Determining the spatio-temporal and kinematic parameters of a signal receiver and its clock by information fusion

• US 6,542,116 B1
• Filed: 06/22/2001
• Issued: 04/01/2003
• Est. Priority Date: 06/22/2001
• Status: Expired due to Term

• Current Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Original Assignee: Enuvis Inc. (Qualcomm, Inc.)
• Inventors: Casadei, Stefano, Chou, Andrew, Mann, Wallace, Sahai, Anant
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H.
• Application Number:
  US09/888,229
• Time in Patent Office: 648 Days
• Field of Search: 342/357.12
• US Class Current: 342/357.62
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073

Abstract

To determine the clock doppler of a signal receiver, sampled data received from a receiver into are divided into data segments of incremental length. The clock doppler is estimated based on correlating each data segment with the expected signal from each satellite, from a set of satellites, that is overhead the receiver. For each data segment, the correlated result of each satellite is used to refine subsequent calculations of the clock doppler of the next overhead satellite. When the clock doppler calculations for a data segment have been performed using all overhead satellites from the set of satellites, then the results for that data segment are used to refine the calculations for the next data segment. If a current bounds for the clock doppler value is within a pre-determined clock doppler bound-width value and a current bounds for a delay value is within a pre-determined delay bound-width value, then a magnitude template is determined using magnitude calculations of the I and Q correlation integrals obtained at various clock doppler values and various delay values.

Claims

1. A method for determining one or more target receiver parameter values wherein the one or more target receiver parameter values is a member of a set of receiver parameter values that are associated with a receiver, the method comprising the computer-implemented steps of:

step A;

receiving from the receiver, sampled data associated with a received signal that is received at the receiver;

step B;

dividing the sampled data into a set of overlapping data segments;

step C;

receiving a set of information that is associated with;

the set of receiver parameter values; and

a set of signal parameter values;

step D;

determining a current region of uncertainty for the set of receiver parameter values using the set of information;

step E;

selecting a data segment that has not been previously selected to be selected data segment and performing the steps of;

step F;

selecting a signal source that has not been previously selected to be a selected signal source, wherein the signal source is from a set of signal sources associated with the receiver signal;

step G;

forming a selected data segment-source pair comprising the selected data segment and the selected signal source;

step H;

for the selected segment-source pair, determining in the current region of uncertainty one or more ranges of interest that correspond to the one or more target receiver parameter values;

step I;

using the selected segment-source pair and using the one or more ranges of interest that correspond to the one or more target receiver parameter values, determining one or more functions that correspond to the receiver parameter values and the signal parameter values;

step J;

updating the current region of uncertainty using the one or more functions; and

step K;

repeating steps E through K until the current region of uncertainty satisfies a pre-determined termination condition.

2. The method of claim 1, wherein using the one or more functions involves expressing the one or more functions as inequalities.

3. The method of claim 1, wherein the set of information that is associated with the set of receiver parameter values and the set of signal parameters comprises linear inequalities, wherein the linear inequalities restrict the receiver parameter values and the signal parameter values.

4. The method of claim 1, wherein the set of information that are associated with the set of receiver parameter values and the set of signal parameters comprises non-linear inequalities, wherein the non-linear inequalities restrict the receiver parameter values and the signal parameter values.

5. The method of claim 1, wherein the set of information that is associated with the set of receiver parameter values and the set of signal parameters are received from one or more systems that uses techniques to solve for a location of the receiver.

6. The method of claim 1, wherein the set of receiver parameter values comprises:

a location of the receiver;

a velocity of the receiver;

a clock Doppler of the receiver; and

a starting time when the received signal is received at the receiver.

7. The method of claim 1, wherein the set of signal parameter values comprises:

a delay value associated with the received signal; and

a carrier frequency value associated with the received signal.

8. The method of claim 1, further comprising the steps of:

determining a selected set of signal parameter values contained in this uncertainty region for selected source;

searching in the selected segment-source pair for the known signal corresponding to the selected source, by means of hypothesizing all the signal parameter values in the selected set of signal parameter values.

9. The method of claim 1, wherein the set of overlapping data segments comprises a nested sequence of data segments of increasing length;

and the selected data segment is greater in length than a previously selected segment.

