[time-nuts] Thunderbolt accuracy...??

Dave Ackrill dave.g0dja at tiscali.co.uk
Sat Dec 20 20:42:11 UTC 2008


Hal Murray wrote:
>> versus junk GPSDO
>>     
>
> It's not junk.
>
> What are you interested in?  Short term stability or long term accuracy?
>   
I'm glad to hear that the Thunderbolt is not classed as 'junk'... :-)

Personally, what I want to do is two things.  1. Keep my PC clock within 
a reasonable time frame when compared with other PC clocks for Amateur 
Radio data mode transmissions.  In this case, the actual time seems less 
important than the effective time between the other station and myself, 
so that we don't try to transmit at the same time, or receive at the 
same time.  What that time is, is not that critical, as far as I can 
see.  As long as we both agree when to transmit and when to receive.

2. I want to keep various transverters reasonably on frequency when 
compared to other people who may, or may not, be 'on frequency' so that 
we have a better chance of finding one another on UHF and SHF bands when 
we set a frequency to transmit or receive on.

The Thunderbolt 10MHz GPSDO seems ideal for this second application.  
The more accurate and stable the better, of course, but in comparison 
with some older transceiver or transverter designs the Thunderbolt 
option to lock in a frequency should be far in advance of many of the 
older hit and miss operations when trying to agree upon what frequency 
is in use on the SHF bands.

 From what I can make out, the next technique to address is to use SDR 
technology to identify when someone is even a few Hz away from where you 
think they might, or should, be.

The pursuit of perfection is a laudable goal, but it can obscure the 
original objectives that you wanted to reach, in my opinion, if you are 
not careful.

Dave (G0DJA)



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