Apparatus for Monitoring Non-Linear Distortions of Radio Signals and a Method Therefor

A front-end unit for use in a radio signal transmitter, the front-end unit comprising:

• a mixer operatively connected to a local oscillator;
• an analogue-to-digital converter to process signals received from the mixer;
• a first digital filter for converting signals received from the analogue-to-digital converter to a baseband signal;
• and
• an adaptive digital filter to time-synchronize its output signal (z(k)) to a reference signal (r(k)), and to remove linear distortions from the baseband signals received from the first digital filter while leaving non-linear distortions unaffected.

A transmitter for transmitting radio signals, the transmitter comprising:

• a digital signal source;
• a compensation unit;
• two digital-to-analogue converters;
• an analogue modulator;
• an amplifier;
• an antenna connected to the amplifier;
• and
• a front-end unit connected to an estimator, the front-end unit comprising:
• a mixer operatively connected to a local oscillator;
• an analogue-to-digital converter to process signals received from the mixer;
• a first digital filter to convert signals received from the analogue-to-digital converter to baseband signals;
• and
• an adaptive digital filter to time-synchronize its output signal (z(k)) to a reference signal (r(k)), and to remove linear distortions from the baseband signals received from the first digital filter while leaving non-linear distortions unaffected.

A transceiver for transmitting and receiving radio signals comprising:

• a receiving section;
• and
• a transmitting section comprising:
• a digital signal source;
• a compensation unit;
• two digital-to-analogue converters;
• an analogue modulator;
• an amplifier;
• an antenna connected to the amplifier;
• and
• a front-end unit connected to an estimator, the front-end unit comprising:
• a mixer operatively connected to a local oscillator;
• an analogue-to-digital converter to process signals received from the mixer;
• a first digital filter for converting signals received from the analogue-to-digital converter to baseband signals;
• and
• an adaptive digital filter time-synchronize its output signal (z(k)) to a reference signal (r(k)), and to remove linear distortions from the baseband signals received from the first digital filter while leaving non-linear distortions unaffected.

A method of monitoring non-linear distortions of radio signals transmitted by a radio signal transmitter comprising:

• converting radio a frequency input signal to an intermediate frequency analogue signal;
• converting the intermediate frequency analogue signal to an intermediate frequency digital signal;
• converting the intermediate frequency digital signal to a baseband digital signal;
• time-synchronizing an output signal of an adaptive digital filter that receives the baseband signal to a reference signal;
• and
• removing linear distortions from the baseband signal while leaving non-linear distortions unaffected.