|
Unaohm S22 Example - Intelsat 9
The following example is taken from a C-Band antenna pointed at Intelsat 9 (58°West), formerly PAS-9.
We are using the 3,720GHz frequency as an example, which has a Symbol rate of 27,700 MSPS.
After setting up LO4 to 5,150 GHz for C-Band LNBs in MENU -> CONFIG -> LOC OSC, we enter the desired frequency by pressing FR and typing 3720 followed by Enter. We make sure we are in FULL SPECTRUM mode by hitting the SPEC key once or twice, to go from Narrow spectrum (50, 100, 200MHz) to Full spectrum (SwpFull) if necessary.
The dotted line clearly comes up on our desired transponder at 3,720GHz.
Hit SPEC to go to Narrow sectrum mode (200MHz is always recommended). The level of signal is currently @ -31.6dBm. The antenna can be fine tuned by looking at this screen. Any major problems with the signal will also be visible here.
To find out our current C/N (carrier to noise) ratio, we use the MKR key to bring up a second marker. We offset the second marker by -22MHz, in the "deep" area between our visible transponders.
The level at marker 2 is currently @ -50.7dBm and the difference between both markers (our C/N ratio) is listed as 19dB. This measure is carried out in Analog mode (the "A" in the upper left corner). To get a Digital C/N ratio ("D"), we would have to set the instrument to DIGI and specify our digital carrier's bandwidth in MENU -> CONFIG -> CHBW.
To find out about the quality of our digital signal, we go to BER mode and enter the SYMBOL RATE of the carrier by hitting the Quick Menu button (above MENU on the instrument) and selecting "Prmt" in the Quick List. We then select "Symb" and enter the Symbol Rate (27700) in the middle of the screen. As soon as the symbol rate is entered, all other value will show up on the screen.
We go back to the "Ber" measures menu by hitting "Ber" in the Quick List to finalize the adjustment of the antenna in digital BER mode. The MER value is extremely usefull to get a good idea of the overall quality of the signal. The Pre and Post Viterby measures are also available for more in depth results. The "Drift" of the LNBF can also be identified with the CFO (Center Frequency Offset) value.
Email your questions.
|
