= Symbol Synchronizer (polyphase filter bank) =
This component recovers symbol timing information using a polyphase filter bank for simultaneous matched filtering and decimation.

 * [source:experimental/components/SymbolSyncPoly development trunk]
 * [http://ossie.wireless.vt.edu/documentation/components/SymbolSyncPoly/index.html code documentation]

== Profiling results ==

Here are the results of some profiling of the SymbolSyncPoly component using [http://oprofile.sourceforge.net oprofile].  For information on how to get these or similar results please see the [wiki:Profiling] page.

{{{
CPU: P4 / Xeon with 2 hyper-threads, speed 3391.93 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped)
  with a unit mask of 0x01 (mandatory) count 100000
GLOBAL_POWER_E...|
  samples|      %|
------------------
   216324 37.7020 SymbolSyncPoly
        GLOBAL_POWER_E...|
          samples|      %|
        ------------------
           172100 79.5566 libsigproc.so.0.0.7
            20587  9.5167 SymbolSyncPoly
            10011  4.6278 libomniORB4.so.0.7
             4588  2.1209 libc-2.4.so
             2786  1.2879 libstandardInterfaces.so.0.0.6
             1885  0.8714 libpthread-2.4.so
             1753  0.8104 ld-2.4.so
             1474  0.6814 libm-2.4.so
              494  0.2284 libstdc++.so.6.0.8
              360  0.1664 libomnithread.so.3.2
              279  0.1290 anon (tgid:27975 range:0xfc8000-0xfc9000)
                4  0.0018 libomniDynamic4.so.0.7
                1 4.6e-04 libossieidl.so.0.0.4
                1 4.6e-04 libossieparser.so.0.0.4
                1 4.6e-04 libxerces-c.so.27.0
}}}

Annotating {{{libsigproc.so.0.0.7}}} produces the following results for the FIRPolyphaseFilterBank filter class (revision [source:SigProc/trunk/SigProc/filters.cpp#3805 3805]).  Notice that nearly 75% of the CPU time is spent in computing the dot product.

{{{
/*
 * Total samples for file : \"/home/jgaeddert/src/SigProc/filters.cpp\"
 *
 * 144909 84.1394
 */

...

               :/// compute filter output from current buffer state using specific filter
               :void SigProc::FIRPolyphaseFilterBank::ComputeOutput(
               :        short &y,           // output sample
               :        unsigned int _b     // filter bank index
  2196  1.2751 :        ) /* SigProc::FIRPolyphaseFilterBank::ComputeOutput(short&, unsigned int) total: 143356 83.2376 */
               :{
               :    // Ensure the requested filter bank index does not exceed the number
               :    // of filters actually in the bank
   425  0.2468 :    if ( _b >= Npfb )
               :    {
               :        std::cerr << \"ERROR: SigProc::FIRPolyphaseFitlerBank::ComputeOutput, \"
               :                  << \" index exceeds filter bank size (\"
               :                  << _b << \" > \" << Npfb << \")\" << std::endl;
               :        throw 0;
               :    }
               :
               :    // Initialize floating point value for output
               :    /// \\todo make this compatable with FPM
               :    float yf(0.0f);
               :
               :    // Set B to memory block in filter bank array
               :    unsigned int B;
    25  0.0145 :    B = _b*h_len;
               :
               :    // Accumulate (apply filter)
 29767 17.2838 :    for (unsigned int i=0; i<h_len; i++)
 99607 57.8354 :        yf += float( v[i] ) * H[B+i];
               :
               :    // Ensure yf is within the scope of short int
  3323  1.9295 :    if ( yf < SHRT_MIN ) {
               :        y = SHRT_MIN;
  1294  0.7513 :    } else if ( yf > SHRT_MAX ) {
               :        y = SHRT_MAX;
               :    } else {
  3062  1.7779 :        y = (short) yf;
               :    }
               :
  1990  1.1555 :}
}}}