Helicopter Autopilot project thread
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leon_heller
- XCore Expert
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- Joined: Thu Dec 10, 2009 10:41 pm
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Not many people actually use that sort of power level. My FT-857D only puts out 100W.
OT, but anyway, wouldn't it be tricky to restrict the power output to mW in many of the ISM bands, since there are intended to be used for " industrial, scientific and medical" use.
Take the micro-owen for an example, it's no magical resonance for liquid water at 2.45 GHz, actual you need to use standing waves in the micro to make a efficient absorption of the EM-waves to the food. The water dipole molecule will only be some degrees of lag behind the electrical field at 2 GHz, making it a rather poor absorbent. (Heavy fog or snowing might be different above 2 GHz)
The leakage is not large for an oven, but it hi enough to disturb any data transmission that would try to occupy the frequency band of the magnetron. I heard that there also are larger micro-owes that works at a longer wave-length in the 915 MHz ISM band.
The very nice thing with the 2.45 GHz band is that it is allowed all over the world, making it easy to produce anything from WLAN to microovens and sell it.
But a 10 cm wave doesn't diffract around corners much, so it´s not so good to be used for communication in rough terrain there the transmitter and receiver doesn't have a free line of sight, making the 900 MHz better for an helicopter ?
Also the 2.45 GHz band is so full of EM-radiation today that you must often use adaptive frequency hopping to find free frequencies to transmit in.
Take the micro-owen for an example, it's no magical resonance for liquid water at 2.45 GHz, actual you need to use standing waves in the micro to make a efficient absorption of the EM-waves to the food. The water dipole molecule will only be some degrees of lag behind the electrical field at 2 GHz, making it a rather poor absorbent. (Heavy fog or snowing might be different above 2 GHz)
The leakage is not large for an oven, but it hi enough to disturb any data transmission that would try to occupy the frequency band of the magnetron. I heard that there also are larger micro-owes that works at a longer wave-length in the 915 MHz ISM band.
The very nice thing with the 2.45 GHz band is that it is allowed all over the world, making it easy to produce anything from WLAN to microovens and sell it.
But a 10 cm wave doesn't diffract around corners much, so it´s not so good to be used for communication in rough terrain there the transmitter and receiver doesn't have a free line of sight, making the 900 MHz better for an helicopter ?
Also the 2.45 GHz band is so full of EM-radiation today that you must often use adaptive frequency hopping to find free frequencies to transmit in.
Probably not the most confused programmer anymore on the XCORE forum.
Leon: If this projects continues, I guess this will be the first Kalman filter on the XMOS, if you haven't ported your old ADI-BF code to XMOS yet.
Probably not the most confused programmer anymore on the XCORE forum.
I am using a 1W 900mhz transmitter, quite overpowered for a helicopter's range.
I am not doing a kalman filter anymore, a DCM algorithm seems better (based on William Premerlani's work).
I have been waiting forever for the PCB from batchpcb to come, as well as a bunch of parts from hong kong (hobbyking).
I am not doing a kalman filter anymore, a DCM algorithm seems better (based on William Premerlani's work).
I have been waiting forever for the PCB from batchpcb to come, as well as a bunch of parts from hong kong (hobbyking).
Please, any references to read about "DCM algorithm" and William Premerlani's work.
You could implement a semi-automatic system with..
Mems Gyro And accelerometer chips, not to mention those gps modules.
The power requirements are minimal compared to the 'Megawatts' you're talking about..
I worked out a project like this yonks ago for farmers to 'visually' patrol their farmlands, but the technology was lacking. You'd need a bigger chopper and with the current tech it could takeoff/fly/land itself.
You should pop into any local airshows (farnborough) and you'll see plently of these UAVs
;)
Mems Gyro And accelerometer chips, not to mention those gps modules.
The power requirements are minimal compared to the 'Megawatts' you're talking about..
I worked out a project like this yonks ago for farmers to 'visually' patrol their farmlands, but the technology was lacking. You'd need a bigger chopper and with the current tech it could takeoff/fly/land itself.
You should pop into any local airshows (farnborough) and you'll see plently of these UAVs
;)
Once you get the mems stuff working Ok, you don't have to worry about filtering (maybe have it as a temporal backup), and use the rest of the cpu power for image compression and transmision.
It's not as if the chopper is wandering off into space.
BUT.. it could be an interesting terrestial concept.
;)
It's not as if the chopper is wandering off into space.
BUT.. it could be an interesting terrestial concept.
;)
I am kind of lost as to where the power discussion and "megawatts" came from.
DCM:
http://gentlenav.googlecode.com/files/DCMDraft2.pdf
Bill is active on diydrones: http://diydrones.com/
DCM:
http://gentlenav.googlecode.com/files/DCMDraft2.pdf
Bill is active on diydrones: http://diydrones.com/
@leon_heller: shouldn't be a 50 watts limit for that band? p.s. are you happy with your yaesu (I am thinking to buy 817 qrp model)?
@lilltroll: without free line of sight you will need some kind of remote vision system, so the "non-long range" 2.4GHz shouldn't be a problem for heli navigation. so far I remember all modern remote radio controls in 2.4GHz band do use adaptive frequency hopping (JR, Futaba, Sektrum). Some time ago where was an amazing post on Hack-a-Day about a plain with remote control in 4xx MHz band with remote vision system using wavelet compression. what a thing!
@rp181: thanks for reference. interesting reading!
Jumping to Kalman filter again. Let's assume the filter is implemented in XMOS chip. What would be the easiest setup to check if it is working right?
@lilltroll: without free line of sight you will need some kind of remote vision system, so the "non-long range" 2.4GHz shouldn't be a problem for heli navigation. so far I remember all modern remote radio controls in 2.4GHz band do use adaptive frequency hopping (JR, Futaba, Sektrum). Some time ago where was an amazing post on Hack-a-Day about a plain with remote control in 4xx MHz band with remote vision system using wavelet compression. what a thing!
@rp181: thanks for reference. interesting reading!
Jumping to Kalman filter again. Let's assume the filter is implemented in XMOS chip. What would be the easiest setup to check if it is working right?