[ntp:questions] Trying to use Dimension 4 time keeper

unruh unruh at invalid.ca
Sun Sep 15 07:09:54 UTC 2013

On 2013-09-15, David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
> On 15/09/2013 00:06, unruh wrote:
> []
>> I was probably refering to the Sure unit which is more difficult.
>> I have never looked at the Adafruit module. Also doesn't the Adafruit
>> also require an extra antenna to work properly?
> Yes, the Sure unit, another low-cost option, does require a little 
> modification to extract the PPS signal at RS-232 levels, although based 

That would completely burn out the RPi GPIO ports.

> on my current experiences likely the more readily available TTL-level 
> PPS signal would actually be satisfactory unless very long cable tuns 
> were involved.  I have detailed the modification required here:
>    http://www.satsignal.eu/ntp/Sure-GPS.htm
> With the Adafruit unit I'm not using an external antenna in my "lab", on 
> the second floor of a two-storey building.  The GPS signal creeping in 
> via walls and roof is enough.  The Adafruit module has both a built-in 

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