On-screen navigator - RC Groups
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Jun 20, 2007, 07:48 AM
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Zbig's Avatar

On-screen navigator

It tooks me several months to complete my own navigation system.
It consist of GPS, horizon sensor, pressure sensor and of course camera and trasmitter/receiver with Z800 gogle.
Information from sensors are displayed directly on-screen, thanks to almost 20KB code inside Atmega 32
There is text information like altitude, speed, distance, vario, time, battery state and location as well as graphically presented course home and position of airplane (tilt and speed of climbing).
Results (sample video) are here:
Cularis with navigation system - landing (0 min 23 sec)

Cularis - 2 TwinStar

Now its time for me to learn how to fly - its not as easy as controlling plane from ground
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Jun 20, 2007, 12:23 PM
Zdrastvyi !
Can you provide more information about the system ? What components did you use ?
This is something I'm very interested in building...
Jun 20, 2007, 01:04 PM
Registered User
Zbig's Avatar
Main sensors are:
-Horizon sensor from FMA CoPilot (thermopile Z-sensor),
-Pressure sensor MPX4115 with 16 bit external ADC (ADS1100).
-GPS OEM module EM411
All logic and On-screen display is done by Atmega32 + some additional elements (e.g. TV synchro separator LM1881).
Code for Atmega is written using BASCOM compiler (Basic + assebler).
Additionally CCD 1/4'' camera, transmitter 2,4Ghz "made in china" and AirWave two-channel diversity receiver.

on-board equippment looks like this
Last edited by Zbig; Jun 21, 2007 at 12:31 AM.
Jun 21, 2007, 04:41 AM
Registered User
Would you be prepared to share the circuit and code with us?

Regards Peter
Jun 21, 2007, 05:14 AM
G'Day ZBig.
Well done. An ambitious project, especially with the amount of coding.
Just a thought thought though regarding the tilt sensor.
What about if you reverse the tilt angle? This will then display an AH (Artificial Horizon). If I was given this aircraft, and used the goggles, as a pilot, I would end up spiralling into the ground, as the natural tendancy is to use the line as an AH.
My 2c, but well done.
Jun 21, 2007, 10:49 AM
JettPilot's Avatar

Im glad to see someone devloping stuff like this, but as it is your OSD is really horrible, and here is why. The horizon is very sensitive, and moves more than the actual airplane, so its useless for knowing what your bank angle is. Also, model planes tend to bounce around alot as it is, the last thing you want is a horizon that exaggerates every little bank.

The indications from the horizon is also reverse from every other horizon on the planet. From General aviation, to military, to airline, every horizon on earth shows level... This one is backwards, very confusing and not good.

You have a great idea developing something like this, but you need to make it standard with what the rest of the aviation world is doing to make it usable for others.

Jun 21, 2007, 11:34 AM
Dionysus Design
This is a great project! I am impressed that you got so many fine lines on the screen. I found myself glued to the stick airplane on the screen. I know that isn't meant to be a horizon line. I hope that you can find the constructive critizism in some of the opinions of others. I also hope that the changes they are suggesting are as simple as multiplying by a constant value. As for me, I would like to see both versions. If I were flying an airplane, the horizon would be nice. But if I were flying a helicopter, it might be helpful to know exactly how it is oriented. A switch that allows the pilot to select the mode would be very cool. So keep up the good work and good luck with your flight training.
Jun 21, 2007, 12:47 PM
Gilrc's Avatar
Well guys, speaking for my self,...., i can understand the criticizm around something new,...., but i canīt remember to see or read for something related to OSD with an HSI that really worked as this,...., so forgive me,...., but i think you did a great job and i canīt find anything that might be improved,....only the PCB size,...., this is what every modeller needs when flying FPV.

Jun 22, 2007, 03:03 AM
Registered User
Great job,

What are the means used to overlay things on video frames ? (I'am noob about that).

As for the attitude indicator, I do believe that russians fighter jet are using this representation, counter to what we are used with on that roll axis. I don't know if it is still the case for the last jet upgrades as they are done by "sagem" I believe.

