jelle737's blog View Details
Posted by jelle737 | Nov 18, 2018 @ 05:37 PM | 1,316 Views
A long running complicated project. The scope is to have a guided aid in the OSD about where to find your flying friend. With telemetry of their trajectory. Like this:

The bar shows from left to right, where they are, how far away they are, the altitude difference, their direction of flight relative to yours and their speed.
There are more visual examples and real life tests to be found on GitHub here.

Current status
Update: A new approach that combats the flaws is released: find it here.
The working code of this project is to be found on GitHub here.
It runs on a minimOSD board, it requires (LTM) telemetry data from both planes.
The minimOSD is wired as in the following diagram:

There where a few design choices I made and why. Since I didn't want an extra radio link for the telemetry I pursued the possibility to use the audio channel to get data from the air to the ground. Since the data of two pilots is now available on the ground, right by the video, the next design choice by using a ground based OSD made sense. And I like the solution I made of making the minimOSD hardware master-slave input to differentiate.

The flaws
I should mention the project as is is working. The challenges are that a very specific hardware setup is required. For the project to work your flying friend needs to provide (LTM) telemetry data and run his video through a minimOSD. And in my case I proved them with the audio chip, so they only needed to setup LTM data in their iNav FC wired to the...Continue Reading
Posted by jelle737 | Nov 18, 2018 @ 12:45 PM | 1,343 Views
Dipole antenna's, they are my favourite go to antenna, sometimes a rubber ducky but in my opinion self-made (and tuned) antenna's really go a far way. Even unchecked a good measured self made dipole usually outperform a wrongly selected cheap rubber ducky.
However remarks about the use of balun's in dipole antenna's are found here and there. A complex topic? A difficulty to implement? I thought it's a good thing to explore!


First and third antenna have balun. The other two are a classic build dipole using a PCB to mount the active and counter-ground part's of the antenna.

For myself I made up the following rule: Use a dipole with a balun on the receiver side, use a dipole without a balun on the transmitter side. If the power of the transmitter is expected to be less then 250mW a dipole with balun could be used on the transmitter side.

But what is a balun?
I'm not the best to explain, but here is a nice write-up and where the idea and my first antenna's came from. Thanks kolins for my antenna's!
What I think it does, is limit the influence of the feeding coax cable, and in that way limit the influence of everything that is mounted beside the coax or on the airframe.
The chip I use is a ETC1-1-13, it's datasheet is to be found here. It is from the datasheet that I deduct that it's only to be used as a transmitter if the power is less then 250mW. Also it's only good for antenna's <3000MHz, so it's not to be used as a 5.8GHz antenna, I guess the chip is huge...Continue Reading
Posted by jelle737 | Nov 02, 2018 @ 07:31 PM | 1,516 Views
Magnetic Encoder Open Servo (MEOS) - 1 turn 360 capable programmable digital servo

A programmable servo capable of turning a defined 1 turn 360 (or more).
Hard to explain but it's basically a regular servo but instead of 90 it can move 360 or any programmable number of degrees. The 360 is easily confusable with a continuous rotation servo which this project is not (although it could be programmed to do this).
Here is a video:
MEOS - 1 turn 360° capable servo demo video (2 min 14 sec)


This might be similar to a GWS (Grand Wing Servo) but since I didn't like the 10 random offset depending on if you're reaching from left of right to a certain position. And related to this since small corrections don't get through making it hard to point the perfect shot. I started looking into 360 degree non continuous rotating servos. Since there are very few available, at an hobby affordable price, I build this idea. And after lot's of work here is my last new project shown to the community. I decided to make this open source, the build is rather difficult but there might just be someone improving on it and sharing back.

