The ASM-20 is a synchronous/asynchronous short range modem operating at selectable rates from 19.2 kbps to 256 kbps, full or half duplex over twisted pair, unconditioned lines. It has a range of 7.5 km (4.7 miles) at 64 kbps.
Conditional diphase modulation ensures efficient transmission. The modem uses conditional diphase modulation (EUROCOM Std. D1) which provides immunity to background noise, eliminates normal line distortion and enables efficient transmission over twisted pair. Transmit timing is provided internally, derived externally from the DTE, or recovered from the receive signal. The carrier may be continuous or controlled for passing control signals end-to-end.
The ASM-20 features diagnostic capabilities complying with the V.54 standard to perform local and remote loopbacks. A built-in bit error rate tester (BERT), activated and monitored from the front panel, complies with the V.52 standard to enable complete testing of both modems and the line.
Several interface options are available: V.24/RS-232, V.35, V.36, X.21, RS-530, built-in Ethernet bridge and G.703 codirectional (64 kbps).
The ASM-20 has line protection circuits against lightning and power surges. It is available as a standalone unit or as a card for the 19-inch ASM-MN-214 rack that holds up to 14 cards.
| Approximate Range (for 24 AWG/0.5 mm) |
| Data Rate - kbps | km | miles
|
| 19.2 | 9.7 | 6.0 |
| 19.2 | 8.7 | 5.4 |
| 19.2 | 7.5 | 4.6 |
| 9.6 | 5.0 | 3.1 |
| 4.8 | 4.5 | 2.8 |
| 1.2-2.4 | 2.2 | 1.4 |
