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Re: [Discuss-gnuradio] WBX and frequencies around 433 MHz?


From: Patrik Eliardsson
Subject: Re: [Discuss-gnuradio] WBX and frequencies around 433 MHz?
Date: Tue, 6 Dec 2011 08:49:56 +0100

> > Hi,
> >
> > While I was testing the DQPSK-(de)modulation blocks in GRC. 
> I found a frequency region where the reception failed. I 
> started with the ISM-band (433 MHz) as the center frequency, 
> and the reception didn't work. After checking my code several 
> times I decided to change the center frequency to 2 GHz and 
> everything started to work. So I tried several other center 
> frequencies with successful outcome, for example 2 GHz, 
> 1.5GHz, 800MHz, 500MHz, 420MHz. If I tuned the frequency to 
> the 430-440 MHz region the reception fails.
> >
> > I've used 2 USRP2s with the WBX and connected them with a 
> cable and 20 dB attenuator.
> >
> > I have 4 different WBX cards and the result is the same for 
> each of them. 
> >
> > Have someone encountered the same problem with frequencies 
> around 433 MHz?
> >
> > Br,
> > Patrik
> >
> >   
> Well, there's a lot of amateur radio traffic in that 
> frequency range, which may be interfering.

I will keep that in mind. But I used a cable between the USRP2s, so I wouldn't 
expect any interference from other systems.

> Also, there's a special frequency at 433.920MHz used for 
> garage door openers.  Are you running
>   your USRP2 with the covers on or off?

The covers are on.

I will have a look at the received spectrum again, as Nick suggested. 

-Patrik


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