FRAME SYNCHRONIZER, FRAME SYNCHRONIZATION METHOD AND DEMODULATOR

• US 20100135335A1
• Filed: 04/25/2008
• Published: 06/03/2010
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Makita, Atsushi, Matsumoto, Hideyuki, Dung, Doan Tien, Mizutani, Yuichi, Yokokawa, Takashi, Futami, Tetsuhiro
• Granted Patent: US 8,385,371 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04H 20/74 of satellite networks
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

The present invention relates to a frame synchronizer, frame synchronization method and demodulator which can more positively establish frame synchronization of an input signal which is likely to have a plurality of frame lengths.

A differential correlation detector 151 calculates a differential correlation value with no pilot which is associated with the absence of a pilot signal inserted in the input signal and a differential correlation value with a pilot which is associated with the presence of a pilot signal inserted in the input signal. The frame period confirmation counters 152-1 and 152-3 perform, based on the differential correlation values with no pilot, frame synchronization control appropriate to the input signals whose frame lengths are 21690 and 32490 symbols, respectively. The frame period confirmation counters 152-2 and 152-4 perform, based on the differential correlation values with a pilot, frame synchronization control appropriate to the input signals whose frame lengths are 22194 and 33282 symbols, respectively.

The present invention is applicable, for example, to a satellite broadcast receiver.

Claims

1. A frame synchronizer for achieving frame synchronization of an input signal transmitted with any one of a plurality of predetermined types of frame lengths, the frame synchronizer comprising:

correlation detection means adapted to calculate a correlation value indicating the correlation between a known sequence, which is a symbol string having a known value inserted in the input signal, and a reception sequence which is a symbol string obtained by detecting the input signal; and

frame synchronization means which are provided in a number equal to the number of types of the frame lengths in a one-to-one correspondence fashion, wherein

the frame synchronization means compare an associated frame length and a peak-to-peak spacing of the correlation value and output a synchronizing signal synchronous with the frame having the associated frame length if the associated frame length matches the peak-to-peak spacing of the correlation value.

2. The frame synchronizer of claim 1, wherein

the frame synchronization means further output, together with the synchronizing signal, a transmission parameter adapted to determine the frame length of the input signal and appropriate to the associated frame length.

3. The frame synchronizer of claim 2, further comprising:

extraction means adapted to extract the transmission parameter inserted in the input signal based on the synchronizing signal; and

determination means adapted to determine the degree of reliability of the extracted transmission parameter by comparing the values of the transmission parameters output from the frame synchronization means and extracted by the extraction means.

4. The frame synchronizer of claim 2, further comprising

decoding means adapted to decode the coded transmission parameter inserted in the input signal in a simplified manner using part of the transmission parameter output from the frame synchronization means.

5. The frame synchronizer of claim 1, wherein

if the known sequence takes on a plurality of values due to the value of the transmission parameter adapted to determine the frame length of the input signal, the correlation detection means calculate correlation values associated with the known sequence with the plurality of values, and

the frame synchronization means compare the peak-to-peak spacing of the correlation value associated with the value of the known sequence appropriate to the associated frame length with the associated frame length.

6. The frame synchronizer of claim 1, further comprising

selection means adapted to select and output the synchronizing signal output from the frame synchronization means associated with the shortest frame length if the synchronizing signals are output from the plurality of frame synchronization means.

7. A frame synchronization method of a frame synchronizer for achieving frame synchronization of an input signal transmitted with any one of a plurality of predetermined types of frame lengths, the frame synchronization method comprising the steps of:

calculating a correlation value indicating the correlation between a known sequence, which is a symbol string having a known value inserted in the input signal, and a reception sequence which is a symbol string obtained by detecting the input signal; and

comparing an associated frame length and a peak-to-peak spacing of the correlation value and output a synchronizing signal synchronous with the frame having the associated frame length if the associated frame length matches the peak-to-peak spacing of the correlation value using frame synchronization means which are provided in a number equal to the number of types of the frame lengths in a one-to-one correspondence fashion.

8. A demodulator for demodulating an input signal transmitted with any one of a plurality of predetermined types of frame lengths, the demodulator comprising:

correlation detection means adapted to calculate a correlation value indicating the correlation between a known sequence, which is a symbol string having a known value inserted in the input signal, and a reception sequence which is a symbol string obtained by detecting the input signal; and

frame synchronization means which are provided in a number equal to the number of types of the frame lengths in a one-to-one correspondence fashion, wherein

the frame synchronization means compare an associated frame length and a peak-to-peak spacing of the correlation value and output a synchronizing signal synchronous with the frame having the associated frame length if the associated frame length matches the peak-to-peak spacing of the correlation value.

9. The demodulator of claim 8, wherein

the frame synchronization means further output, together with the synchronizing signal, a transmission parameter adapted to determine the frame length of the input signal and appropriate to the associated frame length, the demodulator further comprising

signal processing means adapted to adaptively change processes to be performed on the input signal depending on the quantity of the known sequence found from the transmission parameter output from the frame synchronization means if the transmission parameter contains a parameter adapted to define the quantity of the known sequence inserted in the frame.