The SX230 has 14x magnification, I’m curious how this feature will translate to actual per inch pixel size at some reasonable vertical distance to give me a good starting point before I strap in the camera to my fixed wing for some real tests.
For my test, I took pictures at 0%, 20% and 50% optical zoom from height of about 100m. I have 2 objectives: to get a good inch per pixel estimate and second, to get the approximate ‘footprint’ or area of the image of each zoom rate.
SHOT 1: Unprocessed 0% zoom rate:
SHOT 2: Unprocessed 20% zoom rate:
SHOT 3: Unprocessed 50% zoom rate:
SHOT 1A: pixel at 0% zoom rate:
SHOT 2A: pixel at 20% zoom rate:
SHOT 3A: pixel at 50% zoom rate:
1) 0 and 20% zoom does not have any real footprint difference.
2) 0 and 20% zoom has a good sized foot print from 100m and probably will do for aerial mapping purposes which requires 3-6 inch pixel resolution.
3) 50% zoom actually has only 25% of the footprint of 0% zoom (not 50%!) however, the resolution is good, I suspect less than 1 inch per pixel as shown in shot 3A.
4) Finally 100m is too low for real aerial mapping work, 400m-700m is probably more appropriate.
I got a used Canon Powershot SX230 SH for only about $70 (brand new this is about $250).. its beat up pretty good but everything works except for the lens cover which doesnt close even if its turned off.. I dont think this is a big issue at all.
This will be used as the mapping component of my Skywalker rig and which needs to be updated with CHDK for added features relevant for my use. Here’s the steps on how to do it:
2) Download the Automatic Camera Identifier and Downloader (ACID) to check for the camera’s installed firmware (mine was 100c) and download the correct CHDK version (http://www.zenoshrdlu.com/acid/acid.html)
3) UNLOCK the SD card and format it using the camera’s format function
4) remove the SD card and insert into your PC/laptop.
5) copy all the files downloaded in step 2 to the root directory of the SD card.
6) Remove the SD card, LOCK it, then insert into the camera. Don’t worry CHDK will just ignore the LOCKED state of the SC card and will still allow the camera to write to the SD card (if this is UNLOCKED, CHDK will not start on bootup after step 10).
7) Press the “PLAY” button (not the on/off).
8) Press the MENU Key and under the ‘play’ tab, look for “Firmware Update…” and press the “FUNC SET” button. After the update, you should see a black/empty screen with “No Image” in the middle (which makes sense since we deleted everything).
9) Press the ‘PLAY’ key briefly, which is the default <ALT> key to bring up the CHDK menu and you should see the CHDK alternate menu.
10) Set the SD card to autoboot to CHDK, by pressing MENU (after step 9), navigating to ‘Miscellaneous Stuff’->’SD Card’->’Make Card Bootable’ and pressing ‘FUNC SET’. The camera will now run CHDK even after turning the camera off.
Installing a Zener Diode and Capacitor to help bullet-proof your Pixhawk is easy. Both components may just help save your plane or multicopter someday.
The Pixhawk design allows for the servo power rail to be used as a secondary or backup power supply for the AP. However, the design has very low tolerances such that if power is to come from servo rail (via the ESC or an independent 5V UBEC – the latter is recommended) the servos must not pull more than 5.7v. Note that most micro servos operate in the 4-6v range (with digital servos going > 10v) and when the voltage pull goes beyond 5.7v, the Pixhawk will reboot, resulting in disaster!
To mitigate voltage spikes beyond 5.7v on this servo rail, the recommended mod is to add a Zener diode. When a zener diode is installed in reverse (ie the anode coupled to the ground and the cathode to the current) it acts as some kind of breaker, activating and capping the voltage spikes once its rated voltage is reached.. this means if the correct zener diode is attached in reverse polarity in the servo rail, it will prevent over voltage and therefore not result in the AP resetting midflight. Installing a capacitor in parallel* to the zener is also recommended as it helps smooth the voltage “ripples” further.
To make a Zener Diode and Capacitor for Pixhawk or HKPilot you need the following:
1) Two (2) servo leads 2) One 1N5339 Zener Diode 3) One 6.3v 220uF capacitor
1) For the Zener – make sure that the polarity is reversed, ie the side with the silver band must be soldered to the current (ie middle) servo lead and the other to the ground.
2) For the Capacitor – install as normal.. ie the positive to the current servo lead and the negative to the ground lead.
Here’s how it looks like installed:
and installed in the HKPilot32:
* Coming from an non-electronics background, understanding what parallel connections should be, is confusing. Thanks to “turdsurfer” over in diydrones.com for pointing out what this meant! =)
CTTools: CT Tool for MinimOSD Extra 188.8.131.52 Pre Release r727.zip
2) Setup EzUHF Receiver to send RSSI or LINK quality values. Since you are using a Pixhawk or HKPilot, the setup should be that all the channels goes through channel 1 which is ‘muxed’. Connect to your EzUHF receiver using a USB cable and open the ImmersionRC Configuration Tool. Once connected, just set channel 8 to either RSSI or LINK (only channel 8 will with MinimOSD for now so its pointless experimenting with other channels). You can use either RSSI or LINK, but I suggest you use LINK as RSSI is all about the signal strength and not the actual quality of the link. Upload the settings to the receiver. Here’s how it looks like:
4) Do not edit any parameters in APM or MP. You do not need to change or update any settings in the AP configuration so leave it as is.
