US 7,065,136 B1Granted

Receiver having equalizing demodulator and a non-equalizing demodulator and method for controlling the same

AssigneeFreescale Semiconductor, Inc.

InventorsJames L. Porter, John W. Diehl, Wayne H. Bradley

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Abstract

A receiver (24) comprises a non-equalizing demodulator (48), an equalizing demodulator (46) and an output control selector (50). The non-equalizing demodulator (48) receives a modulated signal (44) and demodulates the modulated signal (44) to produce a first digital bit stream (54). The equalizing demodulator (46) receives the modulated signal (44) and equalizes and demodulates the modulated signal (44) to produce a second digital bit stream (52). The output control selector (50), coupled to the non-equalizing demodulator (48) and the equalizing demodulator (46), selectively delivers a first one of the first digital bit stream (54) and the second digital bit stream (52) for at least a predetermined period of time (30) before selectively delivering a second one of the first digital bit stream (54) and the second digital bit stream (52) responsive to a predetermined decision criterion (e.g., bit error rate 68). The first one of the first digital bit stream (54) and the second digital bit stream (52) is different from the second one of the first digital bit stream (54) and the second digital bit stream (52).

Claims28

Dependent claims

A receiver comprising:

a non-equalizing demodulator adapted to receive a modulated signal and adapted to demodulate the modulated signal to produce a first digital bit stream, wherein the modulated signal includes a plurality of frames, each frame having an amble portion;
an equalizing demodulator adapted to receive the modulated signal and adapted to equalize and demodulate the modulated signal to produce a second digital bit stream;
and
an output control selector, coupled to the non-equalizing demodulator and the equalizing demodulator, adapted to selectively deliver a first one of the first digital bit stream and the second digital bit stream for at least a predetermined period of time before selectively delivering a second one of the first digital bit stream and the second digital bit stream responsive to a predetermined decision criterion, wherein the first one of the first digital bit stream and the second digital bit stream is different from the second one of the first digital bit stream and the second digital bit stream and wherein the predetermined decision criteria comprises a quality metric associated with the modulated signal, the quality metric further comprising a bit error rate associated with the modulated signal;
wherein the output control selector produces a first control signal to selectively enable and disable the non-equalizing demodulator to permit the non-equalizing demodulator to deliver and not deliver, respectively, the first digital bit stream;
and
wherein the output control selector produces a second control signal to selectively enable and disable the equalizing demodulator to permit the equalizing demodulator to deliver and not deliver, respectively, the second digital bit stream;
and
wherein the output control selector further comprises:
a bit error rate (BER) long term averager adapted to receive the amble portion of each frame, adapted to determine bit error rate of the amble portion of each frame, and adapted to average the bit error rate of the amble portion of each frame over time to determine a long term average BER associated with the modulated signal;
and
a switch adapted to receive the first digital bit stream and the second digital bit stream and adapted to selectively deliver one of the first digital bit stream and the second digital bit stream responsive to a third control signal.

9 more elements

A receiver comprising:

a non-equalizing demodulator adapted to receive a modulated signal and adapted to demodulate the modulated signal to produce a first digital bit stream, wherein the modulated signal includes a plurality of frames, each frame having an amble portion,
an equalizing demodulator adapted to receive the modulated signal and adapted to equalize and demodulate the modulated signal to produce a second digital bit stream;
and
an output control selector, coupled to the non-equalizing demodulator and the equalizing demodulator and adapted to receive the modulated signal, including:
a bit error rate (BER) long term averager adapted to receive the amble portion of each frame of the modulated signal, adapted to determine a bit error rate of the amble portion of each frame, and adapted to average the bit error rate of the amble portion of each frame over time to determine a long term average bit error rate associated with the modulated signal,
wherein the output control selector is adapted to selectively enabling a first one of the non-equalizing demodulator and the equalizing demodulator and selectively disabling a second one of the non-equalizing demodulator and the equalizing demodulator to selectively deliver a first one of the first digital bit stream and the second digital bit stream for at least a predetermined period of time, corresponding to a predetermined number of frames of the modulated signal, before selectively disabling the first one of the non-equalizing demodulator and the equalizing demodulator and selectively enabling the second one of the non-equalizing demodulator and the equalizing demodulator to selectively delivering a second one of the first digital bit stream and the second digital bit stream responsive to the long term average bit error rate, wherein the first one of the non-equalizing demodulator and the equalizing demodulator is different from the second one of the non-equalizing demodulator and the equalizing demodulator, and wherein the first one of the first digital bit stream and the second digital bit stream is different from the second one of the first digital bit stream and the second digital bit stream;
and
wherein the output control selector selectively delivers the first digital bit stream for the at least the predetermined period of time responsive to the long term average BER being below a first threshold and selectively delivers the second digital bit stream for the at least the predetermined period of time responsive to the long term average BER being above a second threshold that is greater than the first threshold.

