What Is Dual-Frequency GPS and Why Is Apple Using It

Quick Tips

• To increase the pinpoint location accuracy, a device can be built to use an additional frequency band. This is called a Dual Frequency GPS
• A single-frequency GPS offers accuracies of up to 5 meters, whereas a dual-frequency GPS can offer accuracies on a centimeter level.
• The main objective of a dual frequency system is to improve the quality of the signal by reducing noise and removing errors.

What is Dual Frequency Band GPS

The turn-by-turn directions on your navigation app are a result of a GPS signal received from a satellite. Like all electronic signals, GPS also operates on a certain frequency system. The range of frequencies over which the signal operates is called a frequency band and there are multiple frequency bands. Today, most GPS systems operate on a single frequency band – called the L1 band (more on it later).

Now, to increase the pinpoint location accuracy, a device can be built to use an additional frequency band. This is called a Dual Frequency GPS.

Single vs. Dual-Frequency GPS

The most prominent difference is that a traditional single-frequency GPS offers accuracies of up to 5 meters, whereas a dual-frequency GPS can offer accuracies on a centimeter level.

As mentioned earlier, most single-frequency devices have been using the L1 band for years now. The biggest limitation of the L1 band is that its signal can’t bypass tall objects, atmospheric distortion, or even dense foliage in the path. This leads to inaccuracies.

This is where the dual-frequency system proves efficient. Apple uses the L1 band along with the L5 band in the dual-band system to overcome the limitations associated with the former band.

While it would make more sense to use the L5 signal alone for more GPS accuracy, it isn’t possible. The L5 band is currently in its pre-operational stage. Hence, Apple combines L1 and L5 to deliver the best without hiccups. Shortly, we might see L5 signals powering our GPS experience on iPhones; you never know.

How Does the Precision Dual-Frequency GPS Work

The main objective of a dual-frequency system is to improve the quality of the input signal by reducing noise and removing errors. A major error that hampers signal processing is called a multi-path error.

What Are Multi-Path Errors

When you request navigation data, you use your watch (or phone) as a receiver requesting signal and information from a satellite, the transmitter. Now, the signal has to travel from the satellite (transmitter) to your device (receiver).

The path between the two is not clear and has a lot of objects in between, from larger objects like skyscrapers to smaller objects like particles in the ionosphere. The signal will reflect off these objects to form multiple signal paths. These reflected new signal paths will not contain any useful information.

This will lead to errors in the received information, they are called Multi-path errors and this needs fixing.

How Does the L5 Frequency Band Strengthen GPS Signals

The L5 band has a lot of advantages over the L1 band, like higher power, and higher accuracy but one main advantage is its ability to detect unwanted reflected signals caused by multi-path errors.

So, once the L1 + L5 bands are in action, they identify unwanted signals and ensure that they do not affect the output information at the receiver’s end.

Another parameter we need to know is the chip rate – the number of pulses per second that are transmitted or received. The chip rate of the L5 signal bands is nearly ten times greater than the L1 signal bands. Error reduction capability is directly proportional to the chip rate. Thus, the errors and noise are reduced ten folds when an L5 band is used.

Do You Need a Dual-Frequency GPS Device

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

• Apple gave us a relatable example during the launch event – the Chicago Marathon. The path of the marathon has a lot of skyscrapers and as mentioned earlier, this might lead to some inaccuracies in the GPS signal. So, the dual-frequency system can help.

• Moreover, if you are an adventure lover and often venture out in the wilderness or live in areas where there is little connectivity, the dual frequency system is for you.

• Since this is present on the iPhone 14 Pro, and the 15 Pro series as well, we’re sure another use case can be using this system to control and land drones safely. A centimeter-level accuracy can help you accurately monitor and position your drones.

Also Read: 5 best titanium bands for Apple Watch Ultra.