Philips Electronics North America Corporation

Jerry Hongbin Hao

William W Kolb

Bill Kolb

A pulse edge detector for detecting edges of a pulse signal in a bit stream. The bit stream, and herewith the pulse signal, is synchronized to a clock having half the resolution of a clock signal used to transmit the bit stream. Falling and rising edges of the synchronized pulse signal are determined. It is further determined whether the falling and rising edges of the pulse signal fall within a first or a second phase of the clock signal. The determined phase result is recorded for further processing by a succeeding circuit such as a counter. By determination of the pulse phase in both phases of the clock pulse, a double resolution pulse edge detector is obtained.

Pulse detector with double resolution

An autobaud method for automatic detection of baud rate and character configuration of a received asynchronous serial data stream by detecting a first predetermined two character sequence in uppercase and lowercase form, notably 'AT' and 'at', from patterns of signal states and their durations, also provides for detecting a second predetermined two character sequence of 'A/' and 'a/' and for substantially immediate automatic echoing of the first and second predetermined character sequences if autoechoing is enabled. The baud rate and character configuration used for subsequent characters is not be changed unless, after the autobaud function is enabled, the first predetermined two character sequence in either uppercase or lowercase form is received, and a different baud rate and/or character configuration is determined from the received pattern of signal states and their durations. The baud rate is determined by measuring the duration of a signal state begun by an apparent transition from a stop bit or idle state, and determining whether the measured duration falls within any of a set of predetermined bit time ranges or legal windows, each corresponding to a different baud rate of a set of predetermined standard baud rates.

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San Jose, CA, United States of America

Jerry Hongbin Hao