Telecommunications – Receiver or analog modulated signal frequency converter – With wave collector
Patent
1988-03-15
1990-11-06
Orsino, Joseph A.
Telecommunications
Receiver or analog modulated signal frequency converter
With wave collector
455278, 375 34, 342383, H04B 106
Patent
active
049692119
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND TO INVENTION
The present invention relates to a transceiver interference cancellation system (adaptive antenna) having an adaptive processor for receiving signals from a number of atennas and for suppressing particular signals received from the antennas.
Known transceiver interference cancellation systems employ adaptive processors which serve to automatically adjust the gain and phase conditions in the path between the antennas and the transceiver so as to cancel particular signals in the channel, but other particular signals pass through to the transceiver relatively unaffected.
Difficulties may arise with existing systems if the wanted and unwanted signals share a common frequency spectrum and the wanted signal is the dominant signal. In such instances there is a risk of accidental cancellation in the adaptive processor of the wanted signal reception. An objective of the present invention is to minimise that risk of accidental cancellation.
SUMMARY OF INVENTION
According to the present invention there is provided a transceiver interference cancellation system having an adaptive processor for receiving signals from a number of antennas and for suppressing particular signals received from the antennas wherein the improvement lies in the provision of a code generator for providing transmitted signals with a predetermined pulse code, a code correlator responsive to the code produced by the code generator and adapted to receive information for detecting a particular signal when it is the wanted signal as indicated by the presence therein of the pulse code, and an adaptive processor control means responsive to such detection by the code correlator for controlling operation of the adaptive processor such that wanted signals when identified are not suppressed, whereby interference only is cancelled.
In a preferred embodiment of the present invention there is provided first switch means whereby the code produced by the code generator can be applied to all wanted signal net transmissions.
In a further embodiment of the present invention second switch means is provided in the adaptive processor control means, the second switch means being operative in dependence upon a control signal from the code correlator indicating detection of the code in the received signal by the code correlator for controlling antenna pattern forming operation.
In a further embodiment of the present invention the adaptive processor control means comprises signal combiner means arranged to be switched into operation consequent upon detection of the code in the received signals for effecting in-phase combination of the signals received by the antennas, whereby the reception of the wanted signal is enhanced.
In the control process of an adaptive processor in a transceiver interference cancellation system in accordance with the present invention, there are two factors, either of which must be established in order to guarantee satisfactory operation. These are as follows:
(a) To exclude from the adaptive nulling control process, those signals which are required to be received, that is to say the wanted signals, and
(b) To determine which of two types of signals wanted or unwanted are dominating the adaptive nulling control process.
The technique in accordance with the present invention is aimed at one or other of these two requirements depending on the manner of its implementation. The basis is as follows:
A wanted signal radio emission is interrupted, for short periodic intervals (windows), generally in a manner which is not detrimental to communications The interrupts can be regular or in an irregular sequence which is coded in some pre-defined manner. The adaptive array control process makes of these coded window sequences in the wanted signal transmission, in the following way:
(1) In the case of requirement (a) the signal environment is sampled during the window period and this information is used to control the adaptive array (in the absence of the wanted signals). In this case it is required that the adaptive array samplin
REFERENCES:
patent: 4047151 (1977-09-01), Rydbeck et al.
patent: 4214244 (1980-07-01), McKay et al.
patent: 4227249 (1980-10-01), Hansen
patent: 4291405 (1981-09-01), Jayant et al.
patent: 4365338 (1982-12-01), McRae et al.
Orsino Joseph A.
Plessey Overseas Limited
Scutch III Frank M.
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