Method and apparatus for frame synchronization

• US 4,984,238 A
• Filed: 03/08/1989
• Issued: 01/08/1991
• Est. Priority Date: 03/14/1988
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Watanabe, Toshiaki, Soejima, Tetsuo, Iguchi, Kazuo
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): CHIN, WELLINGTON
• Application Number:
  US07/320,588
• Time in Patent Office: 671 Days
• Field of Search: 370/100.1, 370/105.1, 370/105.4, 370/106, 375/31, 375/32, 375/106, 375/114, 375/116
• US Class Current: 370/509
• CPC Class Codes: H04J 3/0605 Special codes used as synchronising signal
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

A frame synchronization method in which a synchronization detection of a frame synchronization signal using one of n-multiplexed frame synchronization signals derived from a sequence of frame synchronization signals each delayed by one bit from the preceding frame synchronization signal, a synchronization confirmation as synchronization guard by detecting a repetition of the synchronization detections of the frame synchronization signal, a confirmation of the subsequent frame identification signal based on the synchronization confirmation; and a separation of the received multiplexed signals into a plurality of channels based on the synchronization confirmed frame synchronization signal and the confirmed frame identification signal are carried out.

Claims

1. A frame synchronization method comprising the steps of:

(a) receiving serial signals including frame synchronization signals and frame identification signals transmitted serially through a transmission line in n-multiplexed form;

(b) converting said received serial signals to parallel signals;

(c) latching said parallel signals;

(d) carrying out synchronization detection of a frame synchronization signal using one of n-multiplexed frame synchronization signals derived from a sequence of frame synchronization signals each delayed by one bit from the preceding frame synchronization signal;

(e) carrying out synchronization confirmation as a guard of synchronization by detecting a repetition of said synchronization detections of said frame synchronization signal;

(f) confirming the subsequent frame identification signal based on said synchronization confirmation; and

(g) carrying out separation of said received multiplexed signals into a plurality of channels based on said synchronization confirmed frame synchronization signal and said confirmed frame identification signal.

11. A method as recited in claim 1, wherein step (d) includes comparing said sequence of frame synchronization signals with a reference frame synchronization pattern.

12. A method as recited in claim 1, wherein the received n-multiplexed signals further include data signals.

2. A frame synchronization apparatus for processing serially n-multiplexed signals received from a transmission line and including frame synchronization signals, frame identification signals and data signals, comprising:

latch means, operatively connected to the transmission line and including a serial to parallel conversion means, a first latch means, and a first frequency division means, for latching parallel signals converted from the serially n-multiplexed signals;

second frequency division means for carrying out 1/n frequency division to produce a control signal;

frame synchronization detection and control means operatively connected to said latch means, including a second latch means, a frame pattern detection means, a frame identification detection means, and a control and guard means, for detecting synchronization of the frame synchronization signals using one of n-multiplexed frame synchronization signals derived from a sequence of frame synchronization signals each delayed by one bit from the preceding frame synchronization signal, for confirming the subsequent frame identification signal, for confirming synchronization as a guard of synchronization detection, and for generating a second control signal for said first and second frequency division means; and

demultiplexer means, responsive to the output of said first latch means and said control signal from said second frequency division means, for separating the n-multiplexed signals into a plurality of channels.

3. A frame synchronization apparatus for processing serially n-multiplexed signals received from a transmission line and including frame synchronization signals, frame identification signals and data signals, comprising:

latch means, operatively connected to the transmission line, for providing a sequence of delayed frame synchronization signals;

frequency division means for providing a first control signal based upon a second control signal and 1/n frequency division of a clock signal;

frame synchronization detection and control means, operatively connected to said latch means, for detecting synchronization of the frame synchronization signals using at least one of the delayed frame synchronization signals, and for generating said second control signal based on said detection of synchronization of the frame synchronization signal;

demultiplexer means for separating the n-multiplexed signals into a plurality of signals in response to said first control signal.

4. An apparatus as recited in claim 3, wherein said frame detection and control means includes:

confirming means for confirming synchronization of the frame synchronization signals based on a least one of the frame identification signals.

5. An apparatus as recited in claim 4, wherein said frame detection and control means includes:

guarding means for guarding synchronization of the frame synchronization signals based on reception of a frame synchronization signal that matches said at least one of the delayed frame synchronization signals and reception of a frame identification signal that matches said at least one of the frame identification signals.

6. An apparatus as recited in claim 3, said latch means includes:

means for delaying each frame synchronization signal by one bit from the preceding frame synchronization signal.

7. An apparatus as recited in claim 3, wherein:

said frequency division means includes means for providing a detection timing control signal based on said second control signal and 1/n frequency division of said clock signal; and

said frame synchronization detection and control means includes means for detecting synchronization of the frame synchronization signals based on said detection timing control signal and said at lease one of the delayed frame synchronization signals.

8. An apparatus as recited in claim 3, wherein said frame synchronization detection and control means includes:

means for comparing said sequence of delayed frame synchronization signals with a reference frame synchronization pattern.

9. An apparatus as recited in claim 3, wherein said frame synchronization detection and control means includes:

means for providing a third control signal based on said detection of synchronization of the frame synchronization signals; and

wherein said latch means includes;

conversion means, operatively connected to the transmission line, for converting the n-multiplexed signals to parallel signals;

second frequency division means for providing a frequency divided signal based on upon said third control signal and frequency division of a clock signal; and

second latch means, operatively connected to said conversion means, for latching said parallel signals in response to said frequency divided signal.

10. An apparatus as recited in claim 9, wherein said demultiplexer means includes means for receiving said n-multiplexed signals from said second latch means.

13. A frame synchronization apparatus for processing serially n-multiplexed signals received from a transmission line and including frame synchronization signals, frame identification signals and data signals, comprising:

latch means, operatively connected to the transmission line, for providing a sequence of delayed frame synchronization signals;

frequency division means for providing a first control signal and a detection timing control signal based upon a second control signal and 1/n frequency division of a clock signal

frame synchronization detection and control means, operatively connected to said latch means, for detecting synchronization of the frame synchronization signals using at least one of the delayed frame synchronization signals, and for generating said second control signal based on said detection of synchronization of the frame synchronization signal, said frame synchronization detection and control means includes means for detecting synchronization of the frame synchronization signals based on said detection timing control signal and said at least one of the delayed frame synchronization signals; and

demultiplexer means for separating the n-multiplexed signals into a plurality of signals in response to said first control signal.

14. A frame synchronization apparatus for processing serially n-multiplexed signals received from a transmission line and including frame synchronization signals, frame identification signals and data signals, comprising:

latch means, operatively connected to the transmissions lien, for providing a sequence of delayed frame synchronization signals;

frequency division means for providing a first control signal based upon a second control signal and 1/n frequency division of a clock signal;

frame synchronization detection and control means, operatively connected to said latch means, for detecting synchronization of the frame synchronization signals using at least one of the delayed frame synchronization signals, and for generating said second control signal based on said detection of synchronization of the frame synchronization signal, said frame synchronization detection and control means includes means for providing a third control signal based on said detection of synchronization of the frame synchronization signals;

demultiplexer means for separating the n-multiplexed signals into a plurality of signals in response to said first control signal; and

said latch means includes conversion means, operatively connected to the transmission line, for converting the n-multiplexed signals to parallel signals;

second frequency division means for providing a frequency divided signal based on said third control signal and frequency division of a clock signal; and

second latch means operatively connected to said conversion means, for latching said parallel signals in response to said frequency divided signal.

15. An apparatus as recited in claim 14, wherein said demultiplexer means includes means for receiving said n-multiplexed signals from said second latch means.