need help with DCF-77 time signal detection

[hugobross]

Hi,

Does anyone know a good method to receive the dcf-77 time signal, not using a complete chip but made up up with different components (like opamps, filters (LC), mixer (IC)...
We're working on a dcf-project at school and I was thinking to receive the signal with ferrit core antenne in parallel with a cap (matched on 77.5khz). I was told that I've got to bring down the frequency with a (balanced) mixer (otherwise the Q-factor of the filter must be extremely high). Can I use a second 77.5 khz signal (on the other mixerinput), so that there will be a DC-component and the double freq. Can I detect the information (= kind of AM pulses) out of this DC-signal (after LPF) or not?
The detected signal will be decoded by own written software...

Any comments or other ideas welcome!

Is it also possible to make a kind of low pass filter with an opamp based on the Gain Bandwidth Product (=constant). So the higher the Gain the lower the bandwith will be (so better selectivity).

Thanks in advance!!
HB.

[hugobross]

we just started to build and simply worked it out