High frequency spread spectrum communication system terminal

• US 4,761,796 A
• Filed: 01/24/1985
• Issued: 08/02/1988
• Est. Priority Date: 01/24/1985
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: ITT Defense Communications
• Inventors: Dunn, James, Sanford, Charles, Kadin, Joseph
• Primary Examiner(s): Cangialosi, Salvatore
• Assistant Examiner(s): Lewis, Aaron J.
• Application Number:
  US06/694,549
• Time in Patent Office: 1,286 Days
• Field of Search: 375/1, 375/107, 381/43, 380/34
• US Class Current: 375/133
• CPC Class Codes: H04B 1/69 Spread spectrum techniques

Abstract

The spread spectrum communication system terminal comprises a first subsystem including a first arrangement to encode a locally generally digital data with an error correcting code, a second arrangement for spectrum spreading of the encoded locally generated digital data in at least one mode of operation of the communication system terminal, a third arrangement to receive remotely generated error correcting code encoded digitla data spectrum spread in the one mode of operation and a fourth arrangement to recover the remotely generated digital data. In addition, a second subsystem includes a fifth arrangement frequency hopping the encoded locally generated digital data prior to transmission to a remote location and a sixth arrangement frequency dehopping the encoded remotely generated digital data received from the remote location. A third subsystem is also provided including a seventh arrangement to provide a predetermined signal for spectrum spreading the encoded locally generated digital data in the one mode of operation and to couple the encoded locally generated digital data to the fifth arrangement and an eighth arrangement to provide a reference frequency for the frequency hopping and frequency dehopping and to couple the frequecny dehopped encoded remotely generated digital data from the sixth arrangement to the third arrangement.

Claims

1. A spread spectrum communication system terminal comprising:

a first subsystem including

first means to encode locally generated digital data with an error correcting code,

second means coupled to said first means for spectrum spreading of said encoded locally generated digital data in at least one mode of operation of said communication system terminal,

third means to receive remotely generated error correcting code encoded digital data spectrum spread in said one mode of operation, and

fourth means coupled to said third means to recover said remotely generated digital data;

said encoded locally generated digital data and said encoded remotely generated digital data being processed in blocks of data bits, a second subsystem including

fifth means frequency hopping said encoded locally generated digital data prior to transmission to a remote location, and

sixth means frequency dehopping said encoded remotely generated digital data received from said remote location; and

a third subsystem including

seventh means coupled to said second means and said fifth means to provide a predetermined signal for spectrum spreading of said encoded locally generated digital data in said one mode of operation and to couple said encoded locally generated digital data to said fifth means, and

eighth means coupled to said third means, said fifth means said sixth means to provide a reference frequency for said frequency hopping and said frequency dehopping and to couple said frequency dehopped encoded remotely generated digital data from said sixth means to said third means,

said first means and second means including

a first processor coupled to said seventh means,

a first decision feedback equalizer/canceller coupled to said first processor, and

a second processor coupled to said first processor and said first decision feedback equalizer/canceller to provide said encoded locally generated digital data, said third means and said four means including

a third processor and said second processor coupled to said eighth means,

said first decision feedback equalizer/canceller coupled to said second processor,

a second decision feedback equalizer/canceller coupled to said third processor, and

said first processor coupled to said first and second decision feedback equalizer/canceller to recover said encoded remotely generated digital data,

said first, second and third processors operating according to predetermined data rate algorithms when said locally generated and remotely generated data rates are from 1200-4800 bits per second and spectrum spreading is not provided in the mode of operation of said communication system,

said first, second and third processors operating according to algorithms providing operation against jamming signals when said locally generated and said remotely generated data rates are below 1200 bits per second and spectrum spreading is provided in this mode of operation of said communication system.

2. A communication system according to claim 1, wherein

said predetermined signal for spectrum spreading is a pseudo noise sequence.

3. A communication system according to claim 2, wherein

said eighth means includes

a satellite synchronized clock continually updated by the NOAA "GOES" satellite, and

a crystal clock coupled to said satellite synchronized clock to provide said reference frequency.

4. A communication system according to claim 1, further including

a fourth subsystem including

ninth means coupled to said seventh means to provide locally generated low bit rate digital speech from a fixed coded vocabulary corresponding to recognized utterances for coupling to said fifth means, and

tenth means coupled to said eights means to receive remotely generated low bit rate digital speech from said sixth means to synthesize audio signals corresponding to said utterances at said remote location.

5. In a communication system employing frequency hopping and spread spectrum techniques, a modem subsystem comprising:

first means to encode locally generated digital data with an error correcting code,

second means coupled to said first means for spectrum spreading of said encoded locally generated digital data in at least one mode of operation of said communication system and to couple resultant digital data to a radio frequency subsystem for frequency hopping,

third means coupled to said radio frequency subsystem to receive remotely generated error correcting code encoded digital data spectrum spread in said one mode of operation and frequency dehopped in said radio frequency subsystem, and

fourth means coupled to said third means to recover said remotely generated digital data,

said first means and second means including

a first processor coupled to a controller subsystem,

a first decision feedback equalizer/canceller coupled to said first processor, and

a second processor coupled to said first processor and said first decision feedback equalizer/canceller to provide said encoded locally generated digital data,

said third means and said four means including

a third processor and said second processor coupled to said controller subsystem,

said first decision feedback equalizer/canceller coupled to said second processor,

a second decision feedback equalizer/canceller coupled to said third processor, and

said first processor coupled to said first and second decision feedback equalizer/canceller to recover said encoded remotely generated digital data,

said first, second and third processors operating according to predetermined data rate algorithms when said locally generated and remotely generated data rates are from 1200-4800 bits per second and spectrum spreading is not provided in the mode of operation of said communication system,

said first, second and third processors operating according to algorithms providing operation against jamming signals when said locally generated and said remotely generated data rates are below 1200 bits per second and spectrum spreading is provided in this mode of operation of said communication system.

6. A modem subsystem according to claim 5, wherein

said encoded locally generated digital data and said encoded remotely generated digital data are processed in blocks of data bits.

7. A modem subsystem according to claim 6, wherein

said spectrum spreading is accomplished by a pseudo-noise sequence.

8. A modem subsystem according to claim 7, further including

a timing generator coupled to said first, second and third processors under control of a system clock generator including

a satellite synchronized clock continually updated by the NOAA "GOES" satellite, and

a crystal clock coupled to said satellite synchronized clock to provide said reference frequency.