I have a non-standard goal I am attempting to accomplish and I believe the easiest solution to get to where I want to go is an OSD module, but what I need from an OSD module is so basic that it seems almost to be overlooked in the manuals and lists of technical jargon gobbledygook.

It will take some explaining and it has almost nothing to do with drones or quads or any of that... but it is RC and it is using hobby FPV systems because that's how I wrote the rules.


I'm developing a tank combat sport.  I don't know if I'll ever build more than two tanks and do one fight for a YouTube video... but that's the idea.

In order to deal real damage but not be lethal for miles (or contain a bunch of mini explosives called ammo)  I opted to use simple commercial co2 pellet pistols and mount them inside of a tank.  Balsa/pine wood armor.  3d printed chassis.  Hobby RC gear to control and power everything.  Doable under $500 no problem and some folks pay that much easily for their aircraft or scale crawlers and whatnot.  FPV because you can't be line of sight to this, clearly.  yay for ideas!  Dangerous ideas... but ideas.

For the record this would be conducted in a safe area with appropriate bunkers (that's what the FPV is for) in an old quarry or similarly safe location for firing pellet guns in random directions with absolutely no one in line of sight or harm's way.  Plenty of places exist.  I have thought of this.  I am not insane.  I acknowledge the ludicrous nature of this idea and ask your indulgence and understanding for my madness.

The problem then arises "How do you aim this pellet gun with any sort of accuracy" (and not get your optics blown out every time because I absolutely will shoot for anything that looks like a vision port... blind = out of the match) and at the end of the day an FPV camera, a 90 mirror, an OSD module for reticle (or integrated somewhere idgaf) seemed like the most effective solution to retain the form factor.  For instance most rifle scopes are both too long and far too wide to be worthwhile.  25mm holes in your turret are a bad day waiting to happen... that's a huge target for a very very accurate pellet gun and someone with a halfway decent chinese lens on their camera setup.  Peep hole will do well enough for the gun sight and those lenses reduce field of view so much that it stops really being an issue.  Primary vision cameras are a different topic not covered by my query this time.

I need a reticle.  That's about it.  I dont need it to do anything other than simply overlay a reticle I can move around to fine tune point of impact with point of view.  It will be harder to create a mount system I can move and lock in place than it will be to just get it close enough with a fixed mount and correct using the OSD crosshair.  I expect damage.  Complicated systems are more prone to being damaged.  Impact is a thing.  High velocity chunks of lead are a thing.  Best it be as robust and simple as is possible.

I considered adding a physical system but the lens focus problem arises and I don't want to use complicated optics (read: expensive to lose every battle because everyone shoots for your camera ports) so it seems like a simple OSD would be enough, but none really specify this as a feature because who the hell is trying to do something like this?  Me, but I'm a serious minority here with my insanely bad idea.

What OSD module would offer the capacity to place and move a reticle/crosshair with any kind of precision?  Cheap is better.
Can you think of a better solution to my problem like different optics types or ways of seeing far and pointing the shooty bit?


Hopefully this post is not too extreme or scary for everyone.  Oh no.  A guy building a tank with a pellet gun.  So dangerous scary ooooo... :\ wouldn't be the first time that happened, sadly.

Yes, I did have this idea while playing World of Tanks.  And I'm 5 years in on the project... so if your first impulse is to try to dissuade me you're far too late.  As Harold and Kumar would say... "we've gone too far."

There are a few stand-alone OSD options (ImpulseRC and Matek, off the top of my head). Your problem is going to be the precision. Most current OSD stuff is character-based, so you've got a very limited number of rows and columns you can place OSD elements in - kind of like a fixed-width font on a computer. I had a quick prod around it looks like you have 16 rows and 30 columns with the MAX7456 chip that most seem to use. If you want more precision with where you place the elements you'll need a pixel-based OSD.

FrSky OSD is one, but it's very young and doesn't seem to have much supported hardware. I've never used it.

All of this will require bringing your tank in to change the crosshair position, BTW. If you want to change the crosshair on-the-fly then that's a massively more complicated problem.

Like Banelle said, the current OSD we use is text based. Making a crosshair means something like this "----+----". But the other problem is you have to custom code for the overlay you want. There is no OSD in our hobby that support movement of the crosshair.

It also sounds like you will need two cameras. One for the FPV feed an done one to aim the gun. Some current FC will allows you to switch cameras on the fly.

Your idea to use 90 degree will give you a flipped image. Some FPV camera will allow you to flip the image. So this is another problem I see.

You are best off mounting a micro size camera on top of the barrel of your gun, and using the length of the barrel as your sight. Kind of like how you fire a rifle or handgun.

Yeah gun sighting is a thing that is done in the garage. OTF sight alignment is not going to be a feature I ever implement unless some new clever way of doing this pops up.

The pixel based OSD solution would probably work. I've seen a few of the interfaces and they had little dot matrix pallets for making custom characters in one... I could get "close enough" with high magnification lenses (16mm is currently installed instead of the 2.8mm it came with... I could stand a bit more though, but that introduces issues like nearby things are not at all focused... like gun sights on the barrel...) and dial it in with some kind of 3d printed system with screws and such in the classical manner of all gun sights. I suppose they knew what they were doing, huh?

