I tried Wireless Video but ended up building a WiFi Jammer (A Fail Story)
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- เผยแพร่เมื่อ 3 มิ.ย. 2024
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Warning!: This video is only for educational purposes. The WiFi Jammer might only be super low power/distance but do not build it on your own.
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In this video I will show you how I tried to build a wireless video system for a drone but instead only ended up with a low power/range WiFi jammer. That means we will explore analog composite video, frequency modulation (FM), voltage controlled oscillators (VCOs) and much much more. Lots of experiments included ;-) Let's get started!
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Thanks to Keysight for sponsoring this video.
0:00 My Wireless Video Goal
1:08 Intro
1:38 How Analog Video works!
3:10 How Wireless Video works! (FM)
5:08 DIY LC Tank Transmitter
6:47 DIY 5.8GHz VCO Transmitter
8:23 WiFi Jammer
9:28 Verdict - วิทยาศาสตร์และเทคโนโลยี
I think it's your opamp. If I read it correctly it's an MCP602, which has a pretty steep gain falloff after 1-2mhz, and a unity gain bandwidth of 2.8mhz. Composite signals can swing much faster than this. You should try looking at the pre and post amplification signals a little closer on the scope, look for ringing etc, and also pay attention to the size of the loops of wire you're creating in your free-air circuit. I'm looking forward to another wireless video... video! Keep up the awesome work!
I agree....I have no idea what it is but sure as hell sounds impressive.👍
I agree with this I used this opamp for vga and got similar looking results. He will need a higher bandwidth/slewrate opamp
so since the signal isnt able to oscillate how it wants because the opamp is too slow its just "jumping" out of the traces like theyre little antennas?
@@penguiin12 Mmmm, yeah but no antenna analogy. In this analysis, probably the horizontal and vertical sync signals are unintelligible to the receiver's decoder. The video levels are probably smoothed out too, but without sync that doesn't really matter.
He should check out an LM6172 or similar. Something like that might be a good start.
Greatscott, it's a good educational video. But I can help you a little further. If you want to amplify an NTSC, SECAM or PAL signal make sure the sync level is maintained (both amplitude and pulse width). The sync level should always be zero volts (which I didn't see at 7:58). Keep in mind that a video signal needs a bandwidth of 5MHz. Make sure you have linear amplification over the full bandwidth. I also recommend using DC amplification and not AC amplification (capacitor) for your video signal.
Thanks for the tips!
Yeah lack of sync will definitely make problems show up, the least of which will be complete and inability for digital tuners to lock into the signal
what do you mean by the dc/ac amplification? Do you mean something along the lines of adding a coupling capacitor to remove the dc offset??
@@lilliampumpernickel9916 yes he meant AC-coupled output I think
Linear / DC amplification... yes, because the signal is already modulated on the 5.8GHz carrier, so you don't want to modulate again - you just want to amplify the whole lot i.e. linearly. No ?
When I worked with some high frequency circuitry before, I noticed you CANNOT just solder through hole components onto the IC components, because the long legs and design of the components give it inductance that’s way too high. I was working with 2.4G WiFi chip, so I think this may be your problem as well
Yeah, on the decouplers it _might_ not matter so long as the legs are used as a mounting point for some low-inductance SMD caps, but for basically everything else it would be best if he just jumped straight to twisted pair for everything with and real length.
Great video! I'm an amateur radio operator who's played around with video transmission a bit - I think there may be a few reasons why this project didn't work. Starting with most likely first:
1. Pre-emphasis and de-emphasis - Because analog FM tends to have more noise in the higher frequencies, to improve the signal to noise ratio over video links almost all analog video systems use some kind of pre-emphasis at the TX and de-emphasis on the RX. Much like the old "Dolby NR" system used on audio cassettes. It's basically a filter/amplifier on the video baseband signal which boosts some frequencies and reduces others. If the transmitted video does not have pre-emphasis to match the RX, when the receiver applies its de-emphasis to the demodulated signal, the frequency response will be distorted, leading to scrambled or no video.
2. Frequency stability - The output of the VCO in question will change by 75kHz for every millivolt change on the tuning pin, so any noise coupled into it will mix and "smear" the signal. A simple potentiometer divider to set the channel will be subject to thermal drift as well. Commercial transmitters use a phase locked loop (PLL) to stabilize the TX frequency - simply put, this works by dividing the output RF signal down and comparing it to a reference oscillator. If the frequency is too high, it will reduce the tuning voltage, and vice versa. You can get synthesizer chips or modules that include all of this - usually controlled by I2C or similar, which would of course require a microcontroller.
