RAD SRM-5S SRM-6S Synchronous Short Range Modems  

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RAD SRM-5S SRM-6S Synchronous Short Range Modems  


The SRM-6S and SRM-5S, Synchronous Short Range Modems, are used for local data distribution, connecting full duplex synchronous DTEs to DTEs or controllers. A pair of modems ensures integrity of data transmission, using unconditioned 4-wire dedicated lines, for distances up to 11 km (6.5 miles), depending on wire gauge and data rate.
  • SRM-5S is a miniature version of SRM-6S. Both modems are fully compatible and offer the same features. SRM-5S is 68 mm (2.7 in) by 18 mm (0.7 in) while SRM-6S is 110 mm (4.3 in) by 22 mm (0.9 in).
  • Innovative circuitry allows the modems to operate without connection to the mains supply, by using ultra-low power from the data and control signals.
  • The low transmit level of 0 dBm minimizes cross-talk onto adjacent circuits within the same cable. Differential diphase modulation provides immunity to background noise, eliminating line distortion and improving transmission and reception of serial data. Data is transmitted and received using a balanced interface, ensuring excellent immunity to circuit noise.
  • The modems are coupled to the dedicated line through isolation transformers, rated at over 1,500 VRMS. The transformers, in conjunction with other circuitry, protect against AC or DC overvoltages. This makes the modems suitable for connection to local circuits provided by most national telephone administrations (P.T.T.s).
  • SRM-6S and SRM-5S are compatible with the CMN-6S card of the 19( CMN-16 modem rack.


  • Synchronous transmission rate, selectable up to 19.2 kbps
  • Full duplex, point-to-point
  • Transmission range up to 11 km (6.5 miles)
  • No AC power required
  • LED indicator for Carrier Detect (SRM-5S only)
  • Transformer isolated
  • Compact, lightweight, easy to install
  • Card version for 19 in rack  

Synchronous Modem

Synchronous Modem (Miniature)

* Specify:
F for female 25-pin connector
M for male 25-pin connector
# Specify line interface for SRM-6S:
RJ-11 for RJ-11 jack
RJ-45 for RJ-45 jack
(Default is terminal block)
+ Specify line interface for SRM-5S:
RJ-11 for RJ-11 jack and terminal block
RJ-45 for RJ-45 jack and terminal block
(Default is terminal block and RJ-45)




RAD Products

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