+// dcblock.h
+/*
+This file is part of a program that implements a Software-Defined Radio.
+
+Copyright (C) 2004-2005 by Frank Brickle, AB2KT and Bob McGwier, N4HY
+
+This program 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 of the License, or
+(at your option) any later version.
+
+This program 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 this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+The authors can be reached by email at
+
+ab2kt@arrl.net
+or
+rwmcgwier@comcast.net
+
+or by paper mail at
+
+The DTTS Microwave Society
+6 Kathleen Place
+Bridgewater, NJ 08807
+*/
+
+#include <dcblock.h>
+
+// NB may have to ramify this a little
+// for other sampling rates; maybe not
+
+PRIVATE REAL
+butterworth_hipass_100_2(REAL xin, REAL *xv, REAL *yv),
+butterworth_hipass_100_4(REAL xin, REAL *xv, REAL *yv),
+butterworth_hipass_100_6(REAL xin, REAL *xv, REAL *yv),
+butterworth_hipass_100_8(REAL xin, REAL *xv, REAL *yv);
+
+void
+DCBlock(DCBlocker dcb) {
+ int i;
+ REAL x, y;
+
+ switch (dcb->lev) {
+
+ case DCB_LOW:
+ for (i = 0; i < CXBsize(dcb->buf); i++) {
+ x = CXBreal(dcb->buf, i);
+ y = butterworth_hipass_100_2(x, dcb->old.inp, dcb->old.out);
+ CXBdata(dcb->buf, i) = Cmplx(y, 0.0);
+ }
+ break;
+
+ case DCB_MED:
+ for (i = 0; i < CXBsize(dcb->buf); i++) {
+ x = CXBreal(dcb->buf, i);
+ y = butterworth_hipass_100_4(x, dcb->old.inp, dcb->old.out);
+ CXBdata(dcb->buf, i) = Cmplx(y, 0.0);
+ }
+ break;
+
+ case DCB_HIGH:
+ for (i = 0; i < CXBsize(dcb->buf); i++) {
+ x = CXBreal(dcb->buf, i);
+ y = butterworth_hipass_100_6(x, dcb->old.inp, dcb->old.out);
+ CXBdata(dcb->buf, i) = Cmplx(y, 0.0);
+ }
+ break;
+
+ case DCB_SUPER:
+ for (i = 0; i < CXBsize(dcb->buf); i++) {
+ x = CXBreal(dcb->buf, i);
+ y = butterworth_hipass_100_8(x, dcb->old.inp, dcb->old.out);
+ CXBdata(dcb->buf, i) = Cmplx(y, 0.0);
+ }
+ break;
+
+ default:
+ break;
+ }
+}
+
+void
+resetDCBlocker(DCBlocker dcb, int lev) {
+ memset((char *) dcb->old.inp, 0, BLKMEM * sizeof(REAL));
+ memset((char *) dcb->old.out, 0, BLKMEM * sizeof(REAL));
+ dcb->lev = lev;
+}
+
+DCBlocker
+newDCBlocker(int lev, CXB buf) {
+ DCBlocker dcb =
+ (DCBlocker) safealloc(1, sizeof(DCBlockerInfo), "DCBlocker");
+ dcb->buf = newCXB(CXBsize(buf), CXBbase(buf), "DCBlocker");
+ dcb->lev = lev;
+ return dcb;
+}
+
+void
+delDCBlocker(DCBlocker dcb) {
+ if (dcb) {
+ delCXB(dcb->buf);
+ safefree((char *) dcb);
+ }
+}
+
+// f == 0.002083 == 100 Hz at 48k
+
+PRIVATE REAL
+butterworth_hipass_100_2(REAL xin, REAL *xv, REAL *yv) {
+ int i;
+
+ for (i = 1; i < 2; i++)
+ xv[i - 1] = xv[i], yv[i - 1] = yv[i];
+
+ xv[2] = xin / 1.009297482;
+
+ yv[2] = (xv[0] + xv[2])
+ + -2.0 * xv[1]
+ + -0.9816611902 * yv[0]
+ + 1.9814914708 * yv[1];
+
+ return yv[2];
+}
+
+PRIVATE REAL
+butterworth_hipass_100_4(REAL xin, REAL *xv, REAL *yv) {
+ int i;
+
+ for (i = 1; i < 4; i++)
+ xv[i - 1] = xv[i], yv[i - 1] = yv[i];
+
+ xv[4] = xin / 1.017247322;
+
+ yv[4] = (xv[0] + xv[4])
+ + -4.0 * (xv[1] + xv[3])
+ + 6.0 * xv[2]
+ + -0.9663776767 * yv[0]
+ + 3.8985609655 * yv[1]
+ + -5.8979831706 * yv[2]
+ + 3.9657998529 * yv[3];
+
+ return yv[4];
+}
+
+PRIVATE REAL
+butterworth_hipass_100_6(REAL xin, REAL *xv, REAL *yv) {
+ int i;
+
+ for (i = 1; i < 6; i++)
+ xv[i - 1] = xv[i], yv[i - 1] = yv[i];
+
+ xv[6] = xin / 1.025606415;
+
+ yv[6] = (xv[0] + xv[6])
+ + -6.0 * (xv[1] + xv[5])
+ + 15.0 * (xv[2] + xv[4])
+ + -20.0 * xv[3]
+ + -0.9506891622 * yv[0]
+ + 5.7522090378 * yv[1]
+ + -14.5019247580 * yv[2]
+ + 19.4994114580 * yv[3]
+ + -14.7484389800 * yv[4]
+ + 5.9494324049 * yv[5];
+
+ return yv[6];
+}
+
+PRIVATE REAL
+butterworth_hipass_100_8(REAL xin, REAL *xv, REAL *yv) {
+ int i;
+
+ for (i = 1; i < 8; i++)
+ xv[i - 1] = xv[i], yv[i - 1] = yv[i];
+
+ xv[8] = xin / 1.034112352;
+
+ yv[8] = (xv[0] + xv[8])
+ + -8.0 * (xv[1] + xv[7])
+ + 28.0 * (xv[2] + xv[6])
+ + -56.0 * (xv[3] + xv[5])
+ + 70.0 * xv[4]
+ + -0.9351139781 * yv[0]
+ + 7.5436450525 * yv[1]
+ + -26.6244301320 * yv[2]
+ + 53.6964633920 * yv[3]
+ + -67.6854640540 * yv[4]
+ + 54.6046308830 * yv[5]
+ + -27.5326449810 * yv[6]
+ + 7.9329138172 * yv[7];
+
+ return yv[8];
+}
projects / dttsp.git / commitdiff