# USRP Source replaced with a file source **URL:** \ **Category:** GNU Radio\ **Created:** [July 20, 2011, 9:46am UTC](https://www.ruby-forum.com/t/usrp-source-replaced-with-a-file-source/209684 "2011-07-20T09:46:49Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![luislavena](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/0ea827/32.png) [@luislavena](https://www.ruby-forum.com/u/luislavena)\ **Post date:** [July 20, 2011, 9:46am UTC](https://www.ruby-forum.com/t/usrp-source-replaced-with-a-file-source/209684/1 "2011-07-20T09:46:49Z")
Hi all To test my program several times with the same data I replaced the “USRP source” with a “file source” and a throttle: Old situation: self.uhd\_usrp\_source\_0 = uhd.usrp\_source( device\_addr=“addr=192.168.10.2”, io\_type=uhd.io\_type.COMPLEX\_FLOAT32, num\_channels=1, ) self.uhd\_usrp\_source\_0.set\_samp\_rate(samp\_rate) self.uhd\_usrp\_source\_0.set\_center\_freq(227360000, 0) self.uhd\_usrp\_source\_0.set\_gain(31.5, 0) New situation: self.file\_source = gr.file\_source(gr.sizeof\_gr\_complex_1, “/home/hoim/WorkDAB/Record8.dat”, False) self.throttle\_0 = gr.throttle(gr.sizeof\_gr\_complex_1, samp\_rate) My problem is that the generated output isn’t every time the same. Has GNU Radio something like a “Master reset” that I had to use before I start my programm? Or have somebody an idea what the origin of the inconsistence could be? Any help will be appreciated Thanks Michael ---
**Author:** ![SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7feea3/32.png) [@SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/u/SSMichael_HSSinSS_S)\ **Post date:** [July 21, 2011, 2:00am UTC](https://www.ruby-forum.com/t/usrp-source-replaced-with-a-file-source/209684/2 "2011-07-21T02:00:55Z")
On Wed, Jul 20, 2011 at 3:27 AM, Michael H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ``` > ) > > ``` > > GNU Radio something like a “Master reset” that I had to use before I > start my programm? Or have somebody an idea what the origin of the > inconsistence could be? > > Any help will be appreciated > > Thanks > Michael If you are running your program from the start each time and therefore removing your flow graph and rebuilding it, there is no need for a “reset” as all blocks have no state left over from the last run. There is some concept of a reset on certain blocks if you are running the flow graph multiple times in a row, though, but only the ones that store memory. So to answer your question is the always reliable “it depends.” It really depends on what you are doing to your signal. Most blocks will behave deterministically, but some (very few) use random numbers that might indicate a problem. If you have your own block(s) in there somewhere, they could also be causing a problem. Tom ---
**Author:** ![SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7feea3/32.png) [@SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/u/SSMichael_HSSinSS_S)\ **Post date:** [July 21, 2011, 5:30pm UTC](https://www.ruby-forum.com/t/usrp-source-replaced-with-a-file-source/209684/3 "2011-07-21T17:30:22Z")
Thanks for your answer Tom. I can isolate the fault to one of my blocks: [http://www.zhaw.ch/~hoim/howto\_ofdm\_symbol\_cutter\_cc.cc](http://www.zhaw.ch/~hoim/howto_ofdm_symbol_cutter_cc.cc) This block has two inputs, both have the same rate. If I connect the input to a file with throttle and the output to a “vector\_sink\_c” I see that the amount of data produced by the block is not always the same. My conclusion is that my block looses data. In this block I cut data out of a stream. Hence from time to time there are rest periods between the data production. Is this a problem for gnu radio? Should I allocate more memory for this block (how can I do that)? Any help will be appreciated Thanks Michael