Spectrum Analyser Mode Functions Menu - Promax PROLINK-4C Manual De Instrucciones

The horizontal lines define the signal level, the broken lines being 5 dB from the
solid ones. The level of the top line (80 dBµV in previous figure), named the Reference
Level, can be altered using the Reference level function in the Spectrum Analyser
mode functions menu (section 4.10.1.3).
The signal level for each frequency is displayed vertically, the lower frequencies
appearing at the left of the screen and the higher ones at the right. The amplitude of the
lobes is calibrated. In the example in previous figure the noise level is at around
37 dBµV and the lobe with the highest signal level (second from the left) is at 64 dBµV.
The frequency range displayed (called span from hereon) can also be altered
using the Spectrum Analyser mode functions menu.
A vertical broken line, called marker, appears on the spectrum display to
identify the tuned frequency.
One of the applications of the PROLINK-4C operating as Spectrum Analyser is
in the search for the best orientation and position of the receiving antenna. This is
particularly important in UHF. Because such frequencies are involved, with wavelengths
ranging from 35 cm to 65 cm, if the antenna is shifted only a few centimetres, the
relationship between the picture, chrominance and sound carrier frequencies change,
affecting the quality of the picture in the receiver.
If there is an excess of sound carrier, tearing or 'moiré' may appear on the
screen due to the frequency beats between the sound, chrominance and the picture
frequencies.
If there is a chrominance carrier defect, then the television colour amplifier must
function at maximum gain, which could result in noise appearing all over the television
screen with points of colour that disappear when the saturation control is reduced; in an
extreme case, loss of colour may occur.

4.10.1 Spectrum Analyser Mode Functions Menu

In the Spectrum Analyser operation mode, pressing the rotary selector [4] leads
you to the next functions menu.
Page 78
USER'S MANUAL. PROLINK-4C
02/2003