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VSAT technology and installation >> iDirect Forum: hubs and terminals >> No. of Terminals in an inroute

Message started by smlt_vsat on Dec 10th, 2008 at 10:19am

Title: No. of Terminals in an inroute
Post by smlt_vsat on Dec 10th, 2008 at 10:19am

What is the calculation and factors included in assigning no.of remotes in an inroute. I think there is npt user guide which tells that but in short is there any other formula which we can calculate approximately.

Please let me know.

Also how I can know a MIDI card is ok or not , recently I saw some terminals in an iroute takes time to lock on RX, everything was running perfectly but it happens sudden. No changes or no terminals added in this inroute and was working last two years but nowadays i see same problem. I guess might be line card has got same problem. Is there any way to check that


Title: Re: No. of Terminals in an inroute
Post by TDMAMike on Dec 10th, 2008 at 11:48am
I dont know of any formula or calculation used to determine remote maximums for an inroute group. áI am pretty sure it is determined by utilization on the blades.

The long lock could be a number of things. áDo all of the nodes take a considerable amount of time to lock? áIf it is common amongst all, I would start looking at:

1, áYour e/s áBDC (make sure you have your stability set it up if necessary).
2. Check your configured UCP. áIs it 9dB? What are the fine and course adjusts set to?
3. Remote (initial) power levels. áCheck each of them and makes sure they are commissioned properly. áUnder clear skies (both sides of the link). áTX initial should be 2-3dB down from the operating power observed under clear skies. áMax power should be set 2-3 dB down from the intial (or at the prescribed 1dB compression point).

The reason those power levels are important and need to be set properly, is in the event that multiple nodes take a bounce (due to a disruption in the downstream or upstream carriers) want to mimimize acquistion time when they all come piling back (re-entering) into the network. áWith a UCP configed for 9dB bursts arriving too high or low may not get picked up by the UCP.

Title: Re: No. of Terminals in an inroute
Post by smlt_vsat on Dec 10th, 2008 at 12:51pm

Configured UCP is 7 dB

FIne Adjust

Below Nominal C/N  -1 dB
After Nominal C/N 1 dB
Power adjust 0.5 dBM

Coarse adjust

BElow Nominal C/N  -3 dB
After Nominal C/N  3 dB
Powr adjust 2

Remote Power Levels are Ok as said , 1 dB Compression is done while commisiong Terminals.

Title: Re: No. of Terminals in an inroute
Post by TDMAMike on Dec 11th, 2008 at 2:11am
7dB is fairly low.  What band are you operating in C or Ku?  

Title: Re: No. of Terminals in an inroute
Post by Darkside on Dec 14th, 2008 at 7:55am
Although it is not the only factor but the surely the most important one , the number of remotes per inroute will be limited by the number of TDMA timeslots available. This can be calculated with the iNPT tool once all the carrier information etc. has been inserted.
Each remote will receive one timeslot by default thus in theory one cannot add more remotes than timeslots allocated. Butů. One can adjust the default minimum CIR  so a remote will receive a timeslot in every second or third frame etc. (Limited to 2 Seconds). Note that this will increase latencies somewhat but it is useful for SCADA networks etc. The other way to make timeslots available to remotes is by putting some of the remotes in sleep mode or deactivate them because this will release the timeslots back to the pool.
iDirect conducts design training in all of their regions a couple of times of year and it covers these topics.

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