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February 10, 20142 min read

A Glossary of P25 Terminology — Part 2 (D to K)


APCO P25 LogoPreviously, we covered the essential P25 terms from A to C. Continuing our series on must-know P25 radio terms, this week we bring you the second installment.


Data Gateway
The data gateway is a function carried out in a Tait P25 base station or P25 console gateway operating in a TaitNet P25 conventional network. It provides a gateway between P25 radios and a data server and requires the Conventional Packet Data Services feature license.

DES (Data Encryption Standard) is an encryption algorithm selected by the APCO P25 committee.

The Digital Fixed Station Interface connects digital dispatch equipment with a base station or TaitNet channel group. It is defined in the Project 25 TIA standard.

The transmission path from fixed equipment to SUs.

Digital Signal Processor.

Dual Mode
The ability to operate as a transceiver in two different ways: analog FM and P25 digital. Dual mode equipment can be configured to support either mode or to switch between modes.

The coding of voice (or data) into unintelligible forms for secure transmission.

Failsoft Mode
Failsoft mode is an optional operational mode of Tait P25 trunked networks. It comes into effect when the channel group loses all connection to the trunking site controller.

Federal Communications Commission. The FCC is an independent United States government agency that regulates interstate and international radio communications.

Forward Error Correction. A method of encoding data so that the receiving end is able to correct transmission errors.

Fixed Station Host.

Fixed Station Interface.

Group Call
A group call is a call that is sent to more than one SU simultaneously.


Holdover Mode
A simulcast base station can enter holdover mode when it loses its 1 PPS pulse. Holdover mode temporarily maintains synchronization by phase-locking the transmit clock to the external frequency reference.

The unique name by which a network element is known on the network.

Improved Multiband Excitation. A voice compression technology patented by Digital Voice Systems, Inc and used in the vocoders of P25 radios.

A control command that can be sent across the CAI to inhibit an SU. An inhibited SU appears to the user as if it is powered off.

Key ID
The Key ID is the identifier for an encryption key variable.

Key Fill Device
A device for defining encryption keys and transferring them into P25 equipment.

Key Variable
The key variable is a parameter used by the encryption algorithm to encrypt or decrypt a message.

For everything related to P25, be sure to download and read our recently released P25 Best Practice guides.


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