Andrew Corporation

Other

Fairfield Industries, Inc.

Richard Michael Bennett

Steven Meade

Peter Kenington

Andrew Bateman

Steven Richard Ring

Antony James Smithson

Paul George Turner

Errors present in the output of an amplifier () are compared with the amplifier input in a control unit () to derive corrected coefficients for a look-up table used by predistorter () to eliminate distortion in the output of the amplifier (). Depending on the format of the predistorter (), at least some of the coefficients are corrected using measured errors that have been rendered independent of the input signal's amplitude.

Signal correction techniques

A lineariser () for reproducing distortion present in the output of an amplifier () (or other signal handling device) generates a predistortion signal from the amplifier input. The predistortion signal is mixed into the amplifier input signal using, for example, a vector modulator (). The predistortion signal may be derived in a quadrature format, the orthogonal components of the predistortion signal being mixed into separate mixers of the vector modulator. The predistortion signal is generated by multiplying the input signal with itself repeatedly to generate components of distortion which are susceptible of independent control. The predistortion signal is generated digitally using DSP (). A multiplier or mixer may be used to square the sampled input signal to produce a reduced frequency signal which the DSP can use to gennerate the predistortion signal. Another lineariser mixes the predistortion signal into the input signal during up conversion.

Lineariser for a signal handling apparatus

A method and apparatus is provided for locking a local oscillator to a reference oscillator. The reference oscillator is arranged to transmit a signal containing two reference pilot tones in a signal sideband. The apparatus samples the received signal and makes a frequency shifted copy where the shift is equal to the expected separation between the reference tones. The non-shifted and shifted signals are then combined in the frequency domain to constructively reinforce one of the reference pilot tones which is then searched for. Once the tone has been identified, a correction to the local oscillator frequency is calculated. The apparatus may be of particular use in a radio telemetry system in which it is important that the frequency of the local oscillators in the transmitters and receivers are very accurately matched to each other and where, in order to reduce interference, all the clocks used in the system are locked to a master clock.

Apparatus for and method of synchronising oscillators within a data communication system

In a remote data acquisition system a control unit transmits a radio signal simultaneously to a plurality of remote units. Each remote unit receives the radio signal at different times dependent on various system delay factors. A compensating delay is added in each remote unit in order to trigger each remote unit for data acquisition at the same time.

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Salisbury, United Kingdom

Richard Michael Bennett