Communications system

• US 4,811,365 A
• Filed: 11/07/1986
• Issued: 03/07/1989
• Est. Priority Date: 11/07/1986
• Status: Expired due to Term

• Current Assignee: SYNE Access Incorporated
• Original Assignee: Phillip E. Manno
• Inventors: Manno, Phillip E.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Wallace, Linda J.
• Application Number:
  US06/928,203
• Time in Patent Office: 851 Days
• Field of Search: 328/120, 370/101, 370/103, 371/47, 371/62, 375/107, 375/108, 375/109, 375/118, 375/120, 380/48
• US Class Current: 375/356
• CPC Class Codes: H04B 7/2126 using a reference station

Abstract

An improvement to a communications system such as a satellite communications system, or the like, wherein a plurality of nodes transmit over a common path on a time sharing basis via a central hub. The method and apparatus permits closer spacing of the communications from the nodes on the path and eliminates wasted delay time. The method comprises designating one of the nodes as the reference node and the remaining nodes as slave nodes. A transmission sequence is begun by having the reference node transmit a repeating, pre-established, pseudo-random, digital sequence at a pre-established bit rate. The reference node continues its sequence, but then omits a portion between the start and end of the sequence. A slave node wishing to join the transmission sequence begins the same repeating, pre-established, pseudo-random, digital sequence at approximately the same pre-established bit rate and then starts transmitting an approximation of the portion of the sequence being omitted by the reference node. By adjusting the bit rate, phasing, framing and sequence portion of the transmission from the slave node until the portion being transmitted thereby exactly matches the portion being omitted by the reference node, the reference node and slave node are placed in precise synchronization. The slave node then informs the reference node that it is in synchronization and ready to begin normal message transmission. Normal message transmission is then begun by the reference and slave nodes. Since the slave nodes are in precise synchronization with the reference node and the length of each node'"'"'s transmission is exact and pre-established, each node can precisely calculate the time at which to begin its transmission without need for delay between transmissions or the danger of overlap.

Claims

1. In a communications system wherein a plurality of nodes transmit over a common path on a time sharing basis, the method for permitting closer spacing of the communications from the nodes on the path comprising the steps of:

(a) designating one of the nodes as the reference node and the remaining nodes as slave nodes;

(b) beginning a transmission sequence by having the reference node transmit a repeating, pre-established, pseudo-random, digital sequence at a pre-established bit rate;

(c) having the reference node continue its sequence while omitting a portion thereof between the start and end of the sequence;

(d) having a slave node preparing join the transmission sequence begin the same repeating, pre-established, pseudo-random, digital sequence at approximately the same pre-established bit rate;

(e) having the slave node transmit an approximation of the portion of the sequence being omitted by the reference node;

(f) adjusting the bit rate, phasing, framing and sequence portion of the transmission from the slave node until the portion being transmitted thereby exactly matches the portion being omitted by the reference node whereby the reference node and slave node are placed in precise synchronization;

(g) having the slave node inform the reference node that it is in synchronization and ready to begin normal message transmission; and

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(h) beginning normal message transmission by the reference and slave nodes.

2. In a communications system wherein a plurality of nodes transmit over a common path on a time sharing basis, the improvement for permitting closer spacing of the communications from the nodes on the path comprising:

(a) means for designating one of the nodes as the reference node and the remaining nodes as slave nodes;

(b) means for beginning a transmission sequence by having said reference node transmit a repeating, pre-established, pseudo-random, digital sequence at a pre-established bit rate;

(c) means for having said reference node continue its said sequence while omitting a portion thereof between the start and end of said sequence;

(d) means for having a slave node preparing to join said transmission sequence begin said same repeating, pre-established, pseudo-random, digital sequence at approximately the same pre-established bit rate;

(e) means for having said slave node transmit an approximation of said portion of said sequence being omitted by said reference node;

(f) means for adjusting the bit rate, phasing, framing and sequence portion of said transmission from said slave node until said portion being transmitted thereby exactly matches said portion being omitted by said reference node whereby said reference node and slave node are placed in precise synchronization; and

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(g) means for having said slave node inform said reference node that it is in synchronization and ready to begin normal message transmission and for beginning normal message transmission by said reference and slave nodes.

3. In a communications system wherein a reference node and at least one slave node transmit simultaneously over a common path to at least one receiving node on a time sharing basis, the improvement for permitting closer spacing of the communications from the reference and slave nodes on the path comprising:

(a) means for causing the reference node to transmit a unique signal at the start of a transmission synchronization sequence;

(b) synchronization means for the slave node to monitor the transmission from the reference node and for adjusting the bit rate, phasing, framing and sequencing of the slave node until the reference node and slave node are placed in precise synchronization;

(c) means for informing the reference node that the slave node is in synchronization and for beginning normal transmission from the reference node; and

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(d) means for beginning normal transmission from the slave node immediately following the end of the normal transmission from the reference node without a gap therebetween.

