I have a question about the basic RX/TX boards. What should I see if I
hook the basic TX board to an oscilloscope if I send out a QPSK
signal? Here is what I do:
I generate a QPSK signal in GnuRadio
I send the signal to a complex file source and the signal looks right
I send the signal to the complex USRP source and have a BasicTX on
it. The outputs TXA and TXB are hooked up to a oscilloscope on channel
1 and 2 respectively.
Now, what should I see on the oscilloscope? Is it the baseband signal?
How does the I and Q phases get mixed together? Does that depend on
the mux values? Unfortunately I couldn’t find a good block diagram of
the TX path on the wiki, i.e., the link to [A system block diagram of
the USRP receiver and transmitter path] on the wiki page
“http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral” is dead.
On Sat, 2006-05-27 at 12:16 -0700, Thomas S. wrote:
Now, what should I see on the oscilloscope? Is it the baseband signal?
How does the I and Q phases get mixed together? Does that depend on
the mux values? Unfortunately I couldn’t find a good block diagram of
the TX path on the wiki, i.e., the link to [A system block diagram of
the USRP receiver and transmitter path] on the wiki page
“http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral” is dead.
If you set the carrier frequency to 0 you will see the I signal on the I
channel out and the Q signal on the Q channel out. This will only be
useful with the LFTX board since the BasicTX will block DC.
If you set the carrier frequency to something other than 0, then the I
and Q signals will be upconverted and sent to the outputs. As long as
the carrier frequency is greater than your signal bandwidth, then you
only need either the I output or the Q output since they are now
double-sided real signals. You can still use the I and Q connectors
with an image-reject mixer if you need.
I send the signal to a complex file source and
Does that depend on
the mux values? Unfortunately I couldn’t find a
good block diagram of
the TX path on the wiki, i.e., the link to [A
system block diagram of
the USRP receiver and transmitter path] on the
wiki page