Unless there’s a competitive element to your event, you’re not really racing. There are a few prevailing methods for timing drone races, but each system has its own distinct set of challenges and benefits.
Why Time Laps?
If you want to find out who is the fastest at an event, you can either run heats in an elimination format, or record each racer’s time and compare them. Elimination tournaments don’t require any precision hardware, but they do often require running a great many heats. While elimination formats are good at finding the best racer in a group, they’re pretty poor at ranking just about everyone else—the best pilot might knock out the second-best pilot in the first round. Timing gives you a performance metric that you can use to compare all racers at an event against each other. The standings reflect not only a ranking order, but how closely matched each pilot is to every other. It’s the only method that is equally fair to all participants—which is especially important if you will be giving away prizes or qualifying for another event based on standings.
Running a timing system gives you a lot more flexibility in how you structure your race event. You can choose a randomized heat structure to let pilots at very different skill levels fly together and still have a fair leaderboard. Or, you can run a qualifying round first and set up your heats with groups of pilots that are closely matched, making for a more exciting event for spectators. Planning the number and schedule of heats allows pilots to prepare and bring the appropriate amount of charged batteries (as opposed to the unknown for an elimination tournament).
Timing can also be used on your own to track self-improvement. Seeing times lets you know when you have had a good or a bad lap, which reinforces the habits that make you faster and helps you get rid of the things that slow you down. It’s a valuable tool for any serious racer.
Infrared Beam Detection
The first method to be used for drone race timing was adapted from the R/C car community. Many infrared (IR) systems exist, having little modification from the existing R/C car timing products. A lot of clubs use the Trackmate system, as it’s endorsed by MultiGP. Another popular system is the I-Lap. DIY/open source solutions have also sprung up which you can build yourself, such as Open Lap and the original EasyRaceLapTimer.
How it Works
This system uses a series of infrared detectors wired to a computer. Each quad carries an infrared emitter that constantly flashes a unique sequence. The detectors translate the flash sequence into an ID code, and software pairs up these ID codes with data entered for each racer. The sensors are mounted along one side of the start/finish, often horizontally across the top bar of a gate (as is common for R/C cars) or vertically on a pole beside it.
The detectors cannot tell anything about the position, speed or direction of an emitter that passes by; only whether or not it is currently being detected. Systems can keep track of how long a particular ID was in view, then split the difference between the time it arrived and the time it left. Less sophisticated systems might use only the arrive time (or the leave time) with less accurate results. For the system to work perfectly, it’s expected that the emitter is crossing perpendicular to the detectors. This is nearly always true with R/C cars—bound to the track surface by gravity—but quads move freely in all dimensions. Crossing at an angle can advance or reduce the detection point by a few feet.
To set up an IR-based timing system, you need a set of IR detection sensors and a computer. Some systems use a decoder unit, and most require cabling between sensors and the computer.
Setting all of this equipment up requires a certain amount of support. You need to power the computer for your entire event. You have to attach your sensors to something, so it’s likely that you will build a special gate or stand to protect and hold the sensors in place. If you don’t want your computer on the ground, you may need to bring a portable table to your event. If you don’t want your computer out in the sunlight and/or potentially exposed if it rains, you’ll want a portable canopy. A long cable running across a field can be easily tripped over and broken, so you may want a wire channel or at least a set of cones. On the computer, you’ll need to install a driver for the IR system, then install timing software that interfaces with it. Finally, all of this equipment needs transported; you’ll likely want a dedicated bag to carry it in.
You’ll also need an IR emitter installed on each quad. (These IR transmitters are often erroneously called transponders, but they do not receive any information back from the detector system.) IR transmitters are typically small and light, but have specific installation requirements. They must be attached to a power source on the quad, face the direction of the detectors as you cross the line, and nothing can be visually blocking the emitter.
Before you bring the system to an event, you have to decide how to install it. Without protecting the sensors and cabling, they could easily be damaged in a crash. Initial system setup also requires finding a computer and installing drivers and software. Plan to spend a few hours finding which software runs on your computer, and testing it to find out what you like.
Before and between events, there are a lot of materials to store and transport. The scaffold you construct for your sensors may be large or heavy, and you must carry the cables and computer. An R/C car club might permanently install their system at a track, but drone races are typically set up and torn down for each event.
