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Thread: EIRP maps - still of any real use nowadays?

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    Default EIRP maps - still of any real use nowadays?

    So, been reading for the last few years what you guys have mentioned with regards to the pitfalls of those EIRP maps on the internet for all your various birds, and my question is, how useful are they still really, today?

    I mean, with DVB-S2/MPEG-4, HEVC/UHD and all the newer FEC codes like 3/5 and 8/9, etc. do they even still give a good idea as to what dish size one should use, the signal level one can expect, etc.?

    As an example, on the main bird that serves S. Africa (Intelsat 20 @ 68.5°E) we have a spot beam with a quoted EIRP beam peak of 55 dBW (53.3 in my region) which usually meant you could have a dish smaller or around 45-50 cm and still get really good signal readings. But, for HD channels, FEC levels we use, and so on, service providers here are now recommending dish sizes upwards of 80-90 cm.

    I often see slight pixellation and momentary signal interruptions on our 65 cm dish. Signal quality levels are between 75 and 99% on the decoder, but how accurate are these anyway, right?

    Technically speaking, is there a factor (in dB) or constants one could add or subtract for all these different effects we get now to give a person a little more of a realistic indication of signal performance? Of course EIRP maps are just a really rough guideline, but I mean at 50+ dBW levels being out by about 50 cm predicted dish size, it must become more "serious" at lower signal levels where we can begin to speak of the difference between installing a 2.5m and 3.5m dish sort of thing.

    What are your guys' opinions on this, are these maps something you use? I always used to, to gauge approximate signal performance, but now, not so sure anymore.
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    Technology is changing all the time and what was the 'Industry Standard' yesterday may not apply today.
    With my limited knowledge I didnt think that the signal from a Satellite 'Up There' could be 'spot' beamed to an area less than Continent but apparently it can.
    I watch the Cycling and its hugely apparent with Digital how it demands the best possible signal path otherwise its a scrambled mess so based on that, its easy to see where communications are critical, getting the best EIRP levels are essential and having a map would assist you to achieve this.
    10 years ago it was all one way, ie from a few Ground stations to the Satellite which then broadcast back to the customers home but today, how many like me actually have an UP Link (Internet) to the Satellite from their home, quite a few now.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Valid point re: various SR and FEC rates, as indicated signal EIRP doesn't take that into account.

    Yes, it's a very broad guide and does give some indication, but by no means, any real degree of accuracy what to expect.

    Like most things RF-related... the real proof is being there with instrumentation.

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    irritant (31-03-17)

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