# File Sink Behavior **URL:** \ **Category:** GNU Radio\ **Created:** [May 8, 2015, 7:56pm UTC](https://www.ruby-forum.com/t/file-sink-behavior/241887 "2015-05-08T19:56:06Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [May 8, 2015, 7:56pm UTC](https://www.ruby-forum.com/t/file-sink-behavior/241887/1 "2015-05-08T19:56:06Z")
I’m testing a radio by sending known data through from a file source, and file sinking the data at the end of the Tx/Rx loopback chain. I’m getting very specific erratic behavior with the contents of the output file. One of two things happens. First, the output data is perfect. Second, the first line of the input file is repeated once, and then the data is perfect there out. I’ll represent the behavior below: Line# InputFile.dat OutputFile.dat w/ Error 1 Hi how are you Hi how are you 2 1234567890 Hi how are you 3 Hi how are you 1234567890 4 1234567890 Hi how are you 5 Hi how are you 1234567890 and so on When doing BER calculations, this makes the measurement useless, because it looks like constant errors due to the first line repeat. I’ve tested this with the File Sink Buffer on and off. It occurs in both situations. There is no recognizable pattern to me, sometimes it happens and sometimes it doesn’t. Is there a buffer that does not get flushed somewhere that could cause this? Has anyone seen this behavior before? v/r, Rich