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Section 4 - Initial Activation (ATSC Transmitters)
4.3.2 Serial terminal Emulators
The Power Drawer can be configured using the serial terminal emulators.
4.3.3 Forbidden operations
There are transmitter parameters which are configured at the factory, parameters defined on
the purchase of the transmitter, which are not available to change.
- Canal
- Equipment model
There are other parameters that are configured in the factory, but allow changes in their values
by using a password. The careful use of the password is to prevent unauthorized access that
can cause the appearance of a reflected power at the transmitter and consecutively decreasing
the value of the output power of the transmitter due to the protective action of the same.
- L.O. Null
- Frequency image adjustment
4.3.4 Safeguards
A – Reflected Power
If the incidence of reflected power at the transmitter due to any external or internal factor occurs,
this can be viewed on the measurement screen (MEASUREMENTS [2000]) by the software's
navigation Menu, in the digital display, according to instructions given in the Operation Section of
the Digital Control System.
If the value of the reflected power exceeds the value of 5%* of rated power, the control will
immediately signal this fact by lighting the LED current alarm on the front panel of the digital
exciter, will provide, on the current alarm screen, and this will trigger the routine protection against
reflected power. This will gradually decrease the value of the forward power until the amount of
power reflected returns to less than 5% of rated output. At this time, the software returns to
gradually increase the value of forward power, foreseeing the possible disappearance of the
reflected power. Thus, the equipment will be oscillating between increase and decrease of the
direct power around the power value that provides a reflected power of 5% of rated power,
always seeking the return to the rated power of equipment.
B - Over-excitation
If an excessive increase in the value of the excitation signal level occurs, the control, through the
ALC, will interact with the excitement, to maintain a constant output power in it's rated value.
* Approximately
Manual Rev. 0.1 - February 2018
4-10
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