[aprssig] EB-432/PCSAT2/APRS Question

[John Ronan]

Hi,

On 26 May 2006, at 15:58, hasan schiers wrote:

> Are you adjusting for doppler, or are you just letting it sit  
> unattended?

> I get quite a few more decoded packets than you are indicating with  
> my D700 in the house sitting on 435.280 with a dual band j-pole at  
> 60' with 110' of LMR-400 and no preamp. I do not do doppler  
> correction, so I deliberately set the vfo 5 khz high to catch the  
> early part of a pass. If you set it dead center, that is the  
> fastest point of relative motion for an overhead pass, and the  
> signal won't be in the passband very long. If you choose a lower  
> pass  the doppler rate is lower, so if you pick the freq  
> judiciously, you can maximize the number of possible packets in the  
> passband, BUT you have to set the VFO freq higher due to doppler  
> (in the early part of a pass).
>
>
Good question.

  I am adjusting for doppler,  every 10 seconds at the moment. I'm  
using a modified version of VK4TEC's doppler correction script. I  
might increase that out to 30 seconds tonight and see if that makes  
much of a difference. It may be that its changing frequency in the  
middle of a packet.  I'll stay with the hardware decoder for the  
moment (reduce the no of unknowns), and try to optimise what I have.   
I am also conscious of the fact that the chimney is quite 'busy', so  
it doesn't have a clear view of the sky.  I'm trying not to put  
anything else up that would arouse the wrath of my neighbours as  
there is a lot up there already (VHF/UHF Omni/2.4Ghz Omni/5.8Ghz Dish/ 
2.4Ghz Dish all above the EB-432 :) ).

Regards
de John
EI7IG

--
John Ronan <jronan at tssg.org>, +353-51-302938
Telecommunications Software &  Systems Group,  http://www.tssg.org