[USRP2]Receiving a DC voltage


#1

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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#2

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


#3

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/2008-10/msg00465.html

Karthik


#4

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


#5

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/2008-10/msg00465.html

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