Method and apparatus for equalization of data transmission system
AssigneeRacal Data Communications Inc.
InventorAldo A. Martinez
Life of this patent
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Abstract
A data communication system, comprising a first and a second transceiver coupled together through a transmission channel, the transmission channel having transmission characteristics. A measurement circuit is coupled to the first transceiver for measuring the effects of the transmission characteristics upon a known signal transmitted from the second transceiver to the first transceiver a mapping of the transmission characteristics to a code is made and the code is transmitted from the first transceiver to the second transceiver. A plurality of predetermined filters for use in filtering signals to be transmitted by the second transceiver is selected upon receipt of the transmitted code.
Claims17
A data communication system, comprising:
- a first and a second transceiver coupled together through a transmission
- channel, said transmission channel having transmission characteristics;
- said first transceiver including a first transmitter and a first receiver;
- said second transceiver including a second transmitter and a second receiver;
- said first transceiver comprising:
- measurement means, coupled to said first receiver, for measuring the effects of said transmission characteristics upon a known training signal transmitted from said second transmitter, to said first receiver, said known training signal having predetermined spectral characteristics known to said first receiver;
- mapping means coupled to said measurement means, for mapping said measured transmission characteristics to a predetermined code;
- and
- means for transmitting said code from said first transmitter to said second receiver;
- said second transceiver comprising;
- filtering means for providing a plurality of predetermined filter characteristics for use in filtering signals to be transmitted by said second transmitter;
- and
- decoding means for receiving said code and for selecting an unique one of said predetermined filter characteristics corresponding to said transmitted code for use by said second transmitter.
A method of providing automatic transmitter equalizer operation, comprising the steps of:
- transmitting an equalizer training sequence from a first modem to a second modem;
- separating said training sequence into upper band edge, lower band edge and carrier frequency signals at said second modem;
- analyzing said upper and lower band edge signals and said carrier frequency signal as a measure of line distortion;
- generating a code word corresponding to said measured line distortion;
- transmitting said code word to said first modem, said code representing a transmitter equalizer appropriate for correction of said line distortion;
- and
- selecting said transmitter equalizer represented by said code word at said first modem.
A method of selecting a transmitter equalizer for a data modem's transmitter, comprising the steps of:
- transmitting a training signal to a remote modem, said training signal having spectral characteristics known to said remote modem;
- receiving a code word from said remote modem, said code word being generated by said remote modem as a function of distortion in said spectral characteristics of said training signal as received and measured by said remote modem;
- matching said code word to one of a plurality of possible predetermined equalizer;
- and
- selecting said equalizer for use by said data modem transmitter.
A method of selecting a transmitter equalizer for a remote modem, comprising the steps of:
- at a local modem, receiving a training sequence from said remote modem, said training sequence having predetermined spectral characteristics known to said local modem;
- filtering said training sequence to produce signals at a plurality of frequency ranges;
- analyzing said signals to obtain an indication of transmission channel distortion;
- mapping said distortion to a predetermined code word;
- and
- transmitting said code word to said remote modem to select said transmitter equalizer for use by said remote modem.
Dependencies are inferred from the claim text.