[amsat-bb] Re: 2.4GHz broadband router on satellite?

[John Stephensen]

Yes, 2.4 GHz was very noisy. AMSAT Eagle was to use a 3.4 GHz high-speed 
(0.5-1 Mbps) BPSK downlink. BPSK was chosen for maximum efficiency in the 
PA. WiFi and WiMAX use complex modulation schemes that are optimized for 
terrestrial applications where the signal is diffused and scattered by 
nearby objects. This results in a PA DC to RF conversion efficiency of less 
than 20%.

73,

John
KD6OZH

----- Original Message ----- 
From: "Mark L. Hammond" <marklhammond at gmail.com>
To: "Trevor ." <m5aka at yahoo.co.uk>
Cc: "amsat-bb" <amsat-bb at amsat.org>
Sent: Friday, February 22, 2013 16:20 UTC
Subject: [amsat-bb] Re: 2.4GHz broadband router on satellite?


> Maybe Drew KO4MA will reply--but I thought he did some "global
> listening" on 2.4GHz with AO-51 (frequency agile receiver).  Seems
> like he published some plots in The Journal?
>
> Take home from what I recall--it was very noisy!
>
> Mark N8MH
>
> On Fri, Feb 22, 2013 at 10:49 AM, Trevor . <m5aka at yahoo.co.uk> wrote:
>> Apart from power budget issues and Doppler the real killer will be the 
>> very high noise level on 2.4 GHz.
>>
>> In urban areas you can expected to receive strong WiFi signals across all 
>> of 2402-2450 almost regardless of where you beam.
>>
>> Any signals from a satellite would need to be strong enough to overcome 
>> this interference. 5 GHz is likely to suffer a similar problem in a few 
>> years as more use is made of that band for WiFi etc.
>>
>> 73 Trevor M5AKA
>>
>>
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>
>
> -- 
> Mark L. Hammond [N8MH]
> _______________________________________________
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