# Re: gr::blocks::peak\_detector2\_fb un reproducible behavior **URL:** \ **Category:** GNU Radio\ **Created:** [December 12, 2014, 5:31pm UTC](https://www.ruby-forum.com/t/re-gr-peak-detector2-fb-un-reproducible-behavior/233430 "2014-12-12T17:31:10Z")\ **Posts on this page:** 1\ **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:** [December 12, 2014, 5:31pm UTC](https://www.ruby-forum.com/t/re-gr-peak-detector2-fb-un-reproducible-behavior/233430/1 "2014-12-12T17:31:10Z")
Hello, a short update before the weekend: I was not able to hunt down the problem of non-reproducibility, but another one. I had an input signal, which had its max. value as the first value getting over the (very high) threshold. This value is not taken as the peak, but any second but largest value within the look\_ahead window. The reason for that is that in line 73ff. of peak\_detect\_fb\_impl.cc d\_peak\_val/d\_peak\_ind are not set, but only with the next iteration, then starting from line 84f (because any value \> -inf). A suitable test case for the qa\_peak\_detector2.py file has input vectors data = [0, 0, 10, 3, 4, 5, 6, 7, 8, 9, 5, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0] expected\_result = (0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) One could change line 73ff. like this d\_peak\_val = iptr[i]; d\_peak\_ind = I; but, then there remains a problem with this test case: data = [10, 0, 1, 3, 4, 5, 6, 7, 8, 9, 5, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0] expected\_result = (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) The first run of work() will output 0 items, if the look\_ahead window is larger than noutput\_items (=the amount of \_in\_put items), and the assert(noutput\_items \>= 2) hurts. Subsequent calls of work() will output 0 items as long as the amount of regarded items is smaller than the window length. Can anybody imagine/explain, why this whole thing stalls? Do you have any ideas how to get out of this miserable position? Thank you for any help. Best regards Stephan Ludwig – Robert Bosch GmbH Corporate Sector Research & Advance Engineering, Communication Technology (CR/AEH4) Renningen 70465 Stuttgart GERMANY > **[Want to know how to live #LikeABosch?](https://www.bosch.com/)** > > Moving stories and inspiring interviews. Experience the meaning of "invented for life" by Bosch completely new. Visit our international website. Tel. +49(711)811-8809 Fax +49(711)811-1052 Mobile +49(172)5630639 removed\_email\_address@domain.invalid Registered Office: Stuttgart, Registration Court: Amtsgericht Stuttgart, HRB 14000; Chairman of the Supervisory Board: Franz Fehrenbach; Managing Directors: Dr. Volkmar Denner, Dr. Stefan Asenkerschbaumer, Dr. Rolf Bulander, Dr. Stefan Hartung, Dr. Dirk Hoheisel, Christoph Kbel, Uwe Raschke, Wolf-Henning Scheider, Dr. Werner Struth, Peter Tyroller