From 9e5ce0cc3b699b95736c56e53cea151c57e376c8 Mon Sep 17 00:00:00 2001
From: ha7ilm <retzlerandras@gmail.com>
Date: Sat, 13 Dec 2014 23:46:41 +0100
Subject: [PATCH] fix parameter naming mistake: rolloff -> transition_bw
---
README.md | 2 +-
libcsdr.c | 4 ++--
libcsdr.h | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/README.md b/README.md
index 33a8485..c306814 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@ Usage by example
- We want to listen to one radio station, but input signal contains multiple stations, and its bandwidth is too large for sending it directly to the FM demodulator.
- We shift the signal to the center frequency of the station we want to receive: `-0.085*2400000 = -204000`, so basically we will listen to the radio station centered at 89504000 Hz.
-- We decimate the signal by a factor of 10. The rolloff for the FIR filter used for decimation will be 10% of total bandwidth (as of parameter 0.05 is 10% of 0.5). Hamming window will be used for windowed FIR filter design.
+- We decimate the signal by a factor of 10. The transition bandwidth of the FIR filter used for decimation will be 10% of total bandwidth (as of parameter 0.05 is 10% of 0.5). Hamming window will be used for windowed FIR filter design.
Sample rates look like this:
diff --git a/libcsdr.c b/libcsdr.c
index 4080307..7d6e449 100644
--- a/libcsdr.c
+++ b/libcsdr.c
@@ -165,9 +165,9 @@ void firdes_bandpass_c(complexf *output, int length, float lowcut, float highcut
}
}
-int firdes_filter_len(float rolloff)
+int firdes_filter_len(float transition_bw)
{
- int result=4.0/rolloff;
+ int result=4.0/transition_bw;
if (result%2==0) result++; //number of symmetric FIR filter taps should be odd
return result;
}
diff --git a/libcsdr.h b/libcsdr.h
index 9898be2..a66d72b 100644
--- a/libcsdr.h
+++ b/libcsdr.h
@@ -86,7 +86,7 @@ float firdes_wkernel_hamming(float input);
float firdes_wkernel_boxcar(float input);
window_t firdes_get_window_from_string(char* input);
char* firdes_get_string_from_window(window_t window);
-int firdes_filter_len(float rolloff);
+int firdes_filter_len(float transition_bw);
//demodulators
complexf fmdemod_quadri_cf(complexf* input, float* output, int input_size, float *temp, complexf last_sample);
--
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