The Second Decoder

This is the second post for this year. And it is the second part of the improved DCF77 decoder. And it decodes seconds. So I think it is most appropriate to call this the Second Decoder.

I even renumbered my project plan to make the second decoder #2 on the list.

  1. Exponential filtering of the signal
  2. Phase locked loop / optimal filter for 1Hz phase reconstruction
  3. Reconstruction of the seconds
  4. Hamming metric based reconstruction of the data
  5. Dealing with signal loss

This decoder is crucial as knowing the correct second is key to decoding the actual time data. See the picture below for an overview or read my DCF77 introduction.

DCF77 Code

DCF77 Code

While I am pushing forward with the software I am now also considering improvements to the hardware. There are two directions I am following. I am evaluating different DCF77 decoder modules and I am looking into improved antenna design. Right now I am reading the following two books:

Das neue Magnetantennenbuch: Selbstbau-Loops für Sende- und Empfangsbetrieb

Außergewöhnliche Empfangsantennen und ihre Anpassung für den Längst- und Kurzwellenbereich

The point here is that the antenna can make a big difference. Once I am through this stuff I will cover it on my blog as well.

For now click here for the Second Decoder.

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