Re: [Discuss-gnuradio] 8-bit samples on USRP2 at 33.333Msps

2011-11-09 Thread Josh Blum
>> There is a configurable scale factor (see the stream args in the grc >> block). It defaults to a value that gives you the upper 8. >> >> -Josh >> > I noticed there was a "scalar=1024" option. Is that just a multiplier > that UHD applies on the host > side for 8-bit samples, or does it affect

Re: [Discuss-gnuradio] 8-bit samples on USRP2 at 33.333Msps

2011-11-09 Thread Marcus D. Leech
My AMD Athlon(tm) II X4 620 Processor does jyst fine with 50Msps FFT plotter. Just sayin :-) Hmmm, is the Athlon II generally better than the Phenom II (insns/clock? ). I suppose I should try it on my 1090T as well, which is rather faster than the 1055T I tried it on tonight. But that mean

Re: [Discuss-gnuradio] 8-bit samples on USRP2 at 33.333Msps

2011-11-09 Thread Josh Blum
On 11/09/2011 07:07 PM, Marcus D. Leech wrote: > Just did a quick test of 8-bit samples on a USRP2, on one of my 6-core > AMD machines. > > I can get to 33Msps with a fairly simple SOURCE-->MULT-->FFT_SINK > flow-graph, but anything more complicated causes overruns. > > If I try 50Msps, I get n

[Discuss-gnuradio] 8-bit samples on USRP2 at 33.333Msps

2011-11-09 Thread Marcus D. Leech
Just did a quick test of 8-bit samples on a USRP2, on one of my 6-core AMD machines. I can get to 33Msps with a fairly simple SOURCE-->MULT-->FFT_SINK flow-graph, but anything more complicated causes overruns. If I try 50Msps, I get near-continuous overruns. This is on an AMD Phenom II X6-10

[Discuss-gnuradio] 8-bit samples

2010-07-12 Thread Jeffrey Lambert
Hello, I have looked everywhere, including through the Verilog FPGA code and in the Python scripts, but nowhere can I find how to use 8-bit samples. According to usrp_fft.py, the -8 and --no-hb options should allow a decimation factor of 4, but nothing I can do will return anything but zeroe

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Chris Stankevitz
Matt Ettus wrote: Look at the samples in the scope sink. Do you see a pattern of A A B B C C D D, meaning instead of unique samples, is every one repeated? If so, it means that the halfband decimator is probably not being bypassed properly. Here are the first 100 8 bit samples from the

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Dan Halperin
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On Jul 11, 2008, at 11:24 AM, Chris Stankevitz wrote: Matt Ettus wrote: Remember that while the ADCs are 12 bits, we carry 16+ bits of precision throughout the signal processing. How do you get 16 bits of precision from a 12 bit ADC? What does

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Chris Stankevitz
Matt Ettus wrote: Remember that while the ADCs are 12 bits, we carry 16+ bits of precision throughout the signal processing. Matt, How do you get 16 bits of precision from a 12 bit ADC? What does 16+ mean? I'm looking at the shorts coming from the USRP and I'm seeing values in the range

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Matt Ettus
Chris Stankevitz wrote: Johnathan Corgan wrote: You *may* be seeing an artifact of the truncation of the ADC samples. Johnathan, others: I believe this is not the case. When I download 16 bit samples from the USRP and remove the 4LSBs myself, the spectrum looks normal. When I ask the US

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Matt Ettus
Chris Stankevitz wrote: Johnathan Corgan wrote: You *may* be seeing an artifact of the truncation of the ADC samples. Johnathan, others: I believe this is not the case. When I download 16 bit samples from the USRP and remove the 4LSBs myself, the spectrum looks normal. When I ask the US

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Chris Stankevitz
Johnathan Corgan wrote: You *may* be seeing an artifact of the truncation of the ADC samples. Johnathan, others: I believe this is not the case. When I download 16 bit samples from the USRP and remove the 4LSBs myself, the spectrum looks normal. When I ask the USRP for 8 bit samples, the

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-11 Thread Chris Stankevitz
Johnathan Corgan wrote: You *may* be seeing an artifact of the truncation of the ADC samples. Johnathan: Thank you, that's exactly what it looks like. Adding USRP pga gain didn't help though. I'll get back to the group... Chris ___ Discuss-gnu

Re: [Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-10 Thread Johnathan Corgan
On Thu, Jul 10, 2008 at 10:39 PM, Chris Stankevitz <[EMAIL PROTECTED]> wrote: > 1. Why does b) show a lobe while a) does not? > 2. Why do b) and c) show lobes at the same pixels (vs shifted .5 MHz)? You *may* be seeing an artifact of the truncation of the ADC samples. In 8-bit mode, only the uppe

[Discuss-gnuradio] 8 bit samples have an odd spectrum

2008-07-10 Thread Chris Stankevitz
Hello, a) Here is a screenshot of 16 bit noise @ 12 MHz: http://img224.imageshack.us/img224/8981/16bitsb0.png b) Here is a screenshot of the same noise with 8 bit samples: http://img60.imageshack.us/img60/5852/8bitqg7.png c) 8 bit noise, tuned to 12.5 MHz http://img224.imageshack.us/img224/1596