From: Keith Packard <keithp@keithp.com>
Date: Tue, 2 Aug 2011 08:49:35 +0000 (-0700)
Subject: altos: Reduce height averaging filter time constant
X-Git-Tag: 0.9.4.5~8
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=6c55bf35b11ae3ddae152795072d69e98184bac1

altos: Reduce height averaging filter time constant

Using the longer time constant could lead to false landing detection
just after apogee, which is definitely not a good idea.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/ao_kalman.c b/src/ao_kalman.c
index ab97fc34..203d727a 100644
--- a/src/ao_kalman.c
+++ b/src/ao_kalman.c
@@ -277,18 +277,15 @@ ao_kalman(void)
 	ao_accel = from_fix(ao_k_accel);
 	if (ao_height > ao_max_height)
 		ao_max_height = ao_height;
+	ao_avg_height_scaled = ao_avg_height_scaled - ao_avg_height + ao_height;
 #ifdef AO_FLIGHT_TEST
-	if (ao_sample_tick - ao_sample_prev_tick > 50) {
-		ao_avg_height = ao_height;
-	} else if (ao_sample_tick - ao_sample_prev_tick > 5) {
-		ao_avg_height_scaled = ao_avg_height_scaled - ao_avg_height + ao_height;
-		ao_avg_height = (ao_avg_height_scaled + 3) >> 2;
-	} else 
+	if (ao_sample_tick - ao_sample_prev_tick > 50)
+		ao_avg_height = (ao_avg_height_scaled + 1) >> 1;
+	else if (ao_sample_tick - ao_sample_prev_tick > 5)
+		ao_avg_height = (ao_avg_height_scaled + 7) >> 4;
+	else 
 #endif
-	{
-		ao_avg_height_scaled = ao_avg_height_scaled - ao_avg_height + ao_height;
-		ao_avg_height = (ao_avg_height_scaled + 15) >> 5;
-	}
+		ao_avg_height = (ao_avg_height_scaled + 63) >> 7;
 #ifdef AO_FLIGHT_TEST
 	ao_sample_prev_tick = ao_sample_tick;
 #endif