3. Bandwidth - if the signal is over modulated (in this case more than 66.6mV p-p modulation on the tune pin), the receiver will lose it's lock or recover a distorted signal. If it's under modulated, the received signal will be noisier and of a lower amplitude than expected, meaning sync or video may not be recoverable.
Others have mentioned that a spectrum analyzer would be very helpful for such a project, and I completely agree. If you're not in the market for one of the $20,000+ commercial units, a more hobbyist-priced alternative would be to use a 5.8GHz downconverter paired with a cheap RTL-SDR USB interface. The downconverter moves a "block" of the 5.8GHz spectrum down to a few hundred MHz which can then be visualized using the SDR and a PC.
Or use something like a Pluto, a SDR that can directly tune to 5.8/2.4Ghz and costs 100 USD(range is 70Mhz-6Ghz
Where can i get this 5.8ghz downconverter?
Nerd
you deserves your won TH-cam
Always good to see a fellow Amateur Radio Operator! What class license do you hold?
High-frequency is another beast. The 5,4GHz is 5,6cm of wavelength, so any piece of wire can turn into a capacitor or an inductor, messing your signal. And any non-linearity in the circuit can cause harmonics that will mess your transmission too.
If you want to work if those frequencies, you will need to design real circuit boards and high-frequencies softwares to simulate the effect of the trails and components. Will probably need a high-frequency analyser to look at the signal too. I don't think trying and error will do the job.
can you share me some HF rf software where I can simulate mm , rf , Ghz wave pcb like Resonator , cavity , flat strip cap and filters ??
@@omsingharjit I know they exist but don't know much more. Googling I could find some online programs... There is a channel called Machining and Microwaves, maybe you can find something interesting over there.
@@rogeriocosta1035 i like Electronic Rf But not Machining Rf technology anyway thanks
The reason why you only got a sort of camera signal from any VCO you have tried was that analog terestrial TV signal has its video signal AM modulated and the audio FM modulated, the old analog satellite TV was FM FM (FM video, FM audio) the reason why the image was sort of there was because you most likely used slope detection without even knowing it, FM slope detection uses AM demodulator tuned to the edge of the FM signal to demodulate it, it works ok-ish for audio but since a composite video signal is so wide in bandwidth, it has no chance. So the key word is AM modulated video signal. And as someone already said, the 7 marking on the TV was most likely just a marking for the dial scale, since you had your TV set to VHF low band, you were tuning somewhere between 54 and 88Mhz.
Looks like the upper end of channel 6 which can overlap with the low end of the B.Cast FM band at least in NTSC
I had a really big improvement on my tiny drone by adding circular polarized antennae - in theory doubles the signal out compared to power output because 'all' of the signal only goes to one polarization, and on the rx side doubles the sensitivity since it rejects all of the left hand signals out there.
Thanks for the tip
As well the modulation is negative video, in that your video signal is inverted, with the bottom of the sync voltage being 5V, and the brightest point being 2V, so the modulation will be recovered properly. This is done in broadcast video so any impulse noise, like RF arcing and lightning, will tend to drive the demodulated signal to the black sync level, not full white, so it is less objectionable in the picture, having a screen go black is easier for the sync circuitry to recover from, than trying to restore the DC levels after going full white. Single 2N2222 as inverting common emitter amplifier with a gain of 2 will do this, just bias it so the bottom of the sync pulse, AC coupled into the base with a 100uF capacitor, will just turn the transistor off, and then your front and back porch, along with the colour burst, should sit around 4V off ground, video peak taking it to 2V.
Thanks for making videos about your failures as well as your successes. You’ve taught me so much!
Entertaining video! It’s not a failure, just demonstrating how to not do it :)
Haha good point😉
Its not murder, just demonstrating how to not do it
This comment is showing that it was added 4 days ago but it was just 2 hr before that this video was uploaded. How is this possible!
@@talarinithesh8551 patreon early viewers
@@Egon1982 wait but how?? Is the patreon get free time machine or something?
The FPV community can help you get more range with an analog setup! What you have in your quad is an all-in-one flight controller, where the vtx portion will only have a max output power of 25mW. The best this setup can do (out of the box) is maybe 30feet before getting significant breakup in the video feed. Some might say to switch to circular-polarized antennas, but this won't provide more range; it just prevents multipath reflections (better for flying around obstacles with less screen static). Some pilots will include an LC filter between the vtx and source, to reduce video noise further; also, we usually solder a large HF capacitor in parallel to the battery to smooth the voltage sag on high throttle moves.
