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Old Feb 27, 2013, 02:57 PM
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Dennis, muerzi is thinking about implementing video-telemetry into max-osd, can you help him out with some questions, here is his thread: http://www.rcgroups.com/forums/showt...1672628&page=7

Take a look at the page I linked.

Muerzi I have some boards and I'm from EU.
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Old Feb 27, 2013, 03:18 PM
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Originally Posted by msev View Post
Dennis, muerzi is thinking about implementing video-telemetry into max-osd, can you help him out with some questions, here is his thread: http://www.rcgroups.com/forums/showt...1672628&page=7

Take a look at the page I linked.

Muerzi I have some boards and I'm from EU.
He is welcome to send me an e-mail or ask questions here, I'll probably not keep an eye on the other thread

But it should be straight forward if you use characters on MAX7456
Use 8 characters or something like that, to represent bits, make a smart protocol and decode

Probably easier said than done, but..

- Making the bits with MAX7456 (if it's acceptable that they are visible in the side or similiar), should be quite easy.

- The protocol.
Make sure to use as few characters as possible and some smart error-handling.

- The decoding must contain a little analog-circuit to bias the video-signal to get within an acceptable range. You can use some analog electronic, or might even be able to use a quick ADC? make a quick calculation and see if it's doable within the time-frame necessary.
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Old Mar 01, 2013, 05:31 AM
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Is anyone here from Europe that have the 2 crystals need for the OSD (16MHz and 27MHz) lying around? When I order these 2 parts from digikey, i have to pay 18€ for shipping and VAT. The postal service wants 12€ for making taxes. That's really expensive for 2 tiny parts. Can anyone send me these 2 parts? I will pay via paypal.

Dennis:
I made a custom charset of 4 character (two bits are 1 character wide) which are representing
"00" (white-white)
"01" (white-black)
"10" (black-white)
"11" (black-black)

and also made a set of 2 character (one bit is 1 character wide)
"0" (white)
"1" (black)

My plan so far is to calculate the Azimuth(absolute to groundstation) and the Elevation.
Azimuth in degress/2 (0-180), than it should fit into 1byte Error is 2°
Elevation from 0-90 should also fit in 1 byte
And 1 byte for checksum.

Any other ideas?
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Old Mar 01, 2013, 08:00 AM
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Quote:
Originally Posted by muerzi View Post
Is anyone here from Europe that have the 2 crystals need for the OSD (16MHz and 27MHz) lying around? When I order these 2 parts from digikey, i have to pay 18€ for shipping and VAT. The postal service wants 12€ for making taxes. That's really expensive for 2 tiny parts. Can anyone send me these 2 parts? I will pay via paypal.
Last time I had the same problem. Eventually what I did is that I got in eBay a kit with several cristals of different frequencies.

See: http://www.ebay.co.uk/itm/10PCS-HC-4...item1c2a88b54f
(Ģ1.85 w/Free shipping)

It was way way cheaper the full kit than buying in digikey or farnell just the ones I wanted and for long time I was giving cristals to everyone and his dog.
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Old Mar 01, 2013, 08:18 AM
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Quote:
Originally Posted by muerzi View Post
Is anyone here from Europe that have the 2 crystals need for the OSD (16MHz and 27MHz) lying around? When I order these 2 parts from digikey, i have to pay 18€ for shipping and VAT. The postal service wants 12€ for making taxes. That's really expensive for 2 tiny parts. Can anyone send me these 2 parts? I will pay via paypal.

Dennis:
I made a custom charset of 4 character (two bits are 1 character wide) which are representing
"00" (white-white)
"01" (white-black)
"10" (black-white)
"11" (black-black)

and also made a set of 2 character (one bit is 1 character wide)
"0" (white)
"1" (black)

My plan so far is to calculate the Azimuth(absolute to groundstation) and the Elevation.
Azimuth in degress/2 (0-180), than it should fit into 1byte Error is 2°
Elevation from 0-90 should also fit in 1 byte
And 1 byte for checksum.

Any other ideas?
The transmitting-end is the "easy part". Get a quick sketch up and running and check how much data you can get through, even with bad video-signal.

I would personally do something like this to get started:
- Make a complete white and a complete black character (to indicate 1 and 0)
- Make a "test-sketch" with characters like this:

White white white
black black black
White white white
black black black
etc.

That will give you 16 lines with same color, and 12 * 3 pixel with same color. That will make it a bit easier to work on the decoding.

You don't have to send any data, as long as you can distinguish between 1 and 0 it's fine.

