Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?

[Martin Braun (CEL)]

On Tue, Feb 26, 2013 at 04:10:55PM -0600, Joel Mayer wrote:
> Dear GNU Radio aficionado's-
> 
> Whatever happened to resistance, capacitance, and inductance?
> When I joined this thread I was hoping you would once in a while
> talk about ways of using the software in the computer to modify
> the resonant circuit in the hardware radio by making adjustments
> to the resistors, capacitors, and inductors.

Oh, one of my favourite topics :)

I'll have to point out that I'm completely biased here:
When I started playing around with radio, the thingy between antenna and
the computer was a total black box, just producing the bits and bytes I
needed. In fact, that's what got me attracted to the SDR world, because
I could already program, but those Smith charts... but that's not the
point.

First, I'll give you a practical answer: This mailing list is about GNU
Radio, which is in a sense very hardware-independent. So there you go.

But it's also very important to understand that Software Radio is not
about modelling hardware. Using software allows the use of DSP, which
means we can do stuff like linear-phase filters etc. (good luck tuning
your R/C/I to do that), and we can create transceivers for digitally
modulated signals very easily, which is really awkward in discrete
hardware (although analog modulations are also easily coded).

So, perhaps I just misunderstood your question. But despite not knowing
how you would modify an inductor through software, this wouldn't help in
building a transceiver that, upon sensing a change in the radio
environment, would reconfigure itself and change the waveform used--
which is one goal of GNU Radio. Of course, this comes with some
abstraction, which means that changing the resonant circuit of my USRP
is nothing more than a library call to set_center_frequency() or
whatever it's called.

MB

-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
Research Associate

Kaiserstraße 12
Building 05.01
76131 Karlsruhe

Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu

KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association

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