[time-nuts] GPS DO Alternatives

Bob Camp lists at rtty.us
Sun Dec 9 00:25:08 UTC 2012


A standard that is good to "8 digits" can be done manually. That's far cheaper than your goal and the software is totally open source. It can be done with off the shelf parts and no wiring at all.  

Problem solved? 

I suspect not….


On Dec 8, 2012, at 1:59 PM, Chris Albertson <albertson.chris at gmail.com> wrote:

> On Sat, Dec 8, 2012 at 9:30 AM, <johncroos at aol.com> wrote:
>> Hello all -
>> "People talk about good deals on Thunderbolts but I have
>> yet to see one.  It seems peak Thunderbolt passed before I was
>> seriously looking."
>> *The box you put it in - suspending it above the bench on inspirational
>> thought probably
>> will not work. A nice box is easily $ 50.00 so who cares about adding
>> another flip flop or
>> counter at 25 cents each.
> The goal, well my goal is to build a GPSDO to this set of requirements
> 1) well under 1/2 the cost of the t-bolt.
> 2) can be made with common parts and skills most people have
> 3) is completely modifiable (open source software)
> So #1 above means you use a low cost box, perhaps the case and old CDROM
> was once housed in or maybe you gut and old PC chassis
> #2 pretty much means you have to keep theparts cound way down.  Yes a chip
> might cost only $1 but as soon as you get more then about three of those 25
> cent cips you need a PCB.   PCB making is not a common everyday skill so #2
> means a way-low parts count
> #3 means the uP is gong to have to come with a very easy to use and free
> open source toolchain.  Adruino is like that, there are others, but a bare
> uP chip is not going to work
> You are right that one way to engineer a product is to first set
> performance numbers.   But another more common way is to first identify a
> target customer and then set a target price.   In this case the target
> customer is a hobbyist with only basic skills who wants a low cost easy to
> build GPSDO that has can understand and modify himself.
> Next with those very hard to meet requirements (low cost, low parts count,
> simple to build) we can ask if the exected perfomance is "good enough"
> What is good enough.  I'd say if you could use the GPSDO a a local
> frequency standard for a counter that has 8 digits you are doing "well
> enough".  If you can get to 10 digital it is pretty good
> -- 
> Chris Albertson
> Redondo Beach, California
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