Receiver for NOAA weather satellite

[Actionscript]

Hi,

I am new at RF. I read from books that the IF can be shifted by mixing a frequency with the input frequency.
I am curious that there's 87-107MHz IC. If I mix the 137Mhz input with an oscillator, say, 45Mhz, is it possible to get the sounds signals from the satellite?

Thanks.

 

[RCinFLA]

A commerical FM receiver will have too wide a bandwidth. The old NOAA system uses a narrow bandwidth FM. The channel bandwidth is about 50 kHz. This is in comparison with 150 kHz for commerical FM and 20 kHz for a normal FM communications scanner which is too narrow.

Your best bet is to convert to 10.7 MHz I.F. and get a filter of 50 kHz to 60 kHz nose bandwidth. The demodulator can be a quadrature detector, just raise the Q of the quadrature coil circuit to reduce the bandwidth which will increase the recovered signal level.

 

[betwixt]

Might be worth checking the broadcasts are still running. Several satellites have gone completely digital now and it is very difficult to decode the data.

Brian.