5 more elements

A receiver comprising:

a non-equalizing demodulator adapted to receive a modulated signal and adapted to demodulate the modulated signal to produce a first digital bit stream, wherein the modulated signal includes a plurality of frames, each frame having an amble portion;
an equalizing demodulator adapted to receive the modulated signal and adapted to equalize and demodulate and the modulated signal to produce a second digital bit stream;
and
an output control selector including:
a switch adapted to receive the first digital bit stream and the second digital bit stream and adapted to selectively deliver a first one of the first digital bit stream and the second digital bit stream for at least a predetermined period of time before selectively delivering a second one of the first digital bit stream and the second digital bit stream responsive to a signal quality metric associated with at least one of the first digital bit stream and the second digital bit stream, wherein the first one of the first digital bit stream and the second digital bit stream is different from the second one of the first digital bit stream and the second digital bit stream, wherein the output control selector selectively delivers the first digital bit stream for the at least the predetermined period of time responsive to the signal quality metric being below a first threshold and selectively delivers the second digital bit stream for the at least the predetermined period of time responsive to the signal quality metric being above a second threshold that is greater than the first threshold, the signal quality metric further comprising a bit error rate associated with the modulated signal;
and
a bit error rate (BER) long term averager adapted to receive the amble portion of each frame, adapted to determine bit error rate of the amble portion of each frame, and adapted to average the bit error rate of the amble portion of each frame over time to determine a long term average BER associated with the modulated signal.

4 more elements

A method for operating a receiver comprising the steps of:

demodulating a modulated signal to produce a first digital bit stream, wherein the modulated signal includes a plurality of frames, and wherein each frame has an amble portion;
equalizing and demodulating the modulated signal to produce a second digital bit stream;
receiving the amble portion of each frame of the modulated signal;
determining a bit error rate of the amble portion of each frame;
averaging the bit error rate of the amble portion of each frame over time to determine a long term average bit error rate associated with the modulated signal;
and
selectively enabling a first one of the non-equalizing demodulator and the equalizing demodulator and selectively disabling a second one of the non-equalizing demodulator and the equalizing demodulator to selectively deliver a first one of the first digital bit stream and the second digital bit stream for at least a predetermined period of time, corresponding to a predetermined number of frames of the modulated signal, before selectively disabling the first one of the non-equalizing demodulator and the equalizing demodulator and selectively enabling the second one of the non-equalizing demodulator and the equalizing demodulator to selectively delivering a second one of the first digital bit stream and the second digital bit stream responsive to the long term average bit error rate such that the first digital bit stream is delivered for the at least predetermined period of time responsive to the long term average bit error rate being below a first threshold and the second digital bit stream is delivered for the at least predetermined period of time responsive to the lone term average bit error rate being above a second threshold that is greater than the first threshold, wherein the first one of the nonequalizing demodulator and the equalizing demodulator is different from the second one of the non-equalizing demodulator and the equalizing demodulator, and wherein the first one of the first digital bit stream and the second digital bit stream is different from the second one of the first digital bit stream and the second digital bit stream.

4 more elements

Dependencies are inferred from the claim text.