DCF77Decoder

Data decoder class in C/C++. Decodes time and date from DCF77 transmitter.

Introduction

DCF77 is time transmitter with signal range over Europe, located in Germany. It works on 77.5kHz frequency with AM modulation and 50kW power (30-35kW EIRP). Frame is in digital format, it's 59 bit binary string and it's transmitted each minute. This class can decode such 59 bits and get all information except weather (it's first 14 bits and they are crypted with DES40).

Usage

Data structs

For definition look into dcf77decoder.cpp file.

Struct DCF77Time stores such informations (certain fields in this struct right below):

struct DCF77Time {
    unsigned short hour, minute, day, weekday, month, year;
}

Please note that year variable is last two digits, for example 96 means 1996.

Struct DCF77Result is designed to handle returned data from decoder class. Fields:

struct DCF77Result {
  DCF77Time time;
  bool antenna, timeChange, summerTime;
}

Usage

For example, please open example.cpp file and look into main() function.

Set functions

To load data, use DCF77Decoder::set(...):

• set(bool data[59])
• set(unsigned short data[59])
• set(std::string data)

After it, you can use function DCF77Result getResult(). Example usage:

std::string data = "00011110001100100010110001000010010010010000110000001010000";
DCF77Decoder decoder;
DCF77Result result;
if (!decoder.set(data))
	std::cerr << "Invalid data";
else
	result = decoder.getResult();
std::cout << "It's " << result.time.hour << ":" << result.time.minute << std::endl;