Re: [amsat-bb] 2.4GHz QRM

[Robert McGwier <rwmcgwier@xxxxxxxxxxx>]

Trevor wrote:
>> ----- Original Message ----- 
>> From: "Tim Tuck" <tim.tuck@penrith.net>
>>     
>>> Given Wifi appears to be moving towards 5.8Ghz, what is going to be the
>>>       
>> primary
>>     
>>> occupier of S band when Eagle is ready to launch ?
>>>
>>> Are there more services moving towards 2.4Ghz or away from it ?
>>>       
>
> WiFi use of 2.4 GHz is growing rapidly and will continue to grow in the coming
> years. 
>
> Many other devices are now using 2.4 GHz and their use will also grow - phones,
> remote control devices, Home Video Senders, Security systems, Bluetooth, Zigbee
> etc.
>
> 5.8 GHz is being used for WiFi but this is in addition to 2.4 GHz it's not
> replacing it. The situation on 5.8 GHz will in a few years resemble that of 2.4
> GHz. WIMAX is sure to be a big user.
>   

We took this into account in our estimations of the impact of 5.8 GHz 
part 15 usage and we made absolutely horrid assumptions about the 
numbers of these devices on the ground and we could still "close our 
links" on the ground with 5.8 Ghz as our downlinnk for our digital 
transponder proposal for Eagle.

In all my reading of WIMAX,  from the WIMAX forum, etc. there are two 
big pushes.    There is the UWB stuff going between 10 and 66 GIGAHertz 
and there is the Mobile WIMAX stuff which is going to add to the misery 
of 2.4 GHz but add 3.4 GHz,  primarily but from my reading in the past 
few days,  5.8 GHz is just not going to be that popular for many 
reasons. UWB is the current "cat's meow" in their eyes and 802.16 
documents everywhere want the Metropolitan Area Networks (HIPERMAN, not 
HIPERLAN) to be in the UWB bands listed.  It is possible to read a lot 
about WIMAX from Intel and the WIMAX forums.

Our downlink band,  20 MHz in the 5.8 GHz band   does not overlap 
802.11a,  only our 5.6 GHz uplink  overlaps this.   It does overlap 
HiperLAN and some proposed HiperMAN frequencies but again,  my readings 
and crystal ball guys say 5.8 Ghz will be "jumped over" to get to UWB.   
Our European friends will have to tell us about Hiperlan but it is my 
understanding that it will fall to the wayside with the advent of 
WIMAX/HiperMAN.

That said,  Hittite is making 1 watt devices for HiperLAN at 5.8 GHz.  I 
can only presume they do not make devices for the fun of it.

As you all can see, the Part 15 world is exploding around us.  We can 
figure out ways to try to find a hole we can use or we can jump into a 
hole and cover our heads.




> It is no longer reasonable to expect to be able to use the 5.8 GHz allocation
> as an Amateur Satellite downlink. 
>   

I disagree but I will check into it more carefully based on further 
reading and further input from the telecommunications experts we have in 
our engineering team who believe differently from your statement.

> Ideally we need 5650-5670 MHz to be made Space-To-Earth as well as
> Earth-To-Space and initially use a section around 5668 (Terrestrial Weak Signal
> Working in EU) for satellite downlinks.
>
> 73 Trevor M5AKA
>
>   
73's
Bob
N4HY

-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr
----
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