[Discuss-gnuradio] gnuradio C++ engineer wanted
I hope no one minds me putting this up here: Path Intelligence Ltd is a multiple award winning start-up company, whose most recent achievement is winning the UK SEEDA Enterprise Hub Showcase event, ahead of more than fifty other innovative start-ups from Oxford and the broader South East region. Although our operations have been historically based in the UK we are looking to broaden into other territories (particularly the US as we have recently closed a round of funding with a Silicon Valley based VC). As a Principal Engineer, you will: o Re-architect the system to prepare for upcoming enhancements o Optimize the existing C++ code base o Assist the existing management team to continue to build the technical team both in the UK and the US o Work closely with the CEO to complete product development and implement new research initiatives o Help shape the future of Path Intelligence Ltd o Work with a young, energetic and ambitious team o Receive an attractive remuneration package The following skills are essential: o Expert C++ skills o Solid understanding of RF o Ability to formally communicate architectural designs and plans o Proven team working experience, within teams consisting of both technical developers and non-technical project/business owners (experience in working with remote teams a bonus) o Experience integrating open source technologies in application development o Proven problem solving skills o Self Starter Desired skills: o Proficiency in Python o Knowledge of RF location techniques o Experience in working on software defined radio projects and/or Gnuradio o Knowledge and experience with RF and FPGA hardware development About Path Intelligence: Path Intelligence has developed an innovative product using software defined radio, that is able to locate mobile phones highly accurately within a confined area. In the first instance Path Intelligence is using this technology to provide shopping centres and mass transit stations with information on people flow through their space. However, this is just the tip of the iceberg of what is possible with this technology and Path Intelligence has plans to move into many different industries, applications and geographies. Path Intelligence has recently concluded a funding round with a Silicon Valley venture capital firm that focuses on leading edge technologies and plans to aggressively expand into the US and Europe in the near future. At Path Intelligence, our goal is to provide the most timely and accurate location information available.To that end, we strive very hard to hire the smartest people. We’re an environment where great ideas shape our vision and true passion drives us to the best solutions to the most challenging problems. Salary: Competitive + Benefits, with the potential for equity Location: UK/US Contact: Sharon Biggar ([EMAIL PROTECTED]) Reference: GNUPATHCP ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Mysterious rapid-capture bug
John Bratteli wrote: > I brought this up some time ago, but no one was able > to help me. I have a little more information now, so > maybe we can make progress. > > In the application we are working on, we would like to > perform continuous split-second captures from the USRP > over days at a time. Unfortunately, it hangs after an > indeterminate amount of time. The power of the > computer running the program seems to have some > bearing on the time before crash, but it is still > pretty random. We have run times from 2min to 23hrs. > I had a similar problem and it was really nasty to figure out, as far as I remember it turns out it was due to memory fragmentation in the Kernel USB buffer causing the USB bus to be starved of data. I think it was Johnathan and Eric that tracked it down so they might have more information. Possibly more importantly the fix was to change the usrp.source to include fusb_block_size=4096 and fusb_nblock=16. Hope that helps. Toby ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Re: gnuradio trellis
Achilleas, Okay. I am primarily interested in the equalization for the time being, but I can see it would seem to make a lot of sense to create the sequence detection as well. In terms of making the isi lookup table for multidimensional modulations, whats the best way to go about it? Is there any published literature on this that I could base it on? Kind Regards, Toby Anastasopoulos Achilleas wrote: > Oliver, > > You are right: > Trellis implementation supports multi-dimensional constellations etc > (through the metric calculation block abstraction, etc), however, > in the examples and the supporting fsm_utils.py files > I have not included support for GMSK, and the automatic > generation of lookup tables for ISI channels is for-one dimensional > modulations. > I think the extension should be straightforward and I'll be glad > to help you in this. > > May I suggest you separate the task into two subproblems for reasons > of usability by others: > > 1) GMSK sequence detection in AWGN channels > (which is a modulation with memory and in theory requires Viterbi > even