The next best thing is higher vtx power (up to 1W modules can be purchased in the US for non HAM users) and diversity on the vrx (RapidFire and TrueD are the best because they can "simultaneously" use both signals). After this, were now into long-range FPV where antenna trackers and high-gain helical antennas are used. The problem with this essentially becomes keeping a laser aimed at the aircraft in flight, losing signal and possibly the aircraft when that laser loses sight, but ranges greater than 30 miles have been achieved using trackers.
There are also 4g/5g and tcp/ip video links that have an almost indefinite range, but the latency is too high for precision flying.
Good luck.
To test if RF equipment works one needs a spectrum analyser. That way you can observe your carrier signal at 5.8GHz. With the video signal, it may be important to see what modulation index is used for the transmitting signal, that way you can emulate it accurately using the amplifier circuit. Also, the bandwidth of the transmitting signal is important for an FM signal.
However, great video, it's great to show that in electronics one doesn't always know how to do things. This is inspiring to us aspiring engineering.
That's why I asking to built Rf spectrum analyser instead using Available devices like tv tuner higer range , fm tuner or may be Satellite receiver ku band or any rf module interfacing with Arduino
TV is VHF (54MHz to 216MHz) and UHF (470MHz to 806MHz). 7MHz is HF. the 7 on the TV is just a tuning Scale
Yeah, I doubt any TV tuner can go as low as 7MHz, a TV channel's bandwidth is 5-8 MHz depending on the standard. Channel 7 would be 147 or 189 MHz, again, depending on the standard.
For extra jammyness the output of the VCO can be fed to an amplifier, and also this VCO will probably be suited to disrupt a lot of wireless stuff on the 2.4GHz range like nRF24L01 based stuff
nRF24L01 ... I have about 20 of them here. They just dont work for me. They are glitching, dodgy and what not. Touch them, get near them, suddenly they stop working completely. I dont know why. 10 meters distance and it was always super unreliable. It tried many modules (hence I have so many of them). I got it working at the end, without changing anything... never again am I buying one of these shits. I am happy that we have LoRa now, like the SX1276. No pain, it just works. And can do so much more too.
Very cool. Definitely looking forward to your next one.
I don't know how you always guess my interests for the videos. Keep up the good work and be *great* , as always ❤️
Thanks :-)
You generally don't make RF Circuit in mid air due to impedance mismatch, powerloss, etc.
Great video! In addition to other suggestions mentioned here, you can try using different power supply (such as battery). Switching power supplies in particular may cause unwanted modulations and mess things up.
The remarkable information you provide to your viewers needs to be applauded. I sincerely appreciate your effort to expand your viewers knowledge. A sincere thank you!
I hope you have fun with your FPV drone and be inspired to build a larger one. Such a fun hobby.
Way back in the eighties when I was so much younger I gave up on antenna building because of the complicated calculations taking in count wavelength, antenna wire thickness, coax length, standing waves, etc. It made my head spin.
Probably it's second nature when you only mention; ''an antenna wire" like everybody knows how it works.
Lots of stuff I didn't get back then, now fall into place watching youtube video like yours. Maby when you explain those calculations needed for an antenna a bit, it can help (not only) me, fit these puzzle pieces together.
Fun to see, I did not expect, in this time and century analoge video is still actively produced and used.
For RF circuits on that high frequency, you cannot use simple wires for connections, because the trace length, as well as the characteristic impedance (typically 50 or 75 Ohms) need to be considered.
Also, after every antenna, you firstly need a stage of a bandpass filter and low noise amplifier, because the signal at this pin will be at nano volt level at best. The length of the antenna is also very important, as this directly influences the antenna gain.
I would suggest to design a proper PCB with controlled impedance, minimal trace lengths and proper rf components (good rf passives, ics, filters and antennas) designed for your needs. Take a look at Phil's Labs yt channel on RF PCB design basics to begin with.
Great Video! FPV and electronics are so much fun! I hope to see more FPV related videos on your channel!
More to come! Hopefully ;-)
Very interesting video! And thanks for explaining analog video signal, I always wondered how this were encoded!
Mini whoop drones are amazingly fun to fly around with! If you want to improve the video signal you could also get a proper receiver, such as the TBS Fusion or Rapidfire modules., they'd do wonders for your goggle image. Your goggles don't have a module bay, but it's easy to connect up with some soldering, the module signal is very exposed.
