PacComm Miniature Modems

The PacComm Miniature Modem line consists of both board level and encased products with a variety of data rates and modulation methods.

The modems are ideal for transmission of bit synchronous data (packet), as well as asynchronous data streams. Supporting software is required in the attached data device.

The 1200 BPS models use the Bell 202 standard AFSK tones for half-duplex transmission over radio. They are jumper configurable for CCITT V.23 tones.

The 2400 BPS AFSK models use a proprietary tone set to accomplish 2400 BPS AFSK data transmission through most unmodified voice radios. They are sold for compatibility with previous installations. New installations are encouraged to use the UAS-24M or USY-24M.

The UAS-24M and USY-24M use Minimum Shift Keying with tones of 1200 and 2400 Hz.

HT-1200A and HT-2400

Models HT-1200A and HT-2400 are miniature modem circuit boards which are small enough to fit into the CCTSS tone board space in handheld radios or other space-constrained locations. Short wiring harnesses and pre-assembled connectors are provided for convenient installation.

UAS-1200, UAS-2400, UAS-24M

The UAS (Ultraminiature Asynchronous) series modems are contained in an anodized aluminum enclosure. Separate cables are provided for convenient installation.

All units share the following features:

Digital filtering of transmitted and received tones with accuracy maintained by a crystal controlled oscillator.
Configurable for RS-232 or TTL data interface.
Radio squelch or modem carrier detect may be used as the source of the DCD signal output to the data device.
Radio squelch line selectable active high or low.
RTS (Request to Send) signal from attached device keys the radio via an onboard transistor.
A watchdog timer is provided to prevent constant radio keying in case of software failure in the attached device.
The UAS models offer jumper configurable selections for:
* RTS or DTR, and CTS or DSR lines.
* Hardware timer delays to control radio keyup time.
* Defeatable watchdog timer for continuous operation.
* Rugged case and cables assemblies.

The modem keys the radio in response to a signal on the Request to Send or Data Terminal Ready line. Data to be transmitted is then sent via the Transmit Data line after a short pause for transmitter stabilization. With the HT models, the software supporting the modem must provide the required delay. On UAS models, a built in timer provides the delay and controls the incoming data flow via RTS/CTS or DSR/DTR lines.

When the radio squelch opens, the modem toggles the DCD line and transfers the received data via the Received Data line. All separation of valid data from noise-generated data is the responsibility of the receiving software.

Technical Specifications

Modulation

HT-1200A and UAS 1200

Audio Frequency Shift Keying (AFSK) 1200 and 2200Hz Bell 202 Tone Set

HT-2400 and UAS-2400

Audio Frequency Shift Keying (AFSK) Proprietary Tone Set

UAS-24M

Minimum Shift Keying (AFSK) 1200 and 2400Hz Tone Set (1200 and 1800Hz at 1200bps)

Deviation

Adjustable from 0 to 5 kHz.

Demodulation Range

2.5 to 4 kHz.

Data Rate

HT-1200A and UAS-1200

Up to 1200bps.

HT-2400 and UAS-2400

Up to 2400bps.

UAS-24M

1200 or 2400bps self-clocked.

Data Signal Levels

TTL

0 to 5 volts.

RS-232

+/- 10 volts (varies with supply voltage)

Power Consumption

20mA at 7.5-12 volts.

UAS-1200, UAS-2400, UAS-24M Connectors

RS-232/TTL Connector(s)

EIA DE-9S (Female 9 Pin Connector)

Radio Connector

8 Pin MiniDIN

Power Connector

2.1mm Coaxial, Center Positive

Dimensions (L x W x H)

HT-1200A and HT-2400

55 x 22 x 13mm (2.175 x 0.85 x 0.50 inches)
Weight: 12 grams (.43 ounces)

UAS-1200 and UAS-2400

72 x 66 x 31mm (3.0 x 2.6 x 1.25 inches)
Weight: 140 grams (5 ounces)

UAS-24M

119 x 77 x 31mm (4.6 x 3.0 x 1.25 inches)
Weight: 224 grams (8 ounces)

Pricing Information

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Last updated: 7/19/2004