Promax US TV EXPLORER II, User Manual

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USER’S MANUAL. US TV EXPLORER II
Page 50 01/2008
Turn the rotary selector [1] to change the tuning channel/frequency. Press the
[12] key to select the type of measurement to visualize on the monitor.
The available types of measurements are:
LEVEL : Level indication on the upper part of the screen (analogue
bar).
C/N : Carrier / Noise ratio measurement.
V/A : Video / Audio ratio measurement.
FM Deviation : Measure the frequency peak deviation for any modulated
analogue carrier in
FM .
WARNING
When at the RF input appear an important number of carriers with a high level the
tuning circuit may become out of control, giving as a result wrong level measurements.
To be able to determinate the equivalent level of a carrier group (with similar levels) at
the RF input, it is possible to use the expression:
Lt=L + 10 log N
Lt: equivalent total level
L: average level of the carriers group
N: number of carriers
So, if there are ten carriers with a level around 90 dBµV, their equivalent level will be:
90 dBµV + 10 log 10 = 100 dBµV
Observe that in this case, loss of tuning by overload of the RF input may occur besides
other effects such as tuner saturation and generation of intermodulation products that
may mask the spectrum visualization.