Did I already mention that it can be programmed to move multiple turns while knowing exactly where it is. A demo video of this behaviour here:
MEOS - 1 turn 360° capable servo multiple turn demo video (0 min 31 sec)
...Continue Reading
Posted by jelle737 | Sep 28, 2017 @ 08:10 AM | 13,799 Views
This tracker seems to be very popular among the Spanish speaking RC pilot's. Yet in this forum there is no information to be found. Once you break the language barrier it's actually a very easy system to setup and use. And therefore I find this system needs to receiver more recognition. Lately I took the time to dig in this project and make one myself. This is a guide with tip's and tricks on how to create and use one yourself based on u360gts. And in general it should be a good guide on how to DIY a proper mechanism for any antenna tracker no mater what brain is driving it. The u360gts supports a variety of different telemetry streams like: MFD, Bare GPS, Mavlink, RVOSD, FrSky X, LTM, PitLab. There is a telemetry autodetect feature! The LTM telemetry is what I use and base this project on. An audiomodem is used to get this telemetry from the air to the ground but different telemetry providing systems could be used, one coming to mind would be the telemetry downlink openLRSng provides.

Here is a visual collection of most of the parts needed to make a 360 antenna tracker. Some are optional:

There are a few must haves and there are a few optional parts, the different approaches to the tracker are discussed and the list of the parts I used are listed after. There must be a magnetometer on the ground station, therefore a naze32 rev5 full is most easy to setup. But if you have a naze32 rev5 acro and a GPS with a HMC5883L magnetometer, that's also a working combination and the...Continue Reading
Posted by jelle737 | Sep 27, 2017 @ 01:50 PM | 5,596 Views
There is no topic dedicated to FSK Modem. Maybe these fell out of the collection because of age. Maybe these are not yet reinvented.
Information about these are spread around on the internet. This should be a collection about some information on this topic.

If you search the internet on this subject you probably found already this blogpost. In short what is an FSK Modem: Frequency-shift keying, it's the sound of the internet when I was little, it's a fax machine. But in short it's a way to convert digital data to audio and back. There is a more technical video available if you want to learn more about this technology.

How is this related to the RC hobby? Well it's an easy way to send telemetry data over audio back to the ground. Back in the day it was invented it used to be hard but these days it actually makes sense to dig out this technology, and add it to your flying object. The main limitation of an FSK modem is that it's slow, it can only manage a baude rate up to 2400baud. What's changed today is that this slow telemetry stream, called LTM or Lite Telemetry is available with just a few clicks in iNav, no need for an extra microcontroller to convert yet again this data. And again on the ground side there are multiple projects that already accept LTM telemetry like this display project or an antenna tracker. Also using the audio channel removes the need of an extra radio link that might elevate the noise and bring down the range of the flying object. It said that in...Continue Reading
Posted by jelle737 | May 19, 2017 @ 09:40 AM | 28,331 Views
Intro

With a few friends we decided to buy/build the same wing with similar components. Here is the story how this adventure advances. Will be updates when time goes by. The innovative things in this project for me are the wing, the iNav flight controller and the Wolfbox reciever. I am only used to drones. The build log is written more in the form factor of a tutorial, as to help other people building the same (like my friends).

Parts list/Specifications
  • Wing: MiniRaceWing
  • ESC: FVT LittleBee Spring 40A
  • Motor: X-FOOT 2207 2600KV
  • Prop: DALProp Cyclone 5050C
  • Battery: Drone Lab CHAOS Edition 1300mah 4s 75-150c (Basically a 4cell battery I have already)
  • Servos: EMAX ES08MA II
  • FC: Omnibus F4 Pro with baro / Omnibus F4 V2 Flight Controller
  • GPS: HOLYBRO Micro UBLOX NEO-M8N
  • PDB (for 5V & 12V): Matek Mini Power Hub w/BEC (5V and 12V)
  • Mounting hardware: Stand-offs, a active buzzer and this Flight Controller Mount or this Flight Controller Mount.
  • Receiver: Wolfbox Taranis compatible transmitter and receiver.
  • FPV Cam: HS1177 or RunCam Split (I switched to RunCam Split now)
  • FPV link: Partom FPV 1.2G

Extra Tools and Parts

This is a list of tools that I didn't know I needed when I thought about building this wing.
  • CA glue, Super glue, epoxy for spars and servo's
  • White laminate for balsa elevons or tape.
  • Clear laminate for wing halves, I do not recommend laminating at this point to prevent deformation. It's a racewing, not an endurance wing.
  • Hobby iron for laminating
  • Coloured
...Continue Reading