Re: [Discuss-gnuradio] help with "safe" and "clean" band

[Mihail L. Sichitiu]

Yes, a cable would be nice and easy, but I'm also planning for a "demo",
and the cable would spoil the effect :-). Additionally, I'm looking for
multiplexing (multiple parallel transmissions) and there the cable doesn't
help.

Thanks,
Mihai



On Thu, 12 Jun 2008, Martin Dvh wrote:

> Mihail L. Sichitiu wrote:
> > Hi there,
> >
> > I'm brand new at this GNU Radio thing, so please forgive me if my question
> > has a "well-known" answer. I'd like to try out some performance tests on a
> > few modulation schemes, so I need a clean band for these tests. Obviously
> > the 2.4GHz ISM band is full of interference, and I assume that this goes
> > for all the other ISM bands, right?
> >
> > If this is the case, is there a well-known relatively quiet band where I
> > can run these tests without interfering with anything important, without
> > being interfered with, and without getting in trouble with FCC?
> The easiest thing to do would be not doing your tests wireless.
> Connect TX twith coax to  an attenuator and connect that to the RX side with 
> coax.
> That is about as clean as you can get, and you won't interfere with anyone on 
> any band.
>
> Make sure you use enough attenuation. The RFX2400 TX side has much more power 
> at its output then the RX side can handle.
> You will blow up your daughterboards if you don't have at least 30 dB 
> attenuation.
>
> The best attenuators I found for high frequencies are the SMA inline types
> You can mount them directly at the TX output and connect a SMA-SMA coax to 
> the RX side of a second RFX2400.
>
> Things are much more relaxed with basicRX and basicTX.
> basicRX can be connected directly to basicTX without any chance of damage.
>
> I do a lot of my testing with basicRX and basicTX.
> The output of basicTX is also very low which is an advantage in this case.
>
> Greetings,
> Martin
>
>
> >
> > I imagine that if I'd have all the daughter boards I could do a long-term
> > (1-2 days) scan and find a quiet band and play in there (the tests are
> > likely short and low powered). The problem is that I only have the 2.4GHz
> > daughter-boards and I'd like to buy only the "right" daughter-boards (as
> > opposed to all of them to find an empty band).
> >
> > Thanks for the help,
> > Mihai
> >
> >
> >
> >
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> >
>
>

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