Learning The Basics of FPV Drones

If you’ve ever wanted to understand how FPV drones work but felt overwhelmed by all the circuit boards and wires, you’re in the right place! Today, we’re going to break things down simply explaining each component and how all the parts work together to make your drone fly.

Understanding these basics will help both beginners and experienced pilots feel more confident working on their drones. Once you know how everything connects and communicates, it becomes much easier to troubleshoot problems, repair your quad, and unlock additional features that you might not have realized were possible.

Transmitter

It all starts with your transmitter, often called a radio. This is the pilot’s main tool for communicating with the drone. The control sticks are the heart of the transmitter: when you move them, they send signals that tell the drone exactly what to do. 

Receiver

To receive those signals, the drone uses a receiver. This component, equipped with an antenna, captures the radio signal and sends the data to the flight controller which is the brain of the quadcopter.

Flight Controller

The flight controller interprets the pilot’s commands and manages information coming from other sensors and parts of the drone. When it receives a signal from the receiver, it processes it and passes the instructions along to the next component: the ESCs, or Electronic Speed Controllers.

ESCs

As the name Electric Speed Controller suggests, ESCs regulate how fast each motor spins. Most modern drones use a 4-in-1 ESC board, which combines four controllers into a single unit, one for each motor. The battery typically connects directly to this board, supplying power to the entire quadcopter. Based on how much you move the sticks on your radio, the ESCs adjust how much power each motor receives. More power means faster rotation, so when you raise the throttle, the motors spin faster and the drone climbs.

Accelerometer and Gyro

But here’s where things get interesting: sometimes the motors speed up or slow down even without any stick input. Why is this you may ask? Because the flight controller has built-in sensors. More specifically, a gyroscope and an accelerometer that constantly monitor the drone’s orientation and movement. Using that data, the flight controller automatically adjusts motor speeds to keep the aircraft stable in the air.

FPV Video System Overview

Now, how does the FPV system fit into all of this? FPV stands for first person view meaning that a pilot can see from the view of the aircraft like they are actually flying it.

It all starts with a camera that is capturing real time video. There are many different kinds of FPV cameras but they all do essentially the same thing, capture a live video. This video is then sent through the flight controller which has an OSD chip that adds an OSD or on screen display to the video. This just means that data will be displayed on the screen that the pilot can see. The video with OSD is then sent to the VTX or video transmitter which sends the video signal out. The video signal is then received by the video receiver that is built into your FPV goggles, where it is displayed on a screen. Allowing for the video to be seen in realtime.

Skyzone is my go to store for FPV goggles. They produce high quality gear that works great with some of the best pricing on the market.

Skyzone store: https://www.skyzonefpv.com/?ref=NERD

FPV Component Compatibility

One of the hardest things for me to wrap my brain around was compatibility because each component comes in different shapes, types, and sizes and only some stuff works together. Let’s talk about the most commonly used gear and how to make sure everything is compatible.

Transmitter and Receiver Protocol Types

Starting off with the radio types. Radios can use different methods of communication called protocols. While there are several different types, there is only one type that is viable today. It is called expressLRS or ELRS. This is an open source system that has better range and less latency than any other. That is why all modern quadcopters use this protocol. To make things slightly more complicated, each protocol can also operate at different frequencies. The most common one and the only one you really need to know for now is 2.4ghz.

Your receiver needs to match your transmitter’s protocol and frequency. For example, if you’re using ELRS at 2.4GHz, you’ll want both an ELRS 2.4GHz receiver and an ELRS 2.4GHz radio. When the protocol and frequency match, you can be confident they’ll work together.

Receivers come with three main antenna types: tower, enamel copper wire, and T-antennas. Tower and enamel copper antennas usually have shorter range and are built directly into the flight controller, so they’re permanent unless you have specialized tools to remove them. Between those two, enamel copper antennas tend to get better range. T-antennas offer the best range overall and are removable and replaceable, but they’re larger and a bit heavier, which makes them better suited for medium to large sized quads.

Flight Controller Types

There are many types of flight controllers out there. Larger quads usually use a dedicated flight controller, while smaller ones often use boards where the flight controller is integrated with other components. Standalone flight controllers typically pair with a separate ESC board that connects through a wire harness.

Smaller quads commonly use All-In-One boards, or AIOs. This just means some or all of the electronics are combined onto a single board. You’ll see 3-AIO, 4-AIO, and 5-AIO options. The number refers to how many components are integrated: flight controller, ESCs, receiver, OSD, and VTX. Always check the product specs so you know exactly what’s included before buying.

