Abstract:
A communication system utilizing a hierarchically modulated signal and method thereof are provided, wherein a receiver system is configured to receive a hierarchically modulated signal. The receiver system includes a receiver device configured to receive the hierarchically modulated signal, which is a function of a time domain, and including a high priority data stream that has a single carrier type modulation, and a low priority data stream having data bits that are spread over a plurality of data symbols of a high priority data modulation. The receiver system further includes a low priority processor device, which includes an OFDM decoder configured to convert the low priority data stream of the hierarchically modulated signal that is a function of the time domain to be a function of a frequency domain by utilizing a FFT, such that an output is emitted that is representative of the low priority data stream.
Abstract:
A communication system and method thereof are provided, wherein the system includes a first satellite configured to re-transmit at least a first transmitted signal at a first frequency band, a second satellite configured to re-transmit the first transmitted signal at a second frequency band, and a first terrestrial repeater configured to re-transmit the first transmitted signal at a third frequency band. The system further includes a third satellite configured to re-transmit a second transmitted signal at the third frequency band that is different than the first transmitted signal re-transmitted by the first and second satellites, such that the first signal re-transmitted by the first terrestrial repeater, and the second signal re-transmitted by the third satellite interfere with one another, wherein the first signals re-transmitted by the first satellite, the second satellite, and the first terrestrial repeater includes substantially the same data.
Abstract:
An antenna assembly, a receiver, and a system configured to superimpose a first received signal from a first antenna and an intermediate signal based on a second received signal from a second antenna onto a single cable. The antenna assembly includes a mixer and an adjustable local oscillator (ALO) that frequency shift the second received signal to generate the intermediate signal. The output frequency of the ALO is controlled by a control signal superimposed on the single cable that is output by the receiver. With this arrangement, a plurality of antennas or antenna elements can be connected to a receiver using a single coaxial cable. Such an arrangement is particularly desirable to manufacturers of automobiles and other vehicles. Also, the receiver can detect if the output frequency of the ALO needs to be adjusted, and so close-loop control of the output frequency is possible.
Abstract:
An in-vehicle communication system configured to receive signals from a transmitter configured to transmit periodically a time-reference signal and receiver specific information. An information transmission time of receiver specific information is timed relative to a reference transmission time of the time-reference signal. The system includes a receiver characterized as having a receiver identification value. The receiver is configured to operate from an off-state to an on-state during an information-expected time interval to receive receiver specific information. The information-expected time interval is determined based on a reception time of the time-reference signal and the receiver identification value. This provides a way to ensure that the transmitter only transmits messages when it knows the intended receiver is on. It also ensures that the receiver is on only when messages that for that receiver are expected to be received.
Abstract:
Long time interleaver and listenable audio performance enhancements for a satellite receiver are presented. One enhancement includes comparing a correlation and a predetermined threshold value and blocking satellite signal data transmission from entry into long time interleaver (LTI) device circuitry and forward error correction (FEC) circuitry when the correlation value is the same as, or less than the predetermined threshold value. Another enhancement includes using Reed-Solomon codeword error checking to prevent erroneous baseband signal data from being accepted as good baseband signal data. A further enhancement includes storing symbol timing and frequency data during a strong signal condition of the satellite receiver and using this stored data when the satellite receiver encounters a weak signal condition. Another enhancement includes mitigating DC offset noise in a satellite receiver having a zero-IF tuner.
Abstract:
High priority data and low priority digital data are transmitted as primary and secondary data in hierarchically modulated, orthogonal frequency division multiplexing (OFDM) from an earth-orbiting satellite. To enable the transmitter amplifier to be operated with less back-off from saturation without clipping, the low priority OFDM symbols have fewer samples than the high priority OFDM symbols, and the high priority samples on which the low priority samples are superimposed are selected according to a first deterministic rule using sample power comparisons of the high priority samples to concentrate the low priority samples on those high priority samples having lower (optimally, the lowest) sample power. The low priority samples are distributed on the selected high priority samples according to a second deterministic rule relating the original low priority sample order to the original high priority sample order.