Methods and apparatus for reducing discrete power spectral density components of signals transmitted in wideband communications systems

A pseudo-random number generator comprising:

• a first linear feedback shift register;
• and
• a second linear feedback shift register coupled to the first linear feedback shift register;
• wherein the second linear feedback shift register is configured to supply a first pseudo-random number sequence to the first linear feedback shift register and the first linear feedback shift register is configured to supply a second pseudo-random number sequence responsive to the first pseudo-random number sequence.

A pseudo-random number generator comprising:

• a first linear feedback shift register configured to generate a first pseudo-random number sequence;
• a second linear feedback shift register configured to generate a second pseudo-random number sequence;
• a combiner coupled to the first and second linear feedback shift registers, the combiner configured to combine the first and second random number sequences;
• and
• a third linear feedback shift register coupled to the combiner, the third linear feedback shift register configured to produce pseudo-random data responsive to the combined first and second random number sequences.

An apparatus for transmitting blocks of data as ultra wideband (UWB) signals having reduced discrete power spectral density (PSD) components, each block including N elements, the apparatus comprising:

• a shift register having cells configured to receive N symbols of pseudo-random data;
• an inverter coupled to select cells of the shift register to receive one bit from each symbol of the pseudo-random data, the inverter being configured to selectively invert respective elements in one of the data blocks responsive to bits in the select cells;
• and
• a transmitter coupled to the inverter, the transmitter configured to transmit the selectively inverted respective elements.

An apparatus for receiving an ultra wideband (UWB) signal transmission of selectively inverted blocks of data, each block including N elements, the apparatus comprising:

• a receiver configured to receive the wideband signal transmission of selectively inverted blocks of data;
• a shift register coupled to the receiver, the shift register having cells configured to receive N symbols of pseudo-random data;
• and
• an inverter coupled to select cells of the shift register to receive one bit from each symbol of the pseudo-random data, the inverter being configured to selectively invert respective elements in one of the received data blocks responsive to bits in the select cells.

A system for reducing discrete power spectral density (PSD) components of wideband signals transmitting blocks of data, each block including N elements, the system comprising:

• means for acquiring N symbols of pseudo-random data, each symbol having K bits;
• means for selecting one bit from each of the acquired symbols to generate N selected bits;
• means for selectively inverting a respective element In one of the data blocks responsive to the selected bits;
• and
• means acquiring one or more bits of pseudo-random data to replace a corresponding one or more respective bits of the acquired N symbols of pseudo-random data.

A computer readable carrier including software that is configured to control a computer to implement a method embodied in a computer readable medium for reducing discrete PSD components of a wideband signal transmitting blocks of data, each block including N elements, the method including the steps of:

• (a) acquiring N symbols of pseudo-random data, each symbol having K bits;
• (b) selecting one bit from each of the acquired symbols to generate N selected bits;
• (c) selectively inverting a respective element in one of the data blocks responsive to the selected bits;
• (d) acquiring one or more bits of pseudo-random data to replace a corresponding one or more respective bits of the acquired N symbols of pseudo-random data;
• and
• (e) repeating steps (b) through (d) with successive ones of the data blocks.