Method and means for automatically detecting and correcting a polarlity error in twisted-pair media

A circuit for testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data which includes link integrity test (LIT) pulses and frames including end of frame delimiter (EOF) waveforms, said circuit comprising

• sensing means receiving said transmission and sensing the polarity of a first LIT pulse and succeeding LIT pulses and producing signals indicative of same;
• counter means responsive to said signals for counting consecutive LIT pulses having the same polarity as the first LIT pulse and providing an enabling signal when the count equals or exceeds a selected number;
• means for producing a selection signal when a LIT pulse of the opposite polarity to said first LIT pulse is received by said sensing means and clearing said counter means in response thereto;
• polarity switching means receiving said transmission and being responsive to said selection signal for inverting said transmission, and
• logic means receiving said transmission from said polarity switching means and being responsive to said enabling signal for passing said transmission.

A method of testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data which includes link integrity test (LIT) pulses and frames including end of frame delimiter (EOF) waveforms, said method comprising the steps of

• sensing the polarity of a first EOF waveform and succeeding EOF waveforms in the received transmission and producing signals indicative of same;
• in response to said signals, counting consecutive EOF waveforms having the same polarity as the first EOF waveform and providing an enabling signal when the count equals or exceeds a selected number;
• producing a selection signal when an EOF waveform of the opposite polarity to said first EOF waveform is received by said sensing means and clearing said counter in response thereto;
• inverting said received transmission in response to said selection signal, and
• passing said received transmission when said enable signal is present.

A method of testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data which includes link integrity test (LIT) pulses and frames including end of frame delimiter (EOF) waveforms, said method comprising the steps of

• sensing the polarity of a first LIT pulse and succeeding LIT pulses in the received transmission and producing signals indicative of same;
• in response to said signals, counting consecutive LIT pulses having the same polarity as the first LIT pulse and providing an enabling signal when the count equals or exceeds a selected number;
• producing a selection signal when a LIT pulse of the opposite polarity to said first LIT pulse is received by said sensing means and clearing said count in response thereto;
• inverting said received transmission in response to said selection signal, and
• passing said received transmission when said enabling signal is present.

A circuit for testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data, said circuit comprising

• first sensing means for receiving said transmission and detecting the presence of positive waveforms of a pre-determined positive threshold voltage level and continuing for a pre-determined duration and producing first output signals in response thereto;
• second sensing means for receiving said transmission and detecting the presence of negative waveforms of a pre-determined negative threshold voltage level and continuing for a pre-determined duration and producing second negative signals in response thereto;
• counter means for counting said first and second output signals, said counter means providing an enabling signal when a selected number of consecutive first output signals or a selected number of consecutive second output signals is counted;
• means for resetting the counter means when the counting of said first output signals is interrupted by the occurrence of a second output signal or when the counting of said second output signals is interrupted by the occurrence of a first output signal and producing a selection signal in response thereto;
• polarity switching means receiving said transmission and being responsive to said selection signal for inverting said transmission;
• logic means receiving said transmission from said polarity switching means and being responsive to said enabling signal for passing said transmission.

A method of testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data, said method comprising

• sensing the presence of positive waveforms of a pre-determined positive threshold voltage level and continuing for a pre-determined duration and producing first output signals in response thereto;
• sensing the presence of negative waveforms of a pre-determined negative threshold voltage level and continuing for a pre-determined duration and producing second output signals in response thereto;
• counting said first and second output signals to provide an enabling signal when a selected number of consecutive first output signals or a selected number of consecutive second output signals is counted;
• when the counting of said first output signals is interrupted by the occurrence of a second output signal or when the counting of said second output signal is interrupted by the occurrence of a first output signal, producing a selection signal in response thereto and resetting the count;
• inverting the received transmission in response to the selection signal, and
• passing the received transmission when said enabling signal is present.

A circuit for testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data which includes link integrity test (LIT) pulses and frames including end of frame delimiter (EOF) waveforms, said circuit comprising

• first sensing means receiving said transmission and sensing the polarity of a first EOF waveform and succeeding EOF waveforms and producing signals indicative of same;
• first counter means responsive to said signals for counting consecutive EOF waveforms having the same polarity as the first EOF waveform and providing an enabling signal when the count equals or exceeds a first selected number;
• second sensing means receiving said transmission and sensing the polarity of a first LIT pulse and succeeding LIT pulses and producing signals indicative of same;
• second counter means responsive to said signals for counting consecutive LIT pulses having the same polarity as the first LIT pulse and providing an enabling signals when the count equals or exceeds a second selected number;
• means for producing a selection signal when an EOF waveform of the opposite polarity to said first EOF waveform or a LIT pulse of the opposite polarity to said first LIT pulse is received by said sensing means and clearing said counter means in response thereto;
• polarity switching means receiving said transmission and being responsive to said selection signal for inverting said transmission, and
• logic means receiving said transmission from said polarity switching means and being responsive to said enabling signal for passing said transmission.

A method of testing the link integrity and correcting the polarity of LAN link transmission media coupled to the MAU circuit of a LAN device that receives the transmission of data which includes link integrity test (LIT) pulses and frames including end of frame delimiter (EOF) waveforms, said method comprising the steps of

• sensing the polarity of a first EOF waveform and succeeding EOF waveforms in the received transmission and producing first signals indicative of same;
• in response to said first signals, counting consecutive EOF waveforms having the same polarity as the fist EOF waveform and providing an enabling signal when the count equals or exceeds a first selected number;
• sensing the polarity of a first LIT pulse and succeeding LIT pulses in the received transmission and producing second signals indicative of same;
• in response to said second signals, counting consecutive LIT pulses having the same polarity as the first LIT pulse and providing an enabling signal when the count equals or exceeds a second selected number;
• producing a selection signal when an EOF waveform of the opposite polarity to the first EOF waveform or a LIT pulse of the opposite polarity to said first LIT pulse is received by said sensing means and clearing said count in response thereto;
• inverting said received transmission in response to said selection signal, and
• passing said received transmission when said enabling signal is present.