Nortel Networks General Information, Scope, Description, RTU-292 Operations Manual

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

1.2.1GENERAL

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

1-1 JPS Communications, Inc.