Very interesting! Good luck!
I am an RF & SDR engineer and we build commercial cell phone detectors and blockers. From my point of view, there are several misconceptions about how RF audio and video modulation, amplification, transmission, reception, demodulation, etc. works. Besides that, at these frequencies usually you don't just hook up (wired) parts because even the slightest parasitic inductance (i.e. a piece of wire or even copper trace) would mess everything up. Most of the time, there are 99 ways to do it wrong and just one or two to do it right. Some comments have mentioned impedance matching, the antenna, etc. I think that's not the most important point as even a very poorly matched system would deliver some performance over a short distance. But if you really want to successfully transmit and receive a signal of significant bandwidth of at least some Megahertz (like a video signal), there are several key aspects, techniques, and components involved, not just a VCO. In a purely analog system, you need some signal conditioning, amplifiers (buffers, LNA,...) mixers, modulators, demodulator, and lastly a VCO and an antenna. You have to tune everything for the correct amplification (so the signal doesn't get distorted), modulation scheme (so transmitter and receiver are actually using the same "language" and "alphabet"), etc.
I am not saying that it is impossible but with your setup it would be pure luck to get everything right. It is way easier to build a jammer by simply modulating a VCO with some arbitrary signal. That is, you just spread some amount of energy in some part of a spectrum. But usually that's not enough to successfully TX and RX information over the air.
But I don't want to sound too pessimistic... you did a great job figuring things out, getting the parts and trying several circuits. It's actually great to learn new things this way, but trial & error is *really* tough when it comes to RF.
As always, Great Video. I was actually thinking about jammer circuits for a couple of days. And you suddenly put a video about it. ❤️
Glad I could help!
@@greatscottlab ❤️
1st time commenting, just wanted to say that it's good to show failures. I actually prefer these types of videos! Keep up the good work!
Very interesting video. Today I learnt about analog video signal. Thanks GreatScott
It’s absolutely funny for me. I was researching jammers and how it works just because of curiosity. Thanks for the upload.
Glad I could help
First of all, welcome to the FPV world, dude! 😃
I do FPV even with rc cars! There are cheap cameras with transmitters in the market and I just stick them with double sided tape to my cars... 😂
Either way, analog FPV doesn't have a very good penetration, but you can get LOTS of range. There are people who flies over 30km! The issue is the EU regulations, you guys are stuck to 25mW... Which doesn't help much. 😬
But there are video transmitters that go up to 1.6W, perhaps even more!
Oh, now there are 3 different HD FPV systems as well... But they're really expensive, so I stick to analog. 😬
Anyway, fantastic video as always!!! 😃
Stay safe and flying (and creative) there! 🖖😊
You need a lot of ground (no breadboard or soldering loose parts). When dealing with RF/IF, impedance matching is very important.
What an amazing video great scott! Have been thinking about wireless fpv video for a long time, i think i even mentioned it as a potential project on the comments section of one of your videos a long time ago. A video like this has been a long time waiting for me, and super stoked that you covered it!
Ps. Love the t shirt design it looks awesome!
Thanks for the feedback :-)
@@greatscottlab I know going into the digital video is a whole lot more work, but i must say that digital wireless signals are often way more resillient, so heres a video that really got my curiosity going related to this topic. I dont have The sufficient technical knowledge to make a circuit that does this, but maybe you can.
th-cam.com/video/0faCad2kKeg/w-d-xo.html
Also, from what i’ve gathered from many hours of googleing, vco’s are very sensitive to em noise and temperature variations. I would suggest you try put your vco in a small faraday cage, say a metal thermos cup, and keep the temperature in their somehow regulated, (idk maybe with ice or in a fridge or something) or at least put the metal shield back on somehow, and have the antenna come out of the faraday cage (obvs) through a small hole or something.
Excellent video as always!
In terms of problem, I wonder if it has to do with the Antenna impedance matching as well? And as other have suggested, an Frequency analyzer will be very useful to help see what the actual frequency is being transmitted, I also think using a coaxial cable or any form of shielded cable will also improve it significantly
Ayo niiiice, my favorite tech yt channel and my favorite Hobby fpv racing together, wow👀🔥
I was always impressed with your hand drawn sine waves (mine look more like... .... .... NOT sine waves) .... But that hand drawn video line at 4:02 is just perfect! I envy your pen skills!
I was sad to see you fail so badly but at least you’re honest which is becoming increasingly rare on TH-cam.
