The DCF77 Scope
It can be used to check for normal or inverted output from a DCF receiver, reception quality and most importantly when using Udo Klein's DCF77 library check for drift from your Arduino's local clock.
Below an example output snapshot from the DCF77 Scope from the serial monitor.
An _ indicates a low signal while X indicates a high signal. Anything in between shows signal transitions / fluctuations.
A typical signal from an Arduino with a quartz local clock. The signal is stable and does not drift to the left or right of the serial monitor.
This shows the DCF77 signal is not shifting relative to the local clock and is perfect for Udo's library.
A typical signal from an Arduino with a resonator as a local clock.
The signal below is shown speeded up to show how the signal is drifting from left to right with time.
This indicates the resonator is fast compared to the DCF77 signal.
Note if the signal drifts the other way then this indicates that the resonator is slow compared to the DCF77 signal.
This Arduino will not work with Udo's library but you can easily add a quartz crystal and 2 capacitors to make it compatible.
Converting an Arduino Uno from a resonator to a quartz crystal as a local clock.
The original Arduino with resonator and resistor to the left of the "WWW" can be seen below.
The resonator and resistor de-soldered and replaced by the quartz crystal and 2 capacitors
The completed board showing new component layout
A typical signal from an Arduino with a very noisy signal.
A typical signal from an Arduino with a inverted signal
A typical signal from an Arduino with no signal.