GUARD INTERVAL ANALYSIS METHOD AND APPARATUS

• US 20090154610A1
• Filed: 08/06/2008
• Published: 06/18/2009
• Est. Priority Date: 07/12/2000
• Status: Active Grant

• Current Assignee: Entropic Communications Incorporated (Maxlinear Incorporated)
• Original Assignee: Trident Microsystems Limited (Avnet Incorporated)
• Inventors: Parker, Jonathan
• Granted Patent: US 7,729,414 B2
• Time in Patent Office: Days
• US Class Current: 375/343
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2666 Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/42607 for processing the incoming bitstream
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/6112 involving terrestrial transmission, e.g. DVB-T
• CPC Class Codes: H04N 5/455 Demodulation-circuits

Abstract

A receiver circuit processes a received signal to determine information regarding a guard interval therein. The receiver circuit typically forms digital samples from the received signal; generates a correlation function with peaks at positions that are determined by the size of the guard interval and a position of the guard interval within the received signal. The receiver circuit includes one or more comb filters, each corresponding to a possible guard interval size, each receiving a series of locations at which the correlation function exceeds a predetermined threshold, and each producing an output that provides information about the guard interval size and/or position. This advantageously allows the receiver circuit to determine the guard interval size quickly, for example, even in the case of received signals with relatively low signal-noise ratio.

Claims

1. A method of processing a received signal, determining a size of a guard interval therein, the method comprising:

a) forming digital samples of the received signal;

b) generating from the digital samples a correlation function with peaks at positions that are determined by the size of the guard interval and a position of the guard interval within the received signal;

c) determining a series of sample locations at which the correlation function exceeds a predetermined threshold;

d) applying at least one comb filter, corresponding to a guard interval size, to the series of sample locations; and

e) deducing information about the guard interval from outputs of the comb filter.