Each event has setup time involved as well. There is the physical setup of the sensors, cables, table, and computer. IR detectors are much less effective in direct sunlight, so a location must be chosen for the detectors that shields them. Since the system is wired, the computer must be fairly close to this location. As pilots check in, each needs to be registered with the software so that you have a database of pilots that corresponds to their transmitter ID codes. Pilots need to install transmitters if they do not own one, and often need to scan it through the system to ensure that the transmitter is working. A good hour of setup time at each event can be dedicated to these tasks.
Another significant challenge is cost. The system itself is usually a few hundred dollars, and individual IR emitters purchased from the system manufacturer often cost upwards of $40 each. Pilots in multiple classes must have one for each quad or spend time removing and installing to another frame. Some flight controllers have IR emitters built in, but may or may not be compatible with your group’s system.
The actual installation of the emitter can be a challenge. Emitters generally have a servo cable which plugs into standard 0.1in pin headers and require a regulated 5V. Most flight controllers no longer offer 1″ pin headers, so you will need to solder directly to the FC or PDB to get the 5V required for the emitter. We also suggest you verify that your setup has the power capacity required to run the emitter. (An emitter usually draws about 20mA.) After getting it powered, there isn’t always a simple way to mount it to the frame. There aren’t many places on some quads where the emitter won’t be obstructed by props or part of the frame if it comes across the line at an angle. After the right position is found, you need to find the right materials to mount the emitter in that place and keep the cables safe. As if that’s not enough, pilots arriving at an event won’t know these restrictions so it must be explained many times over. Some flight controllers have a built-in IR emitter, but you’ll need to verify that it works with your system.
Even though the transponders are fairly light, simply carrying one is a challenge for micro quads. You won’t be timing your Tiny Whoops with an IR-based system anytime soon.
The number of challenges with this system is extensive, but the large setup hassle front-loads the work. Running the actual race heats becomes almost effortless. In some software, you just select a race type and start. Because every racer is uniquely identified, you don’t even have to set up who is racing in each heat—the computer will determine it based on the ID codes it detects on the course. For a new race, just press start again. There’s virtually zero delay between heats and the event can proceed very quickly.
The ability to choose from a large variety of software gives you great flexibility in how you run your event. Some software will set up an event and plan out qualifiers, heats, and finals based on the structure you choose. Some software helps manage frequencies (though it’s often geared toward R/C cars). There are options for Mac, PC, and Linux. Some software connects with online databases for competitions run in different geographic areas. Different software provide a variety of race and timing options, like running a race for a defined number of laps or a specific amount of time, and more exotic options like open qualifying, (the system runs without stopping and ranks only best lap,) and staggered starts, (each racer’s clock starts when they cross the line the first time). There’s an immense wealth of features available.
Race software often keeps historical race and event data, which allows you to easily run reports to get rankings like best lap times and best total times for each race class. These reports can give each racer their individual lap data for personal records and self-improvement.
When it Makes Sense
- You are timing for a large group, such as organized race events
- It’s okay to transport a large amount of equipment
- You have enough time to set up equipment and check racers into the system before the event
- You need races to run almost immediately one after another
- You want advanced software options
Video Frequency Scanning
A newer timing method developed for drone racing is to use video frequency. Some examples are the ImmersionRC LapRF, the TBS RaceTracker, and again open source solutions like Open RF and the second generation EasyRaceLapTimer.
How it Works
A receiver module monitors the signal strength of a particular radio frequency. When the strength increases above a certain level, a lap will be recorded. The exact time for the lap is recorded when the signal flips from gaining strength to losing strength. The timing unit is placed directly on the finish line.
Each scanner module can only monitor one frequency at a time, and must know what frequency to look for. Single-scanner units sometimes support multiple racers at once by repeatedly switching the scan frequency. Because the unit only looks at one frequency at a time, accuracy drops for each pilot added—there’s more time between scans for each pilot. If two quads fly by at exactly the same time, a single-scan unit may put one ahead of the other because it scanned one first before switching to the other. The frequency cycling is very fast and should work great with informal races, but a single-scan unit is not good enough for highly competitive events. High-end event systems that use this method include multiple scanners in the same timing box.
This system doesn’t have any way to uniquely identify a racer; it just times a frequency. It also assumes a quad is crossing perpendicular to the start/finish line. Crossing at an angle can advance or reduce the detection point by a few feet.
All you need is the scanner, power, (usually from an internal battery,) and a device with software to read the data (usually smartphone and app). The scanner is generally small and easily portable. There’s nothing to install on the quad. As far as extras, you might take steps to protect the scanner unit from a crash and from weather. You also need to make sure the battery is charged, or have a spare if it’s replaceable.
One challenge to using a frequency-based system is that each race heat needs set up individually. The tracker needs to know which frequencies to scan, so somebody has to find out who is flying next and reconfigure it to match the frequencies they will be using. If you’re only flying with a few people it may not be a problem, but for running an event it becomes a constant hassle if you haven’t rigidly assigned specific frequencies to be used.
The system uses a signal strength threshold to decide if you are near enough to the gate to worry about, so the scanner needs calibrated to look for that level. Both distance and transmitter power affect signal strength. If your scanner does not calibrate for each pilot individually, then all pilots racing at the same time need to use the same power level on their video transmitters. If different power levels are used, pilots will trigger the gate at different distances. This might mean some pilots trigger laps from another area of the course, or that a pilot may not be considered close enough to ever trigger at all. If you accidentally calibrate for the wrong size or power level, all of your times can be off. We unknowingly did this once and had to throw away all of the timing data for an entire event.
For software, you’re usually stuck with the app that’s specifically designed for the hardware. So far, these have far less features and options than the software available for IR timers. You are pretty much required to use a standard race format; options like staggered starts don’t exist. Perhaps the greatest deficit in some apps is a lack of stored race history. To run an entire event, you will have to do your own bookkeeping separately and constantly record race information before clearing it.
One final consideration: will these VTx-based systems be future-proof? We already use FHSS digital signals for radio control. How long will it be before that is common for video? A system like this will not be usable if the scanner cannot isolate the signal from each quad. For example, the Connex Prosight is only supported in “fixed frequency” mode—a sign that its other modes will be much more difficult to develop for.
Compared to an IR system, using a VTx scanner is extremely easy. There’s no extensive installation, no pre-event setup, and almost no software configuration. Often, everything you need can be carried in one pocket. This also cuts down on the number of things you have to remember to do before an event: charge up beforehand, and you are ready to go. Not having anything to install means there is no specialized setup for event participants. Nearly any FPV-capable quad can use this system, including micro quads like the Tiny Whoop.
The cost for a single-scan unit is much less expensive than an IR system, often no more than $100. If you already have a smartphone, there are no other expenses to get started. Multi-scan event systems cost upwards of $1000, though, which is typically a few hundred more than an IR system.
When it Makes Sense
- You want a timer that’s very portable and easy to set up
- You only want to time quads with 5.8GHz FPV equipment
- Everyone in the club uses a standard VTx, or the club has a standard VTx power level
- It’s okay to reconfigure the timer between every race heat
- It’s okay to have limited software options
An innovative developer figured out how to use video image analysis as a timing system, and came up with Whoop Laps.
How it Works and What’s Needed
A smartphone is placed on the start line and actively monitors the camera picture. A processing algorithm detects movement and triggers a lap when an object moves across the camera.
The only thing you need is a modern smartphone with a camera, and the app.
Using motion tracking means the camera can’t tell objects apart. There’s no way for it to tell one quad from another, so multiple pilots cannot race together with the same timer. For that matter, it can’t tell the difference between a quad and anything else roughly the same size and shape—like a bird or a pet. You may get false positives if anything else crosses the camera. To fly simultaneously with others, you’ll need to be creative. One solution is a separate gate and phone for each pilot—and hope nobody accidentally crosses through the wrong one.
Having no other equipment means placing your smartphone on the course. It might be fine if you crash into it with a Tiny Whoop (which can barely cause meaningful damage to anything but itself). Other things might not be so forgiving: larger quads crashing or a person accidentally stepping on it could suddenly cost you hundreds of dollars for a replacement phone.
Using image analysis is the least expensive and requires the least hardware of all. You can get started timing immediately with almost no effort.
When it Makes Sense
- You only want to time a single racer (practice by yourself)
- Your budget is almost nothing
- It’s okay to risk placing your phone on the course
Lap timing has a lot of great benefits and brings legitimacy to an event. How you choose to record time really depends on your budget and needs. Each system has its individual strengths: cost, speed, flexibility, and ease of use. The that’s right system for you and your group will differ from others and depends a lot on what you fly and if you are timing just for yourself, occasionally with a few friends, or running local group events. We’ll be following up this article with reviews of specific products as we have a chance to test them. If you’re in the market for a timing system, check back with us and we’ll share what we’ve found.