Method for tuning a spread spectrum receiver

• US 6,560,270 B1
• Filed: 03/04/1999
• Issued: 05/06/2003
• Est. Priority Date: 03/04/1999
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Northrop Grumman Corporation
• Inventors: Hischke, Mark D.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/262,800
• Time in Patent Office: 1,524 Days
• Field of Search: 375/130, 375/136, 375/206, 375/134, 375/344, 375/345, 330/132, 331/1.R, 331/7, 331/10, 331/2, 455/77, 455/193, 455/75, 455/184.1, 455/136, 455/150.1, 455/160.1, 455/161.1, 455/173.1, 455/182.3, 455/188.1, 455/191.1, 455/192.3, 340/870.2, 370/342, 370/350
• US Class Current: 375/136
• CPC Class Codes: H04B 1/70775 Multi-dwell schemes, i.e. multiple accumulation times

Abstract

A method for tuning spread spread spectrum receivers to a frequency of a digital signal within a specified frequency band as the steps of coarse tuning the receiver while a preamble of the digital signal is being received, fine tuning the receiver while the preamble of the digital signal is being received, and demodulating the signal. Preferably, the step of coarse tuning the receiver comprises dividing the specified frequency band into a plurality of first sub-bands, and sequentially measuring a receive signal strength within each of the sub-bands until a receive signal strength is greater than a predetermined threshold. Preferably, the step of fine tuning the receiver comprises the dividing at least one first step-band which is found to have a receive signal strength greater than a predetermined threshold into a plurality of second sub-bands when a receive signal strength is greater than the predetermined threshold, sequentially measuring a receive signal strength within each sub-band so as to determine which second sub-band contains a signal having a receive signal strength above a predetermined threshold, and determining which second sub-band contained the signal with the greatest receive signal strength.

Claims

1. A method for tuning a spread spectrum receiver to a frequency of a digital signal within a specified frequency band, the method comprising the steps of:

a) coarse tuning the receiver while a preamble of the digital signal is being received, the coarse tuning comprising;

i) dividing the specified frequency band into a plurality of first sub-bands;

ii) sequentially measuring a received signal strength within each first sub-band until the received signal strength is greater than a predetermined threshold;

b) fine tuning the receiver while the preamble of the digital signal is being received, the fine tuning comprising;

i) dividing at least one first sub-band which is found to have the received signal strength greater than a predetermined into a plurality of second sub-bands when the received signal strength is greater than the predetermined threshold;

ii) sequentially measuring the received signal strength within each second sub-band so as to determine which second sub-band contains a signal having the received signal strength above a predetermined threshold;

iii) determining which second sub-band contains the signal with the greatest received signal strength; and

c) demodulating the signal, comprising demodulating the signal in the second sub-band which has the greatest received signal strength.

2. The method as recited in claim 1, wherein the step of sequentially measuring a received signal strength within each first sub-band until a received signal strength is greater than a predetermined threshold comprises averaging a plurality of separate received signal strength measurements within each first sub-band.

3. The method as recited in claim 1, further comprising the step of verifying the second sub-band by demodulating at least a portion of the preamble of the digital signal.

4. A method of tuning a spread spectrum receiver to a frequency of a digital signal within a specified frequency band, the method comprising the steps of:

a) coarse tuning the receiver, the coarse tuning comprising;

i) dividing the specified frequency band into a plurality of first sub-bands;

ii) sequentially measuring a received signal strength within each of first sub-band until a received signal strength is greater than a predetermined threshold;

b) fine tuning the receiver, the fine tuning comprising;

i) dividing at least one first sub-band into a plurality of second sub-bands;

ii) sequentially measuring a received signal strength within each second sub-band containing a signal strength above a predetermined threshold; and

determining which second sub-band contains the signal with the greatest received signal strength.

5. The method as recited in claim 4, further comprising:

a) demodulating frame synchronization data; and

b) demodulating a message.

6. The method as recited in claim 4, further comprising:

a) demodulating frame synchronization data;

b) demodulating a message ID; and

c) demodulating a message.

7. The method as recited in claim 4, further comprising:

a) demodulating frame synchronization data;

b) demodulating error correction code;

c) demodulating message length; and

d) demodulating a message.