Abstract: Adjusted maximum transmit PSD levels have an effect on the SNR. If the ADC noise is assumed to be the limiting factor, then there can be a benefit for reducing the maximum transmit PSD level. For example, by lowering the maximum transmit PSD level from ?50 dBm/Hz to ?70 dBm/Hz results in an increase in SNR for subcarriers above 30 M Hz. The SNR for subcarriers above 30 MHz can increase from 30 db (?80-(?110)) to 50 db (?80-(?130)). Therefore, by changing the maximum transmit PSD level, applying a ceiling on PSD mask, the aggregate sum of the available SNR's over the available subcarriers is therefore increasing the obtainable OFDM data rate. In other words, a maximum transmit PSD mask can be used to lower the transmit PSD value of at least one subcarrier which results in an increase in SNR for at least one subcarrier.

Abstract: Adjusted maximum transmit PSD levels have an effect on the SNR. If the ADC noise is assumed to be the limiting factor, then there can be a benefit for reducing the maximum transmit PSD level. For example, by lowering the maximum transmit PSD level from ?50 dBm/Hz to ?70 dBm/Hz results in an increase in SNR for subcarriers above 30 MHz. The SNR for subcarriers above 30 MHz can increase from 30 db (?80?(?110)) to 50 db (?80?(?130)). Therefore, by changing the maximum transmit PSD level, applying a ceiling on PSD mask, the aggregate sum of the available SNR's over the available subcarriers is increased, therefore increasing the obtainable OFDM data rate. In other words, a maximum transmit PSD mask can be used to lower the transmit PSD value of at least one subcarrier which results in an increase in SNR for at least one subcarrier.

Abstract: A communication system for sending a sequence of symbols on a communication link. The system includes a transmitter for placing information indicative of the sequence of symbols on the communication link and a receiver for receiving the information placed on the communication link by the transmitter. The transmitter includes a clock for defining successive frames, each of the frames including M time intervals, where M is an integer greater than 1. A modulator modulates each of M carrier signals with a signal related to the value of one of the symbols thereby generating a modulated carrier signal corresponding to each of the carrier signals. The modulated carriers are combined into a sum signal which is transmitted on the communication link. The carrier signals include first and second carriers, the first carrier having a different bandwidth than the second carrier.

Abstract: A method for operating a computer to reduce the memory needed to store seismic data. The seismic measurements are first organized into a multi-dimensional data array. The multi-dimensional data array is than sub-band coded to form a coded data array by applying a one-dimensional transformation corresponding to each dimension of the data array to that dimension of the data array. The transformation is determined by the frequency content of the corresponding dimension of the data array. The sub-band coded data array is then quantized to provide a compacted data array.