Method and device for eliminating same-frequency and adjacent-frequency interference in analog domain
An adjacent frequency interference and interference elimination technology, applied in the direction of echo reduction, transmission system, electrical components, etc., can solve the problems of amplitude compression, signal noise floor increase, application limitation, etc., to improve the effect, reduce noise floor increase, interference Scope widening effect
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Embodiment 1
[0035] Such as figure 1 As shown, this embodiment relates to the same-channel interference cancellation applied to the same-frequency repeater system.
[0036] The same-frequency repeater is used to amplify the useful signal received by the receiving antenna from the distant main tower and retransmit it to improve local area coverage. Usually, the receiving antenna of the co-frequency repeater will receive the interference of the co-frequency signal sent by its own transmitting antenna at the same time as receiving the effective signal, which is called echo, and the echo signal is often larger than the received main frequency signal. The signal is much stronger and therefore belongs to the interference signal described in the present invention.
[0037] For example, in this embodiment, the frequency of the repeater station is channel 25, which is set up on a hillside, and is more than 80 kilometers away from the main TV signal transmission tower that is also channel 25, and b...
Embodiment 2
[0047] Such as image 3 As shown, this embodiment involves adjacent channel interference cancellation: the main transmitting device with a receiving antenna is simultaneously interfered by broadcast signals of nearby upper and lower adjacent channels.
[0048]In this embodiment, the main transmitting device has a main receiving antenna and a main transmitting antenna, and the transmitting power is only 10w (40dbm). Because the signals sent and received are not on the same frequency point and are far apart, there is no need to deal with the same-channel interference caused by its own transmitting antenna. However, on the same transmitting tower as the main device, there is also a transmitting antenna working on the broadcast signal of its upper and lower adjacent frequencies, and it is an omnidirectional antenna with a relatively large transmitting power (2kw, corresponding to 63dbm), so even after the bandpass of the transmitter Filter, a single transmitter still reaches 27db...
Embodiment 3
[0064] Such as Figure 4 As shown, this embodiment is applied to the situation where the same-frequency repeater system suffers from both the same-frequency interference and the upper-lower-adjacent-frequency interference.
[0065] In this embodiment, the interference signal includes not only the same-frequency echo signal from the transmit antenna of the repeater itself, which is 35dB higher than the main signal, but also the echo signal from the same transmission tower working at the upper and lower adjacent frequencies. 30dBm adjacent frequency interference generated by broadcast signal omnidirectional antenna. If the analog domain interference elimination method described in the present invention is not used, it will not work normally.
[0066] For the co-channel interference in this embodiment, the interference signal source comes from the echo generated by the signal transmitted by itself, which is a known signal, so it can be directly connected through the feeder line,...
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