On Tue, Jul 15, 2008 at 02:46:33PM +0200, Sebastiaan Heunis wrote: > Hi > > I was wondering if anyone could please help me? I'm doing some > measurements on the Microtune Cable modem module. I already modified > the .py file to be able to set the 3 gain stages independently. I am > trying to see how the gains should be set to get an input signal of > 2Vp-p to the ADC to be able to use the dynamic range as efficiently > as possible. From what I understand, pins 17 and 18 of the cable > modem module are the outputs that go to the ADC. This is a > differential signal, right? We don't have a differential probe, so I > am measuring pins 17 and 18 on 2 oscilloscope channels and then > displaying the difference of the two. This should give me the signal > that goes to the ADC, right? I'm inputting a 100MHz sine wave, so > this should be a 43.75MHz sine wave? Somewhere I am doing something > wrong, as this is not what I get. Can anyone who has done something > similar please tell me how to do it? > > Then I also have a few questions regarding the module itself. From > what I understand, the signal gets captured, amplified by the RF amp, > mixed down to 43.75MHz, amplified by the IF amp and then sent to the > ADC, right? > > Thank you for your help. > Sebastiaan
Hi Sebastian, Matt's used three different Microtune modules for the TV RX's. Below is a link to the first one he used, along with an app note re noise figure. The differences between the different modules aren't that big, mostly whether they do a second downconversion and the frequency of the IF. You can figure that stuff out by looking at gr-usrp/src/db_tv_rx.py http://comsec.com/usrp/microtune/4937-DI5-3x8899-2.pdf http://comsec.com/usrp/microtune/NF_tutorial.pdf Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