Lol your wording of this is so harsh, made me lol
On the fpv side of things, when we run into this issue with entry-level goggles we normally figure out a way to get analog video into them and then use a diversity receiver module Bay that we plug something like a crossfire receiver into. But this is really cool :-)
Nice and educational video man..!
The exact moment you showed that waveform, I'm like... hehe, that's composite video!
(Proud wave form recognition moment).
So that 5.8ghz chip can extend its range with a circular polarizing cloverleaf antenna and inverse polerized matched receiver antenna.
Yeah, this reminded me of the time I tried playing Super Mario Kart by plugging my SNES into my analog oscilloscope. It, of course, wasn't the best.
Once again great idea from Great Scott. There is no
such thing as failed project , just another point on learning curve ;)
Only failed project is the one you haven't tried or gave up before start ;)
I would look that modulating signal at input of VCO... You are aware that inverting configuration of op-amp wouldn't work. Or maybe it is getting inverted inside module ?
Maybe your video amp self oscillates ?
I would start from there.
Keep up the great work
Cheers
try using ferrites on transmitters and receivers in order to clean the video signal. Ferrites may appear incomprehensible sometimes, but I think it's really worth the try ! Awesome video like always. Keep up !
As many people already noted, what I personally think is that it all has to do with the high frequencies involved, you need pretty tight timings on all the parts involved, and the op-amp could be suspicious for example?
Loved this one,please continue making wireless video content
I will see what I can do
Very nice that you've showed you're little journey through RF Engineering.. Anyway it's important to say that it is very dangerous to play around with free running Oscillators connected to antennas. Especially in Germany where BNetzA is very strict.
Besides that,.. Your problem is most due to required bandwidth in relation to the low carrier frequency in your first try. The second VCO attempt really needs video signal pre conditioning to make sure that the frequency modulation is withing range of the receiver bandwidth of your TV.
I'm working as an RF engineer for several years now... And let me tell you, it's that one field in electronics where it is almost impossible to get stuff running safely without proper knowledge and even more important, proper measurement tools.. :)
Ask Keysight for a fieldfox!
Thank you for sharing videos like this. Even though it didnt yield the results you'd hoped there was still a lot of useful and interesting information.
Love your radio videos
Rf circuits of that frequency range are whole black art too themselves! There are just so many factors to consider component length, connection length the shape of the circuit no sharp corners etc. Good luck with your endeavors.
A few things to note. The board you were searching for a transmitter on was the main board. Not the video transmitter. The processor chip you found could have been used for some internal timing of components/signals on the drone itself. There is a timing circuit between the camera and the video transmitter. Some cameras don't play well with all transmitter systems. I love your channel and this is the first time im compelled to speak up. I feel as if your transmitter is missing some key components and I anxiously await more drone based videos and a revisit of this circuit.
Also you want ensure the antenna is the same impedance as the system. That will maximise the power transfer and thus the range. You probably need to use VNA for this.
That's the topic I want to know thanks scott.🤟🏻
I think you'd have a much easier time of things by modulating the signal at a much lower frequency, like regular RF frequencies, then use a final output stage that does some frequency multiplication up to 5.8ghz and then amplify that output. As a bonus you can take your intermediate signal and feed it into a regular TV tuner if you shoot for around 50MHz or so.
As CuriousMarc would say, microwave electronics is the blackest of black arts. Everything matters when you get up there: trace routing, PCB dielectrics, component placement, etc. As others have said, just soldering components together in midair is going to leak your signal out into the aether and all you'll get out the antenna is a pitifully weak signal full of noise. Reducing the number of components working at that frequency will make for greatly reduced headaches.
how can you feed IF signal to tv tuner if it only outputs it . instead feeding it to demodulator ?
At some level I'm sure that's true for almost all electronics, it just gets harder to deal with /naively/ as you increase the frequency.
@@jnharton The effects are always there, sure. But as a random example, the 15pF of junction capacitance in a 1N4001 diode has a reactance of 212 ohms at 50MHz, but only 1.8 ohms at 5.8GHz. 212 ohms of effective parallel resistance is something you can probably deal with in a circuit, but at 1.8 ohms you no longer really have a diode in your circuit at all. These parasitic capacitances and inductances really eat your signal as you go up in frequency.
You're moving into the Darkside with those frequencies - voodoo! Very interesting exploration, thank you.
