WRAT Modem

Overview

Bell 202 ModemThe WRAT 202 piggy-back modem is specifically designed to interface either radio or wire-line communication signals with the 6008, 608 or 604 family of single board controllers.

The modem piggy-backs on all boards. It requires a regulated input voltage within the range of 12 VDC to 15 VDC to operate.

Features

The modem is designed with five indication LEDs.

• RX (Receive Data)
• CD (Carrier Detect)
• TX (Transmit Data)
• KY (Radio Key On) and
• LK (Transmit Lockout)

The RX LED will illuminate when the modem is receiving data. The CD LED will turn on when it has detected a band of carrier energy. The TX LED comes on when the modem is transmitting data. The KY LED illuminates when the modem is keying its radio for data transmission. The LK LED will turn on when the modem is in transmit mode for more than 12 seconds.

The modem has an Originate (ORIG) button provided for testing purposes. When the ORIG button is pressed and held, the modem will continually transmit its Mark and Space signals until the button is released. Another way to force the modem to continuously transmit its Mark and Space signals is by installing the jumper switch S1 (this is the same as pressing and holding the ORIG button). In normal operation, the jumper switch S1 is removed.

For proper operation of the modem, the jumper switch S2 must be installed in either the position 1-2 or 2-3. For wire-line communication interface, jumper switch S2 should be installed in position 2-3. Jumpering position 2-3 will activate a temperature compensation circuitry that is designed to compensate for the signal drop in the wire-line interface card (Wire card).

The voltage provided by the external 12 VDC is protected by the modem's 1.6 A PolySwitch fuse PCP1 (located next to the modem's input voltage terminal block TB1). Following the PolySwitch fuse PCP1, is the transient protection circuitry designed and tested per the IEEE 472.1974 surge test specification.

Specifications

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