Larger quads either have individual ESCs mounted on the arms or, more commonly, a single ESC board. That ESC board is usually sold as a set with the flight controller. ESCs are rated for how much current they can safely handle, measured in amps. Smaller quads might use ESCs rated as low as 5 amps each, while larger builds can require 60 to 80 amps. A good rule of thumb is the higher the battery voltage and the larger the quad, the higher the ESC amp rating you’ll need.

For Beginners, AIO flight controllers can be a great way to start because they are already connected to the flight controller and greatly simplify a build. BetaFPV has been one of my favorite companies for the small quadcopter known as tiny whoops. They are inexpensive, durable, and easy to get in the air.

BetaFPV Store: https://betafpv.com?sca_ref=10155059.OwaDwjisyF&utm_source=socialmedia&utm_medium=socialmedia&utm_campaign=affiliate-canyon-mccallister

How do The Components Communicate with the Flight Controller?

As mentioned above, the main electrical components that connect to the flight controller is the receiver, video transmitter, Camera, and ESCs. If your flight controller does not come with one or more of those components built in, then you will need to connect it to the flight controller manually through a plug or by soldering to the correct pads on the FC.

Every flight controller should have a wiring diagram that tells you which solder pads should be used to connect the components. Flight controllers use UARTS (Universal Asynchronous Receiver Transmitter) to talk to the receiver, video transmitter, and other optional components like a GPS. This is just a fancy name for how the flight controller sends and receives information.

Each Flight controller will have a certain number of available UARTS. The exact number depends on the Flight controller. A UART consists of two pads. A receiver pad and transmitter pad. They are often labeled as R and T respectively. These letters are then followed by a number to denote which UART it is. For example R1 and T1 would be UART 1 and R3 and T3 would be UART 3.

Connecting a Receiver to the Flight Controller

Receivers typically have four solder pads labeled RX (receive), TX (transmit), 5V (power), and GND (ground).

The RX and TX connections can seem a little counterintuitive at first. RX always connects to TX, and TX connects to RX. In other words:

• Receiver RX → Flight Controller TX pad
• Receiver TX → Flight Controller RX pad

This is because one device’s transmit (TX) line must connect to the other device’s receive (RX) line.

On a flight controller, these pads are part of UARTs, usually labeled R1/T1, R2/T2, R3/T3, etc. Each pair belongs to the same UART.

When wiring a receiver, both wires must go to the same UART pair. For example:

• Receiver TX → R1
• Receiver RX → T1

You cannot mix UARTs. If you connect to R1, you must also use T1. Using something like R1 and T2 will not work because they belong to different UARTs.

Connecting a Camera to the Flight Controller

The camera will typically have three main wires: Video, Power (Voltage In), and Ground (GND).

• The Video wire connects to the pad on the flight controller labeled “CAM“.
• The Power wire connects to a pad that provides the correct voltage for the camera.
• The Ground wire connects to any GND pad on the flight controller.

It’s important to check the voltage requirements of your specific camera, because different models are designed to run on different voltages (for example one camera may only except up to 5V voltage while others can except a range of 7-36V). Make sure the power pad you choose matches what the camera supports to avoid damaging it.

Connecting a Video Transmitter to the Flight Controller

A video transmitter (VTX) will typically have four pads: RX, Video, Power (Voltage In), and Ground (GND).

• The RX pad connects to a TX pad from a UART on the flight controller. This allows the flight controller to communicate with the VTX for things like changing channels or power levels.
• The Video pad connects to the VTX pad on the flight controller. This carries the video signal from the camera, through the flight controller, and out to the transmitter.
• The Power pad connects to a pad on the flight controller that provides the correct input voltage for the VTX.
• The Ground pad connects to any GND pad on the flight controller.

Just like cameras, different VTXs support different input voltages, so make sure the power pad you use matches what the VTX is designed to handle.

Programming your Quadcopter

Once all of the components are wired together, the final step is configuring everything in an online program called Betaflight.

This software allows you to tell the flight controller what is connected to each UART, enable your receiver, configure the video transmitter, and set up other basic functions. Without this step, the hardware may be wired correctly but the flight controller won’t know how to communicate with it.

Betaflight configuration can easily be a full tutorial on its own, so we’ll keep things simple for this guide. The main goal is just to make sure each component is enabled on the correct UART and that the basic settings are configured so everything works together.

The Basics of FPV Motors

Moving on to brushless motors. Motors are categorized by size and turning speed. Size is shown with four digits. The first two digits represent the diameter and the second two represent the height.

The turning speed is called KV and is measured in RPM per volt. You can estimate RPM by multiplying battery voltage by KV. Smaller drones usually have higher KV motors because they run on lower voltage, while larger, higher-voltage builds use lower KV motors. In general, higher KV means more spinning speed but less torque.

