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General purpose satellite link budget

Tooway link budget - return link

Information about the Tooway network

Tooway in the UK

Explanation of satellite links

VSAT gateway dish transmitting

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
Uplink gateway Bandwidth Hz
Satellite uplink G/T dB/K
Uplink C/N dB

Downlink frequency GHz
Downlink receive antenna diameter m
Downlink system noise temperature (antenna + LNA) K
Downlink receive antenna gain dBi
Downlink bandwidth (one customer beam)
Downlink receive antenna G/T dB/K
Downlink satellite EIRP dBW per customer beam
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

Tooway Out Link Budget

Outlink from gateway hub to remote customer VSAT site.


Uplink from gateway (bw=1030 MHz):

The outlink comprises 4 carriers per beam, comprising 3 carriers of 52 Msps plus 1 carrier of 40Msps, making a total used bandwidth of approx 206 MHz, out of the allocated 236 MHz per beam. Each gateway transmits to 10 customer beams. Total uplink bandwidth per polarisation = 5 x 206 = 1030 MHz (1 HPA)

Uplink satellite G/T assumed to be (-3 dB contour) +50.6dBi - 3 - 10 log (400) = 21.5 dBK

Each of two gateway HPAs is rated 350 watts multi-carrier operating composite power at the multi-carrier operating point -1.5 dB out. Comtech Xicom Model number XTD-500KaL. 0.5 dB switch/waveguide/feeder loss.

Downlink to customer  (bw=236 MHz):

EIRP, for each beam, towards the beam centre = 50W + 50.6 dBi = 67.6 dBW

Operating EIRP towards the -3dB edge of beam remote sites = 67.6 - 3 = 64.6 dBW


The input figures above are all my 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.

* Recent spectrum measurements suggest there are 3 carriers of 52 Msps and 1 carrier of 40 Msps.  The total occupied bandwidth corresponds to use of the 236 MHz of Ka band bandwidth per beam.  Total bit rate estimated as 3x130 + 1x100 = 490 Mbit/s per beam in clear sky. 

Any problems or comments please e-mail Eric Johnston    

Copyright  23 Feb 2012 Satellite Signals Ltd All Rights Reserved
Last Revision: 11 March 2016