Noise detecting circuit

A noise detecting circuit for receiving a train of data pulses including an initial start pulse of a known duration and noise pulses of characteristically shorter duration and for identifying a first incoming pulse as either a start pulse or a noise pulse, comprising:

• means for generating clock pulses;
• first circuit means including a counter receiving the data pulses, the noise pulses, and the clock pulses, said counter counting the clock pulses upon receipt of a first incoming pulse;
• means for generating a noise verification pulse in response to said counter counting to a first predetermined count, the first predetermined count being reached after an interval which is greater than the characteristic duration of a noise pulse and less than the duration of a start pulse;
• and
• second circuit means receiving the data pulses, the noise pulses and the noise verification pulse for providing an electrical indication of a lack of time coincidence between the first incoming pulse and the noise verification pulse when the first incoming pulse is a noise pulse, thereby identifying the first incoming pulse as a noise pulse rather than a start pulse.

A circuit for processing data pulses in a train of pulses including an initial start pulse of known duration and noise pulses of characteristically shorter duration and for identifying a first incoming pulse as either a start pulse or a noise pulse, comprising:

• means for generating clock pulses;
• a first circuit, including a counter, receiving the data pulses, the noise pulses and the clock pulses, said counter counting the clock pulses upon receipt by said first circuit of a first incoming pulse;
• a second circuit for generating a noise verification pulse in response to said counter counting to a first predetermined count, the first predetermined count being reached after an interval which is greater than the characteristic duration of a noise pulse and less than the duration of a start pulse;
• a third circuit receiving the data and noise pulses and the noise verification pulse for generating an electrical signal indicative of a lack of time coincidence between the noise verification pulse and the first incoming pulse when the first incoming pulse is a noise pulse, thereby identifying the first incoming pulse as a noise pulse rather than a start pulse;
• and
• a data processing channel receiving the data and noise pulses and responsive to said counter counting to a second higher predetermined count for processing the received pulses, said first circuit being responsive to the electrical signal generated by said third circuit for inhibiting the counter from counting to said second higher predetermined count when the first incoming pulse is a noise pulse and for permitting the counter to count to said second predetermined count when the electrical signal is not generated, thereby allowing said data processing channel to process subsequently received data pulses only when the first incoming pulse is a start pulse and inhibiting the data processing channel from processing subsequently received pulses when the first incoming pulse is a noise pulse.