Each motor uses a propeller, and frame size determines how large of props you can run. Propellers come with different blade counts, ranging from two blades to five or more. Fewer blades are more efficient but produce less lift and grip, so the quad can feel more floaty. More blades create more lift and better air tracking but reduce efficiency.

Long-range quads usually run bi-blades. Freestyle quads typically use tri-blades. Cinewhoops carrying heavier cameras often use quad- or penta-blade props.

It’s also important to note that motors have different shaft sizes, usually ranging from 1 mm to 5 mm. The propeller’s center hole has to match the motor shaft size. Tinywhoops and very small quads use press-fit props that simply friction-fit onto the shaft. Small to medium motors sometimes use small bolts to secure props. Larger quads almost always use a lock nut to hold the propeller in place.

Everything you Need to Know about FPV Video Systems

Finally, let’s take a slightly deeper look at FPV video systems. There are two main types: analog and digital. Analog sends live video as a continuous radio signal, which gives you that old-fashioned looking video feed. Digital, on the other hand, sends compressed video data that your goggles decode, resulting in a much higher quality image.

Analog Versus Digital

The main difference between the two is latency. Analog has less lag. While some digital systems can get close to analog latency, those usually cost quite a bit more. Recently, some budget digital systems have come out that are priced similarly to analog while offering better video quality. However, that quality still doesn’t match high-end digital systems, and the latency is noticeably worse.

The Basics of Analog FPV

Analog cameras come in all sorts of sizes and types, but the most common today are 14mm for tinywhoops and small quads, and 19mm for medium to large builds. Prices range anywhere from about $10 to $100 for the camera. Spending more usually gets you better image quality and stronger low-light performance. That said, no matter how good the camera is, analog will always suffer from signal breakup when interference is present. Competing signals like household Wi-Fi or physical obstacles like trees can introduce static into your feed and that’s just the nature of analog.

Analog Video Transmitters

Modern analog VTX  systems run on 5.8GHz due to its ease of use. There are different frequencies that are used such as 1.3, 2.4, or 3.3ghz but I am not going to cover that because very few people use them. You can match any analog VTX and camera giving you nearly endless options for customization.

VTXs range usually range from $15 to $100 and come in different sizes and transmission power levels. Smaller quadcopters usually run lightweight, low-power transmitters, while larger builds can carry heavier, higher-powered ones. Just keep in mind that even high-power transmitters are still susceptible to interference. More power can improve range and penetration, but it doesn’t make analog immune to signal noise. 

Power levels range from as little as 25mW to 2500mW or 2.5W of power. Range will depend on your antennas and environmental factors. But you would be surprised how far low levels of transmission power can travel with decent equipment. For example I have gotten about 4km away with 800mW transmission power. People have recorded flights of 20+Km with analog setups but I believe most people will find that 500 meters range is plenty.

The Basics of Digital FPV

Digital systems, on the other hand, each have their own ecosystem and usually only work within that brand. That means no mixing and matching cameras and transmitters across systems. The most well-known digital brand, DJI, even uses its own proprietary mounting setup for cameras, which can make installation less convenient. Some other digital brands do stick with standard 14mm or 19mm mounting though.

Digital systems typically come as a camera + VTX combo and cost anywhere from about $35 to $200. Paying more generally gets you lower latency and/or better video quality. Unlike analog, digital doesn’t show static when interference hits. Instead, it usually holds a clean image until the signal gets weak enough then the picture blurs or freezes. It also tends to have better penetration through obstacles compared to 5.8ghz analog, though strong enough interference can still overwhelm it.

Range is highly dependent on the system itself. DJI is known for its range and low latency. You can expect 10-15km with perfect conditions and high quality antennas. Every other digital system tends to be lower range than DJI. 

For viewing options, there are countless ways to watch analog video. Anything from a simple 5.8 GHz monitor to box goggles or even the highest-end goggles. The beauty of analog is that the underlying technology has stayed the same for years, which means almost everything is cross-compatible. Digital goggles, on the other hand, tend to be brand-locked and offer fewer choices. Digital companies also upgrade their systems every few years, which can create even more compatibility headaches. For example, some older DJI goggles won’t work with their newer camera systems.

Conclusion

And that my friends wraps everything up. We’ve covered every commonly used component in FPV quadcopters, how they connect to the flight controller, and the different FPV video systems. Don’t worry if everything didn’t click right away, that was a lot to take in. If you’ve got questions, I’d love to chat about them in the comments.

If you know you want to start flying but don’t know how. Here is my complete guide on how to get into the air: https://mediocrenerd.com/how-to-start-fpv-drones-on-a-budget-beginners-guide/