Re: [Discuss-gnuradio] FSK - implementation

[Marcus Müller]

Hi Przemek,

so, first a hint: it's easier (really, it is!) to use this mailing list
directly via email, and not with the ruby-forum interface. We don't
really like ruby-forum, because it tends to mix up the order of replies
and makes communication unnecessarily complicated. Sign up at:
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

Then, I've already replied to you on stackOverflow [1]. I really don't
mind if you discuss this here, but maybe you'd want to address why my
answer doesn't actually answer your questions, so that you get the
information you need faster.

Best regards,
Marcus

[1]
http://stackoverflow.com/questions/31886310/gnu-radio-bfsk/31892042#31892042
Marcus Müller wrote:
>
> No, you typically leave your symbol length alone. You're right, these
> symbols will then contain different amounts of periods, but that's
> typically not really a problem, because it doesn't matter for your
> demodulation.
>
> There's some fine mathematical differences in the energy these symbols
> might have, but in a system where that matters, you simply can't chose
> arbitrary frequencies -- that's where OFDM comes into play.
>
> You're right, however, this is just barely a GNU Radio question. Maybe
> you're better of on the ham radio stack exchange, or the DSP stack
> exchange site.
>

On 08.08.2015 11:59, Przemek Lewandowski wrote:
> I have a question about BFSK/M-FSK modulations in GnuRadio.
>
> If I have a symbol 1 or 0 and it has got 64 samples (2 periods of
> sin/cos) and I want to modulate it with 2 different frequencies for
> example: f1 = 175 KHz = 5,7 us f2 = 225 KHz = 4,4 us
>
> Problem is that 0 or 1 binary are same width - 64 samples but width for
> cos/sin periods are diferent and longer period will be cut for shorter
> symbol.
>
> Do I need to generate two diferent symbols width for 0 or 1 ? what with
> bigger M-FSK ?
>
> thank you in advice :)
>