10. A method for determining a clock doppler value of a receiver, the method comprising the computer-implemented steps of:

receiving from the receiver, sampled data associated with a received signal;

dividing the sampled data into a set of data segments, wherein each successive data segment from the set of data segments is formed by including all previous data segments plus additional data from the sampled to reach a pre-determined segment length; and

using each data segment for estimating the clock doppler value based on results corresponding to a set of satellites that is overhead the receiver.

11. The method of claim 10, further comprising selecting a shortest data segment that has not been previously selected from the set of segments to be a selected data segment for performing computations for estimating the clock doppler value.

12. The method of claim 10, wherein the clock doppler value is implicitly determined by estimating a carrier frequency value of the received signal.

13. The method of claim 10, further comprising the steps of:

using a shortest data segment that has not been previously selected from the set of data segments in conjunction with information associated with a selected satellite that has not been previously selected from the set of satellites that is overhead the receiver for updating a current bounds on a carrier frequency value of the received signal and for updating a current bounds on a delay value; and

continuing to update the current bounds on the carrier frequency value and the current bounds on the delay value by using the shortest data segment in conjunction with information associated with a next selected satellite that has not been previously selected from the set of satellites until all the satellites have been selected.

14. The method of claim 10, further comprising the steps of:

using a shortest data segment that has not been previously selected from the set of data segments in conjunction with information associated with a selected satellite that has not been previously selected from the set of satellites that is overhead the receiver for updating a current bounds on a carrier frequency value of the received signal and for updating a current bounds on a delay value; and

continuing to update the current bounds on the carrier frequency value and the current bounds on the delay value by using the shortest data segment in conjunction with information associated with a next selected satellite that has not been previously selected from the set of satellites until a pre-determined level of accuracy of a clock doppler value is reached.

15. The method of claim 10, further comprising the steps of:

if a current bounds for a delay value and a current bounds for a carrier frequency value has not been previously computed, then;

computing the current bounds for the delay value with respect to a selected satellite based on;

an approximate time that the receiver received the received signal; and

a relative approximate position information between the selected satellite and the receiver; and

computing a current bounds for the carrier frequency value with respect to the selected satellite based on;

relative clock correction factors between the selected satellite and the receiver;

a navigation bit information associated with the selected satellite; and

characteristics of a filter used to sample the received signal.

16. The method of claim 10, further comprising the step of:

if a current bounds for the delay value and a current bounds for a carrier frequency value have been previously computed, then using an updated current bounds for a delay value as the current bounds for the delay value and an updated current bounds for the carrier frequency value as the current bounds for the carrier frequency value.

17. The method of claim 10, further comprising the steps of:

if a current bounds for a carrier frequency value exceeds a pre-determined bound-width value for the carrier frequency value and a current bounds for a delay value exceeds a predetermined bound-width value for the delay value, then performing the steps of;

dividing a range of frequency of interest into a first set of frequency intervals and a second set of frequency intervals;

selecting a data segment from the set of data segments to be a selected data segment;

dividing the selected data segment into a set of data blocks corresponding to the first set of frequency intervals;

for each data block within the set of data blocks, calculating an I correlation integral and a Q correlation integral based on the selected satellite;

for every frequency interval of the second set of frequency intervals, summing the I correlation integral over all the data blocks from the set of data blocks without re-calculating the I correlation integral;

for every frequency interval of the second set of frequency intervals, summing the Q correlation integral over all the data blocks from the set of data blocks without re-calculating the Q correlation integral;

for each hypothesized delay value within the current bounds of the delay value, calculating a magnitude of the of the I and Q correlation integrals that were previously summed over all the data blocks, to produce a set of magnitude calculations, wherein the set of magnitude calculations correspond to the hypothesized delay values;

selecting as an estimate for the carrier frequency value, the carrier frequency value corresponding to a highest magnitude calculation from the set of magnitude calculations; and

selecting as an estimate for the delay value, the delay value corresponding to the highest magnitude calculation from the set of magnitude calculations.

18. The method of claim 10, further comprising the step of:

if a current bounds for a carrier frequency value is within a pre-determined bound-width value for the carrier frequency value and a current bounds for a delay value is within a pre-determined bound-width value for the delay value, then determining a magnitude template using magnitude calculations of I and Q correlation integrals that are calculated at a plurality of carrier frequency values from within the current bounds for the carrier frequency value and at a plurality of delay values from within the current bounds for the delay value.

