Subcarrier communication system
First Claim
1. A communication system using a subcarrier within a commercial FM channel bandwidth for transmitting data to mobile receivers, comprising:
- means four generating a signal having a predetermined frequency defining a subcarrier signal of an FM broadcast channel for a commercial FM broadcast station;
coding means for encoding digital data received at an input thereof with an error correcting code, said digital data being defined by a plurality of consecutive bits;
means coupled to an output of said coding means for adding a plurality of bits in a predetermined first sequence to said encoded digital data to form a digital message;
subcarrier modulation means having (1) a first input coupled to an output of said means for adding said plurality of bits for receiving said digital message therefrom, and (2) a second input coupled to said generating means for modulating said digital message on said subcarrier signal;
means for coupling said modulated subcarrier signal to an FM transmitter of said commercial FM broadcast station for frequency modulation of said modulated subcarrier signal on a carrier signal of said FM broadcast channel;
means for receiving said FM broadcast channel transmitted by said commercial FM broadcast station, said receiving means including FM demodulation means for recovering said modulated subcarrier signal from said modulated carrier signal;
subcarrier demodulation means coupled to said carrier demodulation means for recovering said digital message from said modulated subcarrier signal;
extraction means coupled to said subcarrier demodulation means for extracting said encoded digital data from said digital message and forming a second sequence of bits therefrom;
decoding means coupled to said extraction means for (1) comparing said second sequence of bits with said predetermined first sequence of bits for establishing a data reliability factor, and (2) decoding said encoded digital data in correspondence with said data reliability factor for providing said digital data to an output thereof; and
,utilization means coupled to said output of said decoding means for receiving said digital data therefrom and operating thereon.
3 Assignments
0 Petitions
Accused Products
Abstract
A communication system (100) is provided for transmitting data to mobile receivers utilizing a subcarrier within a commercial FM channel of a radio station (55). The data transmitted is first encoded in encoder (112), utilizing a forward error correction code. The sequence of the encoded data is altered in interleaver (116), subdivided into a plurality of subframes, in framing and synchronization circuit (120), which also adds channel state bits to each subframe. The framed data is modulated onto the subcarrier in the differential quadrature phased shift keying modulator (130), the output of which is coupled to the FM modulator (52) of radio station transmitter (50). The transmitted radio frequency signals may be received by a vehicle antenna (12) for coupling to the vehicle'"'"'s FM receiver (80). The modulated subcarrier is recovered from the FM demodulator (84) of the receiver (80), the modulated subcarrier being demodulated to recover the encoded digital data therefrom. The channel state bits included with the data are extracted from the digital data and utilized to form a data reliability factor for each bit of the encoded data. The data reliability factors thus obtained are associated with each bit of the data in a deinterleaver (360). Deinterleaver (360) provides each data bit in proper sequence, with its associated data reliability factor to a decoder (370). The decoded digital data is provided to a vehicle traffic computer (90) for processing and presentation of traffic information to a user on a display (92).
