ST-804A New Product Bulletin ST-804A New Product Bulletin

ST-804A Multi-Format Encoder

DTMF ANI/ENI Two Tone Sequential Burst Tone

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The new ST-804A is a highly versatile encoder module compatible with three popular land mobile radio signalling formats: DTMF ANI/ENI, Two-Tone Sequential, and Burst (Single) Tone. This single miniature module, measuring only 1.15"L x 0.84"W x 0.15"H, replaces the following Selectone encoder models: ST-110, ST-202, and ST-803.

Applications include Automatic Number Identification (ANI) and Emergency Number Identification (ENI) to provide positive identification of the transmitting radio in fleet dispatch systems; a paging encoder for signalling two-tone sequential decoders; and a burst tone encoder for remote control, status reporting, and other basic telemetry applications.

The ST-804A is field programmable to any of the three signalling formats using a PC and Selectone Product Manger™ Software, available in both DOS and Windows formats. Complete programming and installation instructions are provided with each unit.


When programmed as an ANI encoder, the ST-804A is activated by the operation of the PTT (Push To Talk) switch of the host radio. The ST-804A responds by sending a pre-programmed sequence of up to 15 DTMF digits at a data rate of up to 20 digits per second. Depending on the programming, the ANI sequence may be generated at the beginning and/or at the end of the PTT action. When received and decoded by the companion
ST-888 ANI Decoder/Display, the ANI sequence provides positive identification of the transmitting station or mobile unit.

When the ENI (Emergency Number Identification) input is activated, a second code sequence is generated which is recognized as an alarm or emergency condition by the companion ST-888 decoder/display unit. The ENI sequence will be repeated for a programmed number of cycles, or until reset by the operator.



When programmed as a two-tone sequential encoder, the ST-804A will generate a two tone page of tone 1 followed by tone 2 for the programmed times and frequencies whenever the primary input lead is grounded. If a secondary input lead is grounded, the ST-804A will generate tone 2 followed by tone 1. If both input leads are grounded at the same time, an "all call" of tone 1 is generated for the programmed all call duration. The tones can be programmed to any frequency between 300 and 3000 Hz, while the duration of each tone is programmable from 50 ms to 3 seconds.

When used as a two-tone sequential encoder, the ST-804A is compatible with the Selectone ST-200A/B or similar two-tone decoder.


When programmed as a burst tone encoder, the ST-804A will generate a single tone at a pre-programmed frequency, either continuously or as a momentary "burst" of tone. The tone frequency is programmable from 300 to 3000 Hz, while the tone duration may be programmed from 300ms to 1 second, or continuous.

When used as a burst tone encoder, the ST-804A is compatible with the Selectone ST-120 or similar decoder.


Like most Selectone products, the ST-804A is PC programmable using the Selectone Product Manager software. The ST-804PM Product Manager is available in both Windows and DOS versions and may be ordered from the factory or downloaded from the Selectone Website by clicking here. Note: DOS version required to program two-tone sequential and burst tone formats.


The ST-954 Programming Kit is required for programming the operating parameters of the ST-804A. The ST-954 kit consists of three items: a ST-954B Programming Adapter which interfaces between a PC and the ST-804A encoder; a 6’ RS-232C serial cable assembly; and a DB9 to DB25 adapter plug. The ST-954 kit may be used to program most Selectone products.

For customers who already have a serial cable, the ST-954B Programming Adapter may be purchased separately or constructed from a circuit schematic available from the Selectone website by clicking here.


Application Notes with detailed installation instructions for a wide variety of mobile radios are available free of charge by clicking here.   For further applications assistance, contact the Selectone Technical Support Department at (714) 998-3021, or by e-mail at


Operating Voltage 5.2 Vdc to 16.3 Vdc
Operating Current <6mAdc
Active Open Collector >40mAdc Vce< .4Vdc
Limit Timer Alert Tone CMOS logic, 10K series resistor
Tone Output Level Adjust 0 to >3 V p-p composite DTMF signal with <1 dB twist
Frequency Range Burst Tone and Two-Tone from 300-3000Hz
Temperature Range -30C to +60C
Tone Output Impedance

Non Signaling



<30 Ohms
Input Logic Levels (All) Logic HI:  >3.4 Vdc
Logic LO: <.9Vdc
Interface 18" flying leads terminated in a 13 pin low profile connector
Size 0.84"W x 1.15"L x 0.15"H
(21.3mm x 29.3mm x 3.8mm)

Specifications and descriptions subject to change without notice

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1999, Communications Specialists, Inc. All rights reserved.
Revision 6/30/99
Last updated August 06, 1999