When you got that running, start using small bits/characters and test how much data you can get through with a descent reliability. Preferably you can do some sort of average bit estimation depending on multiple lines, that you know will contain same bit. That will even allow you to do some estimation on the received data, compare with last received data and compare with the "accuracy " on the receiving bits.

On a side-note, bright/white will usually be high, and black will be low. Using white as logic high seems more logical. But that's just a detail
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Old Mar 01, 2013, 08:44 AM
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With 2bytes per line i already got good results. See in my thread. There is also the code to "decode" the data.

What about the audio modem you used some posts ago? Would be a very nice feature.
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Old Mar 01, 2013, 09:06 AM
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Dennis Frie, could you fix the typo in the thread title please?
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Old Mar 01, 2013, 10:38 AM
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Originally Posted by muerzi View Post
With 2bytes per line i already got good results. See in my thread. There is also the code to "decode" the data.

What about the audio modem you used some posts ago? Would be a very nice feature.
Sounds good.

I havent really done anything in regard to downlink. I did a quick test with audio, but the audio on Lawmate transmitters are just terrible.

Quote:
Originally Posted by npre View Post
Dennis Frie, could you fix the typo in the thread title please?
Haha, I've never noticed that
It have been corrected.
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Old Mar 01, 2013, 12:23 PM
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I havent really done anything in regard to downlink. I did a quick test with audio, but the audio on Lawmate transmitters are just terrible.
I'll try with audio. Maybe some other guys want to use it.
In which part of the code should it be entered?

What circuit have you used when you tried it?
Have you desoldered the audio amp, desoldered the mic and cut the trace to maybes camera mic?

Do you have some parts left for the osd? Maybe crystals or the atmega?
I sit i austria and will pay via paypal.

Nr
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Old Mar 01, 2013, 01:50 PM
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Originally Posted by IceWind View Post
Last time I had the same problem. Eventually what I did is that I got in eBay a kit with several cristals of different frequencies.

See: http://www.ebay.co.uk/itm/10PCS-HC-4...item1c2a88b54f
(Ģ1.85 w/Free shipping)
Nice, but i already have 27mhz smd, but larger than neede. Searched the original ones used in the schematic. Have to wait for the pcb. Msev is sending me one. Don't know which crystal can fit on it. Will try
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Old Mar 01, 2013, 02:05 PM
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you should be able to take the BOM I converted to part numbers for digikey and plug them into a website close to you - http://j.mp/15WGzek
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Old Mar 01, 2013, 04:45 PM
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Originally Posted by muerzi View Post
Nice, but i already have 27mhz smd, but larger than neede. Searched the original ones used in the schematic. Have to wait for the pcb. Msev is sending me one. Don't know which crystal can fit on it. Will try
Pm me if need a 16mhz. I have a couple of spares.
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Old Mar 01, 2013, 05:46 PM
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Originally Posted by muerzi View Post
I'll try with audio. Maybe some other guys want to use it.
In which part of the code should it be entered?

What circuit have you used when you tried it?
Have you desoldered the audio amp, desoldered the mic and cut the trace to maybes camera mic?

Do you have some parts left for the osd? Maybe crystals or the atmega?
I sit i austria and will pay via paypal.

Nr
It was just some simple frequency-modeling with an AC-coupled PWM-signal and voltage-divider to match the required signal-level. I just quickly tuned it, to make sure the signal didn't clip.
You cant use normal audio meanwhile, so microphone and mic-amp should not be connected at all.

I only did a quick bench-test as a prove of concept. Made sure I could transfer data, and decided not to work more on the project, due to the audio-performance on Lawmate.

You should check Jalves project. He have been working on the audio-modem. Not sure how well itīs working though.


I would really prefer not to sell parts. I have been getting quite a few requests and just don't have the time to sell parts etc. I've sold a few parts to fellow FPV'ers in DK which have been plenty
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Old Mar 02, 2013, 03:03 PM
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Dennis,

needless to say, bravo!

That CPU has most certainly met its menace. Could CloudBuster be linked to this?

http://www.holmea.demon.co.uk/GPS/Main.htm
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Old Mar 02, 2013, 03:56 PM
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Originally Posted by ifrkey View Post
Could CloudBuster be linked to this?

http://www.holmea.demon.co.uk/GPS/Main.htm
With some work it could, but it would be a huge waste of time and resources.
That project was more of a proof of concept rather than a viable alternative to integrated solutions. Its really expensive too.
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