19. The method of claim 10, further comprising the steps of:

if a current bounds for a carrier frequency value is within a pre-determined bound-width value for the carrier frequency value and a current bounds for a delay value is within a pre-determined bound-width value for the delay value, then performing the steps of;

selecting as an initial carrier frequency value, one of the carrier frequency values that has not been previously selected from within the current bounds for the carrier frequency value;

selecting a delta value corresponding to the initial carrier frequency value;

selecting one or more candidates of delay values from within the current bounds for the delay value;

for each candidate of delay value, calculating an I correlation integral and a Q correlation integral at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

for each candidate of delay value, calculating a magnitude of the I and Q correlation integrals at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

for each candidate of delay value, curve-fitting to produce a magnitude template using the magnitude of the I and Q correlation integrals that are calculated at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

for each candidate of delay value, selecting as a new carrier frequency value, a carrier frequency value that corresponds to a peak of the magnitude template;

selecting as an estimate for the carrier frequency value, an average of the new carrier frequency values corresponding to all the candidates of delay value; and

selecting as an estimate for the delay value, the delay value that corresponds to the average of the new carrier frequency value.

20. The method of claim 10, further comprising the step of:

if an estimate for a carrier frequency value satisfies a pre-determined tolerance value for the carrier frequency value and an estimate for a delay value satisfies a pre-determined tolerance value for the delay value, then updating a current bounds for the carrier frequency value and updating a current bounds for the delay value based on an estimate for the carrier frequency value and the estimate of the delay value to produce an updated current bounds for the carrier frequency and an updated current bounds for the delay value.

21. The method of claim 10, wherein each successive data segment has a length that is a function of a duration of the sampled data.

22. The method of claim 10, wherein a pre-determined segment length for a (j+1)^th successive data segment is 3 to the power of j, wherein j ranges in value from zero to a total number of successive data segments.

23. The method of claim 10, wherein a pre-determined segment length for each (j+1)^th successive data segment is 1.62 to the power of j, wherein j ranges in value from zero to a total number of successive data segments.

24. A method for determining a clock doppler value of a receiver, the method comprising the computer-implemented steps of:

receiving from the receiver, sampled data that includes signal information from a plurality of signal sources;

dividing the sampled data into a set of data segments, wherein each successive data segment from the set of data segments is formed by including all previous data segments plus additional data from the sampled to reach a pre-determined segment length; and

for each data segment performing the steps of;

determining an estimate of the clock doppler value based on the signal information of a first signal source from the plurality of signal sources;

using the estimate of the clock doppler based on the signal information of the first signal source in determining the estimate of the clock doppler based on the signal information of a second signal source from the plurality of signal sources.

25. A method for determining a clock doppler value of a receiver, the method comprising the computer-implemented steps of:

Step A;

receiving from the receiver, sampled data associated with a received signal;

Step B;

dividing the sampled data into a set of data segments, wherein each successive data segment from the set of data segments is formed by including all previous data segments plus additional data from the sampled to reach a pre-determined segment length;

Step C;

selecting a shortest data segment that has not been previously selected from the set of data segments to be a selected data segment;

Step D;

selecting one satellite that has not been previously selected from a set of satellites that is overhead the receiver to be a selected satellite;

Step E;

estimating the clock doppler value based on the selected satellite and the selected data segment;

Step F;

repeating step D through step F until all the satellites from the set of satellites have been selected as the selected satellite; and

Step G;

repeating steps C through G until all data segments from the set of data segments have been selected to be the selected data segment.