Oh cool your getting into fpv. I see other people saying switch to CP antennas and I second that. You can also get a better (diversity) receiver. Higher gain antennas, reducing interference (I use the ham bands outside of the wifi channels), and increasing power.
Imho TBS makes some if the best VTX equipment. Its really cool to see the engineering aspects of them. FPV and rc stuff got me into EE.
If you wanted longer range I recommend goggles with external sma connectors and buying some better antennas. If you want more output power you can buy vtx for example from tbs
if i recall correctly, a simple vco should just make the carrier signal, you will need to create the fm modulation on your own. also impedance is very important in rf, make sure everything is well matched.
As a drone pilot who used to fly analog, the best way to get better range on your drone is
A) get the DJI digital system which has its own caviats, mainly the video transmitter weighing 25g problem and the whole needing 2s-6s input voltage. (and digital fpv at the time of writing is a total shitshow, best bet is to wait for dji v3 to come out, or for HDzero to improve a bit more for whoop usage.)
B) get better antennas on the aircraft and drone
C) upgrade the stock analog vtx to a more powerful vtx.
Hey there... I really do enjoy your videos... It's really educative
Happy to hear that!
Bruh you just Answered My long ago Question when i took apart a Random Drone with 3 wires red blk and Yellow you Brother are the best im happy i subbed almost day 1 on your channel ... And thank you So much Brother !!
Love your works
Oh! I just remembered it now, but there's an open VTX project out there! And it works great!
You are going to inspire new generation to pursue tech🔥🔥
Informative video, as always
Thanks :-)
Welcome to frustrating RF world, i only add a 5Ghz RFamp, to the transmitter, and ready. Great video.
I did that on purpose 3 years ago using 4 video xmitters in parallel with no signal on input and 3 channels apart each. It worked at only a few meters, but that was enough to discourage people from doing their daily job during meetings instead of listening to others.
Please complete this project. It was great to learn 👍
I have the same betafpv quadcopter! It's so much fun!
Awesome! Yeah, fun stuff :-)
Filters and boosters! While I have no experience or knowledge, my first thought is that some of the signal components are more important than others. So boost those signals before transmitting and filter back to normal on the receiver. Think of it like Dolby. Don’t like hiss? Double the boost of the music that shares the range with hiss, then halve it on playback. Boom, half the hiss, noise reduced!
This was an interesting experiment nonetheless! Drone builders usually just buy pre-made video transmitter and receivers that already conform to a standard, because trying to make your own circuits is very finicky.
It might be that all wires interfere with your signals. Every millimeter counts. But very nice you tried and found some nice "features"
You might try using smd components as well. Much better frequency response. Along with creating the circuit on a perfboard with nice even solder traces,that will help a little
I think you should try crystal oscillator mixing and filtering out higher order harmonies so you can get high frequency carrier as is used in most moder receivers as well.
omg yess thiss!!!
Noted
Ah yes superheterodyning if speled it corectly
Esentialy this often done in recivers
So instead of having a demodulator work acros entire AM band you take in case of AM 455kHz as frequency you demodulate at, but 455kHz is only one frequency I hear you say. Well we take input signal and mix it it with oscilator working on our frequency + 455 kHz result of this is we will get our signal on 455kHz and aditional harmonics but it can be easly filtered.
For transmiter same proces but in revearse
You are the powerhouse of the cell.
Danke, thanks a Lot! I really Like your content.
Thanks for the support :-)
You also make non-PCB circuit art all the time, i somehow love and hate that at the same time :D
great video, in order for a person to learn there has to be some failure, keep it up man👍
Thanks, will do!
Welcome to FPV!! Wait til you get some time on a digital HD system like DJI's air unit or caddx vista. I've been flying drones for nearly 8 years and there is nothing better right now . But some competitors are starting to get close
On these tiny FPV drones cheap and crappy dipol-antennas are used. On the bigger ones like my 5inch quad circular polarized antennas deliver a much better range. Maybe you can find a small enough one to upgrade the TX antenna. Opening up the goggles and upgrading the RX antenna would certainly help aswell, because these rtf kits usually don't use the most advanced gear anyway.
the range of video transmission depends mostly on good antennas. You can make a flight of 2 km with a 10mW vtx. On the drone you have - cetus pro - there is only a short wire. You can try to attach small good antenna and your range will increase significantly.
Tbh I think it is the normal Cetus with the brushed motors. I for my self have the Cetus pro and will try your trick to improve my video range
Cool video. Hope this gets a followup video where we get to know where the fault was and the proper solution!! :D
I hope so too!
