-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Aditya, Hi Pablo,
the multiples-of-carrier-frequency problem is being solved in hardware (you can't do this in software, since mixing is still analog domain). Anyway, as Aditya explained, since you are processing baseband signals, a lowpass is actually a bandpass (you might at least think of it as such) from -f_c to +f_c. You need to do this, because the FM receiver should only deal with the signal in the interesting band. Greetings, Marcus On 11.02.2014 17:35, Aditya Dhananjay wrote: > To continue: It is always easier to process signals in baseband > (centered around 0) than it is to process RF signals (due to the > high sampling rates required). > > Given that the bandwidth you are interested in is in the order of > 100kHz (typical of FM radio signals), it is easy to see why radio > receivers are designed the way they are. > > > On Tue, Feb 11, 2014 at 11:31 AM, Aditya Dhananjay > <adi...@cs.nyu.edu>wrote: > >> >> >>> In the FM receiver: Why a LPF is used instead of a BPF in order >>> to select the Radio channel that we want to hear? That is the >>> only part I don't understand. >>> >>> >> Hello Pablo, >> >> Let's say you are trying to receive an FM signal centered around >> 100MHz. In other words, the signal of interest is from >> (100-delta)MHz through (100+delta)MHz. >> >> My understanding is that at the receiver, you are first >> demodulating the signal by multiplying the incoming signal with >> the carrier frequency of 100MHz. This leads to two bands: >> >> a) Centered around 0: (-delta through +delta) >> >> b) Centered around 200MHz: (200-delta) Mhz through (200+delta) >> MHz. >> >> Signal (a) is what you are interested in, while signal (b) needs >> to be eliminated. This is where the LPF comes in. >> >> Best, Aditya >> >> > > > > _______________________________________________ Discuss-gnuradio > mailing list Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJS+lWUAAoJEAFxB7BbsDrLr8oH/iTpkA8ohIKeifYY75LuOPPs B8dZn4vo2c/6lSUL7ucM9l/pD215nrGytBClVPOq2QJHvHwQ5O+BWNVXH/Fm7sRn iB0rb1eYsbnqZnABZyG3K7TE34KoAmmrTm6IIW7fH6Gk7qGODYH8mtaqbKcLna7G bXbWh7J3woNJpYClq/VfEJubh8trb0DKfKzFzgIqwJBy42QOqO1Cca9szB/psl7t cb/fqUKUe6UrfQnmQcCCkN4DCXeixd7Olx4Zju/o9PvsBmiup63AfKeEh5aHbCbG h7jOMhG95g5g2VjchCF4xi5TNPxYrj+uXvFrb8LwH5eZWmceipNuUJVASGCJXKk= =Y11I -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
