Method for synchronizing the transmissions in a simulcast transmission system

• US 5,014,344 A
• Filed: 03/19/1990
• Issued: 05/07/1991
• Est. Priority Date: 03/19/1990
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Goldberg, Steven J.
• Primary Examiner(s): Kuntz, Curtis
• Application Number:
  US07/495,819
• Time in Patent Office: 414 Days
• Field of Search: 455/18, 455/51, 455/56, 455/33, 340/825.44, 340/825.5, 375/107, 370/103, 370/108
• US Class Current: 455/503
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

Abstract

A method for synchronizing message transmissions in a simulcast transmitter system is described. A master controller couples to a plurality of regional controllers for enabling message transmissions and for initiating delay measurement signal transmissions in each of a plurality of regions. The master controller generates a first delay measurement signal which is transmitted from a selected one of a plurality of regional transmitters operating within a first transmission region. The regional controller within the first transmission region measures the propagation delay of the selected one of the plurality of regional transmitters within the first transmission region. The master controller next generates a second delay measurement signal which is transmitted from a selected one of the plurality of regional transmitters operating within a second transmission region adjacent to the first transmission region. The regional controller within the first transmission region measures the propagation delay of the selected one of the plurality of regional transmitters within the second transmission region. The intra-regional differential propagation delay is computed from the measurements of the propagation delays measured from the first and second transmission regions. The additional transmission delay is computed for each of the regional transmitters within the first and second transmission regions, and the transmission delays for each regional transmitter are adjusted to equalize the intra-regional differential transmission delays between the first and second transmission regions.

Claims

1. A method for synchronizing message transmissions in a simulcast transmitter system, the system comprising at least two transmission regions, each transmission region having at least one regional receiver coupled to a regional controller for receiving delay measurement signals, each transmission region further having a plurality of regional transmitters having adjustable transmission delays, the regional transmitters being responsive to the regional controllers, for transmitting the messages and the delay measurement signals, the system further comprising a master controller coupled to each regional controller, for enabling the message transmissions, and further for initiating the transmission of delay measurement signals for the measurement of propagation delays, said method comprising the steps of:

generating a first delay measurement signal at the master controller;

transmitting the first delay measurement signal from a selected one of the plurality of regional transmitters operating within a first transmission region;

measuring the propagation delay of the first delay measurement signal with the regional controller controlling the transmissions within the first transmission region;

generating a second delay measurement signal at the master controller;

transmitting the second delay measurement signal from a selected one of the plurality of regional transmitters operating within a transmission region adjacent the first transmission region;

measuring the propagation delay of the second delay measurement signal with the regional controller controlling the transmissions within the first transmission region;

computing a intra-regional differential propagation delay from the propagation delay measurements derived from the transmission of the first and second delay measurement signals;

computing the transmission delays required to equalize the transmissions of each of the plurality of transmitters within the first and second transmission regions in accordance with said step of computing the intra-regional differential propagation delay measurements; and

adjusting the transmission delays for each of the regional transmitters operating within the first and second transmission regions.

2. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 1, further comprising the steps of:

initiating an inter-regional measurement control signal at the master controller;

generating a delay measurement signal at the regional controller for each transmission region in response to receiving the measurement control signal by the regional controller;

transmitting the delay measurement signal from each of the plurality of transmitters within each transmission region;

measuring the propagation delay with the regional controller controlling the transmissions for each transmission region;

computing a inter-regional differential propagation delays between each of the plurality of transmitters within each transmission region;

computing the transmission delays required to equalize the transmissions of each of the plurality of transmitters within each transmission region in accordance with said step of computing the inter-regional differential propagation delay measurements; and

adjusting the transmission delays for each of the plurality of regional transmitters within each transmission region.

3. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 2, further comprising the steps of:

computing a maximum inter-regional differential propagation delays for each transmission region;

computing the additional transmission delays required to equalize the transmissions of each of the plurality of transmitters within each transmission region in accordance with said step of computing the maximum inter-regional differential propagation delay measurements for each transmission region; and

further adjusting the transmission delays for each of the plurality of regional transmitters within each transmission region.

4. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 2, further comprising the steps of:

computing a average inter-regional differential propagation delays for each transmission region;

computing the additional transmission delays required to equalize the transmissions of each of the plurality of transmitters within each transmission region in accordance with said step of computing the average inter-regional differential propagation delay measurements for each transmission region; and

further adjusting the transmission delays for each of the plurality of regional transmitters within each transmission region.

5. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 2, wherein the delay measurement signals transmitted for the inter-regional propagation delay measurements are transmitted from each of the plurality of regional transmitters in each transmission region in a predetermined sequential order.

6. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 1, further comprising the steps of:

periodically initiating the measurement of intra-regional transmission propagation delays; and

further adjusting the transmission delays for each regional transmitter operating within the first and second transmission regions corresponding to the computed intra-regional differential propagation delays between the first and second transmission regions.

7. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 2, further comprising the steps of:

periodically initiating the measurement of inter-regional transmission propagation delays; and

adjusting the transmission delays for each of the plurality of regional transmitters within each transmission region corresponding to the periodically computed inter-regional differential propagation delays within each transmission region.

8. The method for synchronizing message transmissions in a simulcast transmitter system according to claim 1, wherein the at least two transmission regions are contiguous to each other.