RTU-292C Operations Manual
3-6
3.4.7.1
Initial Adaptation
The two-wire to four-wire hybrid in the RTU-292C adapts to the phone line each time the TEL
LINE/RADIO button is engaged. To adapt, it measures the characteristics of the line by placing
a white noise source (built into the unit), on the line for a short time. While the noise burst is
connected, the amount of signal “reflected” from the phone line is measured and adaptation
begins. The adaptation algorithm adjusts the adaptive hybrid to minimize the reflected signal,
throughout the audio frequency spectrum, from the phone line. During the adaptation process,
the TEL LINE/RADIO LED will flash. When adaptation is complete, the noise source is
switched off, the LED is lit continuously, and the unit is ready for operation. This adaptation
procedure normally takes less than one second.
For adaptation to be successful, the far end of the phone line must be quiet (there must be no
signal coming into the RTU-292C from the phone line during adaptation). If there is incoming
audio, the unit may not be able to adapt, but will keep trying for up to ten seconds. For example,
the telephone user at the far end of the phone line should not talk during the adaptation cycle. If
the TEL LINE/RADIO LED does not stop flashing within the normal second or two after the
TEL LINE/RADIO button is pushed, wait a short time longer. If the LED still continues to flash,
chances are that there is excessive noise on the phone line, and it is best to hang up and redial.
Because the adaptation algorithm is very robust, connection to an unquiet phone line is about the
only case where the RTU-292C will fail to adapt, as the hybrid has the ability to adapt to line
conditions from a short-circuit to an open-circuit, as well as the impedance presented by the
extremely complex distributed network of a telephone line.
3.4.7.2
Continuous Adaptation
Once the initial adaptation is complete and the unit begins operating, hybrid adaptation proceeds
continuously using receiver audio sent down the telephone line (the noise burst is not needed
again). This feature enables the RTU-292C to automatically adapt its hybrid balance to changing
line conditions.
3.4.8
MANUAL PHONE PATCH PROCEDURE
A telephone patch establishes a communications link between a distant radio, a local radio
(interfaced directly to the RTU-292C via the P1 Radio connector) and a distant telephone that is
connected to the unit via the telephone line. This distant telephone will be patched through the
local radio set to the distant radio set allowing communication directly between the distant radio
set and the distant telephone.
Begin with the RTU-292C installed and its power on:
3.4.8.1
The operator first establishes a link between the local radio set and the distant radio set using the
RTU-292C’s handset with the radio, as described in Section 3.4.6. Alternatively, the operator
may have received a radio call from a distant radio party wishing to make a phone patch.
Using the RTU-292C’s internal telephone set, the operator now places a call to the distant
telephone.
Содержание RTU-292C
Страница 4: ...RTU 292C Operations Manual 4 Blank Page...
Страница 12: ...RTU 292C Operations Manual 12 This page intentionally left blank...
Страница 35: ...RTU 292C Operations Manual 2 17 Figure 2 1 Outline Dimensions...
Страница 37: ...RTU 292C Operations Manual 2 19 Figure 2 3 Location of Internal Option Settings...
Страница 38: ...RTU 292C Operations Manual 2 20 Figure 2 4 Internal Option Settings Details...
Страница 39: ...RTU 292C Operations Manual 2 21 Figure 2 5 Audio Interface Wiring Diagram...
Страница 40: ...RTU 292C Operations Manual 2 22 Figure 2 6 Interface Details...
Страница 42: ...RTU 292C Operations Manual 2 24 Blank Page...
