System and method for communicating with plural remote transmitters

• US 6,600,774 B1
• Filed: 07/09/1999
• Issued: 07/29/2003
• Est. Priority Date: 08/30/1996
• Status: Expired due to Fees

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Otto, James C.
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/349,958
• Time in Patent Office: 1,481 Days
• Field of Search: 375/130, 375/141, 375/147, 375/140, 375/139, 375/295, 342/357-6-3, 342/450, 342/463, 701/215, 701/216
• US Class Current: 375/139
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04L 27/103 Chirp modulation for spread spectrum techniques H04B1/69

Abstract

A system for communicating with plural remote transmitters in which the transmitters send messages without a common synchronization source or polling by a controlling receiver. In one embodiment, the system uses the time position of frequency chirp signals to encode the identity and/or other information sent from the receiver. The system may use relatively low cost transmitters because the transmitters do not need to have a message or clocking signal receiving capability and the internal clocking signal source within the transmitter may be a relatively inexpensive device or circuit.

Claims

1. In a system for locating a mobile transmitter, a transmitter comprising:

(a) means for creating a unique identification for said transmitter, wherein said means for creating is located at said transmitter;

(b) means for transmitting a modulated signal from said transmitter, wherein said modulated signal has encoded therein the unique identification, and wherein the unique identification comprises a unique set of time differences between successive pulses of a signal.

2. The transmitter of claim 1, wherein said means for creating a unique identification includes ROM programming.

3. The transmitter of claim 1, wherein said means for transmitting a modulated signal includes an amplifier.

4. A system for communicating information from a mobile transmitter to a receiver in a fixed location comprising:

a means for providing the information to be communicated to the transmitter;

said transmitter including a chirp signal generator and a controller for receiving the information to be communicated and for controlling the chirp generator so that chirps are generated to thereby encode the information to be communicated;

a source of a carrier signal;

a modulator having as one of its inputs said carrier signal; and

a timing control circuit for applying chirp signals to said modulator in a timed relationship between chirp signals to thereby encode the information as a modulation of said carrier signal.

5. The system of claim 4, wherein said means for providing the information includes a switch.

6. The system of claim 4, wherein said means for providing the information includes a button positioned for activation by a user of the transmitter.

7. The system of claim 4, wherein said controller includes an analog to digital converter.

8. The system of claim 4 further comprising a means for transmitting the encoded information to a receiver.

9. The system of claim 8, wherein said means for transmitting includes an amplifier.

10. The system of claim 8, wherein said means for transmitting includes an antenna.

11. A method of communicating from a mobile transmitter to a receiver in a fixed location comprising the steps of:

(a) providing the information to be communicated to the transmitter;

(b) controlling a chirp generator in the transmitter so that chirps are generated to encode the information to be communicated;

(c) modulating a carrier signal by applying the generated chirp signals to the carrier signal in a timed relationship between chirp signals to thereby encode the information as a modulation of said carrier signal; and

(d) transmitting the modulated signal from the transmitter to the receiver.