SRM-5A/M/RJ45/NEW and SRM-5A/F/RJ45/NEW are Miniature Asynchronous Short Range Modems
SRM-5A/M/RJ45/NEW and SRM-5A/F/RJ45/NEW from RAD are Miniature Asynchronous Short Range Modems for local data distribution, connecting full duplexasynchronous DTEs to computers.
SRM-5A/M/RJ45/NEW and SRM-5A/F/RJ45/NEW operate at distances up to 12 km (7.5 miles) depending on the wire gauge and data rate (see Table 1 in the data sheet for more information). These modems ensure integrity of data transmission, using unconditioned 4-wire dedicated lines at data rates up to 19.2 kbps. An internal filter overcomes both radiated and conducted noise,
and provides surge protection.
Innovative circuitry of the SRM-5A/F/RJ45/NEW and SRM-5A/M/RJ45/NEW allow the modems to operate without connection to the mains supply, by using ultra low power from the V.24/RS-232 data and control signals. The modems will operate even if only Transmit Data is connected, i.e. without any control signals. Both positive and negative signals are generated, irrespective of constantly high or constantly low Transmit Data.
The low transmit level of the RAD SRM-5A/F/RJ45/NEW and SRM-5A/M/RJ45/NEW minimize crosstalk onto adjacent circuits within the same cable. Data is transmitted and received at a balanced interface, ensuring high
immunity to circuit noise.
SRM-5A features a switch-selectable DCE/DTE option. This allows the modems to operate as DTE for connection to a DCE (such as a multiplexer port) without the need for a cross cable.
The SRM-5A/F/RJ45/NEW and SRM-5A/M/RJ45/NEW are coupled to the dedicated line via isolation transformers rated at over 1,500
VRMS. The transformers, together with other circuitry, protect against AC or DC overvoltages. This makes SRM-5A suitable for connection to local circuits provided by most national telephone administrations (P.T.T.s).
Two connectors are provided for the line interface: a five-screw terminal block, an an RJ-45 connector