Saturday, February 28, 2015

Built a smaller quadcopter

A new build from parts ordered from China. This time I'm using the excellent OpenPilot flight controller. Here's an early flight in the back yard.

Thanks Cat for filming.

It's basically this "kit":

I didn't use their supplied power distribution board as I didn't have any documentation and had one at hand.

I used a Fly Sky 6 channel remote transmitter and receiver (these are great by the way).
Also a compact 3s (cell) Lipo battery.

One frustration is that the motors could not be bolted in place with the supplied components and I had to hunt around to get 2.5mm x 6mm bolts and some nuts.

The OpenPilot CC3D software is amazing and I don't have it properly tuned just yet but it's great fun to fly around the back yard. The motors get hot and give off a satisfying burning smell after a bit of use.

Sunday, February 22, 2015

Wyong field day 2015 - Damp but entertaining

The weather wasn't great for the big feature of the Wyong field day, the car boot sale. The ARNSW Home Brew group had a great display and spent time chatting with interested visitors. Here's John VK2ASU with Mal VK2BMS:

I showed the OpenRadio SDR on the home brew table:

While I didn't buy anything there were gifts of useful components from John and Stephen which are greatly appreciated! Some things I didn't buy:

It was great to retire to the classy bar:

For some tea, Jatz biscuits and cubes of cheese.

Built a larger quadcopter

The tiny drones are great for indoors, but to carry cameras I needed something larger. A collection of parts and a 450mm frame was ordered and finally it's flying.

I'm using a Fly Sky FS T6 transmitter and receiver and a KK2.1 flight controller.

Neither the remote or controller came with the interconnecting cable so I'm using single wire jumpers until proper cables arrive. The flight controller was recommended by Terry and is great because you can test everything and tune it by using its built-in LCD display and buttons.

While I can fly this thing the PI tuning isn't right and I'm getting oscillations while hovering. Lots to learn. Lots to learn.

Thursday, February 12, 2015

Tiny Quadcopters - Hubsan X4 and friends

We are having too much fun at the office (during lunch breaks) flying tiny quadcopters. The best of them seems to be the Hubsan X4.

A close second is a clone sold as the "Top Selling X6".

Both sell for about $40. The Hubsan you can order from China, the "Top Selling" is available at Paddy's Market in Sydney. Don't be fooled by the price saying $49 reduced to $45, they'll take $40 in a heartbeat.

For a little bit more, $50, you can get models with a camera:

Some drones like the UFO drone have a remote with buttons for taking still or video.

Great to have "High Agily Control":

The cameras are not great but kind of fun. Here's me checking the gutters.

The video is motion jpeg and seems to drop a lot of frames:

The trick to getting decent video with these tiny MJPEG cameras is to use a fast microSD card. Here's a recording with a Class 10 card and it's much better.

The motors are interchangeable and the other "consumable", the propellors, are available at low cost.

So far, I've learned:

  • Fly calmly, avoid dramatic corrections, and you'll be fine.
  • Expert mode, by pressing the left controller (mode 2) is more responsive and not really any harder to control.
  • The motors do die - I had one that went stiff after a crash, but are pretty easily replaced.
  • There is a "ground effect" and a "ceiling suck effect". Take off to about a meter in height and then get stable. Avoid the ceiling.
  • It helps to calibrate the accelerometers - the instructions explain this in broken English but it's worth doing. I've heard that calibration in expert mode is better.
  • If the video drops frames get a faster memory card. Class 10 works for me.

Flying indoors:

In a larger room:

Great fun.

Sunday, February 01, 2015

OpenRadio SDR kit build

Linuxconf this year in Aukland had a radio track where a low cost software defined radio receiver with some limited ability to transmit was launched. My kit arrived last week.

The OpenRadio SDR is based around the recently popular Si5351 oscillator which is controlled by an Arduino Nano. It's rather like the Softrock design but because the Si5351 has extra outputs there is ability to transmit digital signals modulated with shift keying. The software includes a beacon mode that can send a short message in, for example, BPSK31.

The OpenRadio SDR kit is lovingly prepared. As you can see above, the components are clearly marked and the makers have been kind enough to be generous with extra components - in particular I tend to lose surface mount capacitors and resistors from time to time.

The construction guide is first class. While there is some surface mount soldering required - a challenge for me certainly, they've been kind enough to pre-solder two of the most difficult devices.

I didn't rush the build and spent a few hours on Saturday doing a bit and then going for a walk. For me, everything worked first go.

The software in the Arduino is a great start but here's where this is where work can be done. You connect over a virtual serial port and get a simple menu for controlling the board.

0.3 Jan 31 2015 09:37:39
Starting up Si5351... Got Rev ID 1

RX Frequency (Hz): 8986000
TX Frequency (Hz): 26959500
TX/RX Relay State: RX
Transmitter State: OFF
Calibration factor: 1.00000000

RX Frequency (Hz): 8986000
TX Frequency (Hz): 26959500
TX/RX Relay State: RX
Transmitter State: OFF
Calibration factor: 1.00000000

1: View current settings.
2: Change RX Frequency.
3: Change TX Frequency.
4: Toggle TX/RX Relay.
5: Toggle TX State.
6: Start BPSK31 Terminal
7: RX VFO Mode
8: Calibration Mode
9: Save Settings
A: Set channel (TX/RX frequency pair)
B: Start Beacon

For tuning around, at the moment you must use RX VFO Mode which gives you keyboard letters for tuning up and down, rather like PowerSDR but you must press enter after each.

RX VFO Mode, press q to exit.

    Up: r   t    y    u    i    o    p
  Down: f   g    h    j    k    l    ;
Amount: 1   10  100   1K   10K 100K  1M

I guess an interesting direction to evolve this would be to implement the protocol used by a popular rig and then SDR software could use Hamlib to control the board - certainly all possible.

My congratulations to everyone involved in this. I think it's a great idea brilliantly executed and I can't wait to see what people build on top of it. The idea of having an Arduino at the core makes it very accessible.