Blind switch diversity control apparatus

A method for receiving a radio signal carrying digitally-encoded synchronization words and data, comprising the steps of:

• selecting one of a plurality of antennas for receiving said radio signal and forming a received signal;
• equalizing said received signal to form an equalized signal, said equalization being controlled by one or more tap weights;
• demodulating said equalized signal to recover said data;
• generating a quality metric dependent on the quality of said recovered data;
• and
• controlling said antenna selection so that after a new one of said antennas is selected in place of a previously-selected one of said antennas, said tap weights are retrained using said synchronization words, and if said quality metric does not equal or exceed a new-antenna-acceptance quality-metric threshold before the end of a forward guard time, another one of said antennas is selected at the end of said forward guard time.

A receiver for receiving a radio signal carrying digitally-encoded synchronization words and data, comprising:

• two or more antennas;
• a selector for selecting one of said antennas to receive said radio signal and to provide a received signal;
• a signal level detector for detecting a signal level of said received signal;
• an equalizer for equalizing said received signal to form an equalized signal;
• a demodulator for recovering said data from said equalized signal and for generating a quality metric dependent on the quality of said recovered data;
• and
• a controller responsive to said quality metric for controlling said selector;
• in which, after said controller controls said selector to select a new one of said antennas in place of a previously-selected one of said antennas, if said signal level is less than a signal-level threshold then said demodulator recovers data from said equalized signal for a predetermined short time and generates a quality metric therefrom, and if said quality metric is less than a low-signal-level, new-antenna-acceptance quality-metric threshold, then said controller controls said selector to select another one of said antennas to receive said radio signal after said predetermined short time.

A method for receiving a radio signal carrying digitally-encoded synchronization words and data, comprising the steps of:

• selecting one of a plurality of antennas for receiving said radio signal and forming a received signal;
• detecting a signal level of said received signal;
• equalizing said received signal to form an equalized signal, said equalization being controlled by one or more tap weights;
• demodulating said equalized signal to recover said data;
• generating a quality metric dependent on the quality of said recovered data;
• and
• controlling said antenna selection so that after a new one of said antennas is selected in place of a previously-selected one of said antennas, if said signal level is less than a signal-level threshold and if said quality metric derived from said recovered data during a predetermined short time after said new antenna selection is less than a low-signal-level, new-antenna-acceptance quality-metric threshold, then another one of said antennas is selected to receive said radio signal after said predetermined short time.

An apparatus for upgrading a receiver for receiving a radio signal carrying digitally-encoded synchronization words and data, to implement blind-switching-diversity reception, said receiver comprising an antenna for receiving said radio signal, an equalizer for equalizing said received signal and a demodulator for recovering said data, and said apparatus comprising:

• antenna means including one or more additional antennas or two or more replacement antennas;
• a selector for selecting one of said antennas to receive said radio signal and to provide said received signal;
• a means for generating a quality metric dependent on the quality of said recovered data;
• and
• a controller responsive to said quality metric for controlling said selector;
• in which, after said controller controls said selector to select a new one of said antennas in place of a previously-selected one of said antennas, said equalizer uses one or more of said synchronization words to retrain on said received signal from said new antenna and, if said quality metric does not equal or exceed a new-antenna-acceptance quality-metric threshold before a predetermined forward guard time has ended, said controller causes said selector to select another one of said antennas when said predetermined forward guard time has ended.

An apparatus for upgrading a receiver for receiving a radio signal carrying digitally-encoded synchronization words and data, to implement blind-switching-diversity reception, said receiver comprising an antenna for receiving said radio signal, an equalizer for equalizing said received signal and a demodulator for recovering said data, and said apparatus comprising:

• antenna means including one or more additional antennas or two or more replacement antennas;
• a selector for selecting one of said antennas to receive said radio signal and to provide said received signal;
• a signal level detector for detecting a signal level of said received signal;
• a means for generating a quality metric dependent on the quality of said recovered data;
• and
• a controller responsive to said quality metric for controlling said selector;
• in which, after said controller controls said selector to select a new one of said antennas in place of a previously-selected one of said antennas, if said signal level is less than a signal-level threshold in a predetermined short time after said new antenna is selected, said demodulator recovers data during said predetermined short time and generates a quality metric therefrom, and if said quality metric is less than a low-signal-level, new-antenna-acceptance quality-metric threshold, then said controller controls said selector to select another one of said antennas to receive said radio signal after said predetermined short time.