Hi everybody,
I’m making a DIY FPV RC car with UNO.
For the video tx I tried using an ESP32-Cam connected via hotspot with my phone. This setup works but the max range is limited to WiFi capabilities (10 to 20 meter). I’m looking for an upgrade to drive the car:
from at least 200 meters (clear line of sight);
max latency around 200ms (enormous but still drivable);
The video resolution as lower as needed (also crazy res. like QQVGA, HQVGA, CIF are ok);
Around 10 FPS;
Every type of aggressive compression allowed like greyscale and jpeg compression.
I know that there are expensive radio tx and rx on the market, but I'm looking for something cheaper. My budget is around $50 for a working video tx and rx system. The main problem is that I have to use a phone or PC as the display for the rx, because a dedicated visor or display costs itself more than $50.
I also thought about driving the car using only a pointer on a map (via GPS), since the car's route is quite repetitive, but the problem is the poor accuracy of the GPS sensor (meters).
Any kind of brilliant idea is welcome!
Thank you.
WiFi will reach 200m if you use the right antenna. For example my home's internet connection is via WiFi, over 1200m. But it's point-to-point, using small but highly directional dish antenna.
In your case it's more difficult because the car is moving and changing orientation relative to "base" (yourself).
So the car's antenna needs to be omnidirectional. But it only needs to be omnidirectional in the horizontal plane. Radio energy sent upwards or downwards would be wasted. So a vertically mounted high gain antenna would help. These send out and receive signals in all directions in the horizontal plane but don't send/receive much signal at angles away from the horizontal plane.
The antenna at the base can be even more directional, not only sending/receiving in the horizontal plane only, but not in all directions, perhaps only around 90 degrees which you can point roughly in the direction of the car. This will be difficult with a smartphone/tablet because they have internal antenna that are meant to be omnidirectional. Perhaps this could be overcome with some portable battery-powered WiFi extender/router.
Hi redbird45,
Your project sounds really interesting! For longer-range video transmission within your budget, you might want to consider using analog FPV transmitters and receivers—they’re quite affordable and can reach a few hundred meters, though the video quality isn’t as sharp as digital systems. Another option could be using lower-power long-range WiFi modules like the ESP8266 with directional antennas to extend your range.
Regarding latency and compression, lowering resolution and frame rate will definitely help. Also, using a phone or PC as the receiver is a smart way to save cost.
Have you checked out open-source projects like OpenHD? It’s designed for HD video over WiFi with low latency, but it might be a bit over budget.
Thank you very much, your answer was really helpful! I think I will use a directional antenna on the car, which, combined with a servomotor and a gyroscope, will maintain reception, while for the transmitter I can connect my phone to my PC, to which I will connect an external antenna. Based on your experience, can you recommend any gain values or angles in degrees for the two antennas? My goal is to achieve a robust connection and minimize the possibility of disconnection, but at the same time, given the apparent robustness and feasibility of your option, it would be even better to extend the range to 500m.
I wouldn't recommend that. Over-complicated and unlikely to work reliably.
Keep it simple, try different antenna and see what works best.
It's not that precise in terms of angles. The edges of the signal beam are not sharp, like light and shadow, they fall off gradually at first, then more sharply, and there is always some leakage in unwanted directions.
The higher the gain, the more directional the beam and the higher the risk of missing the beam and getting effectively no signal. It's a trade-off.
Oh, and take the gain of antenna claimed by manufacturers/sellers with a large pinch of salt. They are rarely tested to measure the actual gain of the design, because that's an expensive process. They may have been simulated, but that's not always reliable. Many claimed gain figures are just educated guesses. So if you compare two or more antenna designs with the same gain figures, you may find that some work much better than others.
