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Re: [Discuss-gnuradio] Understanding the limitations of USRP1
From: |
Vanush Vaswani |
Subject: |
Re: [Discuss-gnuradio] Understanding the limitations of USRP1 |
Date: |
Thu, 12 Feb 2015 18:35:08 +1100 |
Aliasing on purpose?
On Thu, Feb 12, 2015 at 11:25 AM, Marcus D. Leech <address@hidden> wrote:
> On 02/11/2015 06:15 PM, Tommy Tracy wrote:
>
> I am using a USRP1, and I'm trying to receive FM radio. I'm using a BasicRX
> daughterboard with a 0-250MHz range. The USRP itself has a LO frequency of
> 64MHz. Does this limit my frequency range to 0-32MHz, or can I get into the
> 100MHz range by somehow multiplying that Local Oscillator frequency?
>
> I get the following error:
>
> -- Opening a USRP1 device...
> -- Using FPGA clock rate of 64.000000MHz...
> -- Tune Request: 102.900000 MHz
> -- The RF LO does not support the requested frequency:
> -- Requested LO Frequency: 102.900000 MHz
> -- RF LO Result: 0.000000 MHz
> -- Attempted to use the DSP to reach the requested frequency:
> -- Desired DSP Frequency: -102.900000 MHz
> -- DSP Result: 25.100000 MHz
> -- Successfully tuned to -25.100000 MHz
>
> --
> --
> Sincerely,
> Tommy James Tracy II
> Ph.D Candidate
> Computer Engineering
> University of Virginia
>
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> address@hidden
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>
> You might be better off getting a TVRX2 card for it.
>
> You're limited on the USRP1 to 64Msps, and since the BASIC_RX does no
> downconversion--it's just an ADC "buffer", you'd be limited to <= 32MHz in
> the
> first Nyquist zone.
>
> You *could* put a very stiff FM-band-only filter and some gain in front of
> the BASIC_RX, and calculate the appropriate "Nyquist folding" for your
> desired
> frequencies, and tune to those frequencies in the DC-32Mhz region.
>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
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>