US 6,983,009 B2 | ||
Median weighted tracking for spread-spectrum communications | ||
Gary R. Lomp, Centerport, N.Y. (US) | ||
Assigned to InterDigital Technology Corporation, Wilmington, Del. (US) | ||
Filed on Jan. 18, 2001, as Appl. No. 9/765,001. | ||
Application 09/765001 is a continuation in part of application No. 08/956740, filed on Oct. 23, 1997, granted, now 6,215,778. | ||
Application 08/956740 is a continuation of application No. 08/669775, filed on Jun. 27, 1996, granted, now 5,799,010, filed on Aug. 25, 1998. | ||
Application 09/765001 is a continuation in part of application No. 09/003104, filed on Jan. 06, 1998, granted, now 6,181,949, filed on Jan. 30, 2001. | ||
Application 09/003104 is a continuation of application No. 08/670162, filed on Jun. 27, 1996, granted, now 5,841,768, filed on Nov. 24, 1998. | ||
Application 09/765001 is a continuation in part of application No. 09/304286, filed on May 03, 1999, granted, now 6,252,866. | ||
Application 09/304286 is a continuation of application No. 08/671068, filed on Jun. 27, 1996, granted, now 5,940,382, filed on Aug. 17, 1999. | ||
Application 09/765001 is a continuation in part of application No. 09/354042, filed on Jul. 15, 1999. | ||
Application 09/354042 is a continuation of application No. 08/671067, filed on Jun. 27, 1996, granted, now 5,953,346, filed on Sep. 14, 1999. | ||
Application 09/765001 is a continuation in part of application No. 09/129850, filed on Aug. 06, 1998, abandoned. | ||
Application 09/129850 is a continuation of application No. 08/670160, filed on Jun. 27, 1996. | ||
Application 09/765001 is a continuation of application No. 09/079600, filed on May 15, 1998. | ||
Application 09/079600 is a continuation of application No. 08/671221, filed on Jun. 27, 1996, granted, now 5,754,803, filed on May 19, 1998. | ||
Prior Publication US 2002/0051482 A1, May 02, 2002 | ||
This patent is subject to a terminal disclaimer. | ||
Int. Cl. H04B 15/00 (2006.01); H04K 1/00 (2006.01); H04L 27/30 (2006.01) |
U.S. Cl. 375—149 | 3 Claims |
1. An improvement for tracking a spreading code in a multipath environment generating a plurality of multipath signals used
in a code division multiple access (CDMA) tracking circuit requiring an error signal, the improvement comprising:
an analog-to-digital converter for sampling an input signal having spread-spectrum modulation, with the spreading code embedded
in the spread-spectrum modulation having a plurality of chips, with the analog-to-digital converter forming half-chip offset
samples and grouping an even set of the half-chip offset samples into an early set of samples, and alternatively grouping
an odd set of the half-chip offset sample into a late set of samples;
a first correlation-bank, adaptive-matched filter, coupled to said analog-to-digital converter, for multiplying each early
set of samples by the spreading code c(n+1), c(n+2), . . . , c(n+L), where L is small compared to the length of the spreading
code and approximately equal to the number of chips of delay between the earliest and latest multipath signals, thereby generating
a first plurality of products;
a first sum-and-dump bank, coupled to said first correlation bank, adaptive-matched filter, for computing a first plurality
of sums from the first plurality of products, respectively;
a first plurality of calculators, coupled to said first sum-and-dump bank, for calculating a first plurality of magnitudes
from the first plurality of sums, respectively;
a first summer, coupled to said first plurality of calculators, for summing the first plurality of magnitudes to generate
an early signal-energy value;
a second correlation-bank, adaptive-matched filter, coupled to said analog-to-digital converter, for multiplying each late
set of samples by the spreading code c(n−1), c(n−2), . . . , c(n−L), thereby generating a second plurality of products;
a second sum-and-dump bank, coupled to said second correlation bank, adaptive-matched filter, for computing a second plurality
of sums from the second plurality of products, respectively;
a second plurality of calculators, coupled to said second sum-and-dump bank, for calculating a second plurality of magnitudes
from the second plurality of sums, respectively;
a second summer, coupled to said second plurality of calculators, for summing the second plurality of magnitudes to generate
a late signal-energy value; and
a subtractor, coupled to said first summer and to said second summer, for calculating a difference between the early signal-energy
value and the late signal-energy value, thereby producing the error signal.
|