in the absense of ISI), > and > 2) GMSK equalization (ie, GMSK + ISI channel + noise -> Viterbi) > > For 1) a modification of test_tcm.py is required and hopefully > an "automated" way to project any given GMSK modulation to its > N-dimensional components; maybe a python implementation of > the Gram-Schmidt (QR decomposition) algorithm... > > For 2) a modification of the test_viterbi_equalization.py or > test_viterbi_equalization1.py is required together with > generalizing the code in fsm_utils.py to generate the lookup table > for multi-dimensional modulations. > > best, > Achilleas > > On Wed, 27 Sep 2006, Toby Oliver wrote: > >> Achilleas, >> >> I hope you don't mind me emailing you, but I have just been having a >> look at your gnuradio trellis code which is very cool. In fact I was >> looking to try it out as an equalizer on some GMSK signals but it seems >> the make_isi_lookup in fsm_utils currently only supports one-dimensional >> modulations. Am I right in assuming the I will need to extend this for a >> GMSK signal? Or am I missing something? >> >> Thanks for adding this to Gnuradio, its a really useful (and incredibly >> flexible) addition. >> >> Kind Regards, >> Toby >> >> >> ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] using 2 channels on 2 USRPs
Hi, Has anyone used 2 USRPs to simultaneously receive 4 different frequencies using DBSRX cards? I just wanted to check the correct way of linking it all up. As I understand it the correct combination is: fg=gr.flow_graph() u0=usrp.source_c(0,decim,2,0,0) u1=usrp.source_c(1,decim,2,0,0) u0.set_mux(0x3210) u1.set_mux(0x3210) tune_result0=usrp.tune(u0,0,usrp.selected_subdev(u,(0,0)),freq0) tune_result1=usrp.tune(u0,1,(1,0),freq1) tune_result2=usrp.tune(u1,0,(0,0),freq2) tune_result3=usrp.tune(u1,1,(1,0),freq3) de_inter0 = gr.deinterleave(gr.sizeof_gr_complex) de_inter1 = gr.deinterleave(gr.sizeof_gr_complex) fg.connect(u0,de_inter0) fg.connect((de_inter0,0), ...) fg.connect((de_inter0,1), ...) fg.connect(u1,de_inter1) fg.connect((de_inter1,0), ...) fg.connect((de_inter1,1), ...) Is the mux correct for this? Or do I need to do something else to ensure the correct DDC works on the correct channel? Cheers, Toby ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] question and a couple of interesting links
Hi, Firstly a quick question, can anyone give me some pointers on the how to calculate the optimal parameters for the least mean squared decision feedback equalizer in Gnuradio, or is this a case of going a reading up in something like Proakis? Secondly I came across a couple of interesting projects which might be useful to some people here (apologies if you are aware of them already): - streamit (http://cag.csail.mit.edu/streamit/) a programming language and a compilation infrastructure from MIT which is basically concerned with optimising streaming of data. It does a number of things, including algebraic simplification of stateless filters (e.g., FIR, FFT, DCT) and stateful filters (e.g., IIR, feedback loops). - spuc (http://spuc.sourceforge.net/) a GPL C++ signal processing library Regards, Toby ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Gnuradio in England
I am working on a mobile phone related Gnuradio application and I was wondering if there is anyone in England who has been using the system who would be interesting in collaborating? It wouldn't have to be just for the intellectual challenge, as I have a small amount of funding available for the right person. Mail me if you are interested. Kind Regards, Toby ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Segmentation fault
Hi Sachi, I had a similar problem running Fedora Core 3 as a vmware guest (i.e. segmentation fault in libfftw3f). Rebuilding fftw *without* --enable-sse as a configure option fixed it for me. I hope that helps. Cheers, Toby Sachi wrote: Hi, Eric I have checked it with gdb, it returned: (gdb) continue Continuing. Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1208514880 (LWP 1030)] 0x007eb73f in m2fv_64_0 () from /usr/local/lib/libfftw3f.so.3 Then gdb stopped. I didn't use any breakpoints in the code. BTW: I can run the demos provided by wxPython. Can you sqeeze any information from this? Or what should I do next? Thanks for your time Sachi --- Eric Blossom <[EMAIL PROTECTED]> wrote: On Sat, Apr 02, 2005 at 01:21:53PM -0500, Raphael Cobo wrote: Hello, I think this is a bug in the underlying libraries for the GUI in a specific distribution. I think that people that use Fedora will experience the same bug. Am I right? Can somebody confirm that the SSE segmentation fault only happens in Fedora or Redhat? FYI, It's highly unlikely that this has anything to do with SSE. That's just the last message printed before it seg faulted. Again, a quick look with gdb will provide real data... In the stab-in-the-dark department, do the wxPython demos run OK on your system? Not our demos, the ones that you can download from wxpython.org. Eric __ Do you Yahoo!? Yahoo! Personals - Better first dates. More second dates. http://personals.yahoo.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
