2-Wire Multirate Short Range Modem

RAD’s ASM-31 2-wire multirate short range modem is a sync/async modem that operates in full-duplex mode over 2-wire twisted pair lines, at selectable data rates from 1.2 kbps to 128 kbps (or 38.4 kbps in asynchronous mode) over distances of up to 5.4 kilometers (3.4 miles). Full duplex is achieved using the adaptive echo cancellation technique. The unit comes equipped with a variety of serial and Ethernet interfaces as well as with extensive testing and diagnostics. The ASM-31 2-wire multirate short range modem has line protection circuits against lightning and power surges. The ASM-31 2-wire multirate short range modem comes as a standalone or can be mounted in the LRS-24 chassis.

• Adaptive equalizer for noise immunity and high performance over low-quality lines

• 2B1Q line coding enables extended transmission distances, regardless of the data rate

• Provides extensive diagnostics, including loopbacks and BER testing

Full-duplex operation is achieved using the adaptive echo cancellation technique. This method entails setting one modem as a master and the other as a slave (switchselectable). 2B1Q line coding provides an operating range of up to 8 km (5 miles) for all data rates, with an internal rate converter that converts all DTE data rates to a line data rate of 128 kbps.

Local and remote loopbacks can be activated from either side of the line, to test both modems and the line. Loopbacks are controlled by a manual switch or from the DTE interface. The modem includes a BER tester for complete end-to-end integrity testing. An error LED indicates each bit error detected. The ASM-31 has line protection circuits against lightning and power surges.

Interface options include V.24/RS-232, V.35, V.36, X.21, RS-530, built-in Ethernet bridge, router and G.703 codirectional 64 kbps. The analog line connectors are RJ-45 and terminal block.

The ASM-31 is available as a standalone unit or as a card for the 19" ASM-MN-214 rack that holds up to 14 cards.