This document defines a Conventional Fixed Station Interface (CFSI). The CFSI is the interface between a conventional fixed station, which is defined in this document as a functional component of a Fixed Station Subsystem, and a Conventional Fixed Station Host (CFSH). A CFSH is defined in this document as a functional component of either an RF Subsystem (RFSS) or a Console Subsystem.¹ Clause 6 describes these elements and their relationship to each other. For the purposes of this scope statement, a fixed station may be either an “analog fixed station” or a “digital fixed station”. An “analog fixed station” supports conventional FM RF resources or their equivalent. A “digital fixed station” supports the Common Air Interface (CAI) for conventional implementations ([8]).

This document fully describes the CFSI including its architecture (clause 6), and protocols (clauses 7 and 8). Clause 7 describes a basic analog audio and control interface, while clause 8 describes a more capable Internet Protocol (IP) ([1]) based digital interface. This interface has been designed to work with IPv4. Use of this interface with IPv6 is for further study.

The functional scope of the CFSI as described herein comprises the following CFSI Analog and CFSI Digital Interface provisions.

The CFSI Analog Interface provides:

1. Transport of clear audio between a fixed station and its host² providing capabilities for full-duplex, half-duplex and simplex communications at the discretion of the fixed station.

2. Transport of E&M control signaling between a fixed station and its host to provide a simple “Push-to-talk” and “COR” capability.

3. Transport of Tone Remote Control (TRC) control signaling from a host to a fixed station to provide a variety of control functions including transmit channel control, squelch control, monitor control, clear/secure controls, analog/digital mode controls, etc.

4. An “Intercom” capability allowing for the transport of audio between the fixed station and its host without initiating an RF transmission.

The CFSI Digital Interface provides:

1. IP based capabilities equivalent to those provided via the Analog Interface.

2. Transport of encrypted audio between a digital fixed station and its host.

3. Transport of Caller-ID information between a digital fixed station and its host. This includes Unit ID from field units to consoles, and “Console ID” from consoles to field units.

4. Transport of Talk-group information between a digital fixed station and its host.

5. Transport of NAC code information between a digital fixed station and its host.

6. Transport of Emergency Alert messages from the digital fixed station to its host.

7. Transport of Emergency indications along with the voice stream between the digital fixed station and its host.

8. Transport of Received voter identification from the digital fixed station to its host.

9. Advanced Control of the fixed station by its host including the disabling of all squelch (monitor function).

10. Transport of intercom audio to and from the fixed station.

11. For Protocol Version 2 interfaces, transport of Packet Data between a digital fixed station and its host.

¹ For the purposes of this document the CFSI is defined as a specialization of the generic Fixed Station Interface (FSI) described in TSB102-C (see [19]).

² Throughout this document the terms “Host” or “host” refer to the CFSH as defined in this document.