Audio routing within trunked radio frequency multisite switch

• US 5,699,354 A
• Filed: 11/04/1994
• Issued: 12/16/1997
• Est. Priority Date: 02/22/1991
• Status: Expired due to Term

• Current Assignee: Pine Valley Investments, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Gulliford, Philip C., Imron, Wim A., Teel, James L.
• Primary Examiner(s): Ton, Dang
• Application Number:
  US08/336,204
• Time in Patent Office: 1,138 Days
• Field of Search: 370/85.1, 370/29, 370/50, 370/68, 370/124, 370/75, 370/76, 370/77, 370/94.1, 370/95.1, 370/95.2, 370/95.3, 370/99.67, 370/68.1, 370/85.11, 370/85.09, 370/274 , 370/278, 370/280, 370/294, 370/310, 370/312, 370/314, 370/315, 370/319, 370/321, 370/323, 370/324, 370/329, 370/338, 370/341, 370/346, 370/347, 370/349, 370/376 , 370/385, 370/387, 370/389, 370/438, 370/451, 370/492, 370/501, 370/502, 370/503, 370/344, 370/330, 340/825.03, 455/3.2, 455/33.1, 455/33.2, 455/83.3, 455/51.1, 455/56.1, 455/54.2, 455/34.1, 455/11.1, 348/6, 348/7, 348/390, 379/60, 379/58, 379/59, 379/63, 379/4, 375/211, 375/216, 375/355, 375/356
• US Class Current: 370/315
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A distributed trunked radio frequency (RF) switching network (multisite switch) distributes audio routing control information and digitized audio signals to communications interface modules (nodes) throughout the multisite switch, thus avoiding a centralized mixing matrix, increasing fault tolerance and providing low routing request latency time. Each audio source, (for example, RF repeater transmitter, dispatch console microphone) is preassigned an audio channel on a time division multiplexed (TDM) digitized "audio network" or bus within the switch. The audio sources continually provide digitized audio signals to all other nodes within the switch over the assigned TDM bus channels. Audio routing is performed at the audio destinations (for example, interface modules/nodes associated with RF repeater receivers, dispatch console speakers) by selectively "listening" to active TDM network channels. In the preferred embodiment, audio is routed undirectionally on an "as needed" basis (for example, in response to radio transceiver "keys" and "unkeys"), and audio routing pathways may change dynamically during an on-going call.

Claims

1. In a digitally trunked radio frequency communications system of a type including plural radio frequency repeater sites having corresponding coverage areas and serving mobile/portable digitally trunked radio transceivers disposed within said coverage areas, said system supporting a bidirectional trunked radio frequency call that includes first and subsequent mobile/portable radio transceiver transmissions, a multisite switch having a distributed control dynamic audio signal routing arrangement for routing digitized audio signals between repeater site interfaces serviced by said switch, comprising:

means for establishing a first unidirectional digitized audio signal routing pathway within said switch between said site interfaces in response to a detecting of a first mobile/portable transceiver transmission by one of said plural radio repeater sites; and

means for establishing additional unidirectional audio routing pathways within said switch different from said first pathway between said site interfaces in response to detection of subsequent mobile/portable transceiver transmissions by one of said plural radio repeater sites, said first and subsequent transmissions being part of a same bidirectional trunked radio frequency call.

2. An arrangement as in claim 1 wherein said first and additional pathway establishing means operate using an autonomous distributed control arrangement and in response to a digital control message generated by a mobile/portable radio transceiver in response to a push-to-talk keying operation.

3. In a digitally trunked radio frequency communications system of a type including plural radio frequency repeater sites having corresponding coverage areas and serving mobile/portable digitally trunked radio transceivers disposed within said coverage areas, and including a multisite switch for distribution of digitized audio signals between said radio repeater sites, each repeater site having a corresponding site interface to said switch, said system supporting a bidirectional trunked radio frequency call that includes plural mobile/portable radio transceiver transmissions, a method of dynamically routing digitized audio signals between said plural repeater sites, comprising the steps of:

(a) detecting a transmission of a first mobile/portable radio transceiver;

(b) establishing a first unidirectional digitized audio signal routing pathway within said switch which is accessible by each site interface in response to said detected first transceiver transmission;

(c) detecting a transmission of a second mobile/portable radio transceiver, said second transceiver transmission responding to said first transceiver transmission and being part of a same call as said first transceiver transmission; and

(d) establishing different unidirectional digitized audio signal routing pathways within said switch between site interfaces, said pathways being distinct from said first pathway and from each other, in response to detecting of further transmissions from a mobile/portable transceiver.

4. A method as in claim 3 further including the steps of:

detecting termination of said first transceiver transmission; and

terminating said first audio routing pathway in response to detecting termination of the first transceiver transmission.

5. A method as in claim 3 wherein pathway establishing steps are performed by an autonomous processor at corresponding site interfaces resulting in a distributed control of audio signal routing within said switch.