Well, I don't really know why you don't get the same n_rcvd as default benchmark. I have never seen that benchmark. Maybe you have some silly "error" when checkin number of wrong bits. Make flowgraph with both your and default correlator and see what's going on. I would probably do that.
Nemanja On Thu, Jun 20, 2013 at 4:13 PM, yeran <yeran0...@hotmail.com> wrote: > Hi Nemanja, > > Thanks for your kind reply! > > I'm trying to design a program which will achieve the same result as the > default benchmark, because I'll use the default benchmark in some part of > the program too. So I use the default threshold 12. I want to make sure > that is means that in the 8 Byte access code, at maximum 12 bits can be > wrong for gnuradio to "find the pkt". Is this correct? > > Specifically, I defined a list 'ac' which is exactly the 64-bit access > code. And then compare each of the received 64-bit data with the relevant > bit in ac. If they match more than 64-12=52 bits, one packet is found. > > But the test result is that using this code will always find more than the > n_rcvd number of packets in default benchmark. (in benchmark, n_rcvd is the > total number of packets found). > > Looking forward to your further suggestions! Thanks a lot! > > Best, > Ada > > ------------------------------ > Date: Thu, 20 Jun 2013 08:52:09 +0200 > Subject: Re: [Discuss-gnuradio] correlator in gnuradio > From: vlasi...@gmail.com > To: yeran0...@hotmail.com; discuss-gnuradio@gnu.org > > > Well, I was studying correlator, and it's pretty straight forward > approach. If you specify threshold of k bits, then it will output 0x3 every > time it finds pattern that differs from given preamble at max. k bits. > Maybe you can provide some more information. In my designs I usually use > threshold 0. > > Best > Nemanja > > > On Wed, Jun 19, 2013 at 10:21 PM, yeran <yeran0...@hotmail.com> wrote: > > Hi everyone, > > I'm trying to learning the algorithm of the correlator in > generic_mod_demod.py. Then use the similar algorithm in my own block. > > In the file digital_correlate_access_code_bb.cc, according to my > understanding, the original algorithm is compare each bit of the 8-Byte > access code with the default 8-Byte access code. If the wrong bits is less > than 12 bits (the threshold), then it is decided as "access code found". > > I wrote a file to detect access code, too. I compared each of the 8-Byte > with the default access code. If the correct bits is more than (64bits - 12 > bits), then it is decided to be found. > > But when I us my program, when decoding the same data, I can always found > more than the original method. For instance, when I use benchmark's > original method, I can get n_rcvd=570 pkt, which means in the > generic_mod_demod correlator, 570 access code are found. But my program > found 577. > > Has anybody been study the correlator block before? and see if there is a > misunderstanding in my work? > > Thanks in advance! > > Ada > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > -- > Nemanja Savić > -- Nemanja Savić
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