Hi Nathan, Thank you very much for the suggestions. I will try them.
Regards, Hasini On Tue, Sep 20, 2016 at 11:44 PM, West, Nathan <n...@ostatemail.okstate.edu> wrote: > Do you really need the count, or do you just need some code to process > FFTs as the block computes them? I suspect a little bit more understanding > of GNU Radio will help you achieve what you want. > > Assuming that I have some DSP stuff I want to operate on an FFT output, I > would go about this in one of the following ways: > > Option 1) Write my DSP stuff in GNU Radio blocks in my own out of tree > module. This is the GNU Radio way to do things. The GNU Radio scheduler > will call my code to process FFT chunks as they are available. > > Option 2) Connect the output of the GNU Radio FFT block to something like > a gr-zeromq block or TCP block and write a receiver for this on my > application. This is better than a file (but can actually *look* like a > file if I use a something like zeromq's ipc:// protocol or a FD block > because an actual file flushes buffers (actually commits the write to disk) > at unknown times, so it may not actually be particularly close to > real-time. Then instead of reopening a file and seeking to the end every > time I can just read from the socket/icp FD to get all of the latest stuff. > > There's no way to get a count of FFTs that are written to the file because > the FFT block and the file block are not deterministicly scheduled. You > could use the performance counters to see how many items the file block has > read, but that's a horrible abuse of that counter and still doesn't > guarantee the number actually written to disk because you don't know when > the file buffer is actually being flushed. Rethinking the problem is likely > the best way forward. > > I highly recommend option 1 and option 2 as a last resort. Option 2 is > better for when you're no longer doing DSP and passing something like bits > to another process that's great at handling bits. > > On Mon, Sep 19, 2016 at 9:07 PM, Hasini Abeywickrama <hva...@gmail.com> > wrote: > >> Hi Nathan, >> >> That's not quite what I want. I do not want the file to have a certain >> number of FFTs. I want to have a counter which is dynamically updated as >> the FFTs are written to a file. Ideally I want to know when a new FFT is >> written to the file so I can trigger another function to process it. I need >> this to be done real time and that's why I'm looking for the most efficient >> way. >> >> Regards, >> Hasini >> >> On Tue, Sep 20, 2016 at 10:34 AM, West, Nathan < >> n...@ostatemail.okstate.edu> wrote: >> >>> >>> On Mon, Sep 19, 2016 at 6:57 AM, Hasini Abeywickrama <hva...@gmail.com> >>> wrote: >>> >>>> Hi Marcus, >>>> >>>> That's what I'm currently doing. It's not very efficient as I have to >>>> constantly check the file size. If I can have a counter that is increments >>>> each time an FFT is written to the file by the flow graph I would be able >>>> to trigger an event based on the counter value. That was my concern. >>>> >>>> Regards, >>>> Hasini >>>> >>>> On Sep 19, 2016, at 3:29 PM, Marcus Müller <marcus.muel...@ettus.com> >>>> wrote: >>>> >>>> If you need to do that externally, I'd just watch the file size and >>>> divide it by the item size (4B per floating point number) and by the FFT >>>> length. >>>> >>>> >>>> Best regards, >>>> >>>> Marcus >>>> >>>> On 09/18/2016 11:21 PM, Hasini Abeywickrama wrote: >>>> >>>> Hi Marcus, >>>> >>>> It's like I need to start reading and processing the file after a >>>> certain number of FFTs are being written to the file. For that I would need >>>> to maintain a counter and I'm trying to figure out how to do it. >>>> >>>> Regards, >>>> Hasini >>>> >>>> >>> You can do this with the head block. It let's N number of items through >>> and then stops the flowgraph. Set N to your certain number and then the >>> file will have N FFTs. >>> >>> >>> >>>> >>>> On Mon, Sep 19, 2016 at 2:58 PM, Marcus Müller < >>>> marcus.muel...@ettus.com> wrote: >>>> >>>>> What would you need that counter for? There's the 1/(FFT length) fixed >>>>> relation between samples processed and numbers of FFTs done, so this is >>>>> pretty much a redundant piece of info, but maybe I'm just missing the use >>>>> case. >>>>> >>>>> Best regards, >>>>> >>>>> Marcus >>>>> >>>>> On 09/18/2016 10:23 PM, Hasini Abeywickrama wrote: >>>>> >>>>> Hi all, >>>>> >>>>> I have a GNU Radio flowgraph which uses a USRP to receive a signal, >>>>> converts it to log power FFT and then writes the result to a file, using >>>>> File Sink. I want to have a counter which increments with each FFT written >>>>> to the file. >>>>> >>>>> Is there a way of maintaining and increasing count of the FFTs written >>>>> to the file, while the flowgraph is still running? >>>>> >>>>> >>>>> _______________________________________________ >>>>> Discuss-gnuradio mailing >>>>> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>> >>>>> _______________________________________________ Discuss-gnuradio >>>>> mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/ >>>>> listinfo/discuss-gnuradio >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >> >
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