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Flight Recorder "on the cheap"

Posted: 22 Jul 2013, 22:04
by Kyrt
This thread is about an off-the-shelf GPS + 4GB storage device that is similar to the Parrot Flight Recorder, but costs £25 (30 euros) and is smaller. It does not require any hardware modification. However, be sure to read the limitations below.
navistick_4gb.jpg
First some history. Some months ago I found this device on the intertubes and bought it purely as a project for modifying the drone. This little stick helped figure out some details of the Flight Recorder before it had even been released, starting because I noticed that the 2.4.1 firmware update included the driver needed to run it and that the drone seemed to recognise it, and eventually culminating in pawelsky's DIY Flight Recorder. I would have posted this before Parrot's own device was even released, but unfortunately my drone died immediately before the final step so I never got to test it. That is, until today when my drone returned from repairs.

First some details about the hardware: it is a Navistick 4GB, distributed in the UK by Norcom and sold by Meridian Chartware. There is also a 2GB version available in the US for $35. Internally is a USB hub, CP2102 USB-serial converter, SirfStar III GPS chip, and a replaceable microSD card (so you could fit a bigger one if you wanted). The eagle-eyed amongst you will notice that although most of the components are exactly the same, the GPS chip is not the same as the SirfStar IV in the Parrot device. This is a previous generation GPS so it may beless sensitive/accurate, and it also has the same limitations as the Globalsat GPS used in pawelsky's mod - i.e. it updates at only 1Hz instead of 5Hz, and does not support all the commands that the drone asks for.

However, I have successfully flown the drone around my local park using the GPS navigation function without any significant hitches, and FreeFlight showed upto 8 satellites and a lock of 1m. I don't have a Flight Recorder and so it's hard to do comparisons, but it is by no means flawless. The drone sometimes seemed to stop moving towards its waypoint before it got there, even though the iPad showed the location on the map correctly. I think the accuracy shown in the top right corner also was going down (from 1m to 3m) at high speeds, which makes sense given the 1Hz update rate. To what degree the accuracy displayed by FreeFlight reflects the "real" accuracy of this device, is not known.

Showing accuracy:
image.jpg
Waiting for satellite lock:
image.jpg
Installed on the drone:
navistick_ardrone.jpeg

Re: Flight Recorder "on the cheap"

Posted: 22 Jul 2013, 22:05
by Kyrt
Now, how to get it working:

WARNING: You will be making changes to the EEPROM configuration of your GPS device. You might cause irreparable damage to it. I can't be responsible if that happens.

1. Buy the device.
2. Install the Windows driver from Silicon Labs.
3. Check it is working normally!
4. Download the Customisation Utility from SiliconLabs (AN721SW.zip).
5. Use the utility to change the VID to 19CF and the PID to 3000. Pawelsky's thread has a screenshot - this process is the same as the DIY flight recorder.
6. Click "Program device" to make the change. After the change has been written, you should hear the USB device disconnect and reconnect. The utility may show an error after validation, it should be OK. I think this is because after writing the changes, the driver no longer recognises the GPS as a standard CP2102... because it is now a Flight Recorder!
7. (Optional) Install Parrot's flight recorder drivers. This should allow you to use it in Windows, e.g. with the apps that came with it. If you install them before step 5 it might prevent the error message, I'm not sure as I didn't do it in that order.
8. Go to a controlled environment where you can't lose your drone or injure anyone.
9. Connect to the drone (firmware 2.4.1 or later), power up and wait for a good lock (it might take a minute).
10. Fly!

Re: Flight Recorder "on the cheap"

Posted: 22 Jul 2013, 22:10
by Kyrt
Some details of the hardware I collected from around the web and the manufacturer:

Product ID on PCB: UGD-152X_V4.1

Same as the following product (looks identical externally but in white):

Taimeta UGD-1523

Memory
512MB ~ 32G Byte Flash Memory

GPS Receiver
GPS Solution: SiRF starIII- GSC3f/LPx
Receiver Type: 20 channels, GPS L1 C/A code

Accuracy
Position (Autonomous): <2.5 m CEP
Position (SBAS): <2 m CEP
Velocity: 0.1 m/s
Time: 1us
Start Up Time (Autonomous, open sky)
Hot Start: < 1 s
Warm Start: < 35 s
Cold Start: < 35 s

Sensitivity
Acquisition: -142 dBm
Tracking: -159 dBm
GPS Antenna: 15.0 x 15.0 x 4.0 mm patch

Electrical Characteristics
Baud Rate: 4800
Interface: USB 2.0
Power Supply: 5.0 V ± 0.5 %
USB A-Type Plug

Power Consumption
Acquisition: ~ 60 mW
Tracking: ~ 45 mW
OS Driver: Windows/WinCE/Linux

