US6282231B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strong signal cancellation to enhance processing of weak spread spectrum signal
Assignee: Qualcomm Inc
•
Filing: 1999-12-14
•
Granted: 2001-08-28
•
Expires: 2019-12-14
Abstract
Abstract A CDMA coded, spread spectrum radio signal containing a strong signal and a weak signal is received, and the interference of the strong signal with the weak signal is computed to enhance the ability to track the weak signal. The codes modulating both signals are known, and the weak signal can be predicted. The interference of the strong signal is calculated as the product of the amplitude of the strong signal and the predicted crosscorrelation of the strong signal with the weak signal. The strong signal may be measured, predicted, or acquired through a combination of both methods. The crosscorrelation may be predicted for a range of weak signal values, and the weak signal selected as the prediction producing the greatest received power.
Inventors
- 👤 Charles P. Norman
- 👤 Charles R. Cahn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:47
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7097; H04B1/7103; H04B1/7107; G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/21; G01S19/24; G01S19/246; G01S19/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
206 words
A method of operating a spread spectrum radio signal receiver having at least first and second signal tracking channels to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) receiving a first compound signal comprising the first and second received signals; (b) operating the first channel to track the first received signal and measure its amplitude, code phase, and received frequency; (c) selecting the received frequency and code phase of the second received signal; (d) operating the second channel at the selected code phase and received frequency of the second received signal to receive a second compound signal comprising the first and second signals; (e) computing the predicted code and frequency domain crosscorrelation of the first received signal with the second received signal; (f) multiplying the amplitude of the first received signal with the predicted crosscorrelation to compute the interference between the first and second received signals; and (g) subtracting the interference from the second compound signal to extract the second received signal including at least one of its received frequency, amplitude, and code phase.
Claim 2
Independent Claim
206 words
A method of operating a spread spectrum radio signal receiver having at least first and second signal tracking channels to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) receiving a first compound signal comprising the first and second received signals; (b) operating the first channel to track the first received signal and measure its amplitude, code phase, and received frequency; (c) selecting the received frequency and code phase of the second received signal; (d) operating the second channel at the selected code phase and received frequency of the second received signal to receive a second compound signal comprising the first and second signals; (e) computing the predicted code and frequency domain crosscorrelation of the first received signal with the second received signal; (f) multiplying the amplitude of the first received signal with the predicted crosscorrelation to compute the interference between the first and second received signals; and (g) subtracting the interference from the second compound signal to extract the second received signal including at least one of its received frequency, amplitude, and code phase.
Claim 3
Dependent Claim
160 words
The method of claim 1 , comprising the further steps of: within step (c), performing the further steps of: selecting a range of received frequencies and code phases for the second received signal; selecting an initial second code phase and received frequency within the respective selected range; and selecting a code phase incremental value and a received frequency incremental value; p 1 performing steps (d)-(f) for the initial second code phase and initial received frequency of the second received signal; performing step (g) to extract the amplitude of the second received signal; repeating steps (d)-(g) for all second code phases and received frequency values within the respective range that are offset from the respective initial values by an integer multiple of the code phase incremental value and received frequency incremental value, respectively; and selecting the second received signal code phase and received frequency at which the extracted second received signal has the largest amplitude for tracking in the second channel.
Claim 4
Dependent Claim
65 words
The method of claim 2 , comprising the further steps of: within step (c), performing the further step of: selecting a frequency domain crosscorrelation threshold value; within step (e), comparing the frequency domain crosscorrelation with the threshold value; and if the crosscorrelation is greater than the threshold value, proceeding directly to perform step (d) for a different value of the second received signal received frequency.
Claim 5
Dependent Claim
15 words
The method of claim 3 , wherein the crosscorrelation threshold value is about 10 dB.
Claim 6
Independent Claim
217 words
A method of operating a spread spectrum radio signal receiver having at least first and second signal tracking channels to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) receiving a first compound signal comprising the first and second received signals; (b) operating the first channel to track the first received signal and measure its amplitude; (c) predicting the first code phase and received frequency of the first received signal; (d) selecting the second code phase and received frequency of the second received signal; (e) operating the second channel at the selected code phase and received frequency of the second received signal to receive a second compound signal comprising the first and second received signals; (f) computing the predicted code and frequency domain crosscorrelation of the first received signal with the second received signal; (g) multiplying the amplitude of the first received signal with the predicted crosscorrelation to compute the interference between the first and second received signals; and (h) subtracting the interference from the second compound signal to extract the second received signal including at least one of its received frequency, amplitude, and code phase.
Claim 7
Independent Claim
217 words
A method of operating a spread spectrum radio signal receiver having at least first and second signal tracking channels to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) receiving a first compound signal comprising the first and second received signals; (b) operating the first channel to track the first received signal and measure its amplitude; (c) predicting the first code phase and received frequency of the first received signal; (d) selecting the second code phase and received frequency of the second received signal; (e) operating the second channel at the selected code phase and received frequency of the second received signal to receive a second compound signal comprising the first and second received signals; (f) computing the predicted code and frequency domain crosscorrelation of the first received signal with the second received signal; (g) multiplying the amplitude of the first received signal with the predicted crosscorrelation to compute the interference between the first and second received signals; and (h) subtracting the interference from the second compound signal to extract the second received signal including at least one of its received frequency, amplitude, and code phase.
