The RTX-12A and RTX12OEM are half-duplex 1200 baud radio modems designed especially for telemetry and remote data transfer applications. While the standard RTX modem is Bell 202 compatible, an optional CCITT v.23 model is available by special order. The RTX modems provide an inexpensive solution to interfacing computers and microcontrollers to radio links. The modem utilizes FSK audio tones to provide reliable communications over narrow bandwidth channels.

The modem is easily interfaced to radios designed for either telemetry or voice communication. It is suitable for hand-held, mobile or base radios. The data interface is designed to be compatible with both standard RS-232 levels and CMOS logic levels. The total power consumption is less than 25 milliwatts, making it ideal for battery powered applications. When operated from a standard RS-232 port, no external power source is required. The modem has it’s own micropower voltage regulator, allowing it to operate from a single polarity unregulated power source as low as +4.6 volts. Thus it can be powered directly from the +5 volt logic supply in microcontroller applications.

The RTX-12 is available in two different versions: The RTX-12A and the RTX-12OEM. Both versions are functionally and electrically identical. The only difference between them is their physical layout and the connectors used for the radio and data interfaces. The RTX-12A is packaged in a custom injection molded case and is designed to plug directly into a standard 25-pin RS-232 serial port. Connection to the radio is through an RJ-11 connector and cable (included). The RTX-12OEM model is intended for embedded applications and is provided without an enclosure. This modem is extremely small (1-1/4” x 1-1/2”) and is easily installed inside other equipment. A single 10-pin header provides connections for both the radio and data interface. An optional color coded ribbon cable is available for this modem.

Both the RTX-12A and the RTX-12OEM are normally supplied with full transmit and receive capability. However, in high volume applications either modem can be specially ordered in a Transmit or Receive Only version at reduced cost.

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Last modified: December 13, 2012