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RE: VSAT Access Providers
Ku is
a cheaper transmission frequency, but is very prone to rain fade, heavy cloud
cover and storms. Usually, the size of your satellite antenna will dictate the
degree of signal loss you experience during bad weather.
C-band
has been more native, and is much more stable than Ku band. However, satellite
service providers have higher running costs on C-band, and as such, may, at
times, pass these costs ont to the client. On a weather scale, only a very
heavy, and I mean very heavy storm could take a signal out, albeit it's very
unlikely. High level humidity can also present some signal deterioration,
although not full blown loss of service.
DVB
[Digital Video Broadcast] is the wave of the future on satellite transmisson
techniques. DVB was meant to replace MPEG, as MPEG required more bandwidth to
transmit video and audio. DVB can include several streams of media and
protocols, independent of each other and using different mapping techniques to
land at their destination. This is the same technology used by Pay-TV satellite
companies such as Multichoice and DStv. It's purely a multicast
service.
On the
same technology, you can include IP, voice and audio. Each stream/session is
encapsulated in the DVB stream, independently journeying it's way to the correct
destination within the frequency.
Currently, DVB is being used as a downlink service
only. A DVB receiver is required, running DVB-compliant protocol software to
de-encapsulate the transmission. A normal 75ohm coaxial cable should suffice for
that. Then, to your network, it connects via a 10/100Mbps fast ethernet
interface. The DVB units can run either proprietory or general purpose software,
such as Linux. Either way, they deliver.
What
this means is you can have an uplink provided by another company, say your ISP,
at 64Kbps or more, and a dedicated DVB satellite downlink with capacity of up to
45Mbps. The DVB receiver can already support this, as the DVB card supports up
to 45Mbps and higher, and the LAN interface supports up to 100Mbps. So, you
really have no problems when it comes to expansion and growth in terms of
Internet downlink bandwidth.
Alternatively, you can have the DVB on the same
satellite as your uplink. The uplink would still have to be a normal SCPC
[Single Channel Per Carrier] link, although new technology is now even making
that more efficient.
I'd
recommend you take a normal SCPC link for the uplink, and a DVB for the
downlink. You may have to check with your provider whether they support DVB. The
satellite provider [like PanAmSat] may support, but the IP provider may
not.
If
initial cots outlay is a factor, then you can rent a leased-line or frame relay
WAN connection to a local ISP, but setup a DVB downlink for you downlink
capacity. That way, you only get to pay your ISP for a one-way, assymetric
uplink service.
Regards,
Mark Tinka - CCNA
Network Engineer
Africa Online
Uganda
5th Floor, Commercial Plaza
7 Kampala Rd,
Tel:
+256-41-258143
Fax: +256-41-258144
E-mail:
mtinka at africaonline.co.ug
Web:
www.africaonline.co.ug
I am new to VSATs - which system is best and why
? I gather the DVB can be with either KU-band or C-Band -
correct?
Please clarify !
Alamicha Chapuma
----- Original Message -----
Sent: Wednesday, March 19, 2003 7:05 PM
Subject: Re: VSAT Access Providers
Hi,
What type of system do want? is it a KU-band, C-band or a DVB system which
is very good and cost effective.
you can try verestar VSAT solution at verestar.com and emperion VSAT
solution.
Paul Ademola Ajayi
Systems/Network
Engineer
Orbit Wireless Internet Services
Plot 32, No. 6 Birabi
Street, Off Presidential Hotel
G.R.A. Phase I Port Harcourt, Rivers State,
Nigeria.
Tel.:234-84-573479Mobile:234-803-324-7220
E-mail:
ajayi4u at hotmail.com OR pademmy at yahoo.com
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