Hi Matteo, It is the difference between "baseband" and "RF". If you take an RF signal that is at 100Mhz and has a bandwidth of 2.5Khz, you can mix it with another signal at 100Mhz and that will produce two outputs, one at 200Mhz, and one at 0Mhz. It will still have a 2.5Khz bandwidth so on the low end it will be between 0 and 2.5kHz so a low pass filter is needed.
This is the fundamental principle behind radios. --Chuck On Tue, May 8, 2018 at 5:59 AM, Matteo Terzi <matteo.terz...@gmail.com> wrote: > Hi all, > I'd like to know why does Micheal Ossmann use a Low Pass Filter in the > Lesson 1 (https://greatscottgadgets.com/sdr/1/ --> minute 22:00). > He says that in that way just frequencies near to the zero Hz can pass but > it doesn't make sense....how radio frequencies can pass if they have a > value of MHz?? > Thanks > > Matteo > > -- > Matteo TERZI > Google Gmail Member > > _______________________________________________ > HackRF-dev mailing list > HackRF-dev@greatscottgadgets.com > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > >
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