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VSAT Question

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Ex Member
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Aug 9th, 2008 at 2:05pm  
Hi,

i have enquiry regarding VSAT technology, i donít have deep experience in VSAT. we are looking to connect our remote sites using our own space segment (no need for VSAT provider) using VSAT.
we are looking to use SCPC - dedicated bandwidth between the branches and the Head Quarter.
what is the best type of modems/routers for this type of VSAT connection?
and what are the required indoor components?

Thanks
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Eric Johnston
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Reply #1 - Aug 10th, 2008 at 9:26pm  
See this example Private VSAT network for Southern Africa

If you need a star network (as you describe), I suggest a single, Vipersat CDM-570L shared outlink carrier from your headquarter site to all the remote sites and either thin SCPC incoming from each remote or a TDMA incoming carrier.  Use a large dish at the hub and smaller dishes at the remotes.   Use the largest dishes you can afford so as to enable 16-QAM if possible and thus halve your space segment costs.

If you need a mesh network, with the possibility of connection direct from one remote to another remote then use moderate size dishes at all sites.  You will need additional demodulators at each site depending on how many incoming carriers are needed at each site.  A Vipersat managment system will dynamically allocate space segment capacity - up to the bandwidth total of your transponder lease.

iDirect also do a low cost entry level hub suitable for small networks. 

Don't underestimate the skills, training and documentation needed to install and operate the system.

Best regards, Eric.
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Ex Member
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Reply #2 - Aug 11th, 2008 at 11:34am  

Dear Eric Johnston

Many thanks for your help. what is the modem type shoul i use in the remote sites? Is it CDM-570L?

what is the best solution to perform Encryption and TCP acceleration in the same time?

Best Regards
Damar
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Admin1
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Reply #3 - Aug 11th, 2008 at 1:53pm  
A CDM570L modem will transmit one carrier and receive one carrier.  If a site needs to receive multiple carriers (i.e. mesh network) you can buy additional CDM562L or CDM564L, which have dual or quad demods.

Read more here: Comtech satellite modems

For example:  If you have a network of 9 remote sites you might have one CDM570L at each remote site.  At the hub (your headquarters) you would have one CDM570L and two CDM564L so at the hub you can transmit one carrier shared to all sites and receive 9 carriers in total (1+4+4).  The outlink might be a 500kbit/s carrier with its capacity assigned with QoS rules.  The return links might be 40 kbit/s each.   VoIP phone calls need 10.8kbit/s each and the hub CDM570 will process up to 64 simultaneous calls. The capacities are just illustrative.  Actual arrangements can be quite complex with dynamic bit rate allocation according to site need.

3xDES Encryption is possible.

In the CDM570L, the acceleration provided for TCP/IP traffic is only packet header compression and packet payload compression.   This is not as good as some acceleration client/server solutions which involve a server PC at the hub which intercepts all internet download traffic and compresses it and substitutes its own alternative to TCP/IP.  The server needs matching decompression/cache software loaded in the end user customer PCs.

Best regards, Eric.
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Reply #4 - Aug 12th, 2008 at 1:54pm  
Damer,

I have two solutions for you .

1) Idirect iSCPC using 5100 modems on each remote and two  5100 at the HQ with a Music box for splitter and combiner.
2) Satpath DAMA  modems with.
3) Depending on where  you are located we can  offer you through our iDirect hub and  do last mile with fiber or radio

We have two hubs  one in Africa  KEnya  and  other in London.

Space.
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