Automatic resynchronization technique

• US 4,807,248 A
• Filed: 05/23/1984
• Issued: 02/21/1989
• Est. Priority Date: 05/23/1984
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Hardt, Ivan E., Bonebright, Cynthia A., Pyatt, Roger A.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US06/613,659
• Time in Patent Office: 1,735 Days
• Field of Search: 375/110, 375/114, 375/115, 375/1, 370/100, 370/105, 370/104, 370/106
• US Class Current: 375/366
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04B 2001/71563 Acquisition
• CPC Class Codes: H04B 2001/71566 Tracking

Abstract

There is disclosed a technique for providing resynchronization for message reception in digital transmission systems, and particularly in digital frequency hopping systems employing data framing techniques. In the transmission of framed data using known digital techniques for frequency hopping systems, synchronization is provided in frames preceding the message frames transmitting digital data. In addition, resynchronization information is transmitted in subsequent frames which are interspersed with data frames including the message data. A predetermined number of frames is set to provide all the resynchronization information so that once those frames have been detected, a receiver will have acquired resynchronization during message transmission. This technique allows improved signal acquisition by providing an opportunity following the first conventional synchronization frame to acquire synchronization or to reacquire synchronization during message transmission.

Claims

1. A data transmission technique comprising:

(a) providing a transmitter capable of transmitting information in a series of different and pseudoramdomly selected frequencies;

(b) providing a receiver capable of receiving information in a series of different and pseudoramdomly selected frequencies;

(c) generating a plurality of synchronization frames and resynchronization frames, for allowing the receiver to frequency synchronize with the transmitter, wherein the information necessary to acquire synchronization is divided among at least two of said synchronization or resynchronization frames with each frame transmitted on a different frequency, said at least two synchronization or resynchronization frames comprising a plurality of identically formatted and timed synchronization frames and a start of message frame;

(d) generating a plurality of message frames including information defining a message to be transmitted and (e) transmitting said plurality of identically formatted and timed synchronization frames and said start of message frames such that said plurality of identically formatted and timed synchronization frames are transmitted prior to the transmission of said start of message frame, each frame is transmitted on a different pseudoramdomly selected frequency and said plurality of resynchronization frames are separated by message frames.

2. A data transmission technique in a frequency hopping system comprising:

(a) providing a transmitter capable of transmission of information in a series of different and pseudoramdom frequency, so that, the frequency of transmission can be varied in order to prevent reception of the entire transmission by unauthorized receivers;

(b) providing a receiver capable of receiving information in a series of different pseudoramdom frequencies, so that, the frequency of reception can be varied in order to allow for the reception of transmissions in a series of different pseudoramdom frequencies;

(c) generating a plurality of synchronization frames and resynchronization frames for allowing the receiver to synchronize with the transmitter, wherein the information necessary to acquire synchronization is divided among at least two of said synchronization or resynchronization frames, said at least two synchronization or resynchronization frames comprising a plurality of identically formatted and timed synchronization frames in a start of message frames;

(d) generating a plurality of message frames including information defining a message to be transmitted; and

(e) transmitting said plurality of identically formatted and timed synchronization frames and said start of message frame such that said plurality of identically formatted and timed synchronization frames that are transmitted prior to the transmission of said start of message frame and such that said plurality of resynchronization frames are separated by message frames;

whereby, in the event that synchronization between a transmitter and a receiver is lost during the course of a transmission, resynchronization can be obtained during that same transmission and thereby minimizing the loss of any information available to the receiver.