Thanks to John and Jim.
I didn't want to upset the apple cart on my first post to the group, so I'll do it on my second...
I've just re-read Tom's presentation about Frequencies for Eagle. I'm a bit concerned about the proposal to use S2 up and C down for ACP - it would seem to make more sense to turn it round and make the uplink on C and the downlink on S2.
Advantages -
1) WiFi on 5.6GHz would not raise the receiver's noise floor significantly, unlike C down where future WiFi might raise the noise floor - like some locations now on S1. 2) Although the 3.4GHz band is not allocated to the satellite service in IARU Region 1, that doesn't stop the vast majority of users listening to an amateur satellite in that band. AFAIK the restrictions in R1, which are largely historical, are to prevent interference by amateurs.
Disadvantages
Users may suffer interference from Broadband Fixed Wireless Access (AKA WimAX) in Europe. WiMax transmitters will use relatively high power (50W or so), I don't know what the exact frequency plans are. HOWEVER - in the UK at least, there is some doubt that WimAX will be a commercial success - despite the hype put out by Intel et. al. It's very muddy waters, but we have a very good ADSL service to the vast majority of those that want it, and WiMAX will not be free - somebody will have to pay for a licence. So far in this country, every time somebody tries to come up with an alternative means of supplying broadband, they have failed - and on at least one occasion, spectacularly. So WiMAX is a total uncertainty.
Are there any other disadvantages to using C-S2? Generating power on 5.6GHz for the uplink is getting easier, almost by the day - there are some very interesting new FETs and MMICs becoming available, and the price/performance gets better all the time. And there are also some very interesting devices for the S2 downlink offering ever-higher performance, particularly better efficiency.
I've also read the report of the SD meeting in June; from what's on Eaglepedia it appears that the S2-C option didn't get much mention, maybe due to the uncertainty about the legalities of listening on a band that is not formally allocated. But AFAIK, there aren't many places in the world were it is illegal to intentionally listen to an amateur transmission, the exceptions of course being the countries where all activity above 500MHz is prohibited, who therefore don't get any microwave access anyway.
If the uplink is on S2 then Region 1 won't be able to use the ACP - period. At least, not until the IARU have managed to secure an allocation for the satellite service at 3.4GHz, and there is the possibility that not every country in R1 will adopt any IARU changes anyway, particularly if WiMax is adopted - or is even talked about. And I haven't seen any timescales for when the IARU would be able to make any changes - or even, if. Whilst many national organisations may want to get the 3.4GHz satellite allocation agreed, the international bodies - IARU included, can take a long time to come to formal agreement on such matters.
Region 1 is huge, and don't forget that Australia has lost it's 3.4GHz allocation as well. To potentially deny access to the ACP in most countries of the world might not go down very well, especially as it seems to me that there is an alternative.
I may have missed something; if so I apologise - I wasn't at the previous meetings, and I haven't got access to any of the attachements that were sent to posts on this list as they are not archived. I'm aware of the BOD meeting on Thurs/Fri and I wonder if there is still time to propose an alternative - I just don't have a good feeling about S2-C.
regards
Grant