SatSig topic:

TX signal Below Nominal

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Feb 3^rd, 2009 at 10:53am

Dear All,
We are using iDirect modem 5300, it facing to IS904
everything seem Ok, but the only thing problem is our TX SNR (upstream) below nominal according to our hub operator, the modem is connected to the satellite (lock) but some time lost connection to the network for some second and connected again. what is could be the problem since we have check all the cable problem may be cause deterioration but they are Ok, its Possible if the BUC power getting weak??
Any one can Help?

Feb 3^rd, 2009 at 12:13pm

If your Hub Operator is telling you that your upstream SNR is low, you should consider:

1. Conducting a peak/pol to ensure you are properly pointed.
2. If a peak/pol doesnt resolve your problem you need to get with the Hub Operator and have him check whether or not you have a proper BUC to close the return link. Also have him determine whether or not you are operating at or near your commissioned 1dB compression point.

Your problem (to me) sounds like classic BUC saturation or poor pointing. I think you will find your answer in one of the two. If the NMS is unable to adjust your tx power to meet the configured UCP, then you are clearly in saturation or need to be repeaked on the spacecraft.

Feb 3^rd, 2009 at 3:02pm

Dear TDMAMike,
Thanks for your response, it was working fine since some months (just said 5 months), but with TX around 3.5 to 5.5 and working well with good speed, then suddenly it behave like this, I have adjust (fine tune) the dish (pointing) and we get max RX SNR same as previous value.

Regards,

Al