diff options
Diffstat (limited to '')
| -rw-r--r-- | hamming.awk | 48 |
1 files changed, 33 insertions, 15 deletions
diff --git a/hamming.awk b/hamming.awk index f7ff9f7..acfde97 100644 --- a/hamming.awk +++ b/hamming.awk @@ -2,35 +2,52 @@ ### hamming.awk
# generate a Hamming window
+# R.W. Hamming, 'Digital Filters': H = '0.23 0.54 0.23'
# https://en.wikipedia.org/wiki/Window_function provides a few values for the
# 'a0' and 'a1' parameters of the raised cosine.
-BEGIN {
- ARGV[1] ? N = ARGV[1] : N = 0
- ARGV[2] ? OFMT = "%." ARGV[2] "g" : OFMT = "%g"
+### Gaussian
+function gaussian(n) {
+ # sigma <= 0.5
+ sigma = 0.4
+ e[n] = (n)/(sigma*M)
+ return exp(-0.5*e[n]*e[n])
+}
- # window interval goes from -M to M
- M = 0.5*(N - 1)
- pi = 4*atan2(1,1)
- ### R.W. Hamming, "Digital Filters"
- # H = "0.23 0.54 0.23"
+### Hamming, raised cosine
+function hamming(n) {
+ ### optimal values for equal-ripple
+ #a0 = 0.53836
+ #a1 = 0.46164
a0 = (25.0/46.0)
a1 = (21.0/46.0)
+ return a0 + a1*cos((pi*n)/M)
+}
- ### optimal values for equal-ripple
- #a0 = 0.53836
- #a1 = 0.46164
- ### VonHann
- #a0 = 0.5
- #a1 = 0.5
+### vonHann, raised cosine
+function vonhann(n) {
+ a0 = 0.5
+ a1 = 0.5
+ return a0 + a1*cos((pi*n)/M)
+}
+
+
+BEGIN {
+
+ ARGV[1] ? N = ARGV[1] : N = 0
+ ARGV[2] ? OFMT = "%." ARGV[2] "g" : OFMT = "%g"
+
+ # window interval goes from -M to M
+ M = 0.5*(N - 1)
+ pi = 4*atan2(1,1)
for (n=-M; n<=M; n++) {
if (N > 1 && M > 0) {
- w[n] = a0 + a1*cos((pi*n)/M)
+ w[n] = hamming(n)
print n + M, w[n]/M
}
else {
@@ -39,3 +56,4 @@ BEGIN { }
}
+
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