Eurobird-9A - comparison of EUMETCast and GlobeCast transponders

This shows the comparison of two different transponders on Eurobird-9A, one carrying the EUMETCast transmission, and the other a GlobeCast transmission.  Links to the full graphs can be found at the bottom of this page, here I compare the results from two near-identical systems placing the graphs next to each other.

See also:

The GlobeCast data was recorded between 15:35 UTC on 2009-Mar-14 and 19:50 UTC on 2009-Mar-21, week 12.  You can see the step down on the daily graph for GlobeCast where the PC was switched from GlobeCast to EUMETCast.

I find it difficult to draw very definitive conclusions from these graphs, especially when compared with data from other sources.

  • The performance of the two systems on the EUMETCast transponder is very similar.
  • From the monthly graph, it is obvious that a higher SNR was seen on the GlobeCast transponder, perhaps by about 1dB.
  • There also appears to be an increase in Signal Quality on GlobeCast by approximately 7%.
  • EUMETCast shows a diurnal variation of up to 1dB.
  • GlobeCast appears to show a diurnal variation of approximately 0.7dB.
  • The diurnal variations of the EUMETCast and GlobeCast signals are in phase.
  • The EUMETCast signal has been more variable during March, and poorer than earlier.

From Arne's graphs, I might conclude:

  • The GlobeCast signal does have a slight diurnal variation, peaking just after midnight like my two signals.  Arne sees less variation - perhaps 0.2-0.4dB.
  • The EUMETCast signal shows a greater diurnal variation - perhaps 0.5dB or more.  However, Arne gets a maximum value during the middle of the day, as opposed to my maximum of the middle of the night.
  • The EUMETCast signal has been roughly steady since the beginning of March, and better than earlier.
  • The EUMETCast signal is about 1dB down on the GlobeCast signal.
Daily EUMETCast
Max Average Current
Quality % 62 59 61
10 * SNR dB 81 75 80
Max Average Current
Quality % 68 64 63
10 * SNR dB 91 83 82
Weekly EUMETCast
Max Average Current
Quality % 63 58 62
10 * SNR dB 82 74 80
Max Average Current
Quality % 68 63 64
10 * SNR dB 91 82 84
Monthly EUMETCast
Max Average Current
Quality % 66 59 61
10 * SNR dB 87 76 78
Max Average Current
Quality % 67 61 62
10 * SNR dB 90 79 81

Arne van Belle's Comparative Data



Original graphs - links to PNG images

Feenix - all EUMETCast
Hydra - a week of GlobeCast
Stamsund - all EUMETCast

Gemini - all EUMETCast but on a Dexatek USB box

Copyright © David Taylor, Edinburgh   Last modified: 2015 Jan 18 at 09:32