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ddwaner

Low Power Tests

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I'd still like to know if anyone has built the unit to read the aircraft values and places the values in the closed captioning line for transmit to the ground. Any monitor with CC could show the values and they could be recorded with the video feed and there would be NO problem with the text overlay singing with transmitter types.

SEEMED LIKE A GOOD IDEA TO ME...That would keep the display clean from the aircraft.

Wonder if it would be hard to mod one of these. http://www.wingedshadow.com/howhigh.html

Edited by ddwaner

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Attention (MODIFICATION OF THE MECHANICAL "plumb Bob" device)

Improvements of the Idea...

No moving Parts added to the aircraft

Inexpensive

Generates 2 values from 1 channel

IMPORTANT(for some) At least 1 Gyro (however inexpensive) would be used!

Accel/Decel/GForce is better compensated for.

The pot and arm with a weight is to be replaced with...

I use a 7 channel PCM receiver, so come out of like channel 7 with a NON Changing under good conditions servo center 1.5 signal and run it into a simple cheap rate gyro with some gain. I have these gyro's in my spare parts drawer so I didn't have to buy any. Mount the gyro so that it detects nose up/down/level changes and program the PCM Channel 7 channel to fail safe something like a servo full down signal. Output the gyro signal into one of the audio channels of the video transmitter (Use a couple of resisters to pad the signal some (My transmitter says it can handle a 3v audio signal)).

ON THE GROUND

Now back to the original Idea of reamp back to a servo signal and place the servo arm in view (maybe make a nice little airplane that looks level with no changes). Now anytime the nose changes (along the gyro sensed angle) the ground airplane will show which direction and some idea of magnitude of change, if you get too far away and the receiver starts fail safe'ing, your little ground airplane will nose down.

Costs a little more but its easy to get the parts and the new "Plumb Bob" has no moving parts and Accel/Decel/GForce is better compensated for and some idea of the ground transmitter signal level at the aircraft would be returned.

Sounds like a fun little project to me (some like fuzzy dice hanging from the rear view mirror).

Cheap Gyro $26.50

2 Resisters $1.00

Amp IC $3.00

Servo $10.00

Edited by ddwaner

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If you send the gyro's signal directly into the audio input of the TX without modulation you'll most likely have a very ugly signal on the ground as the bandwidth of the audio channel is nowhere near the video one, it won't cope with the signal edges that will get "rounded", and the servo most likely will go nuts.

Also expect garbage on the video, a lot of transmitters don't like their audio channel to be overdriven and some crosstalk can take place.

Worth trying though ;)

I'd still like to know if anyone has built the unit to read the aircraft values and places the values in the closed captioning line for transmit to the ground. Any monitor with CC could show the values and they could be recorded with the video feed and there would be NO problem with the text overlay singing with transmitter types.

No. That is something that would be more complex than any OSD that is out there at the moment. And yes you could maybe record it in the video feed, but only if you use a good'ole VHS, that sort of thing is not kept with digital encoding. That would have to be recorded separately.

Edited by Kilrah

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Ok butt.....

If the tx/rx can carry a audio signal from 50Hz~20kHz and the sound card input of a computer is the same range. A transmitter buddy signal with 8 ppm channels running can be inputted to a computer sound card audio input at the mic jack and decoded into the 8 pulse channels cleanly enough to use that input to fly a 6-8 channel simulator with a standard transmitter. The range for only 1 channel would be much easier to send. I'm bread boarding the circuit now to see, so far so good, the ground amp restores the pulse input level fine.

Overdriven??? I gonna send a line level signal (prob <100mv). (Not Modulation..., attenuation)

Edited by ddwaner

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Firstly I doubt the audio channel has 20KHz bandwidth. Then, it doesn't change a thing if you transmit 1 channel or 8, what defines the required bandwidth here are the edges. And, I don't know if you have looked at the waveform that the PC captures, it's all rounded and ugly. That's no problem with a PC as it has software that knows what to expect and can "correct" the rounding for example by measuring times on the zero-crossings. A stupid servo has good'ole analog circuitry that we don't know what will do with a crappy signal. That should be expected to vary between servos.

By overdrifing I don't only mean the level, but the TX's circuitry isn't designed to accept spikes.

Everything might work well, but what I'm trying to say is that it's really stretching things out of what they're designed to, so it may or may not work. It may work on a certain combination of components, but might not if you change one.

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Ok...

I am cleaning up the edges when I come out of the reciever and raising the signal back to a level that a servo can use. I still have a little more to go to get a working device. :P

I had to laugh, "A stupid servo has good'ole analog circuitry", OH BUT WHAT IF I USE A DIGITAL SERVO.... Never Mind...

Edited by ddwaner

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I thought about that, but considered that it would be deemed too expensive for the low-cost component of the project :P

More seriously, the digital servo has a digital input that will sense low or high above/under certain thresholds. Depending on the signal that can mess up too. The PC is sampling an analog value fast and thus has the whole graph to figure out where to do the measurement.

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A digital servo would cost too much unless its one from the junk drawer that is to be used for a bomb drop or something. I plan on using a HT55 that I would not trust to fly a airplane. The device must be cheap, cheap to build and use, Oh Yeh, it needs to be light in the aircraft too (a micro gyro and 2 resistors (<10gr including wiring @<11ma)).

Edited by ddwaner

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Design Mods

Tx has been updated to a regulator less design. The transmitter assembly can now operate in still air till the battery runs down, I expect about 2 hours per charge . Only the transmitter case is warm to the touch. I will range check soon.

Rx has been updated to a 1/4 wavelength antenna from 1/2 wavelength. Far less drop outs at short range. Long range tests soon.

post-6-1184052675_thumb.jpg

Edited by ddwaner

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