90 Citations
34 Claims
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1. A communication system using a subcarrier within a commercial FM channel bandwidth for transmitting data to mobile receivers, comprising:
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means four generating a signal having a predetermined frequency defining a subcarrier signal of an FM broadcast channel for a commercial FM broadcast station; coding means for encoding digital data received at an input thereof with an error correcting code, said digital data being defined by a plurality of consecutive bits; means coupled to an output of said coding means for adding a plurality of bits in a predetermined first sequence to said encoded digital data to form a digital message; subcarrier modulation means having (1) a first input coupled to an output of said means for adding said plurality of bits for receiving said digital message therefrom, and (2) a second input coupled to said generating means for modulating said digital message on said subcarrier signal; means for coupling said modulated subcarrier signal to an FM transmitter of said commercial FM broadcast station for frequency modulation of said modulated subcarrier signal on a carrier signal of said FM broadcast channel; means for receiving said FM broadcast channel transmitted by said commercial FM broadcast station, said receiving means including FM demodulation means for recovering said modulated subcarrier signal from said modulated carrier signal; subcarrier demodulation means coupled to said carrier demodulation means for recovering said digital message from said modulated subcarrier signal; extraction means coupled to said subcarrier demodulation means for extracting said encoded digital data from said digital message and forming a second sequence of bits therefrom; decoding means coupled to said extraction means for (1) comparing said second sequence of bits with said predetermined first sequence of bits for establishing a data reliability factor, and (2) decoding said encoded digital data in correspondence with said data reliability factor for providing said digital data to an output thereof; and
,utilization means coupled to said output of said decoding means for receiving said digital data therefrom and operating thereon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A communication system having a high data rate using a subcarrier within a commercial FM channel bandwidth, comprising:
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means for generating a signal having a predetermined frequency defining a subcarrier signal of an FM broadcast channel for a commercial FM broadcast station; coding means for encoding digital data received at an input thereof with an error correcting code, said digital data being defined by a plurality of consecutive bits; interleaving means coupled to an output of said coding means for altering an order of bits of said encoded digital data such that consecutive bits of said encoded digital data are separated by a predetermined number of bits; means coupled to an output of said interleaving means for adding a plurality of bits in a predetermined first sequence to said encoded digital data to form a digital message; subcarrier modulation means having (1) a first input coupled roan output of said means for adding said plurality of bits for receiving said digital message therefrom, and (2) a second input coupled to said generating means for modulating said digital message on said subcarrier signal; means for coupling said modulated subcarrier signal to an FM transmitter of said commercial FM broadcast station for frequency modulation of said modulated subcarrier signal on a carrier signal of said FM broadcast channel; means for receiving said FM broadcast channel transmitted by said commercial FM broadcast station, said receiving means including FM demodulation means for recovering said modulated subcarrier signal from said modulated carrier signal; subcarrier demodulation means coupled to said carrier demodulation means for recovering said digital message from said modulated subcarrier signal; extraction means coupled to said subcarrier demodulation means for extracting said encoded digital data from said digital message and forming a second sequence of bits therefrom; decoding means coupled to said extraction means for (1) comparing said second sequence of bits with said predetermined first sequence of bits for establishing a data reliability factor for each bit of said encoded digital data, and (2) decoding said encoded digital data in correspondence with said data reliability factor for providing said digital data to an output thereof, said decoding means including deinterleaving means having an input coupled to an output of said extraction means for removing said predetermined number of bits from between consecutive bits of said encoded digital data and associating a respective data reliability factor with each bit thereof; and
,utilization means coupled to said output of said decoding means for receiving said digital data therefrom and operating thereon. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of communicating data at a high data rate using a subcarrier within a commercial FM channel bandwidth of a commercial FM radio station, comprising the steps of:
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a. receiving digital data defined by a plurality of consecutive bits from a data source; b. encoding said digital data with an error correcting code; c. dividing said encoded digital data into a plurality of data frames, each of said data frames being formed by a plurality of data subframes; d. adding a first channel test word to each of said plurality of data subframes to form a plurality of corresponding message subframes, said first channel test word being defined by a plurality of bits in a predetermined sequence; e. providing a first signal having a predetermined frequency to define said subcarrier; f. modulating said subcarrier with said plurality of message subframes; g. providing a second signal having a predetermined frequency defining a carrier signal for a commercial FM channel of said commercial FM radio station; h. frequency modulating said modulated subcarrier on said carrier signal, said frequency modulated carrier signal being coupled to an antenna for broadcast to a plurality of mobile receiving systems; i. receiving said frequency modulated carrier signal by at least one of said mobile receiving systems; j. demodulating said received frequency modulated carrier signal to recover said modulated subcarrier; k. demodulating said subcarrier to recover said message subframes; l. extracting each of said plurality of data subframes from said plurality of message subframes and forming a plurality of second channel test words, each of said second channel test words being formed by a plurality of consecutive bits; m. comparing said plurality of consecutive bits of each of said second channel test words with said predetermined sequence of bits of said first channel test word to establish a data reliability factor for each bit of each of said plurality of extracted data subframes; n. sequentially decoding said digital data from each of said extracted data subframes in correspondence with said data reliability factor; and
,o. transmitting said decoded digital data to a utilization device. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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Specification