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Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear

From: Eng. Firas
Subject: Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
Date: Mon, 3 Sep 2007 20:04:16 -0700 (PDT)

Hi Vincenzo,

1) What is your recording system (PC specifications)?.
2) How fast your hard drive can read/write data? because working with 8MHz
means that your hard drive must be able to sustain writing 32MByte/sec?
3) Do you use ext2 or ext3 ? Ext2 is very efficient in writing. 
4) Are you recording complex or interleaved Short 8 MHz samples?


Vincenzo Pellegrini wrote:
> Matt,
> Tonight
> I have been recording slices of commercial FM spectrum, all centered
> right where a good station transmits, 
> the first slice was 300Khz wide, 
> the second was 2MHz 
> the third was 4MHz
> then I sent all these signals to my Hifi FM receiver via the basicTX...
> all went fine and I could hear a good stereo sound from my recordings..
> then I tried my nightmare: the 8MHz slice of spectrum....
> the output was extremely weak but you could easily tell from what you
> could hear that the samples were not being sent out at 8Msps: the very
> poor audio was also "slow" as it happens when you set the interpolation
> rate too high, compared to the sample rate your samples were taken at...
> well, this is not just some attenuation next to the shoulder of my ofdm
> signal.. this is the whole signal .. gone..
> So, I'm really not asking you, Matt, to solve a problem which is my duty
> to solve...and don't even want to bother the whole list with this
> stuff...
> ...but please say it loud, say it clear: "vincenzo, you've made very big
> mistakes, because the USRP really can transmit an 8MHz wide signal
> without distorting it significantly, I've tested it"...
> ..so even if this means that I still got much to learn, and much to work
> to find out where I'm doing wrong...
> ...well, it would be much better than being forced to give up what I'm
> working upon..
> please...
> thanks
> vincenzo 
> PS. 
> I'm using default FPGA configuration...
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> Discuss-gnuradio mailing list
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