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VSAT technology and installation >> iDirect Forum: hubs and terminals >> transmission problem
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Message started by chaady on Feb 13th, 2008 at 11:47pm

Title: transmission problem
Post by chaady on Feb 13th, 2008 at 11:47pm
hi all

i have problem in transmisson side
it has a lot of error
ping not stable and the noc said
the transmisson is very low

please note the buc is extended and its new
the dish pointing very good

the problem start in 5 station in the same time
in different places

Title: Re: transmission problem
Post by TDMAMike on Feb 14th, 2008 at 12:12am
How are they diagnosing the "transmission low" problem?  Upstream SNR?  


Title: Re: transmission problem
Post by chaady on Feb 14th, 2008 at 10:43pm
thanks 4 replay

tx power -20
rx snr 11.2
dish sgnal 16 v
dish andrew 1.2
buc 3 watt extnede
cable 20m rj 6

Title: Re: transmission problem
Post by TDMAMike on Feb 15th, 2008 at 11:59am
All of the above looks good.  What did the NOC say your upstream SNR was and did they say that your system (modem) has been asking for power offsets (power adjustments)?  Rx looks good (C/N wise).  Your tx power appears to be in a nominal range of the iDirect remote (unsure of where you sit in the beam contour line)

If your upstream SNR is within the UCP and your system has not been asking for power adjustments, your uplink RF chain is more than likely good. However, if they say you are taking packet loss, you need to start looking at the baseband, its ether cables, and such.

Is this a NMII+ or iNFINITI?

Title: Re: transmission problem
Post by Forum Admin on Feb 15th, 2008 at 2:15pm
You said the problem affected 5 sites.

As TDMAMike says, get the hub to explain the expression "transmission low" and  investigate the cause. They need to make observations and measurements of transmit bursts from all five sites. Compare with good sites...  Use spectrum analyser...  Carrier level measurements... Noise floor measurements...  Use diagnostics to investigate individual bursts, errors, burst timing etc...

Maybe an interferer is raising the noise floor, at the hub, across the bandwidth where your return link bursts appear.   The interferer could be continuous noise and affecting all sites and all traffic using that return link frequency or it might be an intermittent bursting interferer and affect just some bursts when it overlaps.    

Regards, Eric.

Title: Re: transmission problem
Post by Lukio on Feb 16th, 2008 at 5:19pm
If, like you say, 5 sites were affected simultaneously it's likely there is a network issue.  Speak to your NOC like Eric and Mike suggest as they may need to speak to the satellite operator.  I've had big problems with both interference and carriers that are too hot on the Xpndr.  They tend to blatt the incoming TDMA cxrs which cause us major problems.  May be worth investigating.
Hope this helps.

Lukio ;.)

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