Analogue video isnt the only option for fpv drones. DJI and caddx make a digital system, it looks much better and has less interference than the analogue versions. It is quite a lot more expensive though.
Hi Scott, in your experiment with the Collpits oscillator it is essential to disconnect the base of the transistor. 1 capacitor of 100 nf between base and ground will start your oscillator. From what I understood in the clip, you obtained a signal from it around 7mhz, which is roughly the spectrum of the video channel (approx. 6mhz). Your oscillator should have worked at least at 100mhz. The fact that you have not received anything there means that it is not oscillating. Try to use a transistor for the radio frequency (BF200, 2SC9018) and on the TV screen when you have tuned it to the frequency of the transmitter you should have a black screen.
Also, I do not recommend this type of oscillator, it is very unstable and as you said, it modulates both in amplitude and in frequency.
For television, you are interested in amplitude modulation, analog terrestrial television has like 6mhz amplitude modulation for the video signal and on that signal, there is also a 6.5mhz fm carrier for sound. As far as I remember, even from the demodulated video signal the 6.5mhz filter was captured, amplified and then with a ratio detector the audio signal was extracted. You are not interested in the audio part anyway.
There are some big brains in these comments, it's amazing!
My thoughts were the legs of the soldered components are probably causing some attenuation/inductance in the high frequency signal. This stuff fascinates me!
You can't really deadbug or free build radio circuits especially in the microwave bands. Because of the wavelength being so short, exteme precision is necessary. NTSC signals are mixed mode, complex, and digitization of receivers has made requisite precision increase quite a bit.
A fun and fascinating rabbit hole to explore, and you certainly learned stuff along the way so it's a good exercise.
My suggestion would be to investigate different antenna types and designs. I managed 2.5km of 1.2ghz video reception with 250mw effective radiated power. That was on an aircraft changing orientation in an RF noisy environment. Just required some experimentation with antennas, lead lengths, impedence matching, polarization etc. KM4KHC
Like others said, things get tricky over the 100MHz range and components stop working as expected. Sometimes even the legs and overall length of a resistor can turn it into an inductor (there's also capacitance between the legs). I think the antenna matching would be out of whack in this case, but perhaps you should still achieve a signal at very low distances. Maybe try again with SMD? Good luck, GHz is ultra-finicky! As an alternative suggestion, maybe (maybe?) try modifying the rx/tx circuit to a lower frequency, where its easier to DIY (also longer range)! (In that case of course check regulations and use ISM bands and very low power.)
Great video! (no pun intended :p)
Oh boy.. I had a RF project once and the components are the least of your worries... Circuit geometry and layout misbehaves at high frequencies. Try to make a simple small pcb with em noise in mind. This might solve most of the issues. Also, remember that at millimeter and submillimeter wavelengths any piece of wire is an antenna
Really making me want one of those drones. Looks like so much fun.
They are really awesome and fun to fly. FPV Drones are a really fun hobby and you can go down the rabbit hole to find the best drone to fly... it's just an awesome (and lately a pretty expensive) hobby. I would recommend you to start with a small analog drone if you want to get into it, maybe a RTF kit to get you started with the all of the gear you need.
@@natter18 Is it the headset that makes it so expensive? Or is it some sort of licensing deal because of the frequencies it uses for video?
@@anon_y_mousse As far as I know a fee for using the Video bands isn't the main cost point (I don't think there are any fees but correct me if I am wrong). It is mainly the cost of the components like the mosfets or the microcontrollers. Because the availability of those has gone down so the prices increase. The biggest price jump lately has effected the Flight Controler (The brain of the drone that has all the sensors), they gone up from like 30 dollars up to 50 or 60 Dollars. Another thing that has also been affected are the ESCs (Electronic speed Controller, it tells the motors how and how fast to spin) they have gone up in price a pretty similar amount.
@@natter18 I guess I haven't been paying attention to the prices, but if I build it from scratch I can just recycle. I'll have to check if anyone has open sourced a design, or design one myself, either way.
There are many Commertial Off The Shelf solutions to this problem BUT that would be a dull video. Credit for trying to play in the black arts of RF :)
Invert your camera signal. Also, the tuning bandwidth of crystal VCOs may not be high enough for video. Though you may get away with audio. For video you will probably need a hell of a lot of pre-emphasis which is usually designed into ICs designed to transmit analog video.
