When you demodulate ads-b it becomes just square waves Sent from my iPhone
> On 30 Jan 2014, at 8:01 pm, Marcus Müller <[email protected]> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Basically, yes, but that's communication theory. I'd refer you to > Kammeyer -- Nachrichtenübertragung, but that's a German book. I guess > Proakis would be a fine source, too, but I don't have his book at hand > right now. > > Anyway, ADB-S should *define* the pulse shape. Best look into Nick's > gr-airmodes code for matched filtering; the matched filter directly > gives you the transmission filter. (But that's even more signal theory) > > Greetings, > Marcus > >> On 30.01.2014 10:44, Andrew Rich wrote: >> Thanks Marcus >> >> Pulse shape and repetition frequency determine bandwidth then ? >> >> Square is the worst - gausian is better ? >> >> - Andrew - >> >> >> ----- Original Message ----- From: "Marcus Müller" >> <[email protected]> To: "Andrew Rich" <[email protected]> >> Cc: <[email protected]> Sent: Thursday, January 30, 2014 >> 5:27 PM Subject: Re: Modulation question >> >> >> Hi Andrew, >> >> just a quick heads-up: I nearly missed your message because it was >> hidden in another thread, since you seem to have hit reply and >> changed subject and text; however, my mail client recognized the >> In-Reply-To header, and sorted you in - please directly write mails >> unless you actually mean to reply. >> >> So now for your question >>>>> Ads-b uses a 1 MHz pulse position modulation scheme >> On 30.01.2014 01:22, Andrew Rich wrote: >>>>> Ads-b uses a 1 MHz pulse position modulation scheme >>>>> >>>>> Is this possible to create on gnu ? >> GNU Radio is only a software radio framework. Basically you can do >> anything with it that can be done in baseband signal of a sample >> rate that your ADC/DAC and mixers (and analog filters, amps and so >> on) support. With gr-air-modes there is a comfortable receiver >> implemented in GNU Radio, and as a not-to-rough simplification you >> can transmit everything with a software radio that you can receive >> with one. >> >>>>> >>>>> Is it the data rate that makes the spectrum wide ? 7 MHz ? >> Ok, I don't really understand your question, could you please >> elaborate? Reception of ADB-S works quite well with a 4MHz sampling >> bandwidth, but I'm not quite sure on the technical requirements of >> ADB-S transmission. >> >> The actual bandwidth of PPM systems of course depends on pulse >> shape and pulse frequency. >> >> Hope I was able to help a little, Marcus > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQEcBAEBAgAGBQJS6iLnAAoJEAFxB7BbsDrLl+wIAJKGfJS0AT3b6WTRdCcm+14B > lgGOBuTPqpf/3loOqZpoPiAkbUetxrJMk4QtCjbnru5DOKI/cJV7vPwsyL/vAyM2 > MzDgvVrCL0n91fk7iWnEYG/1PrPwJJcoJIdxBL7oBr4b2DHqg6Delsdbai9YK1B3 > FY+6kjKnwUQNdVeEK3G7ifxotUEvEDfrz7pul84HfP6MqZA59CXCsatPgnUTtl6P > TqIRjbyZNQXePdoBfdmmDA9PiM4FXhAMc7oQEDmsBrlG6wpYqEZSo4xoJbQ2SIEw > gVPpX/tfBWPhIBtnZCGdQlmKLCmKK7SK4lUbfztdieLV4Jip1m7s9+RjalpnmHc= > =riRq > -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