Camera switching is a real feature I like. You've got 14 tanks on a field each one with FPV cameras... how many feeds before you saturate and can't get decent signal anymore? Minimum you've got 14 channels already eaten... give everyone 2 and it's 28... I don't like the idea of tanks having multiple channels, so a camera swapping function would increase views available (and open image processing from a SBC to send an alert signal back indicating you should swap views) without having to pollute the air more with extra FPV transmissions. Solidly sold on FC with an OSD... so that takes us to...

What FC with a pixel OSD and camera switching is affordable enough to be potentially destroyed all the time? Or I could use standalones... I'm not married to single component or integrated solutions. I'm married to -cheap- solutions.

The 90 flip... what if I had a second 90? Would that not flip it back around? U shape instead of L shape. I suppose I could get one of the corrected 90 mirrors but that's adding more cost than a second $3 chinese mirror. This does not yet solve the "cant focus on nearby objects while using ridiculous lens" problem though. Any suggestions for how to get magnification required to see(and hit) a 5 inch target at 200 feet through an FPV camera? remember we need enough magnification to make our very rough pixel "sort of here" crosshair system effective. Alternatively we need a way to focus clearly on an object only a few inches from the camera AND objects 200 feet out... which is a feat I do not know enough to accomplish... so I'm here. LOL We take for granted how much work our eyes do when it comes to guns and sights.

Frsky OSD. You will also need a flight controller FC with two camera inputs. Or have a separate switcher, which will allow you to buy pretty much any FC.

https://www.getfpv.com/frsky-mini-osd-board.html
https://www.racedayquads.com/products/vi...m-switcher


As for your saturation question, use 4-8 video signals is best. The 5.8ghz band is not wide enough to accommodate anymore. Everyone will need to run only 25mW power max. The FC will switch the camera input, so you are not running a separate frequency for the second camera. If you are having someone else running the gun and you driving, then that is a different story.

They do make micro autofocus camera, but I don't have any experience with them.

Hm. 8 is a touch low for the end goal. Is there another way to handle the video perhaps? I know a lot of RaspberryPi competitors offer quite a lot of computing power and various inputs... is there some combination that would allow the analog conversion and transmission over classic wifi router networks? I could deploy a wifi router mesh network and let tanks route their video feeds through that... it would then just cap each tank's bandwidth on the wifi network to something like 20mbps (14 tanks at 20mbps is close to 300mbps total which is all I'd ever expect to realistically get... more camera feeds means more chance you get lag or issues, so that's a trade for the players to make).

The issue is I'm not aware of a set of products or pieces of software that would do that. I might be able to bodge together some security camera monitoring software, but the workload just skyrocketed. Is there no easier way to allow more than 8 transmitters?

I'm kind of stopping the whole question of a reticle until I've resolved this new snafu I had not anticipated. 8 players can work, but that's not the epic battle I envisioned.

We are really limited to the frequency bandwidth that is legal. For legal range for 5.8gz is somewhere between 5.7-5.9ghz. Here are the band and frequency. We usually stick with frequencies in the A, B, E, F and R bands. The others are technically illegal. R band is considered the most spread out and that is what they use for race competition.

https://oscarliang.com/5-8ghz-frequency-...ent-brand/

As for wifi, the latency is too much for Quad FPV. For tanks, I don't know what you can tolerate for latency. I know that wifi system do exist, I am just not familiar with them.

I would guess that anything below 250ms would be fine. if I can play a video game at ~200ms ping I can do this... it's effectively the same thing and I'm going to have limits for motors to help cap the speeds at relatively close to scale so these won't be flying around at a zillion miles an hour like those quads end up doing. Hopefully someone else will chime in with knowledge of something I could use to get more than 8 vehicles operating.

Problem seems solved.

Mesh network. Check.
USB webcam with lens. Check. (but way more expensive than I hoped, sigh)
RaspberryPi/other SBC. Check.
Security system software. Check.

Combine them together and I can stream the USB camera inputs across the mesh network using something like iSpy software. Latency will exist, but not enough to really cripple functionality I think. Testing with a RasPi and a pcDuino will need to be done, but I feel like this concludes this particular section.

If anyone has a BETTER way than this that does not require a ton of development on my end I'd love to hear it. As it stands "plug stuff in and configure software" is very doable even if the components themselves are massively outside the budget I hoped to use for them. $50-60 camera/lens packages vs the analog $10 camera and $10 lens... a $40+ SBC vs the $10 fpv tx... so yeah it's a bit more costly, but it would allow as many users as my network bandwidth could handle. Offers another area of choice to the end user: do you have a few high resolution feeds or a lot of lower resolution feeds? Their problem.

Thank you to everyone who provided information so far. This has been extremely helpful.

Very good. Glad I could be of help. Would love to see some destruction footage when you get it up and running.