It's quite interesting video, and I have managed to make kinda video transmitter by simply injecting composite signal through to customly built fm radio transmitter circuit tuned to 583.25Mhz (Channel 35,UHF) which sorta works, albeit missing colour information & very noisy with few other problems so will have to add a ton of filtering and keep monitoring signal transmission for ways to improve the circuit.
Hi. Something similar that I tried to do in the past was to build, instead a NTSC video transmitter, an ATSC transmitter. This one is the digital standard used in USA to transfer audio and video over UHF in a digital way. Here in Mexico is used ATSC Too, so, that could be an option to improve your project. Best regards :)
Also you can convert the analog signal to digital and send it through nrf24 modules.
Hi,
1) 2N2222 has not enough bandwidth. I think it's bellow 300MHz. BTW this transistor is suitable for switching applications, not for FM modulation . You may need some transistor which works more linearly and suitable for FM Video-signal modulation. But it would be interesting if you had tried it to adjust it some where between 40-200MHz.
2) Analog TV channels are bellow GHz frequency which means you can't tune them to 2.4 or 5.8GHz frequency. Which means even you have successfully modulated signal you will be able to receive only some sub GHz harmonic of it.
Great Video, Keep going even if they are "fail stories".
Or perhaps use a WiFi range increaser for the 5GHz VCO. I don't think it will work but it's worth a try. Good luck!!
I have played with extending the range of ~5GHz signals i.e. WiFi but surely the easier approach is to increase the antenna gain. Even if you only modify the headset antenna you should be able to make a useful improvement in range. Of coursem high gain wifi antennas are cheap and easily available which helps !
This is the most sane and reasonable suggestion I've seen here. I don't understand why Scott is trying to re-invent the video transmitter. Seems like increased antenna gain would work and if even more gain is wanted an active gain stage (i.e. linear RF amplifier) could be inserted between the existing transmitter chip and the antenna.
Welcome to the channel, I don't come to greatscott for careful analysis and engineering, I come here for hamfisted experimentation done with wild abandon and very uneven results. It helps me feel better about my own uneven work, and I do sometimes learn a thing or two, even if it's how not to approach a problem :)
Gain means directionality, though, and he probably wants an omnidirectional antenna since it's a drone.
Several things missing:
Analog video uses almost 6MHz, a basic op amp won't get it done. But it will pass sync and most of the luminance.
When you get up to these higher frequencies circuits get very fuzzy. At 5.8GHz the wavelength is only 5 CM. Everything affects the circuit, component lead lengths matter greatly, lead widths affect impedance, even the temperature changes things.
Analog TV over FM is a mile wide too. With a good modulation depth the signal can be 30 MHz wide.
Greatscott, the problem is FM Overmodulation. At 7:26 we see that the sensitivity of the VCO is 75MHz/V, (Vt=0.5-4.5V). The standard amplitude for the video signal is 1V/75 ohms. You amplified the video signal using the operational amplifier to 5V. Applying this signal to the VCO, the frequency deviation will be 5V*75MHz = 375MHz (the width of a radio channel is 20 MHz, wildlab.org/wp-content/uploads/2015/07/RTC6705-DST-001.pdf - page 7), so you have exceeded the limits of a channel. A resistive divider must be used at output of videocamera, so that the amplitude of the signal is 0.08V, this leads to the following calculation: 0.08V * 75MHz/V = 6MHz (maximum frequency deviation). Resistive divider has 71 Ohm and 6 Ohm, or we use a potentiometer instead of the 6 ohm resistor connected to the ground. A separation capacitor must be used. The command voltage for VCO must be between 0.5V and 4.5V (Vt=0.5-4.5V), so a second resistive divider must be used at the VCO input (divided from +5V) to ensure a voltage between 1V and 4V(for example ,this voltage establishes the carrier frequency), a potentiometer can also be used. A Emitter Follower scheme can also be used.
I hope that my simple solution will help you complete this project successfully.
Wow, so detailed!!
OPEN HD is the thing to go for to get it cheap
In the UK is a greek guy pushing it to the limits who also has youtube channel I can not remember right now but based on raspberry pi or a chinese clone power house or jetson nano .
The channel is called MarioFPV - I guess best spot to go to for this task.
The best solution for range increase is to use a better antenna at the receiver and possibly the transmitter. You'll probably have a lot better signal outdoors too.
Careful now, getting into FPV is a slippery slope! It starts with a cheap brushed whoop but before you know it you'll be bingeing Joshua Bardwell and have all of Oscar Liang cached while you wait for your 8th replacement set of motors to come in