Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcso!hpldola!paul From: paul@hpldola.HP.COM (Paul Bame) Newsgroups: sci.electronics Subject: Re: Weather Satellite Receiver Question Message-ID: <10960018@hpldola.HP.COM> Date: 27 Sep 89 19:51:58 GMT References: <744@anasaz.UUCP> Organization: HP Elec. Design Div. -ColoSpgs Lines: 20 >I am interested in building a system to receive WEFAX APT >pictures from at least the polar orbiting weather satellites >and maybe also from the geosynchronous ones. One question >I have is: what is a good receiver to use? I have a scanner >that can receive 137.5MHz but it's bandwidth is either 6kHz or 200kHz. >I understand that the appropriate bandwidth would be about 50kHz. I'm curious about this bandwidth thing too. I have trouble believing the FM signal actually has a short-term deviation of 50kHz - but I *can* believe this might be wide enough to copy the signal during the doppler shift from AOS to LOS (I haven't calculated this though, or looked it up). Would a NBFM (6kHz mentioned above) receiver work just as well as one with a 50kHz bandwidth as long as the center frequency was periodically changed to account for the doppler shift? -Paul Bame paul@hpldola.hp.com hplabs!hpldola!paul