Promax PROLINK-4 Manual De Instrucciones página 153

USER'S MANUAL. PROLINK-4
In addition to the video carrier / audio carrier ratio (15.0 dB in previous figure)
this also shows the frequency or channel, depending on the tuning mode selected, and
the level of the video carrier and audio carrier.
4.9.1.3 Measuring the Carrier / Noise Ratio (C/N)
The PROLINK-4 offers two ways to make this measurement:
Auto:
Reference noise:
To select the measuring method activate the TV mode functions menu by
pressing the rotary selector [4], then turn it to select C/N setup function and finally press
it again. The monitor will show a screen displaying two possibilities: C/N (Auto) and
C/N (Reference noise), then turn the rotary selector to select the desired option and
finally press it to confirm.
When selecting the C/N (Reference noise) mode it is necessary to define the
noise frequency: access the functions menu and now turn the rotary selector to select
Reference noise function and finally press it again. A screen titled REFERENCE
NOISE will be displayed showing the noise frequency in use. To change it press key
[31], the current frequency value will disappear and, using the keyboard, you will
be able to enter the new reference noise frequency in MHz and with two decimals
figures. This frequency also can be modified in the Spectrum operation mode (see
4.10.2.2. C/N (Referenced) Measurement).
The PROLINK-4 carries out C/N ratio measurement in four different ways,
according to the carrier type and the band in use:
A) Terrestrial band, analogue carrier
Carrier level is measured using a quasi-peak detector (230 kHz BW). Noise
level is measured with an average detector and corrected to refer it to channel
bandwidth (according to the standard in use).
B) Terrestrial band, digital carrier
Both measurements are done with an average detector (230 kHz) and the same
corrections are introduced on them (bandwidth corrections).
C) Satellite band, analogue carrier
Carrier level is measured using a quasi-peak detector (4 MHz BW). Noise level
is measured with an average detector (4 MHz) and corrected to refer it to
channel bandwidth.
02/2003
The PROLINK-4 defines the frequency where noise level
is measured automatically.
The user defines the frequency where noise level is
measured (by means of the Reference noise function).
This frequency will be used to measure noise level for all
channels.
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