Channel Tuning; Video Carrier + V/A + C/N Measurement; Audio Carrier Measurement And Demodulation; Cso-Ctb Distortion Products Measurement - Promax 8 plus Manual Del Usuario Y Operador

4.2.3.1

Channel tuning

4.2.3.1.1

Video carrier + V/A + C/N measurement

If the tuned channel has been defined as
analogue by means of the Edit Channel Plan
function (see section 4.2.1 Global Configuration
Menu), the PROMAX-8+ will display a screen as
the one shown in the attached figure.
The tuned channel (C69 in the figure)
appears in the higher left hand corner; this may
be changed by turning the rotary selector [9]. At
its right appears the frequency (855.25 MHz) and
the active channel plan (CCIR in the figure).
Below is shown the video carrier level, VIDEO Carrier (80 dBµV in the
example). The units of measurement may be changed using the Global Configuration
Menu (section 4.2.1). At the bottom, a bar-graph displays the level with a resolution of 1
dB.
Also the ratios between the video and the audio carriers (V/A) and the
video carrier and noise (C/N) are shown. The example in previous figure shows a
channel with a Video/Audio ratio of 16 dB and a C/N ratio of 54 dB.
4.2.3.1.2

Audio carrier measurement and demodulation

For the
demodulate an audio signal and show
its characteristics (level and frequency
offset), press the rotary selector [9] again. In the
attached figure, the audio carrier level (AUDIO
Carrier) is 64 dBµV and the frequency offset is 5.50
MHz ( F). It also shows if the audio (whether Level,
FM or AM) is activated (a speaker appears) or not
(no icon appears). To change the audio carrier
offset ( F) and the audio modulation (Level, FM or
AM) accede to the Channel-Frequency configuration menu (section 4.2.3.3).
4.2.3.1.3

CSO-CTB distortion products measurement

The active devices present in the distribution systems, when working in its
nonlinear zone, generate interferent signals, called distortion products, that can fall
within the video bandwidth. From a certain level this interference becomes visible on the
TV image.
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PROMAX-8+ to
INSTRUCTION MANUEL. PROMAX-8+
Figure 15.- Level, V/A and C/N.
Figure 16.- Audio demodulation and
measurement.
May 2001