26. A method for determining a clock doppler value of a receiver, the method comprising the computer-implemented steps of:

Step A;

receiving from the receiver, sampled data associated with a received signal;

Step B;

dividing the sampled data into a set of data segments, wherein each successive data segment from the set of data segments is formed by including all previous data segments plus additional data from the sampled to reach a pre-determined segment length;

Step C;

selecting a shortest data segment that has not been previously selected from the set of data segments to be a selected data segment;

Step D;

selecting one satellite that has not been previously selected from a set of satellites that is overhead the receiver to be a selected satellite;

Step E;

estimating the clock doppler value based on the selected satellite and the selected data segment by performing the steps of;

Step F;

computing a current bounds for a delay value and a current bounds for a carrier frequency value associated with the received signal if not previously computed based on the selected satellite;

Step G;

updating the current bounds for the delay value and updating the current bounds for the carrier frequency value based on the selected satellite and the selected data segment if a set of criteria is satisfied, wherein the set of criteria comprises;

if the current bounds for the delay value and the current bounds for the carrier frequency value are previously computed; and

if an estimate of the carrier frequency value satisfies a pre-determined tolerance value of carrier frequency value and an estimate of the delay value satisfies a pre-determined tolerance value of the delay value;

Step H;

repeating step D through step H until all the satellites from the set of satellites have been selected as the selected satellite;

Step I;

repeating steps C through I until all data segments from the set of data segments have been selected as the selected data segment;

Step J;

extracting the clock doppler value from the estimate of the carrier frequency.

27. A method for determining a clock doppler value of a receiver, the method comprising the computer-implemented steps of:

Step A;

receiving from the receiver, sampled data associated with a received signal;

Step B;

dividing the sampled data into a set of data segments, wherein each successive data segment from the set of data segments is formed by including all previous data segments plus additional data from the sampled to reach a pre-determined segment length;

Step C;

selecting a shortest data segment that has not been previously selected from the set of data segments to be a selected data segment for performing the steps of;

Step D;

selecting one satellite that has not been previously selected from a set of satellites that is overhead the receiver to be a selected satellite;

Step E;

if a current bounds for a delay value and a current bounds for a carrier frequency value associated with the received signal have not been previously computed, then performing the steps of;

Step F;

computing current bounds for the delay value with respect to the selected satellite based on;

an approximate time that the receiver received the received signal; and

a relative approximate position information between the selected satellite and the receiver;

Step G;

computing current bounds for the carrier frequency value with respect to the selected satellite based on;

relative clock correction factors between the selected satellite and the receiver;

a navigation bit information associated with the selected satellite; and

characteristics of a filter used to sample the received signal;

Step H;

if the current bounds for the delay value and the current bounds for the carrier frequency value have been previously computed, then using an updated current bounds for the delay value as the current bounds for the delay value and an updated current bounds for the carrier frequency value as the current bounds for the carrier frequency value;

Step I;

determining an estimate for the clock doppler value and an estimate for the delay value using the selected data segment by performing the steps of;

Step J;

if the current bounds for the carrier frequency value exceeds a pre-determined bound-width value for the carrier frequency value and the current bounds for the delay value exceeds a pre-determined bound-width value for the delay value, then performing the steps of;

Step K;

dividing a range of frequency of interest into a first set of frequency intervals and a second set of frequency intervals;

Step L;

dividing the selected data segment into a set of data blocks corresponding to the first set of frequency intervals;

Step M;

for each data block within the set of data blocks, calculating an I correlation integral and a Q correlation integral based on the selected satellite;

Step N;

for every frequency interval of the second set of frequency intervals, summing the I correlation integral over all the data blocks from the set of data blocks without re-calculating the I correlation integral; and

Step O;

for every frequency interval of the second set of frequency intervals, summing the Q correlation integral over all the data blocks from the set of data blocks without re-calculating the Q correlation integral;

Step P;

for each hypothesized delay value within the current bounds of the delay value, calculating a magnitude of the of the I and Q correlation integrals that were previously summed over all the data blocks, to produce a set of magnitude calculations, wherein the set of magnitude calculations correspond to the hypothesized delay values;

Step Q;

selecting as an estimate for the carrier frequency value, the carrier frequency value corresponding to a highest magnitude calculation from the set of magnitude calculations;

Step R;

selecting as the estimate for the delay value, the delay value corresponding to the highest magnitude calculation from the set of magnitude calculations;

Step S;

if the current bounds for the carrier frequency value is within the pre-determined bound-width value for the carrier frequency value and the current bounds for the delay value is within the pre-determined bound-width value for the delay value, then performing the steps of;

Step T;

selecting as an initial carrier frequency value, one of the carrier frequency values that has not been previously selected from within the current bounds for the carrier frequency value;

Step U;

selecting a delta value corresponding to the initial carrier frequency value;

