# Gnuradio on ubuntu touch **URL:** \ **Category:** GNU Radio\ **Created:** [July 14, 2014, 5:21pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953 "2014-07-14T17:21:32Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [July 14, 2014, 5:21pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/1 "2014-07-14T17:21:32Z")
Is gnuradio able to run on Ubuntu Touch? I want to use my tablet with gnuradio and rtl-sdr. Do you guys think its possible with Ubuntu Touch? Or there is another way to do it? Thanks Regis – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [July 14, 2014, 5:55pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/2 "2014-07-14T17:55:32Z")
Hi Regis, I don’t know anything about Ubuntu touch. But if it’s a proper linux, then yes, GNU Radio will run on it, probably. The question is however if your tablet is powerful enough to do something useful with the data, since we tend to use strong computers to do realtime signal processing. Greetings, Marcus ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [July 14, 2014, 6:47pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/3 "2014-07-14T18:47:27Z")
Hi Marcos, thank you for your reply. What would be the minimum required configuration for a computer to run gnuradio without problems? Regis – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49325.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49325.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [July 14, 2014, 6:53pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/4 "2014-07-14T18:53:25Z")
Running Linux 🙂 The thing is that GNU Radio is but a framework, and has little computational overhead; the load you are seeing is primarily defined by the signal processing you do, so I can’t answer that question. I like to bring up a analogy: It’s like asking what the minimum requirement for playing games on a computer is. If you’re only playing a text-based adventure, then a graphic calculator will be fine; if you’re aiming for photorealistic graphical effects, you will need something more beefy. With best regards, Marcus ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:34am UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/5 "2014-08-06T04:34:33Z")
It might be Disk I/O is too slow. Try going from RTL-SDR source to Null Sink. ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 5, 2014, 11:48pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/6 "2014-08-05T23:48:19Z")
Hi Marcus, back to this discussion after a few tests. I decided to try RTL-SDR and GNU Radio on a Single Board Computer. I’m currently using the Banana Pi which is a ARM Cortex-A7 dual-core, 1GHz, Mali400MP2 GPU, 1GB DDR3 DRAM, using a debian based system. The first thing I tried was just a simple RTL-SDR Source to File Sink - just saving the receiving data to a file at 2e6 sample\_rate. The problem is that I get the “0” characters on the terminal indicating overflow status. I don´t know if I’m doing something wrong or if the banana pi can´t handle real-time signal process. What do you think about that? – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49773.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49773.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 2:26pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/7 "2014-08-06T14:26:03Z")
On 08/06/2014 04:56 AM, Marcus M. wrote: > overhead, which includes at least one copy from libusb/rtl-sdr buffer > Greetings, > Marcus > Also, the rPI (and clones) is a pretty-anemic CPU. Think of it as being > about 1/5th to 1/8th as powerful as your garden variety desktop X86 > machine. I think the culprit here is a mix, though, as Marcus M. says. Even a class-10 SD card is about 1/5th as fast as a good hard disk or SSD. ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 10:57am UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/8 "2014-08-06T10:57:46Z")
We don’t have much optimization for ARMs yet, and I assume that the rtl-sdr source somewhere has to convert from whatever comes through USB into floats. Furthermore, USB2 bulk transfer has a maximum packet length of 512B [citation needed], which would at an assumed 2B/complex equal but 256 == 2^8 Samples/package. Now let 1MS/s \approx 2^20 S/s = 2^12 USB packets per second. That _can_ be lot for a CPU running at 1GHz, because a USB handler in the Kernel has to handle each of them, they have to be put through libusb (which is luckily very efficient) and then converted by rtl-sdr/gr-osmo into something that your flowgraph can deal with. Then you get the GNU Radio scheduling overhead, which includes at least one copy from libusb/rtl-sdr buffer to a GNU Radio buffer, and then you get the filesystem overhead, which can be significant depending on what kind of file system you use. Then you get the overhead of accessing the storage device. I don’t know the banana pi, but I’d take a chance and say it’s a USB storage device, so you get the same hassle as on the RTL dongle side, but on this side with higher data rates. Or, you are storing to an SD card, which could simply be too slow, as Vanush correctly assumes (trick: most SD cards today have a “Class N” printed on them; that’s a usually slightly exaggerated multiplicator for a 2MB/s write rate. Greetings, Marcus ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 3:45pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/9 "2014-08-06T15:45:52Z")
I tried what Vanush said and just connected RTL-SDR Source to a Null Sink and got no overflows. I’m using a class 10 sd card, that must be the problem. I did some demodulation with no problem, but when I add a Low Pass Filter, the overflow happens again. Would the filter do the same thing as the file sink and buffer the data causing the overflow? – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49799.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49799.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:00pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/10 "2014-08-06T16:00:08Z")
