What is Dual GPS and why does Apple use it?

Apple seems to be in a league of its own with the Watch. At an event in September 2022, the tech giant launched a brand new addition to its smartwatch lineup alongside the Apple Watch Series 8 and the second-generation Apple Watch Ultra SE. They’ve certainly gone to the extreme with the Ultra by fitting it with accurate dual-frequency GPS. The same feature has also been added to the iPhone 14 Pro lineup.

Dual-frequency GPS on Apple Watch Ultra and iPhone 14 Pro

It’s no secret that one of our favorite features is the ability to use GPS to navigate, whether it’s directly from our wrist or through a smartphone. But the GPS is already accurate. So, what is dual-band GPS for?

Well, Apple is trying to improve the accuracy of GPS signals with this process. But the feature itself is not new. If you have a OnePlus, Xiaomi or even Huwaei phone, you might already be using this feature. Let’s dive in to find out more about it and whether you need it.

What is dual frequency GPS

The turn-by-turn directions in your navigation program are the result of the GPS signal received from the satellite. Like all electronic signals, GPS also operates on a specific frequency system. The range of frequencies in which a signal operates is called the frequency range, and there are several frequency ranges. Today, most GPS systems operate on a single frequency band – the so-called L1 band (more on that later).

It is now possible to create a device using an additional frequency range to increase the accuracy of pinpointing. This is called dual frequency GPS. This was one of the main focuses of Apple when they introduced the new Apple Watch line and the iPhone 14 Pro Series. (Don’t miss these brand new iPhone 14 series wallpapers).

Let’s take a closer look at the difference between single-frequency and dual-frequency GPS.

Single vs Dual GPS

The most notable difference is that traditional single-frequency GPS provides an accuracy of up to 5 meters, while dual-frequency GPS can offer centimeter-level accuracy.

As mentioned earlier, most single frequency devices have been using the L1 band for years. And the biggest limitation of the L1’s range is that its signal can’t get around tall objects, atmospheric distortion, or even thick foliage in the way. This leads to inaccuracies.

This is where the dual frequency system proves its effectiveness. Apple uses the L1 band together with the L5 band in a dual-band system to overcome the limitations associated with the first band.

Although it would make more sense to use only the L5 signal for better GPS accuracy, this is not possible. The L5 range is currently in pre-commissioning. So Apple combines L1 and L5 to provide the best without hiccups. In the near future, we may see L5 signals powering our iPhone GPS experience; you never know.

How Precision Dual-Frequency GPS works

The main purpose of a dual-frequency system is to improve the quality of the input signal by reducing noise and removing errors. The basic error that prevents signal processing is called a multipass error.

What are multipath errors

When you request navigation data, you use your watch (or phone) as a receiver that requests a signal and information from a satellite, a transmitter. The signal should now travel from the satellite (transmitter) to your device (receiver).

Illustration of the L1 range
In the L1 bands, your device also receives a signal reflected from an object, say a building.

The path between them is unclear and has many objects in between, from large objects like skyscrapers to smaller objects like particles in the ionosphere. The signal will be reflected from these objects, forming multiple signal paths. These mapped new signal paths will not contain any useful information.

This will cause errors in the received information and these are called multipath errors and this needs to be corrected.

How the L5 frequency range amplifies GPS signals

The L5 band has many advantages over the L1 band, such as higher capacity and higher accuracy, but one of the main advantages is its ability to detect unwanted reflected signals caused by multipath errors. Thus, when the L1 + L5 bands are engaged, they detect unwanted signals and ensure that they do not affect the output information at the receiver side.

Illustration of the range L1 + L5

Another parameter we need to know is the frequency of the chips – the number of pulses transmitted or received per second. The chip frequency of the L5 signal bands is almost ten times higher than that of the L1 signal bands. The ability to reduce errors is directly proportional to the frequency of microcircuits. Thus, errors and noise are reduced by a factor of ten when using the L5 band.

You need a dual frequency GPS device

The purpose of the dual-band frequency system is to improve the accuracy of GPS data. But let’s face it, we don’t have many users complaining about the current single-band GPS technology. So who is it for?

Apple gave us an example during the presentation – the Chicago Marathon. There are many skyscrapers along the marathon route, and as mentioned earlier, this can lead to some inaccuracies in the GPS signal. So a dual frequency system can help.

What’s more, if you’re an adventurer who often ventures out into the wilderness or lives in areas with little connectivity, the two-piece system is for you. In addition, Apple has also released an emergency SOS feature via satellite for your safety.

Since this is also present in the iPhone 14 Pro series, we are sure that another use case could be using this system to control and safely land drones. Accuracy down to a centimeter can help you accurately control and locate drones.

Now we have to wait for these devices to be put to the test in the real world to see how the new GPS works and see if it can help in more situations than we might think.

Dual-band GPS for ultra-accurate GPS

That’s everything you needed to know about dual-band GPS on the Apple Watch Ultra. Interestingly, this technology was only used in high-end industrial systems. The L5 band is also a band previously reserved for aeronautical radio services only. But thanks to the availability of inexpensive components, we can see it in devices like the Apple Watch Ultra. We’re excited to see this happen in the real world, and we hope you are too!