You could add a real time direction/distance to waypoint based on the GPS velocity vector to marshal to the take off wp. In case of spatial disorientation.

have good flights.
Jun 22, 2007, 05:27 PM
Dude, this is wicked kewl. I concur about it being about as good as it gets!!! Nicely done!!!
Jun 23, 2007, 12:36 PM
Registered User
Zbig's Avatar
Thanks for comments and suggestions.
Sensivity od horizon is calibrated before take off. It is done by tilt model 90 degree in both sides. Probably I forget to do it .
As you can guess this is NOT horizon, but aeroplane. In most cases you simply see real horizon on screeen, so I decided that better idea is to show tilt and climbing speed of model. But I'm not familiar with HUD systems, so for sure it do not conform any standard.
Of course it can be changed easily and even this option can be added to on-screen cofiguration menu.
(If you don't know what to do, make an option )
I'm thinking about utilise two-axis horizon sensor and make "full" horizon, with up/down shift based on real location.
PCB is one-layer home-made with only few SMD parts and can be easily reduced 2 or 3 times. Another option is to mix on-board only data with video signal (like in teletext system) and then decode it and do OSD display on ground. It will reduce size and weight of on-board equipment.
Jun 23, 2007, 07:04 PM
G'Day ZBig.
Good to see others following the thread. I've looked at a few comments, and your own. If you were doing the overlay on the ground, then the current config is OK, so that if you lose the picture, you can still see what the aircraft is doing, and keep it wings level. If it is staying overlayed on the current picture, then AH is the only way to go. As for a minimum, from my point of view that I would want:
Airspeed, Altitude (selectable feet/metres), Direction (I'm sure there are cheap magnetometres out there that can get real time, rather than dirived from the GPS, tach or volts depending on aircraft (elec or IC).
As far as FPV is concerned I think RTB (Return To Base) heading and distance is highly desirable, especially if flying in a new area. Maybe have it so that Base Location can be input with a button press at the field before launch.

Lastly but not least,
if anyone says the system is poor, use that as inspiration to continue.
The above are not criticisms, but merely suggestions.
You're a genius.
Melbourne Australia.
Jun 24, 2007, 04:15 AM
Registered User
Zbig's Avatar
Base location is stored automatically after power-up. At the top of the screen there is navigation bar, which shows desired return-to-home direction. If you fly to home, white square is straight ahead, if a base is on you right, square moves half right etc. full right or full left position means that base is opposite of your current direction.

distance from the base (meters) is shown at the upper-left corner, below is the speed relative to ground (kph). At the left upper corner there is altitude (m) between then there is climbing speed (m/s)

At the left bottom corner there is a time since power-up or reset, replaced every minute with actual GMT time
below there is distance in WE/NS orthogonal directions (meters) or actual GPS position.
On the bottom right corner there is main battery voltage.

Additionally there is on-screen menu, where you can change main settings like GPS diagnostics, activate/deactivate main features (horizon, timer, navigator, GPS) and of course re-initialize of system (store base position, ground altitude, time and sensitivity of horizon sensors).

It is first version, and like all first versions it is not perfect, so all suggestions are highly desired.

Originally Posted by rjfon1
Airspeed, Altitude (selectable feet/metres)
yes, some people still use such a strange metrics . It is rather simple calculation. Fortunately my algorithm which calculates distances and directions works well on each locations on earth (I hope), not only in my country

Originally Posted by rjfon1
I'm sure there are cheap magnetometres out there that can get real time, rather than dirived from the GPS
I hope so, although I haven't found it yet in shop near my house . Another issue is that electric or even gas engine may cause interference.

Tacho is interesting idea, and of course challenge, because this is another real-time task to do with single-thread processor...
Last edited by Zbig; Jan 24, 2015 at 05:14 PM.
Jun 24, 2007, 05:04 AM
Registered User
CrashingDutchman's Avatar

Congratulations on what you have achieved so far! Very interesting.

I was wondering if you are using PAL system in Poland. If so, could you direct me to information on PAL in combination with the LM1881. I have this video synchronizer too and I am going to use it with an Atmega8. I have found some code for how to do it with NTSC, but don't know yet how to translate that for using with PAL.

Jun 24, 2007, 05:37 AM
Registered User
Zbig's Avatar
Originally Posted by CrashingDutchman
I was wondering if you are using PAL system in Poland
Yes, I'm using PAL. But LM1881 supports all formats:

The LM1881 Video sync separator extracts timing information
including composite and vertical sync, burst/back porch
timing, and odd/even field information from standard negative
going sync NTSC, PAL and SECAM video signals with
amplitude from 0.5V to 2V p-p.
There is no changes in application regarding different formats. I brought schematic directly from application note (datasheet).
there are additional elements (transistors, diodes ad DC parts) to build video mixer which don't harm nominal parameters of video signal, especially levels of sync, black and white signals. This is my proprietary circuit

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