4. The improvement to a communications system of claim 3 wherein said synchronization means comprises:

(a) means for causing the reference node to continue its transmission of said unique signal while omitting a portion between the start and end thereof;

(b) means for having the slave node begin a same said unique signal at approximately the same pre-established bit rate;

(c) means for having the slave node transmit an approximation of said omitted portion of said unique signal;

(d) means for adjusting the bit rate, phasing, framing and sequence portion of said transmission from the slave node until said portion being transmitted thereby exactly matches said portion being omitted by said reference node whereby the reference node and the slave node are placed in precise synchronization.

5. The improvement to a communications system of claim 4 wherein:

said means for causing the reference node to transmit a unique signal and said means for having the slave node begin said same unique signal each include a pseudo random number generator generating the same pseudo random number sequence which is used as said unique signal.

6. The method of operating a communications system comprising a plurality of nodes transmitting over a common path on a time sharing basis to permit closer spacing of the communications from the nodes on the path comprising the steps of:

(a) designating one of the nodes as the reference node and the remaining nodes as slave nodes;

(b) beginning a transmission synchronization sequence by having the reference node begin transmission of a repeating, pre-established, pseudo-random, numerical digital sequence at a pre-established bit rate;

(c) continuing the transmission synchronization sequence by having the reference node continue its digital sequence while omitting a portion thereof between the start and end of the sequence comprising several digits of the sequence;

(d) having a slave node preparing to synchronize to the transmission sequence begin the same repeating, pre-established, pseudo-random, numerical digital sequence at approximately the same pre-established bit rate;

(e) having the slave node begin transmission of an approximation of the portion of the sequence being omitted by the reference node;

(f) adjusting the bit rate, phasing, framing and sequence portion of the transmission from the slave node until the portion being transmitted by the slave node exactly matches the portion being omitted by the reference node whereby the reference node and slave node are placed in precise synchronization;

(g) having the slave node inform the reference node that it is in synchronization and ready to begin normal message transmission; and

,

(h) beginning normal message transmission by the reference and slave nodes.

7. In a communications system wherein a reference node and at least one slave node transmit over a common path on a time sharing basis, the improvement for permitting closer spacing of the communications from the nodes on the path without delays therebetween comprising:

(a) the reference node including a first pseudo-random numerical sequence generator outputting a signal at an output thereof, means for switching the source of signal being transmitted by the reference node to said signal output from said first sequence generator, and means for selectively interrupting said signal from said first sequence generator at a pre-selected numerical sequential portion thereof;

(b) the slave node including a second pseudo-random numerical sequence generator functionally identical to said first pseudo-random numerical sequence generator and outputting a signal at an output thereof, means for switching the source of signal being transmitted by the slave node to said signal output from said second sequence generator, and means for selectively interrupting said signal from said second sequence generator during the time other than the time said preselected numerical sequential portion of said sequence is being interrupted by said reference node;

(c) synchronization means at the slave node for monitoring the transmissions from the slave node and the reference node and for adjusting the bit rate, phasing, framing and sequencing of the transmission from the slave node until the combined transmission signal from the reference node and slave node identically represents said sequence of said first and second signal generators without interruption whereby the reference node and slave node are placed in precise synchronization;

(d) means at the slave node for informing the reference node that the slave node is in synchronization and for switcing to normal transmission from the reference node and the slave node; and

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(e) means for causing the slave mode to begin its normal transmissions immediately following the end of the transmission from the preceeding node without a delay therebetween.

8. The method of operating a communications system comprising a reference node and at least one slave node transmitting simultaneously over a common path to at least one receiving node on a time sharing basis to permit closer spacing of the communications from reference and slave the nodes on the path comprising the steps of:

(a) causing the reference node to transmit a unique signal at the start of a transmission synchronization sequence;

(b) causing the slave node to monitor the transmission from the reference node;

(c) causing the slave node to adjust its bit rate, phasing, framing and sequencing until the reference node and slave node are placed in precise synchronization;

(d) informing the reference,, node, that the slave node is in synchronization and thereafter beginning normal transmission from the reference node; and

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(e) beginning normal transmissions from the slave node immediately following the end of the normal transmissions from the reference node without a gap therebetween.

9. The method of claim 8 and additionally including the steps of:

(a) causing the reference node to continue its transmission of the unique signal while omitting a portion between the start and end thereof;

(b) having the slave node begin generating the same unique signal at approximately the same pre-established bit rate;

(c) having the slave node begin transmission of an approximation of the omitted portion of the unique signal;

(d) adjusting the bit rate, phasing, framing and sequence portion of the transmission from the slave node until the portion being transmitted thereby exactly matches the portion being omitted by the reference node whereby the reference node and the slave node are placed in precise synchronization.

10. The method of claim 9 including the step of:

causing the reference node and the slave node to generate the same pseudo random number sequence which is used as the unique signal.