Getting Started

The GC-1000-GPS is a drop-in replacement board for the GC-1000 radio disciplined clock, giving some life and utility back to your super accurate radio synchronized clock!

Where to start?

Once you have a kit, check out the Assemble the GC-1000-GPS section to begin the process of installing and configuring your board for the first time!

How it works

The original GC-1000 synced with the WWV station in colorado for precise control over the disciplined oscillator. The GC-1000-GPS board uses GPS to accomplish much the same goal, syncing a local RTC to use as a high precision source and not drifting over time.

Sequence Diagram

        sequenceDiagram
   participant GPS
   participant Arduino
   participant RTC

   Arduino->>RTC: Is sync required?
   RTC-->>Arduino: Check if RTC is not synced,<br/>time between sync is too long,<br/>or gps is available

   Arduino-->>GPS: Check if GPS is ready<br/>Sat number, last time, etc
   GPS->>Arduino: Crack a valid gps time
   Note left of GPS: GPS may not have<br/>valid sync yet.<br/>Arduino will wait here.
   Note right of Arduino: We set a flag here and advance the<br/>second counter. We will wait for the GPS<br/>Inturrupt to trigger
   Arduino->>Arduino: Set SyncReady Flag
   critical Inturrupt Sequence
     GPS-)Arduino: PPS inturrupt!
     RTC-->>Arduino: Compare time to rtc to calculate drift
     Arduino-)RTC: Set precise time.
   end
    

GPS Time Spec

The gps time spec is formatted like such…

Disciplined Oscillator

Note

The current revision of boards do NOT have a disciplined oscillator mode. This may be changed in the future!

Extra tidbits

• Original Manual + schematics pdf.

• PRC68.com/Brooke Clarke has some interesting time disecting their gc-1000 and the info was very helpful for making this project.