5) Get the maximum and minimum RSSI or LINK PWM values in MinimOSD. For this next step, both segments of the MinimOSD must be powered or any updates in the configuration you make with the MinimOSD will not be saved. The OSD output end must be powered with 12v and the other end is plugged to your laptop with an FTDI cable. Like so:
Use the configuration tool to set up the RSSI values (in Panel 1). Make sure you write the configuration to MinimOSD. On the main ‘Config’ panel make sure that you’ve set the ‘RSSI Channel’ to Channel 8… AND make sure the RSSI Enable RAW is checked.
Save the configuration, remove the MinimOSD, plug it into the Pixhawk cable and Vtx/Camera cables and power up your system. On the OSD screen where you’ve set the RSSI to be, you should see a number. Take note of this as this is your ‘maximum’ link quality value. Unplug your transmitter and take note of the value. This time you should see a smaller number. This is the minimum link quality value. For my setup, the highest was 1793 and the lowest was 1056. I just set it to 1800 and 1050 since the OSD is limited to steps of 10. Now power down the system, disconnect all cables, connect 12v power source to the MinimOSD and plug back the MinimOSD to your laptop.
6) Update the MinimOSD PWM Min and Max RSSI Values. Finally, fire up the MinimOSD CTools again and change the Minimum and Maximum RSSI values to the one you got in step 5. Also set uncheck the ‘RSSI Enable Raw’ so you can see the values in percentage format. Save the configuration and test.
I decided to bite the bullet and go with the HobbyKing HKPilot32 instead of the Pixhawk for the reincarnation of my Skywalker FPV rig. By most accounts the HKPilot32 works as advertised and why shouldnt it? it has the same design and uses the same chips as the open source Pixhawk. Thank you open source and market forces!
Here’s the content of the packet (L to R: USB cord, Servo wire, Power Module, the HKPilo32, cables for the gps, buzzer, arming button, stickers and vibration pads, free memory card/usb adapter and extension board) and a 4MB sd card pre-installed in the device. The only major downside is it does not come with the 6-pin cable needed to connect the HKPilot to the Quanum Lea-6H GPS.
What surprised me is the size of the HKPilot. it has the same dimensions as the APM 2.6 which is great.
I’ve heard about the poor quality of the soldering and board layout of the HKPilot.. personally, for the price, I couldnt care less as long as it works reliably. Anyway, out of curiosity I checked the board.
In my opinion, the board design and layout is not bad, a bit dirty to be honest but not bad. The soldering while not topnotch seems to look solid enough at any rate.. of course I’m comparing this to the usual hardware I see (computing and networking appliance’s boards). You can judge for yourself above.
So does it work? so far yes, I was able to load the latest ArduPlane firmware and didn’t really have an issue connecting MissionPlanner (except I had to set the connection speed to 38400)
This is the manual of the the Boscam TS582000 is a powerful 5.8Ghz VTx. The best thing about this transmitter is its listed output obviously.. but that’s the only advantage, in my opinion and one could get a lower powered transmitter which can probably get almost the same range. As effective range is affected by several factors afterall.
Here are my comments about this transmitter:
1) Replace the Stock Antenna. Using this with the stock yagi antenna, is pointless because of the donut hole effect which results faded signals when the plane is above you. It works best using a circular polarized antenna like the Immersion RC Spironet. In fairness, this holds true to all 5.8 transmitters available in the market today. All I’m saying the cost difference of putting in a circular polarized antenna (instead of the yagi) for such a powerful transmitter would probably have made little price difference.
2) Limited Mounting Options. You’d think by now that the VTx’s which are being sold as for ‘FPV’ would have better mounting options, but they dont. Again, this holds true for almost all of the antennas out there. In my case, I had to reverse the antenna so I can use the mounting screws of the fan to screw it to a custom mounting using a phone card.
3) Clunky Channel Panel. Unlike other transmitters, this particular one is a pain when changing channels. Not only are the switches really small, there’s no visual feedback to show which channel is active. Other transmitters have a small digital-like screen to show the active channel which is really handy specially in the field. In a couple of instances I had to embarrassingly request other FPV flyers if they can change their channel as the 2W is overwhelming everybody and as I said changing the channel on this transmitter is a real pain in the @ss.
My replacement FPV platform is finally here.. after losing the 1900 Skywalker 2014 due to a bad GPS caused by the vibration of a bad motor (bad bearings) activated by a bad operator (yours truly who ran out of TX juice), I decided to use the same platform but this time with better components (specially the motor!). The platform remains the 1800 Skywalker 2013 CF tail boom (and wooden pan for the FPV cameras) with the elevator on top of the rudder but this time from FPVModel.com.
Here’s how it came in:
and the contents:
Here’s the Lowdown:
1) The 1880 wings seems to be thicker and looks like it also has a slightly longer root chord than the 1900 wings.
2) Unlike the 1900 wings it doesn’t come with a CF strip on top for added strength although I don’t think its needed considering its thickness and the fact that it also has a longer dihedral, covering 1/3 of the wing.
3) Because of the large dihedral, this wing doesn’t come with flaps, it only has enough room for the the ailerons.
1) This is the T-tail version, with the elevator attached on top of the rudder. I think this is a good idea, in my SW 1900 the elevator is attached to the base of the rudder. This has a tendency to get skewed by the tall grass I occasionally land in.
2) The connecting plastic mechanism to snap into and remove the elevator to the rudder seems innovative although looks a little bit flimsy to me. Looks like I need to do a little mod on this.
All the usual parts seems to be complete. Will post the components list next.