Re: [Discuss-gnuradio] USRP2 + WBX How to use a 32 MHz signal band?

[Tom Rondeau]

On Wed, Dec 1, 2010 at 5:02 PM, Nick Foster <address@hidden> wrote:
> On Wed, 2010-12-01 at 13:53 -0800, Vladutzzz wrote:
>> The problem is that I am in the middle of a project, time is of the essence
>> and I don't have time to start stumbling around with UHD, right now I have
>> to use Simulink, hence UDP. GnuRadio Companion still doesn't work with UHD,
>> right (I am very new to python)?
>
> GRC has always worked with UHD. You might try downloading the latest UHD
> and giving it a shot.
>
>> So no chance of UDP working with 2 USRPs at once, huh?!
>
> No.
>
>> Let me ask you something else then, if I manage to synchronize 2 USRPs
>> working on separate computers to start sensing a band of 16MHz each, and
>> their central frequency being 16MHz apart, saving those two bands in a file
>> , what block (system of blocks) can I use to compose a 32MHz band (and I
>> mean the whole band not just their power measurements) from the two 16MHz
>> halfbands originating from the "From File" blocks?
>> Naturally the samplerate of the new signal should be the double of that of
>> the halfbands.
>> If I just use a 2:1 multiplex the halfbands appear superimposed and the
>> resulting signal band still occupies 16MHz.
>
> Assuming your signals are mixed to baseband you can interpolate both to
> 32Msps and mix one sideband up and the other down so they sit where they
> are supposed to, and then add the signals together. There's probably a
> smarter (faster) way to do it.
>
> --n

There's the pfb_synthesis_filterbank that could do this, too, but it's
probably not faster than your way if you are just doing two
"channels." This code also needs a bit of a SIMD burst for the
internal filters, and there's another tweak that I will be making so
that you can more easily upsample and smash the channels together for
perfect reconstruction (that is, if you're using a real Nyquist
filter).

But yeah, for right now, I'd do it the way Nick suggested.

Tom



>> Any ideas?
>> Your help is really appreciated,
>>
>> Vlad.
>>
>>
>>
>> Marcus D. Leech wrote:
>> >
>> > On 12/01/2010 05:49 AM, Vladutzzz wrote:
>> >> Thank you Marcus, for the very prompt and exhaustive reply!
>> >> Mostly it's what I expected, but I am a wee bit worried about the IP
>> >> addressing process:
>> >> I need to change the IP of one of the USRP2 modules, how do I do that,
>> >> considering I use an UDP FPGA image and not UHD?
>> >> Also, what IPs should I use in the USPR2 source blocks, now that there's
>> >> 2
>> >> of them?
>> >> Thanks!
>> >>
>> >> Vlad.
>> >>
>> > My advice would be to screw up your courage, bite the bullet, and
>> > convert to UHD.
>> >
>> > Theres a UHD utility, usrp2_addr_burner that can be used to change the
>> > IP address.
>> >
>> > The factory address is: 192.168.10.2, you'll need to change it to an
>> > address on a different
>> >   subnet, like 192.168.20.2  or some such.  The idea is that you have
>> > two GiGE ethernet ports,
>> >   and you configure your system with the appropriate subnet on each
>> > ethernet port, and program your
>> >   USRP2 addresses accordingly.
>> >
>> >
>> >
>> > --
>> > Principal Investigator
>> > Shirleys Bay Radio Astronomy Consortium
>> > http://www.sbrac.org
>> >
>> >
>> >
>> > _______________________________________________
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>> >
>> >
>>
>
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