Step V;

selecting one or more candidates of delay values from within the current bounds for the delay value;

Step W;

for each candidate of delay value, calculating the I and Q correlation integrals at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

Step X;

for each candidate of delay value, calculating the magnitude of the I and Q correlation integrals at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

Step Y;

for each candidate of delay value, curve-fitting a magnitude template using the magnitude of the I and Q correlation integrals that are calculated at the initial carrier frequency value, at the initial carrier frequency value plus the delta value, and at the initial carrier frequency value minus the delta value;

Step Z;

for each candidate of delay value, selecting as a new carrier frequency value, a carrier frequency value that corresponds to the peak of the magnitude template;

Step ZA;

selecting as the estimate for the carrier frequency values corresponding to all the candidates of delay values;

Step ZB;

selecting as the estimate for the delay value, the delay value that corresponds to the average of the new carrier frequency value;

Step ZC;

if the estimate for the carrier frequency value satisfies a pre-determined tolerance value for the carrier frequency value and the estimate for the delay value satisfies a predetermined tolerance value for the delay value, then updating the current bounds for the delay value based on the estimate for the carrier frequency value and the estimate of the delay value to produce the updated current bounds for the carrier frequency and the updated current bounds for the delay value;

Step ZD;

repeating steps D through ZD until all the satellites from the set of satellites have been previously selected to be the selected satellite;

Step ZE;

repeating steps C through ZE until all data segments form the set of data segments have been previously selected to be the selected data segment;

Step ZF;

extracting the clock doppler value from the estimate of the carrier frequency.

28. A method to determine a plurality of estimates, wherein each estimate is for one receiver parameter belonging to a set of receiver parameters associated with a receiver, the method comprising the steps of:

step A;

receiving at said receiver, a received signal which contains a plurality of known signals, wherein each known signal is associated with one source from a set of possible sources;

step B;

dividing said received signal into a set of possibly overlapping segments;

step C;

determining a selected segment-source pair consisting of a selected segment from said set of possibly overlapping segments and a selected source from said set of possible sources;

step D;

searching in said selected segment for the known signal associated with said selected source by using an uncertainty region representation;

step E;

updating said uncertainty region representation;

step F;

estimating one or more receiver parameters by means of said uncertainty region representation;

step G;

iterating steps D,E,F and F until said uncertainty region representation satisfies a pre-determined termination condition or all possible segment-source pairs have been processed.

29. The method of claim 28, where step D (searching) comprises the steps of:

Step 1;

representing a set of signal parameters for said selected source; and

Step 2;

deriving a signal uncertainty region for said set of signal parameters by means of said uncertainty region representation.

30. The method of claim 28, where step D (searching) comprises the steps of:

Step 1;

representing a set of signal parameters for said selected source, wherein said set of signal parameters comprises a signal delay and a carrier frequency; and

Step 2;

deriving a signal uncertainty region for said set of signal parameters by means of said uncertainty region representation.

31. The method of claim 30, wherein said set of receiver parameters comprises a receiver location parameter, a receiver velocity parameter, a clock offset parameter, and a clock Doppler parameter.

32. The method of claim 30, wherein step D (searching) further comprises the steps of:

step 1;

determining a selected set of signal parameter values contained in said signal uncertainty region;

step 2;

considering a hypothesized signal parameter value from said selected set of signal parameter values;

step 3;

searching in said selected segment for the known signal corresponding to said selected source and to said hypothesized signal parameter value; and

step 4;

repeating step 2 and step 3 until said known signal is found or until all signal parameter values in said selected set of signal parameter values have been hypothesized.

33. The method of claim 32, wherein step G further comprises the steps of:

Step 1;

iterating through an increasing sequence of selected segments; and

Step 2;

iterating through said set of possible sources each time that a new selected segment is selected.

34. The method of claim 30, wherein said selected segment includes any selected segment that was selected during a preceding iterations.

35. The method of claim 30, wherein step G further comprises the steps of:

Step 1;

iterating through an increasing sequence of selected segments; and

Step 2;

iterating through said set of possible sources each time that a new selected segment is selected.

36. The method of claim 35 where said set of receiver parameters comprises a receiver location parameter, a receiver velocity parameter, a clock offset parameter, and a clock drift rate parameter.

