Re: [Discuss-gnuradio] USRP2 - BasicTX first Nyquist zone frequencies

[Ronaldo Nunez]

Thanks Eric,

I will try your suggestion, if I get it I will share the information
with the community.

Regards,

Ronaldo

2009/3/16 Eric Blossom <address@hidden>:
> On Mon, Mar 16, 2009 at 07:04:11PM -0300, Ronaldo Nunez wrote:
>> Hi Eric,
>>
>> i felt like you when I read it, but take a look here
>> (http://gnuradio.org/trac/wiki/USRP2GenFAQ) :
>>
>> "With Basic TX board, USRP1 can generate maximum of 44 MHz frequency,
>> What USRP2 is capable of ?
>>
>> 44 MHz is the highest frequency in the first Nyquist zone on the USRP1.
>> Much higher frequencies can be used in the higher zones. The USRP2
>> takes 100 MS/s rates and interpolates up to 400 MS/s. Direct
>> frequencies up to ~170 MHz should be usable. "
>>
>> Maybe I interpreted wrong... Be free to correct me...
>>
>> Regards,
>> Ronaldo
>
> Ronaldo,
>
> The firware sets up the DAC (AD9777) in the interpolate by 4, no
> modulation mode. Given that, the remarks about 50 MHz apply.  Feel
> free to experiment with the on-chip modulator and let us know how it
> works out.  FYI, the code that initializes the DAC is in u2_init.c
>
> Eric
>
>
>> 2009/3/16 Eric Blossom <address@hidden>:
>> > On Mon, Mar 16, 2009 at 10:05:28AM -0300, Ronaldo Nunez wrote:
>> >> Hello,
>> >>
>> >> I read in faq that the bigger frequency of the first Nyquist zone of
>> >> USRP2 is about 170 MHz, using a BasicTX daughter board.
>> >> My USRP2 couldn't get more than 50 MHz with this daughter board.
>> >>
>> >> I'm using 9939 firmware revision.
>> >>
>> >> Somebody observed the same problem with usrp2?
>> >> There is a way to fix it?
>> >>
>> >> Thanks
>> >
>> > I'm not sure where you found the 170 MHz number, or where it may have
>> > come from, but the USRP2 DACS run at 100 MS/s.  With the Basic Tx
>> > 50 MHz is what you would expect to see as the edge of the first
>> > Nyquist zone.
>> >
>> > Eric
>



-- 
__________________________________
Ronaldo A. Viera Nunez
Acadêmico/Engenharia Elétrica
Universidade Federal de Santa Maria

Santa Maria - RS - Brasil