On Fri, 2017-03-17 at 14:36 -0400, Andy Walls wrote: > > Hi Sverre, > > > > hm, I've taken the time to look at pulse_shaper_bs.py[1], but I didn't > > fully understand what it does, mathematically/technically. > > > > > > > > It does in fact look like a very complicated way to do something that > > I'm not 100% sure wouldn't be covered by a simple FIR filter, but > > lacking a bit of documentation, and not finding the time to go into > > all the if()-cases right now, can you explain what it does? > > Hi Marcus: > > The pulse shaper bs block looks like an MSK I or Q bit to half-sine > pulse convertor, which one would use when generating MSK as an Offset > QPSK with half-sine shaped pulses. > Definitely the hard way to generate MSK, when using FSK with square > pulses is much easier. > > The pulse shape block seems fairly inflexible WRT sample rate, and is > using integers - as if it were a prototype for an FPGA implementation.
FWIW: The original pulse shaper implementation seems to be described in section 7.3.1 of this paper: https://brage.bibsys.no/xmlui/bitstream/handle/11250/2369767/350718_FULLTEXT01.pdf?sequence=1&isAllowed=y See appendix A, Listing A.3 for the original C++ code. This paper describes the current python pulse shaper implementation in question on pages 26 and 27: https://brage.bibsys.no/xmlui/bitstream/handle/11250/2405115/14772_FULLTEXT.pdf Which all would have been very nice to have with the original posed question. -Andy > Sverre, > The whole block would be much faster in C++ instead of python. > If it is just straight MSK that you need to generate, just use a repeat > block followed by a frequency modulator block and then a filter block to > limit the occupied bandwidth. > > I'm not that familiar with DSRC, but that's an odd pulse shaping for ASK > (ASK usually has no pulse shaping). Also ASK is usually horrible for > anything but the simplest remote functions. Is another aspect of the > system that uses PSK or FSK? > > -Andy > > > You told me the bit rate, but not the sampling rate of the USRP sink, > > but that would be very relevant here! > > > > Best regards, > > Marcus > > > > [1] > > https://github.com/sverrets/dsrc/blob/master/gr-dsrcmod/python/pulse_shaper_bs.py > > On 03/17/2017 01:04 PM, Sverre Turter Sandvold wrote: > > > > > Hi, thank you for answering! > > > > > > > > > I'm using a USRP N200 with a CBX daughterboard. > > > > > > > > > > > > I think the problem is that the block "pulse_shaper_bs" is not > > > processing fast enough, and then the USRP Sink don't receive data > > > fast enough and this causes the underrun. > > > > > > > > > > > > I want to send a packet with bits to a DSRC-unit. The main specs > > > are: > > > > > > * Carrier Frequency: 5,8025 GHz > > > * Modulation: Two level amplitude modulation > > > * Data Coding: FM0 > > > * Bit rate: 500 kbit/s > > > > > > SverreTS > > > > > > > > > > > > > > > > > > ____________________________________________________________________ > > > Fra: Discuss-gnuradio <address@hidden> på vegne av Marcus Müller > > > <address@hidden> > > > Sendt: 16. mars 2017 19:38 > > > Til: address@hidden > > > Emne: Re: [Discuss-gnuradio] Problem with underruns > > > > > > Hi SverreTS, > > > > > > > > > can you be more specific? Why do you think it's the problem? Can you > > > give us a rough idea of what your program does? At which rates are > > > you working, with which hardware, and so on. > > > > > > > > > > > > Best regards, > > > > > > Marcus > > > > > > > > > > > > On 03/16/2017 01:52 PM, Sverre Turter Sandvold wrote: > > > > > > > Hi! > > > > > > > > > > > > Need some help with this gnuradio-block called "pulse_shaper_bs": > > > > https://github.com/sverrets/dsrc/blob/master/gr-dsrcmod/python/pulse_shaper_bs.py > > > > used in this program: https://github.com/sverrets/dsrc . I got alot > > > > of underruns and think the "pulse_shaper_bs" is causing the problem. > > > > > > > > > > > > > > > > Anyone want to help? > > > > > > > > > > > > SverreTS > > > > > > > > > > > > > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio