What is HDZero? - ATX AIRBORNE

HDZero, formerly known as Shark Byte, is one of the newest FPV video systems to enter the market. In this article, I’m going to cover what HDZero is, what its strengths and weaknesses are, and how it compares to the other video system options available to you. By the end of this page, you should have a clear idea of whether HDZero is the best choice for your use in a drone, and what you would need to get started with it.

HDZero Basics

HDZero is a digital FPV video system that operates wirelessly in the 5.8 GHz band, similar to analog FPV video systems. It offers a maximum resolution of 1280 x 720 at 60 frames per second, and boasts very low latency of 15-30 milliseconds glass-to-glass (from camera lens to goggle screen). It offers cameras and video transmitters that are small and light enough to be usable on even the smallest drones, and is designed to work seamlessly with the other components of an FPV drone system.

More simply, HDZero is a digital FPV video system that provides significantly better image quality than analog video while retaining many of its benefits. It’s a viable option that is available to you to use on quadcopters, planes, and other types of remote-controlled FPV craft.

If you want to know the low-level details of how HDZero works, I have a deep technical explanation at the end of this article.

Let’s take a closer look at some of the strengths and weaknesses of HDZero.

HDZero Strengths

HDZero offers several benefits over other FPV video systems. The items I’m covering here are the ones that I think are most important for FPV.

Clean digital image. Because HDZero is a digital video system, it offers higher $\"HDZero$ resolution than analog video. This results in a much sharper and more clear image that will directly improve your flying by making it easier to perceive your surroundings. The digital signal also eliminates the most annoying forms of analog “breakup”, which occurs when you are receiving a poor-quality signal. With analog video, breakup often appears as major discoloration in the image, or even the entire screen flashing or strobing. Although HDZero does have breakup in poor signal situations, the breakup is (in my opinion) much less distracting than that of analog video.

Smooth, low-latency video. HDZero streams data continuously from the drone to the goggles and displays the data as soon as it is received. This results in lower latency than other digital systems, as well as a video feed that updates smoothly with no jitter or dropped frames. The latency with HDZero is always a fixed amount, no matter how far away the drone is from the goggles or how many obstacles are in the way. This results in a video signal that appears as smooth and consistent as analog video. Some pilots refer to this as a “locked in” feeling.

Options for all sizes of drones. There are video transmitter (VTX) options available for all sizes of drones, from tiny 65mm whoops to large planes intended for long-range flight. This means that you can use HDZero across your entire fleet, reducing complexity and limiting the amount of gear you have to buy.

Rapid pace of development. The pace of development on the HDZero system has far exceeded that of any other FPV video system in recent memory. Divimath, the company behind the HDZero technology, has been extremely responsive to user feedback and has been releasing new products and features frequently. While I’d always recommend you make buying decisions based on current capabilities rather than future promises, I feel that it’s a good bet that HDZero will continue to evolve and improve, and likely at a faster pace than any of the other options.

HDZero Weaknesses

Every technology has its downsides, and HDZero is no exception. Here are a few of its biggest weaknesses that I think you should be aware of.

Lesser image quality than DJI. The image quality of HDZero is less than that of DJI’s FPV video system. Because DJI’s transmission protocol allows the goggles to re-request data from the drone, it’s able to provide a signal that is free of breakup and ultimately higher quality than that of HDZero. DJI’s image quality does not surpass HDZero in all situations, but on average, DJI will have a better image.

Size and weight. HDZero’s VTXes are still much larger and heavier than analog VTXes. Whereas with analog you can get a tiny VTX that weighs 1 gram, or even an all-in-one flight controller with an integrated VTX, with HDZero you will need to use a much larger board that weighs at least 4.5g. This can be a challenge for particularly small or lightweight drones.

Setup complexity. While things are improving rapidly, HDZero is still more complicated to install and set up than other common FPV video systems. The VTX is straightforward to solder into a drone, but does require that extra step compared to analog video, where the VTX may already be built into your flight controller. HDZero also requires you to keep firmware up-to-date on the VTX and video receiver (VRX) for maximum performance.

Availability of parts. Due to the ongoing global chip shortage and the fledgling nature of the system, it can be difficult to find HDZero components in stock at your preferred FPV retailer. We are already seeing this improve as the system grows, but you may have a difficult time finding parts for HDZero.

What Do You Need To Get Started?

If you want to use HDZero as your FPV system of choice, or just want to experiment with it, you’ll need a few different components.

Video Receiver (VRX) or HDZero-compatible goggles. You’ll need a
way to receive the HDZero video stream and display it so you can fly, which is $\"Skyzone$ the purpose of the receiver. If you already have newer FPV goggles with an HDMI input, you can use the HDZero VRX to receive the video signal and output it over HDMI to your goggles. This receiver mounts to the front of your FPV goggles and can allow you to get into the system without making another expensive goggle purchase.
On the other hand, you can purchase goggles with an integrated HDZero receiver. Currently, the only goggles with this functionality are the Fat Shark Scout HD goggles, which I liked (I reviewed them on my YouTube channel). HDZero has announced that they are working on their own brand of goggles, but that product has not yet been released.

