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Latitude and longitude explanation

Link budget calculator

Satellite beam design

IET satellite communications summer school

Remotes to Hub return (upstream) link budget

Uplink power control UPPC

Broadband satellite internet in Middle East

Broadband satellite internet in Asia

Antenna beam width calculator

Views of the earth from various geo orbit positions

Explanation of satellite links

Symbol rate

EbNo measurement and EbNo Calculator

Link Budget VSAT outlink link from Hub to remote sites: Downstream.

Uplink frequency GHz
Uplink antenna diameter m
Uplink antenna transmit gain dBi
Uplink antenna, power at the feed W
Uplink EIRP dBW
Range (35778 - 41679) km
Uplink path loss dB
Uplink pfd at satellite dBW/m^2
Bandwidth Hz
Satellite uplink G/T dB/K
Uplink C/N dB
Transponder "gain" input PFD to output EIRP
Downlink frequency GHz
Downlink receive antenna diameter m
Downlink system noise temperature(antenna+LNA) K
Downlink receive antenna gain dBi
Downlink receive antenna G/T dB/K
Downlink satellite EIRP dBW
Downlink path loss dB
Downlink C/N dB
Uplink C/interference dB
Uplink C/N dB
Satellite C/intermod dB
Downlink C/N dB
Downlink C/interference dB
Total link C/N dB


The outlink comprises a single carrier occupying a full transponder.

Symbol rate 29.270 Mbsps

Uplink contour at the hub is +6 dBK and transponder gain step is set to PFDsat=-86 dBW/m2

The single carrier operating point is -1 dB in and -0.5 dB out. 

Power spectral density at the satellite is -86 -1 = -87 dBW/m2

Saturated EIRP towards the edge of beam remote sites = 51 dBW.

Operating PFD produces a downlink EIRP = 51 - 0.5 = 50.5 dBW

This conversion (-97 in and + 50.5 out) has been put into the link budget as the Transponder "gain". It applies to single carrier operation.

The input figures are all guesses and estimates.  You need to overwrite the figures with your own assumptions.

Amend any white boxes and then click the calculate button to obtain results in the green boxes.

A carrier with symbol rate = 29.27 Msps would provide a data rate of 43 Mbit/s.

If you use a DVB-S2 type outlink the capacity increases due to 8PSK modulation and less FEC.

Any problems or comments please e-mail Eric Johnston

Copyright (c) 23 Feb 2012 Satellite Signals Ltd All Rights Reserved
Last Revision: 19 Feb 2015