General Electric Company

Sanjay K Bose

Lewin T Baker

Charles M Puckette

Paul G Huber

George W Ellis

A method for transmission of digital data utilizes a carrier frequency offset in a first frequency direction for a first binary condition, and offset in a second frequency direction for the remaining binary condition, at the start of a bit time interval. The carrier frequency is swept in a preselected frequency direction during each bit time interval, to produce a chirped frequency-shift-keyed waveform in the frequency domain, for transmission of each bit of binary data. Frequency-shift-keyed demodulation is utilized at a receiving end, with the receiver synchronized to the transmitter bit time interval, to recover the transmitted digital data. Apparatus for data transmission using this chirped frequency-shift-keyed modulation waveform is disclosed.

Method and apparatus for data transmission using chirped

In a power line data communications system, high-bit-rate digital data is transmitted through a communications media, having high harmonic noise content, by use of a frequency-modulated chirp waveform. The chirp waveform instantaneous frequency is at a predetermined center frequency at the start, midpoint and end of each bit time interval, and makes substantially linear frequency changes to a maximum frequency and a minimum frequency at selected ones of the one-quarter and three-quarter bit-time-interval times. A binary-one data bit is transmitted by increasing the instantaneous frequency to reach the maximum frequency at the one-quarter interval time, then decreasing the frequency to reach a minimum frequency at the three-quarter interval time, and reducing the instantaneous frequency thereafter to reach the center frequency at the end of the bit time interval. A binary-zero data bit is transmitted by initially decreasing the instantaneous frequency to reach the minimum frequency at the one-quarter interval time, then increasing the instantaneous frequency to reach the maximum frequency at the three-quarter interval time, and reducing the instantaneous frequency thereafter to reach the center frequency at the end of the bit time interval. One presently preferred embodiment of apparatus for transmitting the chirp frequency-modulation signal, and one presently preferred embodiment of apparatus for receiving the chirp frequency-modulated waveform for recovering the data modulated thereon, and associate timing information, are disclosed.

Methods, and apparatus, for transmitting high-bit-rate digital data in

In a digital data communications system having a plurality of slaved data transceivers transmitting data to, and receiving data from, a master station, the master station classifies a received signal, in each of a multiplicity of bit time intervals, as one or the other of the pair of binary signal states. The received binary signal state is echoed to all of the slaved stations, to cause those stations which did not previously transmit that binary state to cease transmitting data. Those slave stations which transmitted the echoed previous bit binary state then transmit the next bit of data, which is again echoed. Slaved stations receiving bit echoes which are different from the previous bit sent will know that there has been a collision and that the master station did not receive their bit of data, whereby the number of slave stations transmitting is reduced, in successive bit time intervals, until only one slave station remains transmitting. The initial portion of the message of the one remaining station need not be repeated, whereby system time is not lost.

Method for digital data transmission with bit-echoed arbitration

In a chirped-frequency-shift-keyed data system, in which a plurality of stations each contain a data transmitter and a data receiver constantly monitoring a common system communications medium even while the companion transmitter is transmitting digital data, the CFSK signal is received during each of a successive plurality of synchronous bit time intervals with a first amplitude. The received signal is: squared and filtered in a first channel; multiplied with a locally generated signal of a second amplitude and associated with a first binary chirp condition, and then filtered, in a second channel; and multiplied with another locally generated signal of the second amplitude and associated with the remaining binary chirp condition, and then filtered, in a third channel. The channel outputs are functions of the signal amplitudes and also of the number of system transmitters simultaneously transmitting one or the other of the binary data states. Comparison of the energy contents of the various channels determines if a collision has occurred; and if a collision is detected, further comparisons arbitrate the collision to the bit state of the larger number of transmitters then active. The collision detection and bit arbitration is carried out without reference to a threshold value.

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Schenectady, NY, United States of America

Sanjay K Bose