Net not activated x3

Dear,

I'm planning to share a single antenna with infinity 5300 and x3 Evolution  Modem.
Before my integration, i made the test with each modem on the antenna. All of them work correctly when connected to the antenna.
I then connected all the modem behind the splitter/combiner. The Infinity modem is working fine but this is not the case for the x3 modem (RX ON, TX ON, NET not activated). It seem that the Hub doesn't get the burst from the x3 Evolution.

What do you think i missed.

You will find a sample of what i'm tryning to achieved in the photo

Hi Admin1,

Thank you for your availability and your  feedback.
I'm using a 20 Watts BUC according to the Vsat Operator Link Budget.

My main concern here is that, when i connected the x3 modem behinnd the combiner/splitter, it's not working. This is not the same problem with the infinity, nevertheless, both of them have the same RF Specification.

dear,

You would find answer for the questions below.




Note that most high power BUCs will give an alarm and stop transmitting if the 10 MHz is absent.

The X3 modem presumably has its TX 10 MHz output switched on.

Is this 10 MHz getting to the BUC?.


Try removing the splitter.  Does the X3 then work OK ?

What level does it output?

Should be about 6 dB lower, due to no splitter loss.
Reinsert the splitter but without the 5300's connected.Does the X3 work ?



What are the three center frequencies of the transmit carriers?.  Call them A,B and C.

Habib
Increase the transmit power level of the x3 modem. This increase should be equal to the insertion loss of the splitter. for example if  the loss is 6 dB in the splitter, increase the transmit power of x3 by 6 dB. Ofcourse take care that you are not saturating the BUC/RFT  and also sufficient power margin in the BUC/RFT.Hope this works.

To see the intermodulation products produced by your BUC, you ideally need a high loss crossed-waveguide coupler (e.g. about -50 dB) between the BUC and the feed. Connect a spectrum analyser (with an adequate frequency range) and plot the entire spectrum from say 5.925 - 6.425 MHz, plus the local spectrum around your transmit carriers.  Often the satellite operator will insist on this for any earth station transmitting multiple carriers via a single BUC. Spurious transmissions and IM products are measured.

If you don't have such test facilities, the hub needs to attempt such measurements, which are difficult if there are many other carriers present in the transponder. Other people are likely to report interference hours or days later and it becomes hard to identify the origin if several people have been adjusting their services meanwhile!

I can understand the iDirect TAC saying that is it not allowed to have iSCPC and TDMA in the same BUC. It may be that is technically not possible also.

One valid method of measurement is to make all your carriers CW and change their frequencies so they are very close together, all well within the bandwidth of one of your intended operational carriers. The IM products may then be seen and measured and the carrier levels adjusted.  You must always have the composite BUC power well below (e.g. about half or -3 dB) the power rating of the BUC. This is called "backed-off" and wastes a lot of the BUC power and cost, which is why multi-carrier operation is avoided unless really necessary. This applies to both earth stations and satellite transponders.  Some manufacturers sell 'linearised' BUCs or HPAs which allow operation nearer to saturation, to save both power and cost. Higher power BUCs often have a built-in broadband power meter to allow  you to monitor the output power.

Get help from your iDirect hub. They will be able to see the transponder spectrum clearly and can measure your carriers.  They also control your X3 power setting using the iDirect hub software.