Forum: GNU Radio [USRP2]Receiving a DC voltage

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Dbek B. (Guest)
on 2009-03-17 14:27
(Received via mailing list)
Hello again,

last time I didn´t get a solution for my problem of interpolating and
decimating using a sinusoidal signal. Now i went even easier. I
connected a
DC Power Supply (with 0.01A max limit) to my LFRX daughterboard. The
USRP2
Source is only connected to a Scope Sink. But with 0.5 Voltage input, I
only
see very small variations about the 0 line. The current is 0.01 A. So,
what
can I do to see a signal? How can I play with the decimation?

This USRP2 issue caused me big trouble, so help will be appreciated

Best Regards

Beken
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Johnathan C. (Guest)
on 2009-03-17 18:38
(Received via mailing list)
On Tue, Mar 17, 2009 at 5:26 AM, dbeken <removed_email_address@domain.invalid> 
wrote:

> last time I didn´t get a solution for my problem of interpolating and
> decimating using a sinusoidal signal. Now i went even easier. I connected a
> DC Power Supply (with 0.01A max limit) to my LFRX daughterboard. The USRP2
> Source is only connected to a Scope Sink. But with 0.5 Voltage input, I only
> see very small variations about the 0 line. The current is 0.01 A. So, what
> can I do to see a signal?

Make sure you don't have AC coupling turned on in your scope block.

Johnathan
Karthik (Guest)
on 2009-03-17 19:15
(Received via mailing list)
On Tue, Mar 17, 2009 at 9:37 AM, Johnathan C. <
removed_email_address@domain.invalid> wrote:

> what
> > can I do to see a signal?
>
> Make sure you don't have AC coupling turned on in your scope block.
>
> Johnathan
>

For receiving DC signals, you need to disable the DC offset removal
which is
automatically performed in the USRP. I am not sure if this happens in
USRP2
as well, most likely it does. This thread has the discussion and how it
was
solved.
http://lists.gnu.org/archive/html/discuss-gnuradio...

Karthik
Dbek B. (Guest)
on 2009-03-23 11:25
Karthik wrote:
> On Tue, Mar 17, 2009 at 9:37 AM, Johnathan C. <
> removed_email_address@domain.invalid> wrote:
>
>> what
>> > can I do to see a signal?
>>
>> Make sure you don't have AC coupling turned on in your scope block.
>>
>> Johnathan
>>
>
> For receiving DC signals, you need to disable the DC offset removal
> which is
> automatically performed in the USRP. I am not sure if this happens in
> USRP2
> as well, most likely it does. This thread has the discussion and how it
> was
> solved.
> http://lists.gnu.org/archive/html/discuss-gnuradio...
>
> Karthik

I looked at usrp2_base file but there is not a line similar to that in
the usrp_base where you can change the offset so easily, I need another
solution, but thanx for your help
Dbek B. (Guest)
on 2009-03-23 11:28
Johnathan C. wrote:
> On Tue, Mar 17, 2009 at 5:26 AM, dbeken <removed_email_address@domain.invalid> wrote:
>
>> last time I didn?t get a solution for my problem of interpolating and
>> decimating using a sinusoidal signal. Now i went even easier. I connected a
>> DC Power Supply (with 0.01A max limit) to my LFRX daughterboard. The USRP2
>> Source is only connected to a Scope Sink. But with 0.5 Voltage input, I only
>> see very small variations about the 0 line. The current is 0.01 A. So, what
>> can I do to see a signal?
>
> Make sure you don't have AC coupling turned on in your scope block.
>
> Johnathan

where do you see if dc or ac coupling is on in the scope sink ?

thanx
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