Claim 8
Dependent Claim
157 words
The method of claim 5 , comprising the further steps of: within step (d), performing the further steps of: selecting a range of received frequencies and code phases for the second received signal; selecting an initial second code phase and received frequency within the respective selected range; and selecting a code phase incremental value and a received frequency incremental value; performing steps (e)-(g) for the initial code phase and initial received frequency of the second received signal; performing step (h) to extract the amplitude of the second received signal; repeating steps (e)-(h) for all second code phases and received frequency values within the respective range that are offset from the respective initial values by an integer multiple of the code phase incremental value and received frequency incremental value, respectively; and selecting the second received signal code phase and received frequency at which the extracted second received signal has the largest amplitude for tracking in the second channel.
Claim 9
Dependent Claim
65 words
The method of claim 6 , comprising the further steps of: within step (d), performing the further step of: selecting a frequency domain crosscorrelation threshold value; within step (f), comparing the frequency domain crosscorrelation with the threshold value; and if the crosscorrelation is greater than the threshold value, proceeding directly to perform step (e) for a different value of the second received signal received frequency.
Claim 10
Dependent Claim
15 words
The method of claim 7 , wherein the crosscorrelation threshold value is about 10 dB.
Claim 11
Independent Claim
180 words
A method of operating a spread spectrum radio signal receiver having at least one signal tracking channel to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) acquiring the amplitude, code phase, and received frequency of the first received signal; (b) selecting the received frequency and code phase of the second received signal; (c) operating the tracking channel at the selected code phase and received frequency of the second received signal to receive a compound signal comprising the first and second received signals; (d) computing the predicted code and frequency domain crosscorrelation of the first signal with the second received signal; (e) multiplying the amplitude of the first signal with the predicted crosscorrelation to compute the interference between the first signal and the second received signal; and (f) subtracting the interference from the compound signal to extract the second received signal including its code phase, received frequency, and amplitude.
Claim 12
Independent Claim
180 words
A method of operating a spread spectrum radio signal receiver having at least one signal tracking channel to increase the interference discrimination between first and second received signals broadcast on the same carrier frequency band and modulated by first and second codes, respectively, the codes each having a known number of code phases, comprising the steps of: (a) acquiring the amplitude, code phase, and received frequency of the first received signal; (b) selecting the received frequency and code phase of the second received signal; (c) operating the tracking channel at the selected code phase and received frequency of the second received signal to receive a compound signal comprising the first and second received signals; (d) computing the predicted code and frequency domain crosscorrelation of the first signal with the second received signal; (e) multiplying the amplitude of the first signal with the predicted crosscorrelation to compute the interference between the first signal and the second received signal; and (f) subtracting the interference from the compound signal to extract the second received signal including its code phase, received frequency, and amplitude.
Claim 13
Dependent Claim
58 words
The method of claim 9 , wherein the receiver includes an additional signal tracking channel, and comprising within step (a) the further steps of: receiving in the additional channel an additional compound signal comprising the first received signal; and operating the additional channel to track the first received signal and measure its amplitude, code phase, and received frequency.
Claim 14
Dependent Claim
157 words
The method of claim 10 , comprising the further steps of: within step (b), performing the further steps of: selecting a range of received frequencies and code phases for the second received signal; selecting an initial second code phase and received frequency within the respective selected range; and selecting a code phase incremental value and a received frequency incremental value; performing steps (c)-(e) for the initial code phase and initial received frequency of the second received signal; performing step (f) to extract the amplitude of the second received signal; repeating steps (c)-(f) for all second code phases and received frequency values within the respective range that are offset from the respective initial values by an integer multiple of the code phase incremental value and received frequency incremental value, respectively; and selecting the second received signal code phase and received frequency at which the extracted second received signal has the largest amplitude for tracking in the second channel.
Claim 15
Dependent Claim
65 words
The method of claim 11 , comprising the further steps of: within step (b), performing the further step of: selecting a frequency domain crosscorrelation threshold value; within step (d), comparing the frequency domain crosscorrelation with the threshold value; and if the crosscorrelation is greater than the threshold value, proceeding directly to perform step (c) for a different value of the second received signal received frequency.
Claim 16
Dependent Claim
15 words
The method of claim 12 , wherein the crosscorrelation threshold value is about 10 dB.
Claim 17
Dependent Claim
65 words
The method of claim 9 , wherein the receiver includes an additional signal tracking channel, and comprising within step (a) the further steps of: receiving in the additional channel an additional compound signal comprising the first received signal; operating the additional channel to track the first received signal and measure its amplitude; and predicting the code phase and received frequency of the first received signal.
Claim 18
Dependent Claim
157 words
The method of claim 14 , comprising the further steps of: within step (b), performing the further steps of: selecting a range of received frequencies and code phases for the second received signal; selecting an initial second code phase and received frequency within the respective selected range; and selecting a code phase incremental value and a received frequency incremental value; performing steps (c)-(e) for the initial code phase and initial received frequency of the second received signal; performing step (f) to extract the amplitude of the second received signal; repeating steps (c)-(f) for all second code phases and received frequency values within the respective range that are offset from the respective initial values by an integer multiple of the code phase incremental value and received frequency incremental value, respectively; and selecting the second received signal code phase and received frequency at which the extracted second received signal has the largest amplitude for tracking in the second channel.
Claim 19
Dependent Claim
65 words
The method of claim 15 , comprising the further steps of: within step (b), performing the further step of: selecting a frequency domain crosscorrelation threshold value; within step (d), comparing the frequency domain crosscorrelation with the threshold value; and if the crosscorrelation is greater than the threshold value, proceeding directly to perform step (c) for a different value of the second received signal received frequency.
Claim 20
Dependent Claim
15 words
The method of claim 16 , wherein the crosscorrelation threshold value is about 10 dB.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-08-27 | 2005-02-26 | 2005-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-27 | 2009-02-26 | 2009-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-27 | 2013-02-26 | 2013-08-28 | $7700.00 | Window Closed / Lapsed |