hi guys
my friend has a Quadcopter, and this Quadcopter send video to radio Control.
a lcd is connected to Quadcopter using hdmi
but we don't need this video :)
we want send data using this path 
, then We do not need to design a 5-kilometer transceiver.
but the problem is that, i dont know how send data using microcontroller to hdmi ( Quadcopter side ), and receive my data from hdmi ( radio Control Side )
Is this possible?
Is this a reasonable approach?!!
HDMI is just the output format. The camera outputs the data in one format, then that probably gets compressed into mpeg data which is sent over the wireless link which is then decoded, decompressed and put into a frame buffer. Then the frame buffer is output via HDMI.
So, technically, what you want to do is achievable, but it would not be trivial. You would need to understand how the whole system works and be able to modify the code so you can insert your data. I wouldn't have thought this would be much of a challenge considering your country is a recognised leader in hacking drones!
My first step to reverse engineering systems is to look at the chips used. See if you can Google datasheets for them.
Short answer - it is not trivial and you'll need something much more powerful than an AVR.
The camera outputs the data in one format,
Most quadcopter cameras output video in the MIPI format....same as cellular telephones. After that its up to the system designer(s) to decide how it hits the airwaves....
Short answer - it is not trivial and you'll need something much more powerful than an AVR.
No argument there.
JIm
There are several versions of "HDMI". Some include other signals apart from just video; eg, Ethernet ...
Quadcopter send video to radio Control.
a lcd is connected to Quadcopter (sic?) using hdmi
Do you mean the LCD is connected to the Radio Control by HDMI ?
Are these commercial products, or things that you've designed and/or built yourself?
If you are going to intercept the frame transmission at the quad end of things then you might as well just learn how the radio data packetization is done and add some additional data packets into the stream with your "private" data.
While (in cars not aircraft) we have used the technique of putting telemetry data into image frames (no one really notices if the first few pixels on the very top line look a bit "corrupt"!) the fact is that this has to survive any compression/decompression employed during the data transport. It's fine if lossless compression is used but if (as is normally the case) lossy compression is used it will corrupt thee exact binary values you are trying to transport.
no one really notices if the first few pixels on the very top line look a bit "corrupt"!
Wasn't that how Teletext worked?
Wasn't that how Teletext worked?
However in the old days the networks themselves also embedded some kind of synchronising data into the top of the picture (to trigger local news to take over form main news or to schedule advert delivery) and that could often be seen as a line of white blobs at the top of the picture. I'm guessing Neil Barnes will be able to tell us an awful lot more about all this as he was one of the technicians at the BBC who was responsible for this kind of thing!
(*) https://en.wikipedia.org/wiki/Teletext#Data_transmission shows that the text data was in the VBI (vertical Blanking Interval).
For the purposes of this thread, delays for electron beams to return to the top left of the raster scan are no longer relevant in 2019 ;-)
I wouldn't have thought this would be much of a challenge considering your country is a recognised leader in hacking drones!
lol, I'm a rookie ( see my profile ), an ordinary person, not a soldier, not an expert in a famous company
Do you mean the LCD is connected to the Radio Control by HDMI ?
yea
I think my friend radio control is this : DJI Lightbridge
Are these commercial products, or things that you've designed and/or built yourself?
my problem is not that avr is good choice or bad choice, i can use/work any arm micro, its not problem, the main problem ...
is there any ic or library for this work? or any micro that support hdmi
is there any ic or library for this work? or any micro that support hdmi
No.
You are trying to hack stuff to make it do things it was never intended to do. You are going to have to work from basic principles.
It will be a lot of work to just reverse-engineer the existing products to find out how they do what they currently do - and that's before you even start to think about any modifications to it!
Matrice 600 Pro
The blurb says it has "customisable buttons" - that may be a better place to look than trying to hijack the video link ... ?
Here is a completely off the wall, left field idea...
On the quad mount a small micro board with a small LCD display (maybe low res OLED or GLCD or perhaps just 16x2?) then position this display so it's in view of the camera. I guess there may be close up focus issues but you might be able to get whatever telemetry it is you want to send (height?) to actually display in the images shown at the base station. No need to send data and decode at the receiver because the data you want to send/display is already in the transmitted pictures.
on a similar theme, if audio is supported, send it as DTMF or use one of the modem standards ... ?
awneil wrote:Wasn't that how Teletext worked?However in the old days the networks themselves also embedded some kind of synchronising data into the top of the picture (to trigger local news to take over form main news or to schedule advert delivery) and that could often be seen as a line of white blobs at the top of the picture. I'm guessing Neil Barnes will be able to tell us an awful lot more about all this as he was one of the technicians at the BBC who was responsible for this kind of thing!
