hackrf: implement BB lowpass filter control

To use the default (automatic) bandwidth filter selection, this should
be set to 0.

2 files changed, 6 insertions, 4 deletions

diff --git a/lib/hackrf/hackrf_source_c.cc b/lib/hackrf/hackrf_source_c.cc
index 5543ea0..e5db62c 100644
--- a/lib/hackrf/hackrf_source_c.cc
+++ b/lib/hackrf/hackrf_source_c.cc
@@ -625,13 +625,13 @@ std::string hackrf_source_c::get_antenna( size_t chan )
   return "ANT";
 }
 
-void hackrf_source_c::set_bandwidth( double bandwidth, size_t chan )
+double hackrf_source_c::set_bandwidth( double bandwidth, size_t chan )
 {
   int ret;
 //  osmosdr::meta_range_t bandwidths = get_bandwidth_range( chan );
 
-  if ( bandwidth == 0.0 )
-    return;
+  if ( bandwidth == 0.0 ) /* bandwidth of 0 means automatic filter selection */
+    bandwidth = _sample_rate;
 
   if ( _dev ) {
     /* compute best default value depending on sample rate (auto filter) */
@@ -643,6 +643,8 @@ void hackrf_source_c::set_bandwidth( double bandwidth, size_t chan )
       throw std::runtime_error( std::string( __FUNCTION__ ) );
     }
   }
+
+  return _bandwidth;
 }
 
 double hackrf_source_c::get_bandwidth( size_t chan )
diff --git a/lib/hackrf/hackrf_source_c.h b/lib/hackrf/hackrf_source_c.h
index ea14944..3e60749 100644
--- a/lib/hackrf/hackrf_source_c.h
+++ b/lib/hackrf/hackrf_source_c.h
@@ -113,7 +113,7 @@ private:
   std::string set_antenna( const std::string & antenna, size_t chan = 0 );
   std::string get_antenna( size_t chan = 0 );
 
-  void set_bandwidth( double bandwidth, size_t chan = 0 );
+  double set_bandwidth( double bandwidth, size_t chan = 0 );
   double get_bandwidth( size_t chan = 0 );
   osmosdr::meta_range_t get_bandwidth_range( size_t chan = 0 );