RFC-1 Installation page 3.11
3.5.3 Radiotelephones and Wireless Extenders
This class of device uses a full duplex radio circuit to extend a POTS telephone line over a radio link. Two small
transceivers are used. One is connected to the telephone line and the remote device emulates the telephone line.
Radiotelephones have a range of roughly 1 to 20 miles depending on terrain. Typically these systems must be
licensed. Channels are usually available in the areas where radiotelephones are most often needed.
Radiotelephone systems can be expensive initially but there is no recurring cost for service once the system installed.
3.5.4 Dedicated Control Port
The RFC-1 may be operated through a non-dial-up communications link such as a dedicated line, a two way radio, a
pager, an STL/SCA link, etc. This additional control method may be used in place of a dial-up line or in addition to a
dial-up line. The dedicated communications link is available as a secondary function through the RJ-11 jack labeled
"Phone" on the RFC-1. The Dedicated Control Port is activated by firmware settings. The Advanced Programming
section of the RFC-1 documentation provides details on making this adjustment.
The Dedicated Control Port is a two-way audio port with 12 volts DC battery to power a telephone. When
the Dedicated Control Port is active, the "Phone" port will be connected in parallel with the "Line" port
during a dial-up connection. Therefore, any device connected to the "Phone" jack will also be connected
to the telephone line and should be FCC Part 68 registered.
This circuit can be used when connecting a leased line to the Dedicated Control Port.
Figure 3.11; Interface for leased line to Dedicated Control Port
The line to the Dedicated Control Port can be any length from a few feet to thousands of feet depending on the
application and tolerable series resistance. C1 and C2 are used to block the 12 volt DC source. If the dedicated line
is connected to a telephone set and the DC voltage source is desired to operate the DTMF keypad, the capacitors
may be eliminated.
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