Filter
Top Products
RTU-292 Operations Manual
1 General Information
1.1 SCOPE
This instruction manual provides the information necessary to install, operate, repair and
maintain the RTU-292 Radio/Telephone Interface.
1.2 DESCRIPTION
1.2.1 GENERAL
The RTU-292 Radio/Telephone Interface Unit will provide a trouble-free automatic connection
between a radio system and telephone or other two-wire line. The unit is suited for use with
HF, VHF, UHF or satellite systems and is applicable to full or half-duplex modes. The RTU-
292 incorporates a full-featured telephone set and monitor speaker. Flexible switching allows
many operating scenarios.
The RTU-292 replaces the JPS Communications RTU-282. The RTU-292 contains all of the
features and capabilities of the RTU-282, along with some major improvements. The new DSP
used in the RTU-292 allows improved Call Progress Detection. Additional circuitry on the
Main Board provides the ability to detect line reversal when a telephone caller hangs up the
phone, allowing immediate call termination when used with phone systems that have Reverse
Battery Signaling. A new standard feature with the RTU-292 is RS-232 control of the unit. A
new optional feature is DTMF Access of the system via radio.
A front panel keypad allows DTMF or Pulse dialing and the built-in handset is pushbutton-
selectable for communication with either the telephone or the radio. Since the telephone may
place and receive calls, the operator can quickly and easily establish a phone patch connection.
When used in the manual mode, the RTU-292 patches a telephone into a radio link by
essentially the same method as with a conventional phone patch; the quality of the patch,
however is greatly improved. First, a radio-to-radio link is established. Then, using the
telephone in the RTU-292, the operator places a phone call to the distant telephone that will be
patched into the radio link. Once the telephone-to-telephone link is made, the operator simply
pushes a front panel pushbutton. The RTU-292 adapts to the phone line, and the distant phone
becomes part of a telephone-to-radio-to-radio communications link. Once this link is
established, the operator may communicate with either party using the RTU-292’s handset, and
may monitor both sides of the conversation with the speaker.
The RTU-292 uses a unique adaptive hybrid implemented with a DSP (Digital Signal
Processor) to eliminate conventional VOX and hybrid adjustments for a quick and simple set-
up. The unit works by measuring the characteristics of the telephone line. A short burst of
white noise is placed on the telephone line. During this burst, the adaptive hybrid in the unit
measures the signal reflected from the phone line and adapts the RTU-292 to the impedance of
the phone line, minimizing the reflected signal. This achieves a broadband hybrid balance on
the reactive phone line. This is simply not possible with any type of conventional active or
passive hybrid. Not only is a deep, broadband null provided, but also the action is completely
JPS Communications, Inc.
1-1