On those single board computers I don’t bother writing to SD. I just route it through the network (assuming large enough bandwidth) to another graph or Python script that dumps it to a disk with faster storage bus. You can use gr-zmqblocks for that. On Wed, Aug 6, 2014 at 11:51 PM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 3:52pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/11 "2014-08-06T15:52:24Z")
The overflow is not a result of buffering; in fact, buffering helps. overflows happen because at any bottleneck in your processing chain, samples start to stagnate, causing back pressure. When all buffers are filled, there’s nothing the rtl source can do but drop samples. That’s an overflow. A computationally intense filter might also lead to overflows, but here it’s because your CPU can’t keep up with the sample rate, whereas with the file sink, your storage can’t sustain the write rates. Greetings, Marcus ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:09pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/12 "2014-08-06T16:09:40Z")
I actually don’t need to write to a file. I just did to test the hardware (I thought writing to a file would be the most simple task). What I really want to do is demodulate the signal and measure the signal strength. That seems to be working fine (no overflows) as long as I don’t use a filter on the RTL-SDR Source. – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49802.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49802.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:19pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/13 "2014-08-06T16:19:48Z")
Sample rate → 2M cutoff → 135k transition width → 10k – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49804.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49804.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:22pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/14 "2014-08-06T16:22:47Z")
Try making the transition width sloppier, like 50k On 2014-08-06 10:17, rejunte wrote: > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [2] Links: ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:15pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/15 "2014-08-06T16:15:38Z")
What are the parameters of your filter? Sample rate, cutoff, and transition width? On 2014-08-06 10:08, rejunte wrote: > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [2] Links: ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:32pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/16 "2014-08-06T16:32:19Z")
Tried that, but still ocurring overflow. Another thing I had was that on my computer I was using a complex to mag^2 → single pole IIR filter → log10 → multiply const (10) to measure the signal strength that is also causing overflow on the single board computer. If I put a RMS block instead, no overflow occurs. – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49807.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49807.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 4:49pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/17 "2014-08-06T16:49:38Z")
Try decimating after the filter, before you start computing log10 at the input rate. There’s no need to do those calculations at the original sample rate once you’ve computing complex-to-mag\*\*2 and filtered. On 2014-08-06 10:30, rejunte wrote: > – > View this message in context: > [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49807.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49807.html) [1] > Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [2] Links: ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 5:12pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/18 "2014-08-06T17:12:51Z")
doing your computations on a reduced sampling rate always makes a lot of sense. Also, if you do complex to mag? prior to filtering, you get the power in the overall nyquist band ignoring power fluctuations that do not pass the low pass, and not the power in the pass band of the filter. Example: Assume we have a complex sine at frequency $f\>f\_\text{cutoff}$ $s(t) = e^{2\pi j f t}$. It has a constant mag? of $|s|^2 = 1$. Now, the low pass of a constant 1 is still 1. Now, let’s low pass first with a filter $h(t)$ and then mag?. Assume filter stop band attenuation is infinite, then $r(t) = h(t) \* s(t) = 0$ because $f\>f\_\text{cutoff}$. It follows that $|r|^2 = 0 \neq 1$. Yet another side note: have a look at the polyphase filter banks (PFBs) that are relatively new in GNU Radio, if you want to process multiple sub-bands at once. Greetings, Marcus ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 6:54pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/19 "2014-08-06T18:54:38Z")
That seems to be a little bit better. Still causing overflow occasionally, but I can work with it. But still can’t use the first low pass filter without overflow – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49816.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49816.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![rejunte](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/a9a28c/32.png) [@rejunte](https://www.ruby-forum.com/u/rejunte)\ **Post date:** [August 6, 2014, 6:59pm UTC](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953/20 "2014-08-06T18:59:59Z")
The first filter is a low pass filter connected to the RTL-SDR Source. After this filter I demodulate the signal and compute the signal strenght – View this message in context: [http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49818.html](http://gnuradio.4.n7.nabble.com/gnuradio-on-ubuntu-touch-tp49315p49818.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). [Next page](https://www.ruby-forum.com/t/gnuradio-on-ubuntu-touch/230953.md?page=2)