|
From: | Laura Huddleston |
Subject: | Re: [Discuss-gnuradio] Frequency hopping code printing UUUUU |
Date: | Wed, 2 May 2018 14:09:34 +0000 |
Hey Derek,
I ran the benchmark_rate and got the following: $ cd opt/gnuradio/default/lib64/uhd/address@hidden examples]$ ./benchmark_rate --rx_rate 25e6 --tx_rate 25e6 [INFO] [UHD] linux; GNU C++ version 4.8.5 20150623 (Red Hat 4.8.5-16); Boost_105300; UHD_3.11.0.git-776-gdca39145 [WARNING] [UHD] Unable to set the thread priority. Performance may be negatively affected. Please see the general application notes in the manual for instructions. EnvironmentError: OSError: error in pthread_setschedparam Creating the usrp device with: ... [INFO] [USRP2] Opening a USRP2/N-Series device... [INFO] [USRP2] Current recv frame size: 1472 bytes [INFO] [USRP2] Current send frame size: 1472 bytes [WARNING] [UHD] Unable to set the thread priority. Performance may be negatively affected. Please see the general application notes in the manual for instructions. EnvironmentError: OSError: error in pthread_setschedparam Using Device: Single USRP: Device: USRP2 / N-Series Device Mboard 0: N200r4 RX Channel: 0 RX DSP: 0 RX Dboard: A RX Subdev: SBXv3 RX TX Channel: 0 TX DSP: 0 TX Dboard: A TX Subdev: SBXv3 TX Setting device timestamp to 0... [WARNING] [UHD] Unable to set the thread priority. Performance may be negatively affected. Please see the general application notes in the manual for instructions. EnvironmentError: OSError: error in pthread_setschedparam Testing receive rate 25.000000 Msps on 1 channels [WARNING] [UHD] Unable to set the thread priority. Performance may be negatively affected. Please see the general application notes in the manual for instructions. EnvironmentError: OSError: error in pthread_setschedparam Testing transmit rate 25.000000 Msps on 1 channels Benchmark rate summary: Num received samples: 250258351 Num dropped samples: 0 Num overflows detected: 0 Num transmitted samples: 250216989 Num sequence errors: 0 Num underflows detected: 0 Num late commands: 0 Num timeouts: 0 Done! I assume this means it is working properly (since when I try it with a transmit/receive rate of 50MS/s, it simply prints a bunch of UUUUU). Following your suggestion, I changed the sample rate to 25M and added a waterfall plot to see what was happening. It now starts off printing UUUU then switches to UDDUUDUD. Attached is the revised flowgraph. Any help would be much appreciated Laura From: Derek Kozel address@hidden
Sent: Tuesday, May 1, 2018 8:46 AM To: Laura Huddleston Cc: address@hidden Subject: Re: [Discuss-gnuradio] Frequency hopping code printing UUUUU Hi Laura,
With 16 bit samples, the default, a 1 Gigabit Ethernet link can only carry 25 MS/s. Thankfully, that's complex IQ samples, so while Nyquist applies the bandwidth is 1x the highest frequency.http://files.ettus.com/manual/page_usrp2.html The N200 has a fixed master clock rate (ADC/DAC rate) of 100 MHz. Only integer factors of that will be possible, if you look at your console output there should be a line saying that 40 MS/s is not a possible value and it is being set to a different one,
either 25 MS/s or 50 MS/s. Either of those isn't what you are expecting so your flowgraph will not produce the correct values. 25 MS/s would be the best rate for you to use as it fits your 20 MHz wide signal with some margin on either side to accommodate filter
roll off. It is also an even divisor of the master clock rate so you'll have better filter performance than using a rate that is an odd divisor.
On Tue, May 1, 2018 at 2:15 PM, Laura Huddleston
<address@hidden> wrote:
I have attached them now. sorry about that. |
chirp_hopper.grc
Description: chirp_hopper.grc
[Prev in Thread] | Current Thread | [Next in Thread] |