1 files changed, 8 insertions, 29 deletions

diff --git a/src/drivers/meas_airspeed/meas_airspeed.cpp b/src/drivers/meas_airspeed/meas_airspeed.cpp
index 159706278..1d9a463ad 100644
--- a/src/drivers/meas_airspeed/meas_airspeed.cpp
+++ b/src/drivers/meas_airspeed/meas_airspeed.cpp
@@ -228,44 +228,23 @@ MEASAirspeed::collect()
 	// the raw value still should be compensated for the known offset
 	diff_press_pa_raw -= _diff_pres_offset;
 
-	float diff_press_pa = fabsf(diff_press_pa_raw);
-	
 	/*
-	  note that we return both the absolute value with offset
-	  applied and a raw value without the offset applied. This
-	  makes it possible for higher level code to detect if the
-	  user has the tubes connected backwards, and also makes it
-	  possible to correctly use offsets calculated by a higher
-	  level airspeed driver.
-
 	  With the above calculation the MS4525 sensor will produce a
 	  positive number when the top port is used as a dynamic port
 	  and bottom port is used as the static port
-
-	  Also note that the _diff_pres_offset is applied before the
-	  fabsf() not afterwards. It needs to be done this way to
-	  prevent a bias at low speeds, but this also means that when
-	  setting a offset you must set it based on the raw value, not
-	  the offset value
 	 */
-	
+
 	struct differential_pressure_s report;
 
 	/* track maximum differential pressure measured (so we can work out top speed). */
-	if (diff_press_pa > _max_differential_pressure_pa) {
-		_max_differential_pressure_pa = diff_press_pa;
+	if (diff_press_pa_raw > _max_differential_pressure_pa) {
+		_max_differential_pressure_pa = diff_press_pa_raw;
 	}
 
 	report.timestamp = hrt_absolute_time();
 	report.error_count = perf_event_count(_comms_errors);
 	report.temperature = temperature;
-	report.differential_pressure_pa = diff_press_pa;
-	report.differential_pressure_filtered_pa =  _filter.apply(diff_press_pa);
-
-	/* the dynamics of the filter can make it overshoot into the negative range */
-	if (report.differential_pressure_filtered_pa < 0.0f) {
-		report.differential_pressure_filtered_pa = _filter.reset(diff_press_pa);
-	}
+	report.differential_pressure_filtered_pa =  _filter.apply(diff_press_pa_raw);
 
 	report.differential_pressure_raw_pa = diff_press_pa_raw;
 	report.max_differential_pressure_pa = _max_differential_pressure_pa;
@@ -345,7 +324,7 @@ MEASAirspeed::cycle()
 /**
    correct for 5V rail voltage if the system_power ORB topic is
    available
-   
+
    See http://uav.tridgell.net/MS4525/MS4525-offset.png for a graph of
    offset versus voltage for 3 sensors
  */
@@ -394,7 +373,7 @@ MEASAirspeed::voltage_correction(float &diff_press_pa, float &temperature)
 	if (voltage_diff < -1.0f) {
 		voltage_diff = -1.0f;
 	}
-	temperature -= voltage_diff * temp_slope;	
+	temperature -= voltage_diff * temp_slope;
 #endif // CONFIG_ARCH_BOARD_PX4FMU_V2
 }
 
@@ -523,7 +502,7 @@ test()
 	}
 
 	warnx("single read");
-	warnx("diff pressure: %d pa", (int)report.differential_pressure_pa);
+	warnx("diff pressure: %d pa", (int)report.differential_pressure_filtered_pa);
 
 	/* start the sensor polling at 2Hz */
 	if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2)) {
@@ -551,7 +530,7 @@ test()
 		}
 
 		warnx("periodic read %u", i);
-		warnx("diff pressure: %d pa", (int)report.differential_pressure_pa);
+		warnx("diff pressure: %d pa", (int)report.differential_pressure_filtered_pa);
 		warnx("temperature: %d C (0x%02x)", (int)report.temperature, (unsigned) report.temperature);
 	}