SatSig topic:

Help Configuring my SAT meter on Badr-6 C-BAND

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Apr 3^rd, 2013 at 11:49am

Dear Members,

I am a newbie to VSATs,,, My ISP has giving me the below details for their transponder on BADR-6 however am not familiar with the given parameters. I have a digital Satellite Meter (SAT )

The given details are:

Satellite Name : Badr 6 - C-BAND
Freq: 4043.6310
Symbol Rate : 2483.076
FEC: 0.793 (My meter has only few options like 1/2, 3/4)
Polrization: Right

Note that the LNB LO is 5150

I have a satellite meter that accepts integer numbers not decimal. And also the FEC shouldn't be a ratio of two integer numbers like 1/2 or 3/4 ?

Please help me by informing me the correct parameters I should enter it to my Satellite meter in order to Lock to the wanted carrier.

Apr 3^rd, 2013 at 12:25pm

Your satellite downlink frequency is 4043.6310 MHz
Your LNB local oscillator frequency is 5150 MHz.

The frequency of the carrier in the cable from the LNB is
5150 - 4043.6310 = 1106.369 MHz

Tune your meter, and your modem, to this L band frequency.

If your meter can only be programmed in 1 MHz steps set it to 1106 MHz.
LNBs come with different LO accuracies. LNBs with DRO type oscillators have frequency errors up to +/-2 MHz. These are fine when receiving giant carriers that are 27 MHz wide. PLL type LNBs have much better frequency accuracy and are suitable for receiving small carriers.

Hopefully your meter will be able to get symbol rate lock on your wanted carrier, with symbol rate 2483.076 ksps. Satellite meters are generally designed for satellite TV DVB-S or DVB-S2 carriers and the associated FEC rates. Your meter may lock on the symbol rate but is unlikely to be able to get FEC lock on an iDirect FEC rate like 0.793 and won't therefore be able to decode the data in the bitstream, and display error rate or similar quality measurement.

When you use the meter it will probably display some indication on each and every satellite when you move the dish. It is listening to broadband noise power (1000 MHz wide) Set the elevation carefully and swing the dish boldly sideways to find something.

Once you find any satellite peak up and mark the angles carefully. Use your modem also to detect the wanted carrier. A 3 dB splitter in the LNB cable, close to the LNB, with the meter on the DC block side and the modem providing DC power to LNB is suggested. Using a satellite TV meter, some people choose to search for a known large digital TV carrier that exists on the same satellite, same polarisatiion and at nearby frequency.

Your modem will provide a better indication and will indicate with certainty when the correct carrier is being received. I prefer to use the customer modem and a laptop located temporarily at the antenna. If unsuccessful, point at several nearby adjacent satellites by carefully going sideways and up or down to move along the geostationary orbit line to each satellite.

If still unsuccessful, change your circular polarisation and try all above again. It is quite common for circular polarisation misunderstanding. See https://www.satsig.net/pointing/circular-polarisation-set-up.htm for more info, but you still may get it wrong 50% of the time!
wxw

Best regards, Eric.

Apr 3^rd, 2013 at 9:15pm

Thank you Eric,

We tried it and It didn't work perhaps the meter is not able to lock it with such a low symbol rate. The factory of it said enter the frequency directly without subtracting it from the LO. Although they said both method will work any way we will try it tomorrow and let you know

If it didn't work then as you said the best option is to use the modem.

Apr 3^rd, 2013 at 10:19pm

Both the meter and the modem start by measuring wide band noise power.

When you move the antenna about look very carefully for the slightest increase in the measurement level. You should detect any and all C band satellites. The initial detected movement may only be a slight movement of the needle.

Once you get a tiny indication, stop and peak up and record the position.

If you point the antenna at the ground or put your hand over the feed window the noise power will go up. This proves that the LNB is powered ON and working.

Even if the meter does not lock to the carrier it will still enable you to peak up successfully on a satellite. Tell me where you are and the make/model number of your antenna and I can tell you what directions to go to see adjacent satellites and check your elevation angle. Start with the elevation angle set accurately to the calculated value.

As you suggest, the modem will work fine as a perfect detector for the wanted carrier. It is perhaps inconvenient to pull the coax cables back outdoors and have the modem, laptop and mains power at the antenna. For safety, do not do it in wet or rain conditions.

Best regards, Eric.

Apr 8^th, 2013 at 1:05pm

Dear Eric,

Can you confirm the below plz?

I got this from www.Dishpointer.com

GPS Location:
Latitude: 15.6°
Longitude: 32.5°

Satellite Name: BADR-6

Antenna Pointing Parameters:
Elevation: 70.2°
Azimuth (true): 203.1°
Azimuth (magn.): 200.3°
LNB Skew : 22.2°

Apr 16^th, 2013 at 6:26pm

Assuming BADR-6 satellite is at 26E orbit longitude.

My calculated azimuth was 201.1 magnetic, but my magnetic bearing calculation may have errors of several degrees in some places. Otherwise, I agree with those angles.

Note the 22.2 deg polarisation tilt. This is applicable only to linear polarisation operation, e.g. Ku band.

In the case of circular polarisation ignore this figure.

For circular polarisation you must assemble the feed correctly with the polarisaer at +/- 45 deg to the LNB/BUC waveguides. One way will work perfectly, the other not at all.

I have edited your location lat/long, to reduce the accuracy.

Best regards, Eric.