37. The method of claim 30 further comprising the step of

deriving an initial uncertainty representation from a set of initial information.

38. The method of claim 30, further comprising the steps of:

deriving an initial uncertainty representation from a set of initial information, wherein said set of initial information comprises a receiver location information;

deriving said receiver location information from an information on cell tower location and an information on direction of arrival of said received signal.

39. The method of claim 30, wherein step D (searching) further comprises the step of:

calculating a correlation magnitude between the known signal of said selected source and said selected segment.

40. The method of claim 30, further comprising the step of:

calculating a correlation magnitude between the known signal of said selected source and said selected segment;

setting a threshold value; and

comparing said correlation magnitude with said threshold value.

41. The method of claim 30, further comprising the step of:

calculating a correlation magnitude between the known signal of said selected source and said selected segment;

calculating a size of said signal uncertainty region;

setting a threshold value based on said size of said signal uncertainty region; and

comparing said correlation magnitude with said threshold value.

42. The method of claim 30, wherein said uncertainty region representation comprises a system of inequalities.

43. The method of claim 30, wherein said uncertainty region representation comprises a system of linear inequalities.

44. The method of claim 30, further comprising the steps of:

using a system of linear equations representing an approximate relationship between said set of receiver parameters and said set of signal parameters; and

defining said uncertainty region representation based on a system of linear inequalities, wherein said linear inequalities are based on said system of linear equations.

45. The method of claim 44, further comprising the steps of:

comparing an updated estimate of receiver parameters with a current estimate of receiver parameters; and

updating said system of linear equations based on the result of the comparison.

46. The method of claim 44, wherein said set of receiver parameters comprises a receiver location parameter and a clock offset parameter;

and said system of linear inequalities comprises a plurality of inequalities for said code-phase parameter, a plurality of inequalities for said carrier frequency parameter, a plurality of inequalities for said receiver location parameter, and a set of inequalities for said clock offset parameter.

47. The method of claim 44, wherein said set of receiver parameters comprises a receiver location parameter, a receiver velocity parameter, a clock offset parameter, and a clock Doppler parameter;

and said system of linear inequalities comprises a plurality of inequalities for said code-phase parameter, a plurality of inequalities for said carrier frequency parameter, a plurality of inequalities for said receiver location parameter, a plurality of inequalities for said receiver velocity parameter, a plurality of inequalities for said clock offset parameter and a plurality of inequalities for said clock Doppler parameter.

48. The method of claim 47, where said system of linear equations are approximated by a first system of linear equations and a second system of equations, wherein said first system of equations is for said receiver location parameter and said clock offset parameter and said second system of equations is for said receiver velocity parameter and said clock Doppler parameter, and wherein said first system of equations and said second system of equations are made independent of each other by eliminating the cross-term from said second system of equations.

49. The method of claim 44, where said pre-determined termination condition is satisfied when a receiver location uncertainty region is contained in a bounding box.

50. The method of claim 44, further comprising the steps of:

calculating a correlation magnitude between the known signal of said selected source and said selected segment;

calculating the size of said signal uncertainty region;

setting a threshold value based on the calculated size of said signal uncertainty region; and

comparing said correlation magnitude with said threshold value.

51. The method of claim 50, further comprising the steps of:

comparing an updated estimate of receiver parameters with a current estimate of receiver parameters; and

updating said system of linear equations based on the result of the comparison.

52. The method of claim 30, further comprising the step of:

using a system of nonlinear equations representing an accurate relationship between said set of receiver parameters and said set of signal parameters;

using a system of linear equations representing an approximate relationship between said set of receiver parameters and said set of signal parameters;

defining said uncertainty region representation based on a system of linear inequalities;

calculating an error bound between said system of nonlinear equations and said system of linear equations; and

adapting said signal uncertainty region to said error bound.

53. The method of claim 52, further comprising the steps of:

calculating a correlation magnitude between the known signal of said selected source and said selected segment;

calculating the size of said signal uncertainty region;

setting a threshold value based on the calculated size of said signal uncertainty region; and

comparing said correlation magnitude with said threshold value.

54. The method of claim 53, further comprising the steps of:

comparing an updated estimate of receiver parameters with a current estimate of receiver parameters; and

updating said system of linear equations based on the result of the comparison.