broadcast signals in the lower frequency band based on the spurious frequency. Then, the signal in the upper frequency band including the spurious frequency is passed. Only the broadcast signals from which spurious is removed through the mixer 6 are removed. On the other hand, the outgoing signals entering the mixer 9 determine the intermediate frequency by the local signal from the frequency synthesizer 13. The intermediate frequency module 10 uses only a high performance band pass filter (crystal, SAW, etc.) to pass only the broadcast signals of the upper frequency band based on the spurious frequency. Then, the signals of the lower wave band including the spurious frequency are removed so that only the broadcast signals from which the spurious is removed are output through the mixer 12. The signals that pass through two intermediate frequency paths are synthesized and amplified and transmitted.

As described above, according to the present invention, it is possible to prevent the retransmission of noise in a broadcast relay device that receives a plurality of airwave broadcast signals, and to improve the performance of the broadcast relay device, thereby extending coverage and transmitting high-quality airwave broadcast signals. It is possible. The biggest problem with broadband communication systems is the in-band noise component, or spurious frequency.

Spurious frequencies, unlike narrowband communications, cannot be completely eliminated. By solving the poor characteristics of the conventional method, it is possible to remove the in-band noise even in the broadband method.

Claims (1)

A splitter (2) for distributing broadcast signals to the variable frequency band attenuator, a frequency synthesizer (8) for generating local signals, a mixer (3) for receiving local signals from the frequency synthesizer, and a microcontroller for controlling local signals from the frequency synthesizer Intermediate frequency module 4 and spurious, which use a processor 14 and a high performance bandpass filter (crystal, SAW, etc.) 5 to pass and amplify only the broadcast signals in the lower wave band based on the spurious frequency. The signals of the upper waveband including the frequency are applied to the mixer 6 to which the removed broadcast signals are applied, while the frequency synthesizer 13 generating different local frequencies in different paths and the mixer receiving different local signals from the frequency synthesizer. (9) and microprocessors (14) and microprocessors for controlling local signals from the frequency synthesizer By using the computer 15 and the intermediate frequency broadcast signals which are interfaced with the signal, the bandpass filter (Crystal, SAW, etc.) 11 having excellent performance is used to display only the broadcast signals of the upper frequency band based on the spurious frequency. The intermediate frequency module 10 and the mixer 12 to which the broadcast signals from the intermediate frequency module are applied to pass and remove and amplify the signals in the lower wave band, and the broadcast signals from which the spurious is removed and other paths in between. A variable frequency band attenuator for improving the frequency selectivity of the broadband broadcast repeater for amplifying (16) the synthesized over-the-air broadcast signals and synthesizing the broadcast signals from the frequency module.