RAD Data comm ASM-20 operation manual Technical Specifications, Unloaded twisted pair 19 to 26 AWG

Chapter 1. Introduction ASM-20Installation and Operation Manual

X.21 Buffer (for

X.21 interface)

Test Pattern

Generator and

Receiver

X.21 External

Clock Buffer

Option

G.703 DTE

Interface

characters. The remote converter will add a shorter stop bit (shorter by 12.5% or 25%) before sending the data to the remote DTE.

A suitable operation of the ASYNC to SYNC converter is selected by adjusting the proper character length and frequency deviation setting (dip switch bank), see Figure 2-3and Table 2-2.

To allow tail-end connection on an X-21 interface, a buffer is provided on received data. When ASM-20 is used in external clock configuration, set jumper JP2 to EXT. When internal or receive clock configuration is used, set the jumper to the opposite side. See Appendix C, IR-X.21B Interface Module for more information.

This feature allows for easy and quick testing of the local modem as well as the communication link. When the PATT button on the front panel is activated, the circuit sends and checks a standard 511-bit pseudo random pattern. If errors are encountered, the ERROR LED remains ON or blinks.

The test can be carried out in local analog loopback, in remote digital loopback or in normal point-to-point operation opposite a remote ASM-20 modem. Press the PATT push button on the remote unit or connect a Bit Error Rate Tester which uses the standard 511-bit pattern.

Available with X.21 interface model only. See Appendix C, IR-X.21B Interface Module for more information.

Available with G.703 interface model only. See Appendix B, IR-G.703 Codirectional Interface (64 kbps) for more information.

1.4 Technical Specifications

Transmission Line Type	Unloaded twisted pair 19 to 26 AWG
Range	See Table 1-1
Level	Strap-selectable to 0 dBm or -6 dBm
Transmit Impedance	150Ω or LOW (strap selectable)
Receive Impedance	150Ω or HIGH (strap selectable)
Return Loss	Greater than 15 dB
Carrier	Controlled by RTS or constantly ON
Modulation	Conditional diphase European Std. D1

1-6 Technical Specifications