From 95ae1a92be169fda5668bd1745dbf44529959dbd Mon Sep 17 00:00:00 2001
From: Gluttton <gluttton@ukr.net>
Date: Thu, 30 Jul 2020 23:45:14 +0300
Subject: [PATCH] limesdr: add ability to set LPF bandwidth

Add ability to set LPF bandwidth via input command line options.
By default the bandwidth is equal to the default sample rate 2.4 MHz.

Test: connect LimeSDR device, try to set different bandwidth and check
    logs:
    $ ./dump1090 --device-type limesdr --limesdr-lpfbw 2500000
    $ ./dump1090 --device-type limesdr --limesdr-lpfbw 500000

Signed-off-by: Gluttton <gluttton@ukr.net>
---
 sdr_limesdr.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sdr_limesdr.c b/sdr_limesdr.c
index 757fbae..1794418 100644
--- a/sdr_limesdr.c
+++ b/sdr_limesdr.c
@@ -60,6 +60,7 @@ static struct {
     char verbosity;
     size_t oversample;
     float gain;
+    float lpfbw;
     lms_info_str_t serial;
     int bytes_in_sample;
     iq_convert_fn converter;
@@ -102,6 +103,7 @@ void limesdrInitConfig()
     LimeSDR.verbosity = LMS_LOG_INFO;
     LimeSDR.oversample = 0; // default oversample
     LimeSDR.gain = 0.75;
+    LimeSDR.lpfbw = 2400000.0;
     LimeSDR.serial[0] = '\0';
     LimeSDR.bytes_in_sample = 2 * sizeof(int16_t); // hardcoded for LMS_FMT_I16
 
@@ -117,6 +119,7 @@ void limesdrShowHelp()
     printf("--limesdr-channel        set number of an RX channel\n");
     printf("--limesdr-oversample     set RF oversampling ratio\n");
     printf("--limesdr-gain           set normalized gain\n");
+    printf("--limesdr-lpfbw          set LPF bandwidth\n");
     printf("\n");
 }
 
@@ -135,6 +138,8 @@ bool limesdrHandleOption(int argc, char **argv, int *jptr)
         LimeSDR.oversample = atoi(argv[++j]);
     } else if (!strcmp(argv[j], "--limesdr-gain") && more) {
         LimeSDR.gain = atof(argv[++j]);
+    } else if (!strcmp(argv[j], "--limesdr-lpfbw") && more) {
+        LimeSDR.lpfbw = atof(argv[++j]);
     } else {
         return false;
     }
@@ -218,7 +223,7 @@ bool limesdrOpen(void)
         goto error;
     }
 
-    if (LMS_SetLPFBW(LimeSDR.dev, LMS_CH_RX, LimeSDR.stream.channel, Modes.sample_rate)) {
+    if (LMS_SetLPFBW(LimeSDR.dev, LMS_CH_RX, LimeSDR.stream.channel, LimeSDR.lpfbw)) {
         limesdrLogHandler(LMS_LOG_ERROR, "unable to set LP filter");
         goto error;
     }