Error detecting method and apparatus for data communications

A method of processing data transmitted on a communications channel in a data word including a plurality of data bits and coded according to a predetermined error correcting code, said method comprising the steps of:

• receiving a data word from the communications channel, each received data bit having a binary state represented by a left half non-return-to zero (NRZ) bit sample and a right half NRZ bit sample;
• checking the right half NRZ bit samples of the received data word according to the predetermined error correcting code to detect the number of erroneous bits;
• error correcting the right half NRZ bit samples of the received data word according to the predetermined error correcting code if the number of erroneous bits is less than a first predetermined number;
• comparing the left half NRZ bit samples to the error-free or error-corrected right half NRZ bit samples of the received data word to determine the number of data bits that are in error;
• and
• discarding the received data word if it has more than a second predetermined number of data bits that are in error.

Data processing apparatus for processing data transmitted transmitted on a communications channel in a data word having a plurality of data bits and coded according to a predetermined error correcting code, said error correcting apparatus comprising:

• means for receiving a data word from the communications channel, each received data bit having a binary state represented by a left half non-return-to zero (NRZ) bit sample and a right half NRZ bit sample;
• means for processing each received data word by:
• checking the right half NRZ bit samples of the received data word according to the predetermined error correcting code to detect the number of erroneous bits;
• error correcting the right half NRZ bit samples of the received data word according to the predetermined error correcting code if the number of erroneous bits is less than a first predetermined number;
• comparing the left half NRZ bit samples to the error-free or the error-corrected right half NRZ bit samples of the received data word to determine the number of data bits that are in error;
• discarding the received data word if it has more than a second predetermined number of data bits that are in error;
• and
• processing the received data word if it has no more than the second predetermined number of data bits that are in error.

A method of processing Manchester-coded data transmitted on a communications channel in a data word including a plurality of data bits and coded according to a predetermined Bose-Chaudhuri-Hocquenghem (BCH) error correcting code, said method comprising the steps of:

• receiving a data word from the communications channel, each received data bit having a binary state represented by a left half non-return-to zero (NRZ) bit sample and a right half NRZ bit sample;
• checking the right half NRZ bit samples of the received data word according to the predetermined BCH error correcting code to detect the number of erroneous bits;
• error correcting the right half NRZ bit samples of the received data word according to the predetermined BCH error correcting code if the number of erroneous bits is less than a first predetermined number;
• comparing the left half NRZ bit samples to the error-free or the error-corrected right half NRZ bits of the received data word to determine the number of data bits that are in error;
• and
• discarding the received data word if it has more than a second predetermined number of data bits that are in error.

A radio telephone, comprising:

• an antenna;
• cellular transceiver means operable on radio telephone channels for communicating data and radio telephone calls, said data transmitted in a data word including a plurality of data bits and coded according to a predetermined error correcting code, each received data bit having a binary state represented by a left half non-return-to zero (NRZ) bit sample and a right half NRZ bit sample;
• control means and memory means for originating and receiving radio telephone calls and for transmitting and receiving the data words, said control means processing each received data word by:
• checking the right half NRZ bit samples of the received data word according to the predetermined error correcting code to detect the number of erroneous bits;
• error correcting the right half NRZ bit samples of the received data word according to the predetermined error correcting code if the number of erroneous bits is less than a first predetermined number;
• comparing the left half NRZ bit samples to the error-corrected right half NRZ bit samples of the received data word to determine the number of data bits that are in error;
• discarding the received data word if it has more than a second predetermined number of data bits that are in error;
• and
• processing the received data word if it has no more than the second predetermined number of data bits that are in error.