Whichever option you choose, you will also need to buy antennas for the receiver or goggles. For HDZero, you should choose 5.8 GHz RHCP antennas with SMA connectors, and you’ll need two or four of them depending on which receiver option you choose.
Video Transmitter (VTX). You will need one VTX for each drone you intend to use with HDZero. The VTX takes the video signal from the camera and transmits it wirelessly to the VRX or goggles. There are several VTX options available, with different board sizes, power requirements, and output power levels.
The VTX also has a UFL antenna connector, and you will need to buy a single 5.8 GHz dipole or RHCP antenna for it.
MIPI cable. The MIPI cable is a special cable that connects the camera to the VTX. These cables come in varying lengths, and you cannot shorten the cable yourself, so it is important to plan out your drone build and make sure to buy the correct cable length. Also, make sure you buy a MIPI cable designed for HDZero. The MIPI cables for HDZero are not compatible with MIPI cables for the DJI FPV system, or any other system.
Camera. You will need to choose an HDZero-compatible camera. There are several camera options available, varying in size and image quality. Make sure to purchase a camera that is compatible with HDZero, because cameras for other FPV video systems will not work.

Should You Buy HDZero?

This is the big question, and of course, the answer is….it depends. Here’s my advice.

First, if you’re new to FPV, I would recommend skipping analog and going straight to HDZero. The image quality and performance are significantly better than analog, and you can save money by not buying analog gear that you will eventually outgrow. The only reasons you might stay away is that HDZero is more expensive than analog, and there are fewer ready-to-flly drones available with HDZero installed. But in my opinion, unless the cost is completely prohibitive, HDZero is worth it over analog.

Next, if you’ve been happily flying with analog, I think you should consider $\"HDZero$ moving to HDZero over time. The positive traits of the system (such as its low, consistent latency) will give you a similar feeling to flying with analog, but the image quality will be a major improvement. You also may be able to use the FPV goggles you already own with the HDZero VRX. This would allow you to save some money and give HDZero a try on one or two of your drones, and transition the rest of your fleet over time. But be warned–once you fly with a digital FPV system, it’s very hard to go back to analog video.

Finally, if you frequently fly in dense urban areas or insist on maximum image quality, HDZero probably is not the right FPV system for you. Although it handles buildings and other obstructions better than analog, it cannot match the performance of DJI’s FPV system in these environments. And in many circumstances, the DJI FPV system is capable of displaying a higher quality image than HDZero. If these characteristics are your primary care-abouts for FPV video, you will be happier with the DJI system.

In the end, you have to make this choice for yourself based on your needs and budget. I personally enjoy HDZero and use it as my primary FPV video system, but it is not the right fit for every pilot.

How Does HDZero Work?

For those of you who are interested in more technical details, I want to explain how HDZero works at a lower level. This will help you understand the reasons behind the system’s strengths and weaknesses, and will give you a better idea of what to expect when using the system.

HDZero uses digital FPV cameras with a MIPI interface, which is a communication standard that supports extremely fast data transfer using a cable made of many small wire conductors. This MIPI interface is standard across every HDZero-compatible camera, so these cameras are interchangeable with each other, but it’s important to note that HDZero cameras are not interchangeable with cameras for DJI or any other FPV system.

On a typical FPV drone setup, you would use an HDZero camera along with an HDZero video transmitter, or VTX. The VTX connects to the camera with a MIPI cable, allowing it to supply power to the camera and receive the video signal from the camera. The HDZero VTX converts the video signal from the camera into data that can be transmitted wirelessly, but the main job of the VTX is to transmit the data so that it can be picked up by an HDZero receiver or goggles.

The way HDZero transmits video is notably different from other FPV video systems. The video is transmitted over the 5.8 GHz wireless spectrum using the same frequency channels as analog video. Currently, HDZero supports channels R1-R8, as well as F2 and F4.

Although the signal is a digital signal, it’s not transmitted an entire frame at a time like streaming video on YouTube or similar services.

Instead, the HDZero VTX transmits the video as a constant bit stream. When the receiver, or VRX, receives this bit stream, it immediately outputs it to the FPV goggles. The result of this transmission method is that the goggles update continuously from the top of the image to the bottom, rather than waiting for an entire frame to be available for display. This results in a smooth video that progressively updates at a consistent rate, similar to analog video.

Of course, every FPV video system will encounter transmission errors as you fly at long ranges, behind obstacles, or in an environment with many other wireless signals. HDZero handles and displays this type of degraded signal in a unique way that has a very distinctive appearance. Unlike systems such as DJI which use a video buffer and can re-request data from the drone, HDZero’s constant streaming signal means that it can’t display parts of the image if they are corrupted in transit.

On the other hand, because it is a digital signal, the HDZero VRX does know whether the data it receives is valid or not. The VRX processes the video data in small “blocks”, and if a block contains corrupt data, the VRX does not display it, and instead replaces it with a rainbow-colored block. This means that a poor-quality HDZero signal will appear to have missing blocks that look like large missing pixels, but the valid image data will never have the characteristics of poor-quality analog video signals, such as discoloration or flashing.

The HDZero VRX does use multiple antennas to increase its chances of picking up usable data from the VTX. All current HDZero-compatible receivers and goggles use four receiving antennas. Although the details of how the signals from these antennas are combined is not public, it’s clear that all four antennas are used simultaneously and all contribute to the final image that you see in the goggles. This number of antennas, as well as the digital nature of the signal, give HDZero significantly better capability at rejecting multipath interference as compared with analog FPV systems.