Each positioning satellite transmits data on several frequencies. And these frequencies are very important for the real accuracy you can achieve!
You also have different degrees of frequency. You have the single frequency antenna, the dual frequency antenna and triple frequency antenna.
Single frequency antennas
Single frequency antennas are basically the cheapest of the bunch, which also explains their poor performance. They use only 1 frequency of the satellite and for GPS that is the L1 band. Why do people still use them? Well they are good for those working in remote areas where there is little to no obstruction from trees or buildings. With a clear view of the sky you can achieve centimetre accuracy. But with the slightest obstruction nearby, your performance deteriorates drastically.
Dual frequency antennas
Dual frequency antennas use the L1 and L2 bands for GPS. They are a class higher and are much better at achieving centimetre accuracy in more challenging environments. Being close to trees, fences or buildings is generally fine with these devices. However, in urban environments, such as cities or dense forestry, accuracy may be reduced.
Triple Frequency Antennas
Triple frequencies are currently the way to go when you need high accuracy in difficult conditions. With the launch of the GPS L5 band and the BeiDou B3, you can achieve centimetre accuracy whenever you want. They perform very well near tall buildings or fairly dense tree canopies. However, with any type of GNSS receiver, you still need a decent elevation view to get a position, so count on reduced performance when the elevation view is barely visible.
But ultimately it also depends on the environment in which you want to measure and whether you need a receiver with a single frequency, a dual frequency or a triple frequency.
Let us know you experiences with a single, dual or triple frequency!