A long time ago. that was the day job. Though I can't recall the details, recall that on both NTSC and PAL the active picture time was only a (large) fraction of the signal; there were a few microseconds at the end of each line when it was blanked to allow the beam to return to the other side of the tube and a few lines at the end of the picture (or the beginning, depending how you look at it) while the beam got back to the top. In the two or three lines immediately before active picture, there was one line which carried the ceefax signal; one line which carried an internal text thing similar to ceefax and from memory decoded the same way called presfax, used to advise national and regional control areas of exact times of program junctions, next program etc; and a third line which carried serial data to, I think, Ladbrokes to update their betting results in the shops. Only the first and last of these were broadcast; presfax was blanked before transmission.
The advert/program change indicators were simpler and carried in the visible picture area for a few seconds before the end of a program or a program segment; a cycle or two of a highish frequency signal gated into the picture.
Neil
Back in the day the CCTV manufacturers used the Vertical Blanking Interval(VBI) to send the control signals to Pan-Tilt-Zoom(PTZ) camera housings on the same coax as the video signal.
Then when I went on to work at the Video Movie cassette company - We were licensed to mass copy movies to video cassettes for rental at the local shops, we would insert the copy thwarting information(macro-vision codes) in the VBI as well.
Ahh the good old days of Analog!
Jim
Back in the day the CCTV manufacturers used the Vertical Blanking Interval(VBI) to send the control signals to Pan-Tilt-Zoom(PTZ)
According to the Wikipedia article, HDMI has an I2C-based interface for that kind of thing. Maybe the OP could look into it ...
we want send data
How much data are you wanting to send?
We do not need to design a 5-kilometer transceiver.
??? What is a 5 km xcvr? VLF? ULF?
Jim
we want send data using this path
Lemme see if I understand what the OP is looking for....
YOu really do not care about the video at all... you want to take the radio components out of the quadcopter and use them to send data from the controller to the remote radio, AND send data from the remote radio to the controller correct?
If that is the case, then answer these questions...
What type of data(RS232, RS422, RS485, TTL, I2C, SPI)?
What speed?
Jim
What is a 5 km xcvr?
The blurb in OP's later post speaks of 5km range - I presume that's what is meant here?
EDIT:
YOu really do not care about the video at all... you want to take the radio components out of the quadcopter and use them to send data from the controller to the remote radio, AND send data from the remote radio to the controller correct?
If that is the case, then answer these questions...
What type of data(RS232, RS422, RS485, TTL, I2C, SPI)?
What speed?
I have a feeling that OP may have naively thought that because there's already a radio downlink for sending inflight video it would be a simple matter to piggy-back on this data transport to send small packets of telemetry at the same time. But, without access to the software that runs the radio link I personally don't see how you can "break in" to the data flow. I suppose there maybe a link from the camera to the radio (I suspect it will be LVDS not HDMI in fact) and some cameras have an SPI/I2C "back channel" for control that it might be possible to "get into". But I don't know how a third party can break into this dataflow.
if one does want a radio link for telemetry I can't help thinking a completely independent radio channel: https://uk.banggood.com/3DR-Radio-Telemetry-Kit-With-Case-433MHZ-915MHZ-For-MWC-APM-PX4-Pixhawk-for-FPV-RC-Airplane-p-1326078.html?gmcCountry=GB¤cy=GBP&createTmp=1&utm_source=googleshopping&utm_medium=cpc_bgcs&utm_content=zouzou&utm_campaign=ssc-gbg-all&ad_id=332556156911&gclid=CjwKCAiArJjvBRACEiwA-Wiqq7yIVbMmVTbMbwLaVdFzSy7tv7CKZNiy2-kZyvWwwdTIsgBNfk6icxoC7j8QAvD_BwE&ID=510651&cur_warehouse=CN might be a better option ?
I suppose there is a concern about cost but perhaps the greater concern is the additional payload weight the craft has to lift into the sky ? However it will almost certainly be the "easier" to implement solution!
In my experience the usual kind of "telemetry" you want to send back from a flying vehicle to the base would be things like altitude, heading, speed, rate of climb/(descent) and maybe stuff like gyro coordinates (x/y/z tilt), GPS and so on.
Jim
