Radio frequency communication system

• US 6,049,561 A
• Filed: 04/30/1997
• Issued: 04/11/2000
• Est. Priority Date: 04/30/1997
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Pezzlo, John, Bennett, C. Leonard, Shaffer, Harry L.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/848,846
• Time in Patent Office: 1,077 Days
• Field of Search: 375/202, 375/200, 375/205, 375/201, 375/132, 370/375
• US Class Current: 375/132
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 2001/7154 with means for preventing interference
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

A spread spectrum radio frequency communication system comprising a plurality of transmitters adapted to operate at different carrier frequencies having a preassigned frequency separation, such carrier frequencies randomly changing in accordance with a common pseudo-random code. Each of the transmitters has a predetermined bandwidth and the carrier frequencies of the transmitters are in accordance with the bandwidth of the transmitters.

Claims

1. A spread spectrum radio frequency communication system comprising:

a plurality of transmitters adapted to operate at different carrier frequencies, such transmitters having initial preassigned relative carrier frequencies, such carrier frequencies changing in accordance with a common pseudo-random code and wherein each of the transmitters has a predetermined bandwidth and the carrier frequencies of the transmitters operate at frequencies arranged in accordance with the relative bandwidth of the transmitters.

2. A spread spectrum radio frequency communication system comprising:

a plurality of transmitters adapted to operate at different carrier frequencies, such transmitters having initial preassigned relative carrier frequencies, such carrier frequencies changing in accordance with a common pseudo-random code and wherein each of the transmitters has a predetermined bandwidth and the carrier frequencies of the transmitters operate at frequencies arranged in accordance with the relative bandwidth of the transmitters; and

wherein transmitters having substantially equal bandwidth have carriers frequencies arranged in accordance with relative transmitter power.

3. A spread spectrum radio frequency communication system comprising:

a plurality of user slots disposed over a predetermined band of frequencies, each of a first portion of the user slots having transmitters adapted to operate at different carrier frequencies within the predetermined band of frequencies, the carrier frequencies of the users in the first portion thereof being changed in accordance with a common pseudo-random code, a second portion of the user slots includes transmitters having carrier frequencies randomly changing within such second portion of the slots in accordance with a code comprising the common pseudo-random code and a pseudo-random code unique to each one of the transmitters in the second portion thereof.

4. A spread spectrum radio frequency communication system, comprising:

a plurality of transmitters, each one being adapted to transmit information at a changeable carrier frequency centered about a predetermined transmitter bandwidth, the transmitters having different preassigned reference carrier frequencies, the carrier frequencies being preassigned in accordance with the transmitter bandwidth, the transmitter bandwidth of each of the transmitters being in a different region of a predetermined system band of frequencies;

a pseudo-random code generator for changing the reference carrier frequencies of the transmitters during each of a sequence of frequency hops in accordance with a common pseudo-random code, the bandwidth of each of the transmitters being in a different region of a predetermined band of frequencies during each of the frequency hops as the carrier frequencies are randomly changed.

5. A spread spectrum radio frequency communication system having a predetermined system bandwidth, such system comprising:

a plurality of transmitters, each one being adapted to transmit information at a changeable carrier frequency centered about a predetermined transmitter bandwidth, the transmitters having different preassigned initial reference carrier frequencies with each one of the transmitters transmitting the information in a frequency spectrum occupying a different portion of the predetermined system bandwidth;

a pseudo-random code generator for randomly shifting the preassigned initial reference carrier frequencies of the transmitters during each of a sequence of frequency hops by a randomly selected frequency increment, δ

, such increment being selected in accordance with a common pseudo-random code;

a processor for determining whether the frequency spectrum of any of the transmitters will, after being shifted the randomly selected frequency increment, δ

, fall outside of the predetermined system bandwidth, and if so, determining the portion, Δ

, of the frequency spectrum remaining within the predetermined system bandwidth, the transmitters with shifted frequency spectra remaining fully within the predetermined system bandwidth having the carrier frequencies thereof shifted by the randomly selected frequency increment, δ

, algebraically added to the portion, Δ

, to shift the bandwidth of such transmitters to one end of the predetermined system bandwidth and the spectrum of the transmitter partially falling outside the predetermined system bandwidth being shifting to the other extreme of the predetermined system bandwidth, the bandwidth of the transmitters being maintained in different regions of a predetermined band of frequencies during each of the frequency hops as the carrier frequencies are randomly frequency shifted.

6. The system recited in claim 5 wherein the carrier frequencies are preassigned in accordance with the bandwidth of the transmitters, the bandwidth of each of the transmitters being in a different region of a predetermined band of frequencies.

7. The spread spectrum communication system recited in claim 6 wherein each of the transmitters has a predetermined bandwidth and the carrier frequencies of the transmitters operate at frequencies arranged in accordance with the relative bandwidth of the transmitters.

8. The spread spectrum communication system recited in claim 7 wherein transmitters having substantially equal bandwidth have carriers frequencies arranged in accordance with relative transmitter power.

9. A spread speftrum radio frequency communication system comprising a plurality of transmitters adapted to hop orthogonally in frequency over a predetermined band of frequencies and wherein each of the transmitters has a predetermined bandwidth and carrier frequencies of the transmitters operate at frequencies arranged in accordance with the relative bandwidth of the transmitters wherein such carrier frequencies change in accordance with a common pseudo-random code.

10. A spread spectrum radio frequency communication system comprising a plurality of transmitters adapted to hop orthogonally in frequency over a predetermined band of frequencies and wherein each of the transmitters has a predetermined bandwidth and carrier frequencies of the transmitters operate at frequencies arranged in accordance with the relative bandwidth of the transmitters;

and

wherein transmitters having substantially equal bandwidth have carriers frequencies arranged in accordance with relative transmitter power.