Bandwidth Calculation
This handy little calculator is designed to help you understand your bandwidth needs with respect to VSAT systems. Enter in the appropriate information below, press "Calculate Bandwidth" and the site will calculate your basic system need. JPI does not make any warranty or claim that this information is correct or accurate. For estimating purposes only. For an official quote, please contact your JPI representative. See the table below for details about the calculation. Contact us if you have a question.
| Description | Comment |
| Number of Simultaneous Users | This is your estimate as to how many users will be on the local network using their workstations at any given time. This figure calculates users based on 12Kbps per user (4K up and 8K down) per active session. |
| Number of VOIP Lines (Voice-Over-Internet Protocol) Internet Telephony | These are the number of lines you hope to maintain. VOIP lines are budgeted in the link at 22Kbps (11K up and 11K down). VOIP should be used through an encrypted tunnel. However MOST sites do not do this. JPI has "split the difference" so to speak. Also the level of CODEC used will change this figure. Better CODEC's will require more bandwidth. |
| Number of VPNs | This is your estimate as to how many simultaneous VPN users there will be on your system. VPN's very greatly in how much bandwidth they require as do secure websites, and other security protocols. JPI chooses a "middle of the road" approach when calculating the link budget for VPNs and sets the estimate at 20K per session (10K up 10K down). Contact your OEM for the VPN to determine the actual amount of bandwidth required on a per user basis for your VPN. |
| Percentage Large Files | Every site will email, FTP, or transfer securely some type of large file. JPI defaults the amount to 10%. If you transfer large JPGs, GIFs, TIFFs, Media files like audio or video, GIS information, do database replications, or work with tool like Lotus or Groove, increase this amount accordingly. |
| Upstream |
The data outbound from your site - to the internet or home offices or other locations. Should be about half of what your downstream bandwidth should be. |
| Downstream |
The data coming from the internet or "down" from the satellite. Inbound date is usually called "downstream" and should be about double your "upstream" capabilities for "normal" operations. |
| SCPC | Single Channel Per Carrier - Dedicated bandwidth - not shared by any other VSAT sites. Usually required higher outbput BUC's, different LNB's, a modulator of some type, and an IDU (Indoor Unit). Usually more expensive. |
| TDMA | Time Division Multiplex Algorithm - Shared Bandwidth - shared based on the contention ratio - expressed as "5:1" or "10:1" - indicates 5 or 10 other sites sharing your signal. Divide the upstream and downstream in your contract by the contention ratio to determine the "realized bandwidth. Example: 128/256 10:1 yields 12.8K upstream / 25.6K downstream at your site for guaranteed usable bandwidth. CR is VERY important in TDMA contracts. Double check yours and compare based on a "per K cost factor". TDMA is usually less expensive than SCPC. |