Distributed voting system and method for land mobile radio system
View Patent ↗A distributed Internet Protocol (IP) voting system and method for use in Land Mobile Radio (LMR) Systems having a central send-and-receive site and one or more receive-only sites. In the distributed voting system, receive-only sites are directly linked to the control point using a network and associated packet transmission protocol. This may be a high-speed asynchronous data link such as a standard IP network link. Each remote site receiving digital data, calculates a bit error for that data. This error calculation is incorporated into the data header information. The data header information and data are placed in an IP packet and transmitted as a User Data Protocol (UDP) message to the control point. The control point selects the lowest bit rate data message, or the first control message, and retransmits it using a standard radio air interface protocol, such as the APCO Project 25 air interface protocol.
1. A distributed voter system for selecting at least one of several signals for transmission, comprising:
a plurality of remote receive-only site systems each remote receive-only site system comprising:
a first receiver configured for receiving a signal transmitted from a communication device,
a first processor configured for determining a quality measure of said received signal, and for producing a transfer signal comprising said received signal and said quality measure;
a plurality of network connections connecting each of said plurality of remote receive-only site systems to a common communications network;
a receive-and-transmit site system communicatively coupled to said plurality of remote receive-only site systems via said plurality of network connections established absent of intermediary voting equipment, said receive-and-transmit site system comprising
a second receiver configured for asynchronously receiving said transfer signals from said plurality of remote receive-only site systems,
a second processor configured for
storing a first transfer signal having a first quality measure as a selected transfer signal in a storage device, and,
if a subsequently-received transfer signal has a quality measure better than said first quality measure, then replacing said first transfer signal with said subsequently-received transfer signal as said selected transfer signal and
at least one transmitter configured for transmitting a broadcast signal comprising substantially said received signal of said selected transfer signal.
2. The system of claim 1 , wherein said transfer signal is comprised of at least one digital packet.
3. The system of claim 2 , wherein said digital packet conforms to a User Datagram Protocol (UDP) format.
4. The system of claim 1 , wherein
said quality measure comprises an estimate of a bit rate error of said received signal, and
said second processor is further configured for selecting said transfer signal having a smallest of a plurality of estimates of bit rate error.
5. The system of claim 4 , wherein said estimate of a bit rate error is obtained using data unit synchronization bits.
6. The system of claim 1 , wherein said common communications network is a Local Area Network.
7. The system of claim 6 , wherein said local area network is a high speed, asynchronous network.
8. The system of claim 1 , wherein said second processor selects said selected transfer signal within a predetermined time window.
9. A distributed voter method for selecting at least one of several signals for transmission, comprising the steps of:
a) receiving an input signal at a plurality of remote receive-only site systems;
b) evaluating, at each of said plurality of remote receive-only site systems, a quality measure of said input signal;
c) generating a transfer signal, at each of said plurality of remote receive-only site systems, by packaging said input signal and said quality measure as at least one data packet;
d) transmitting, from each of said plurality of remote receive-only site systems, said transfer signal to a transmit-and-receive site system using a plurality of network connections of a common communications network that are absent of intermediary voting equipment;
e) receiving asynchronously a first transfer signal and at least one subsequent transfer signal at said transmit-and-receive site system;
f) recording said first transfer signal having a first quality measure as a selected transfer signal, and, if said subsequent transfer signal has a quality measure better than said first quality measure, then replacing said first transfer signal with said subsequent transfer signal as said selected transfer signal; and,
g) transmitting a broadcast signal from said transmit-and-receive site system, said broadcast signal comprising substantially said input signal of said selected transfer signal.
10. The method of claim 9 , wherein said data packet is a digital packet.
11. The method of claim 10 , wherein said generating step c) further includes the step of conforming said digital packet to a User Datagram Protocol (UDP) format.
12. The method of claim 9 , wherein
said evaluating step b) further includes calculating an estimate of a bit rate error of said input signal, and
said transmit-and-receive site system is further configured for selecting said transfer signal having a smallest of a plurality of estimates of bit rate error.
13. The method of claim 12 , wherein said estimate of said bit rate error is calculated using a data unit's synchronization bits.
14. The method of claim 9 , wherein said common communications network includes a Local Area Network.
15. The method of claim 14 , wherein said Local Area Network includes a high speed, asynchronous network.
16. The method of claim 9 , wherein said recording step f) is performed until expiration of a predetermined time window.
17. A distributed voter system for selecting at least one of several signals for transmission, comprising:
a plurality of remote receive-only site systems, each remote receive-only site system is configured for receiving an input signal, evaluating a quality measure of said received input signal, and producing a transfer signal comprising said input signal and said quality measure;
a network for asynchronously transferring said transfer signals from said plurality of remote receive-only site systems to a transmit-and-receive site system using a plurality of network connections absent of intermediary voting equipment; and,
said transmit-and-receive site system configured for asynchronously receiving said transfer signals, and
selecting one of said transfer signals received by said transmit-and-receive site system based on said quality measure, by recording a first transfer signal having a first quality measure and, if a subsequently-received transfer signal has a quality measure better than said first quality measure, replacing said first transfer signal with said subsequently-received transfer signal as said selected transfer signal, and
transmitting a broadcast signal comprising substantially said input signal of said selected transfer signal.
18. The system of claim 17 , wherein said transfer signal further comprises a digital packet.
19. The system of claim 17 , wherein said digital packet conforms to a User Datagram Protocol (UDP) format.
20. The system of claim 17 , wherein
said quality measure comprises an estimate of a bit rate error of said input signal, and
said transmit-and-receive site system is further configured for selecting said transfer signal having a smallest of a plurality of estimates of bit rate error.