[evilandy]

Quote  “As for cost, the Ultimate GPS is less money than the IMP”

Ultimate GPS = 40

Antenna        = 13

Antenna adapter = 4

==================

               $57 USD

Most GPS time applications will require, in most cases, the sensitive active, external, remote

antenna and antenna adapter for inside use. Buyer beware. 

Electric IMP = 30

IMP breakout = 13

Level shifter = 4

======================

               $47 USD

Note: The Electric IMP “cloud” server could disappear at any time.

One requested feature for the Electric IMP was for their servers to

generate automatic DST local time. x = time(PST or PDT) for west coast users.

So all you would need to do is add or remove the WIFI SD card to the

Alpha Clock Five with absolutely no firmware changes.

[evilandy]

The only major downside to the IMP is when their server “cloud” goes down you lose your GMT time.

As for the Ultimate GPS, we had “chicken wire plaster” in our homes and the the reception of the GPS signal was stopped dead in its tracks.  So we had to purchase the active GPS antenna Adafruit provided for the GPS.

Having multiple precision clock sources does help alot.

  

[evilandy]

Quote “it sounds like you are saying there is some relationship between having the GPS signal and adjusting the time for DST.”

I tried to state, indirectly, that by not having a GPS signal or fix is not necessary for DST.

Question “Are you trying to compute DST time changes based on the GPS coordinates?”

No, we are using a RTC present date to compute for the “projected” DST dates using a DST table.
When the date arrives (spring forward or fall back) we adjust the RTC +- 1 hour.

Quote “I thought about getting the time from the ‘net using a wifi adapter, but the Ultimate GPS works so well, and it doesn’t have to be configured with SSID, password, etc.”

The Electric IMP uses a “LCD screen blink-up” from an Android or IOS device. The Wifi settings are set in this ARM SD cardin about one minute. No programming is necessary.

Using the Atomic clock, GPS or Wifi, we found the Wifi the easiest to implement, reliable and somewhat precise. Above all, the Wifi provided the best cost solution.

 

 

 

 

 

 

[evilandy]

In our project “Doomsday Atomic Alpha Clock Five Project” we also used the Ultimate GPS, along with Wifi and a WWVB Atomic Clock.

Link: http://forum.pjrc.com/threads/17369-Doomsday-Atomic-quot-Alpha-Clock-Five-quot-Project-using-the-Teensy-3

The Ultimate GPS proved to be very sensitive but we also added Adafruit’s active remote GPS antenna.

For auto DST, we used an internet projected 10 year table for DST time changes. This way, with no GPS signal, the
clock knows when to change on the projected DST date. We had this luxury because we used a pre-processor
Teensy 3 ARM stamp.

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