Abstract: A system and method is provided for using a first data channel to pass working data and a second data channel to pass error correction information. For example, this second data channel may be defined along a redundant data path. For example, this error correction information may be forwarded error correction (FEC) information such as Hamming code information or any other type of error correction information. Use of the redundant path to forward FEC information provides several advantages: 1) the FEC information can be used to correct bit errors that occur within the system, making the system high-quality and more reliable and 2) use of the protected path provides an efficient method to constantly monitor the quality of both the working and redundant path. Monitoring is accomplished by using the FEC information on the redundant path in conjunction with the information on the working path to accurately count the number of errors that occur on the working and redundant paths.

Abstract: A technique is presented for simplifying the recovery of two synchronous data signals having a common symbol rate after each signal has respectively modulated a different one of a pair of quadrature-related carrier signals. In the transmitter, the data signal which modulates one of the quadrature-related carrier signals is delayed relative to the data signal which modulates the other quadrature-related carrier signal. This delay is related to an IF frequency chosen at the receiver. After passing through a noisy transmission channel, the quadrature-related carrier signals are coupled in the receiver to a serial combination of an equalizer and analog-to-digital converter. This combination outputs multiple, substantially distortion-free samples of the data signals each symbol interval. The two data signals are then recovered by selecting a subset of the samples provided each symbol interval.

Abstract: A technique for digitally synthesizing the amplitude modulation of one or more carrier signals with a random digital data signal is disclosed. Pursuant to the present invention, a memory unit is addressed by a plurality of binary coded digital symbols in the data signal. For each address, at least two digital representations are read out. Each representation corresponds to a different sample of the carrier signals which has been amplitude modulated by a composite of the spectrally shaped data signal. The disclosed technique can be adapted to synthesize a variety of modulation formats, and can provide compensation for fixed in-rail and cross-rail distortions.

Abstract: A technique for decoding a vestigial sideband signal formed from a double-sideband signal having modulated quadrature-related carrier signals is disclosed. Within the receiver, the vestigial sideband signal is demodulated into a pair of received signals. Each of these received signals comprises a data signal which has been distorted by the double-sideband to vestigial sideband transformation. Pursuant to the present invention, each data signal is recovered in response to the associated received signal and the other data signal. Advantageously, the disclosed technique reduces the bandwidth required to transmit a given amount of information in systems which transmit modulated quadrature-related carrier signals.

Abstract: A power supply for a high intensity discharge lamp is provided wherein the secondary windings of a pair of lamp strike pulse transformers are connected in series with the HID lamp directly across the AC supply, the impedance of these secondary windings acting as the only ballast elements of the power supply. The HID lamp is chosen to have relatively high operating and maximum starting currents so that warm-up time of the lamp is dramatically reduced while employing the lamp strike pulse transformers to perform the dual function of starting the lamp when either hot or cold and acting as the current limiting ballast for the lamp both during warm-up and under normal operating conditions.