About

Gender

Male


Location

Kirkland, WA


About Me:

I am an avionics engineer for a major aircraft manufacturer. I specialize in aircraft navigation and guidance.


Please tell us a bit about your UAV interest

I am working on my own tightly-coupled GPS/INS navigation system and a flight control computer/autopilot. Process is slow because free time is short.


Hometown:

Chattaroy, WA


Activity Feed

Tom Yochum commented on Georacer's blog post Altitude Comparison: barometer vs GPS
"@Georacer:
You are correct that as satellites come into and out of view the GPS position solution can "jump". The slow variation of a few meters is the result of normal noise in the measurements.
DGPS essentially corrects the ionospheric delay.…"
May 28, 2013
Tom Yochum commented on Georacer's blog post Altitude Comparison: barometer vs GPS
"Different altitude sources are best used for different things. For example, barometric altimetry (MSL) is great for keeping relative distance within an airmass, since everyone's sensors are affected by the local conditions by the same amount. For…"
May 24, 2013
Tom Yochum commented on Georacer's blog post Altitude Comparison: barometer vs GPS
"You do realize that GPS outputs geometric altitude, and not mean sea level (MSL) altitude, right? They use different coordinate systems, which accounts for some of the discrepancy. Also, barometric altitude is a function of many parameters,…"
May 24, 2013
Tom Yochum commented on Tian's blog post Drones vulnerable to terrorist hijacking, researchers say
"@Mathew
How does the inertial guidance system know the GPS is wrong? What if the GPS is working fine and the inertial is wrong? How can you tell the difference?
"A man with two watches doesn't know what time it is."
Augmenting the inertial with…"
Jun 27, 2012
Tom Yochum commented on Tian's blog post Drones vulnerable to terrorist hijacking, researchers say
"Spoofing is difficult to do, but given a few years I am sure there will be some tools out there for those that want to be mischievous.
In order to work well the spoofer needs to know the location of the target. Then they need to introduce false…"
Jun 26, 2012
Tom Yochum replied to Aizzat's discussion Anyone knows how to measure the lateral crosstrack error ?
"Here's another place to look:
http://www.movable-type.co.uk/scripts/latlong.html"
Jun 25, 2012
Tom Yochum commented on Chris Anderson's blog post Dealing with GPS blocking/jamming
"I happen to work with commercial aircraft navigation systems. It is apparently common for aircraft flying around Seoul to have their GPSs drop out. Their mischievous neighbors to the north are suspected of playing games. So far it seems they are…"
Jun 19, 2012
Tom Yochum commented on Ron Curry's blog post How long will unregulated FPV and RC last?
"I find all the comments about "a lot of sky" and using probability to show the risk of collision as missing the two most important aspects that the poster brought up.
First, the idea that aircraft fly "random paths" through the sky is false. All…"
Apr 10, 2012
Tom Yochum commented on Gary Mortimer's blog post The Law and Operating Unmanned Aircraft In the U.S. National Airspace System
"bcrow,

The air above Montana is part of the US NAS. Below 700' AGL has special regulations, but it is still part of the NAS.

By the way, Kalispell is one of the most beautiful places in the world. The best airshow I ever saw was there.

Tom"
Mar 14, 2012
Tom Yochum replied to Jan Kaas's discussion Inertial navigation in Arducopter
"Hi Jan,
The arduino does not have enough processing power to run an inertial navigator in addition to the autopilot code. Try checking out Open Pilot.
 
Tom"
Nov 22, 2011
Tom Yochum replied to Sarunas's discussion Ultimate IMU
"IMU's do not output position. An IMU outputs angular rates and lateral accelerations. You need software to turn that information into something useful, such as orientation, position, and velocity. An AHRS uses an IMU to output orientation. If you…"
Nov 3, 2011
Tom Yochum replied to Caleb Chamberlain's discussion New multi-rotor autopilot
"Nice Caleb!
 
I have a few questions I am hoping you can answer:
Did you use the same accels and gyros from your IMU board?
Why the two processors? Is one running the GPS/IMU code and the other autopilot code?
Cost? Are you going to be selling any?…"
Sep 16, 2011
Tom Yochum commented on Jesse's blog post A simple INS - the beginnings
"So how is what you are making an INS? It sounds like you are making an AHRS (attitude heading reference system).
 
An INS computes position and velocity using the inertial sensors. An AHRS provides attitude only, which is what this sounds like.
 …"
Jun 17, 2011
Tom Yochum replied to Kim Skatun's discussion GPS formulas
"I find this site full of useful info."
May 26, 2011
Tom Yochum replied to Caleb Chamberlain's discussion Putting the Rotorcraft/Accelerometer Question to Rest
"Great stuff Caleb! Thanks for sharing."
May 23, 2011
Tom Yochum replied to Mike Metcalf's discussion New Low-Cost Wind Tunnel
"Your brocure does not mention any force or moment measuring capability. Can you?
I get the impression that you are not interested in publishing your rates. Why? Can I ask if your rates are less than $300 an hour?"
May 18, 2011
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