[time-nuts] adafruit $40 GPS

[Jim Lux]

On 5/14/13 9:02 AM, Chris Albertson wrote:
> The adafruit GPS has a built in antenna.  But you can add an external one.

it doesn't say that it has an antenna, and all the pictures show it 
connected to an external antenna.
>
> But why use this for timing?  They don't even give a spec for timing
> accuracy and it is likely NOT a timing GPS.  It is  a navigation unit.
>   Pretty much useless for timing.
>

It's pretty darn useful if your need is only 1 or 0.1 second.

Perhaps even at the 1ms level.  There's lots of applications for which 
that is just fine: A nice example might be acoustic location of where 
gunshots were fired.. 1 ms is 1 foot, roughly... you have a data logger 
that listens for the impulse, and time stamps it appropriately using the 
1ms accuracy GPS, and you get the position of the sensor for free.

Not everyone needs 1E-15 ADEV at 1000 seconds for all applications.



> Also the price is to high.  You can do better in eBay, real timing
> units sell for as little as $15.


eBay is fine for one-off experiments: it's not so wonderful if you want 
to do something repeatable.  It's no different than seeing some nifty 
project you want to build that depends on a surplus part that was a 
manufacturing overrun, so they just dumped them for $10, but if you 
bought them new, they cost $1000.

(or the classic ham thing of "I used this X that I got at a hamfest in 
1965 and has been in my garage for the last 40 years"..)