Re: [Discuss-gnuradio] Modulation question

[Marcus Müller]

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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"
> <address@hidden> To: "Andrew Rich" <address@hidden> 
> Cc: <address@hidden> 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
> 
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