Variometer - Revision history

Cmair at 19:10, 30 September 2009

2009-09-30T19:10:01Z

Johan: /* Variometer */ - typo

2008-10-08T17:12:50Z

‎Variometer: - typo

Gulu at 13:27, 8 September 2008

2008-09-08T13:27:06Z

DolfjeBot1: Replacing 'OpenMoko' with 'Openmoko'

2008-08-23T09:29:42Z

Replacing 'OpenMoko' with 'Openmoko'

Pproc: /* Hardware */

2007-09-11T15:36:09Z

‎Hardware

Pproc: /* Hardware */

2007-09-11T15:30:41Z

‎Hardware

PTT: some remarks

2007-08-14T22:04:13Z

some remarks

PTT: /* Hardware */

2007-08-08T21:22:11Z

‎Hardware

PTT: /* Variometer */ simpler to use a digital sensor like SMD500

2007-08-08T21:12:42Z

‎Variometer: simpler to use a digital sensor like SMD500

PTT: /* Hardware */ added better applicaple sensors

2007-08-08T21:08:11Z

‎Hardware: added better applicaple sensors

← Older revision		Revision as of 19:10, 30 September 2009
Line 89:		Line 89:
	*SPI or I2C (or through the debug board connector ?)		*SPI or I2C (or through the debug board connector ?)
	*HID device (ex: Oak USB Sensor Atmospheric Pressure [toradex.ch])		*HID device (ex: Oak USB Sensor Atmospheric Pressure [toradex.ch])
		+
		+	The page [[I2C_Pressure_Sensor]] describes how to add a pressure sensor connected to the I2C bus.

@@ Line 3: / Line 3: @@
 ===Variometer===
-The variometer signal is simply the derivative of the barometer signal. It gives a much more accurate vertical speed signal than is possible with GPS.This kind of measurement is used by the flee flying community (hanggliding, paragliding, ballooning). A device that allows teams of pilots to share position and speed (with accurate vertical speed) data would be lots of fun.
+The variometer signal is simply the derivative of the barometer signal. It gives a much more accurate vertical speed signal than is possible with GPS.This kind of measurement is used by the free flying community (hanggliding, paragliding, ballooning). A device that allows teams of pilots to share position and speed (with accurate vertical speed) data would be lots of fun.
 [http://en.wikipedia.org/wiki/Variometer Variometer Reference]

← Older revision		Revision as of 13:27, 8 September 2008
Line 80:		Line 80:
	*Pilots with Openmoko based variometers can choose to publish their status on a central service.		*Pilots with Openmoko based variometers can choose to publish their status on a central service.
	*Based on location - the system will notify pilots of the presence of others that can participate in group flying.		*Based on location - the system will notify pilots of the presence of others that can participate in group flying.
		+
		+
		+	====Freerunner====
		+	Maybe it is possible to do that on the Freerunner ?
		+
		+	Connection :
		+
		+	*SPI or I2C (or through the debug board connector ?)
		+	*HID device (ex: Oak USB Sensor Atmospheric Pressure [toradex.ch])

@@ Line 78: / Line 78: @@
 ====Server Based Services====
 Auto discovery service
-*Pilots with OpenMoko based variometers can choose to publish their status on a central service.
+*Pilots with Openmoko based variometers can choose to publish their status on a central service.
 *Based on location - the system will notify pilots of the presence of others that can participate in group flying.

@@ Line 13: / Line 13: @@
 *[http://www.intersema.com/site/technical/ms5540.php Intersema MS5540B Altimeter/Barometer Module], 2.2 - 3.6V, 3-wire serial interface, 6.2 x 6.4 mm
 *[http://www.bosch-sensortec.com/content/language1/html/3477.htm Bosch SMD500 digital pressure sensor: altimeter and barometer], 2.2 - 3.6V, I2C interface, 5 x 5 x 1.5 mm, included temperature sensor
 ====Hardware solution====

@@ Line 7: / Line 7: @@
 ====Hardware====
-It could be best to filter and differentiate the analog pressure signal and then digitize. Another possibility is to differentiate the height in software. Maybe it's even possible to add detail based on the accelerometers.
+It could be best to filter and differentiate the analog pressure signal and then digitize. Another possibility is to differentiate the height in software. A robust solution is to compute a linear regression of a sliding window of height samples. The height samples can be computed using integer arithmetic by a pressure->altitude lookup table followed by interpolation. Maybe it's even possible to add detail based on the accelerometers.
 References to applicable transducers:

@@ Line 3: / Line 3: @@
 ===Variometer===
-The variometer signal is simply the derivative of the barometer signal. It gives a much more accurate vertical speed signal than is possible with GPS. It would probably be best to filter and differentiate the analog pressure signal and then digitize. This can be done inside the sensor package if a digital sensor like the SMD500 is used. This kind of measurement is used by the flee flying community (hanggliding, paragliding, ballooning). A device that allows teams of pilots to share position and speed (with accurate vertical speed) data would be lots of fun.
+The variometer signal is simply the derivative of the barometer signal. It gives a much more accurate vertical speed signal than is possible with GPS.This kind of measurement is used by the flee flying community (hanggliding, paragliding, ballooning). A device that allows teams of pilots to share position and speed (with accurate vertical speed) data would be lots of fun.
 [http://en.wikipedia.org/wiki/Variometer Variometer Reference]
 ====Hardware====
 References to applicable transducers:
@@ Line 13: / Line 14: @@
 *[http://www.bosch-sensortec.com/content/language1/html/3477.htm Bosch SMD500 digital pressure sensor: altimeter and barometer], 2.2 - 3.6V, I2C interface, 5 x 5 x 1.5 mm, included temperature sensor
-====Signal Conditioning====
+====Hardware solution====
 The absolute pressure signal needs to be:
@@ Line 24: / Line 26: @@
 It might be best to use a single chip solution if we can find the right fit e.g.: [http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4590 Max1464]
-====A/D====
+The software solution can simply be done in the variometer application with some very simple math.
 We would need two A/D channels:
 #Absolute Pressure - 12 bit minimum (assuming a operating range of 0 - 12000 meter 12 bits would give resolution of 2.9304 m)

@@ Line 9: / Line 9: @@
 References to applicable transducers:
-*[http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPX4100 Freescale MPX4100 (was Motorola)]
+*[http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPX4100 Freescale MPX4100 (was Motorola)] - needs 5V power supply, 11 x 11 x 6 mm
 ====Signal Conditioning====