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From: mtr on 20 Jul 2010 07:15
Hello. We are making some sdr thing. So there is a need to catch carrier
frequency for down shifting. We know nothing about baseband signal, except
may be that it was digital or analogue modulated. Could anyone suggest any
method?
We're computing everything with modern pc, so there is no problem with
arg(), log10(), sin()/cos(), square or square root and so on.

Thank you in advance


From: Jason on 20 Jul 2010 08:01
On Jul 20, 7:15 am, "mtr" <baranov.mv(a)n_o_s_p_a_m.gmail.com> wrote:
> Hello. We are making some sdr thing. So there is a need to catch carrier
> frequency for down shifting. We know nothing about baseband signal, except
> may be that it was digital or analogue modulated. Could anyone suggest any
> method?
> We're computing everything with modern pc, so there is no problem with
> arg(), log10(), sin()/cos(),  square or square root and so on.
>
> Thank you in advance

There is no universal technique for carrier recovery that works across
all analog and digital modulations. You're not going to be able to
make an "SDR thing" without knowledge of what it's going to receive.
An AM receiver is different from an FSK receiver, which is different
from an OFDM receiver. The allure of a software-defined receiver is
that it can easily be reconfigured to receive different modulation
formats, not necessarily that it is a universal receiver that can
handle all combinations at once.

Jason
From: mtr on 20 Jul 2010 09:03
Ok, it's obvious that it's not always possible to get carrier for any
modulation type using the same way. But we want to code as fewer different
methods as possible. Is there some method for any digital angular
modulation (M-fsk, M-ask, M-psk and qam)?
From: Jason on 20 Jul 2010 09:06
On Jul 20, 9:03 am, "mtr" <baranov.mv(a)n_o_s_p_a_m.gmail.com> wrote:
> Ok, it's obvious that it's not always possible to get carrier for any
> modulation type using the same way. But we want to code as fewer different
> methods as possible. Is there some method for any digital angular
> modulation (M-fsk, M-ask, M-psk and qam)?

No.

Jason
From: Mark on 20 Jul 2010 09:31

>
> > Ok, it's obvious that it's not always possible to get carrier for any
> > modulation type using the same way. But we want to code as fewer different
> > methods as possible. Is there some method for any digital angular
> > modulation (M-fsk, M-ask, M-psk and qam)?
>


http://en.wikipedia.org/wiki/Costas_loop

Mark
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