Added gr-pager component to trunk by merging from r3474:r3537 in

branch developer/jcorgan/pager.  Currently implements most of the FLEX
pager protocol demodulation, but doesn't yet decode individual pages.


git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3538 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 100 insertions, 0 deletions

diff --git a/gr-pager/src/pager_slicer_fb.cc b/gr-pager/src/pager_slicer_fb.cc
new file mode 100644
index 000000000..98e8a2b00
--- /dev/null
+++ b/gr-pager/src/pager_slicer_fb.cc
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2004,2006 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <pager_slicer_fb.h>
+#include <gr_io_signature.h>
+
+pager_slicer_fb_sptr pager_make_slicer_fb(float alpha, float beta)
+{
+    return pager_slicer_fb_sptr(new pager_slicer_fb(alpha, beta));
+}
+
+pager_slicer_fb::pager_slicer_fb(float alpha, float beta) :
+    gr_sync_block ("slicer_fb",
+                   gr_make_io_signature (1, 1, sizeof(float)),
+                   gr_make_io_signature (1, 1, sizeof(unsigned char)))
+{
+    d_alpha = alpha;
+    d_beta = beta;
+    d_max = 0.0;
+    d_hi = 0.0;
+    d_avg = 0.0;
+    d_lo = 0.0;
+    d_min = 0.0;
+}
+
+// Tracks average, minimum, and peak, then converts input into one of:
+//
+// [0, 1, 2, 3]
+unsigned char pager_slicer_fb::slice(float sample)
+{
+    unsigned char decision;
+
+    // Update DC level and remove
+    d_avg = d_avg*(1.0-d_alpha)+sample*d_alpha;
+    sample -= d_avg;
+
+    if (sample > 0) {
+        if (sample > d_hi) {                // In max region
+            d_max = d_max*(1.0-d_alpha) + sample*d_alpha;
+            decision = 3;
+        }
+        else {
+            d_max -= (d_max-d_avg)*d_beta;  // decay otherwise
+            decision = 2;
+        }
+    }
+    else {
+        if (sample < d_lo) {                // In min region
+            d_min = d_min*(1.0-d_alpha) + sample*d_alpha;
+            decision = 0;
+        }
+        else {
+            d_min -= (d_min-d_avg)*d_beta;  // decay otherwise
+            decision = 1;
+        }
+    }
+
+    d_hi = d_max*2.0/3.0;
+    d_lo = d_min*2.0/3.0;
+
+    //fprintf(stderr, "%f %d\n", sample, decision);
+    return decision;
+}
+
+int pager_slicer_fb::work(int noutput_items,
+                          gr_vector_const_void_star &input_items,
+		                  gr_vector_void_star &output_items)
+{
+    float *iptr = (float *) input_items[0];
+    unsigned char *optr = (unsigned char *) output_items[0];
+
+    int size = noutput_items;
+
+    for (int i = 0; i < size; i++)
+        *optr++ = slice(*iptr++);
+
+    return noutput_items;
+}