Mechanical Characteristics
Dimensions: 59.2 x 20.9 x 9.3 mm

Environmental Characteristics
Operating temperature: -20 °C ~ +70 °C
Storage temperature: -40 °C ~ +85 °C
Humidity: 5 % ~ 95 %

Operational limits
Altitude: <60,000 ft
Velocity: <1,000 knots
Dynamics: <4G

Individual Components:

GPS:
Taimeta EF-1513S
SN: 110909291783
SiRF GSC3
_Sensitivity : -159/-142 dBm
_Hot/Cold start : <1/35 s
_Power consumption : 23/46 mW
_Package : 13.1 x 15.9 x 2.0 mm

Antenna:
Taimeta SA-15L30F
Cirocomm 569D
_SiRF GSC3
_Antenna : 15 x 15 x 4 mm patch
_Package : 17.0 x 18.0 x 7.0 mm
_UART interface
_Wire to board connector

UART bridge:
Silicon Labs CP2102
DCF05V
0938+

Re: Flight Recorder "on the cheap"

Posted: 22 Jul 2013, 22:28
by pawelsky
Cool, that saves some soldering. :)

Re: Flight Recorder "on the cheap"

Posted: 22 Jul 2013, 22:46
by Kyrt
pawelsky wrote:Cool, that saves some soldering. :)
Think I will still do your mod, I have had all the bits for a while and I'm fairly sure it's better than this sirf III gps. Honestly I'm surprised it flew so well - might be a fluke though!

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 10:18
by Ruyton
Fascinating mod Kyrt :D

I'm almost temped to give this a try to see how it compares with the Parrot FR - I've only ever seen an accuracy of 2m with FR.

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 10:22
by Kyrt
Ruyton wrote:Fascinating mod Kyrt :D

I'm almost temped to give this a try to see how it compares with the Parrot FR - I've only ever seen an accuracy of 2m with FR.
Interesting. I got 1m with the drone just sitting on my car next to my house, not exactly clear skies. And then in the middle of the park of course. I found that while moving around it tends to be 2m or 3m.

By the way one thing I noticed after 2 batteries of flying around, the GPS and battery were quite hot... I reckon the sirf IV power consumption should be lower, so maybe the FR doesn't get as hot?

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 10:47
by Ruyton
My standard 1000mAh battery gets very hot after an 8 minute flight. The FR is also hot, but I can't decide if this is due to the battery heat or is the FR producing heat too?

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 16:50
by Kyrt
My GPS does produce a fair bit of heat, e.g. if connected to a laptop.

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 17:21
by Jayson Hanes
okayyyy.. I've just bit the bullet and ordered one.. it was only $29 + $6.50 shipping... I'm willing to gamble on it to save $100, lol.. thanks for this Kyrt! I hope I can follow those steps and get it working.. who knows when it'll get here though, I bet it'll still be shipped from Taiwan.

Re: Flight Recorder "on the cheap"

Posted: 23 Jul 2013, 18:52
by garrock
Good Stuff !!!

Re: Flight Recorder "on the cheap"

Posted: 24 Jul 2013, 06:19
by Darklo
I wonder what's the weight of this thing?

My Flight Recorder is 35 g (official spec says 31) and reduces flight time on standard battery by about two minutes and a half compared to a 7 g SanDisk USB drive. I guess they could have easily reduced weight by half if they removed the female USB port and velcro and used stick form factor with thinner plastic.

Re: Flight Recorder "on the cheap"

Posted: 24 Jul 2013, 11:13
by pawelsky
Kyrt wrote:
pawelsky wrote:Cool, that saves some soldering. :)
Think I will still do your mod, I have had all the bits for a while and I'm fairly sure it's better than this sirf III gps. Honestly I'm surprised it flew so well - might be a fluke though!
In the meantime I'm working on a mod that will allow to use any GPS (not only SiRF) as a Flight Recorder. Prototype I have does report the data to FF app. I'll try that in flight when I find some time.

Re: Flight Recorder "on the cheap"

Posted: 24 Jul 2013, 13:30
by Jayson Hanes
Yup. Orders from the website for USA delivery are indeed coming from Taiwan:

Wednesday, July 24, 2013 at 20:09
Origin Service Area: HSIN CHU - JUBEI - TAIWAN
Destination Service Area: TAMPA - EAST, FL - LUTZ - USA

No mention of ETA, however.

Re: Flight Recorder "on the cheap"

Posted: 25 Jul 2013, 00:35
by Kyrt
I'll weigh it tomorrow night if I remember.

Bear in mind though the reduction in flight time isn't just a reflection of the weight - GPS will consume a modest but perhaps non-trivial amount of power.