[amsat-bb] Re: Full band transverters for satellite operations?

Michael Tondee mat_62 at netcommander.com
Thu Jun 14 19:24:38 PDT 2007

    I find myself kind of curious on the question of whether this will 
be a more or less economical way of satellite ops than a traditional 
satellite radio? For the moment I had to sell my gear and will be 
looking to dive back in about the time the HEO birds launch. I still 
have my computer, of course, and would love to go the SDR route when I 
set up again if it's economically feasible for me.
Michael, W4HIJ
Grant Hodgson wrote:
> Tony Langdon wrote:
>> Neat.  Hopefully I can look at getting the uWSDR going once I get my 
>> HPSDR up and running.  Just a comment.  Firstly, I notice there are 
>> plans for Rx only on 2400 MHz.  
> There might be a cut-down, 2.4GHz-only version, but the only cost 
> savings would be the TX power amplifier (100mW-200mW o/p) on the RF 
> board and maybe the TX D/A converter on the baseband board, which is 
> only a few dollars and might be offset by the fact that it would be a 
> different build.  If there is a lot of demand we'll look into the 
> possibility of it but I don't think the cost savings will be significant.
> I should point out that the VK
>> terrestrial weak signal segment is 2403 MHz, so if I was to obtain a 
>> 13cm module, I would want Tx and RX on the 2400-2404 MHz segment (Rx for 
>> 2401, Tx/Rx for 2403).
> The 2.3-2.4GHz amateur band is the most fragmented band that we have; 
> there are at least 6 regional variants that I'm aware of.  One of the 
> goals is that we want to cover the whole 2.3-2.45GHz band, and we now 
> have a paper design that will do just that without compromising key 
> parameters such as out-of-band filtering etc.  I'm not aware of any 
> other amateur radio product that will cover the whole 150MHz at 13cms.
>> I'm also interested how the Ethernet and UDP/IP interface and 
>> communications goes.  
> I believe that the transmission of the digitised audio has already been 
> successfully demonstrated over Ethernet using UDP.  The use of Ethernet 
> allows for long cable runs enabling the uWSDR to be mounted at the 
> masthead and just running power and CAT5 cable into the shack.  No need 
> for lengthy runs of coax.
> All other SDRs I've seen use a soundcard(ish),
>> USB2 or Firewire interface.
> The uWSDR approach is similar to that of the HPSDR, i.e. we have 
> designed our own sound card, and after some considerable work we have 
> opted for the same very high performance D/A converter that the HPSDR 
> uses.  This way we have absolute control of all the key parameters, and 
> it's also cheaper than buying a Delta-44.
> regards
> Grant
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