Quick Answer
The Here3+ is a single-band GPS module. It gives a solid, steady lock for most drones. The Here4 uses dual-band GPS. It locks on faster and holds position better, especially near buildings or trees. Both connect over DroneCAN. Both can work as an RTK rover. The Here4 costs more, but the upgrade pays off most on mapping drones.
What GNSS and Bands Mean
GNSS is the general term for GPS and other satellite systems, such as GLONASS and Galileo. A receiver can use more than one at once. This gives it more satellites to work with. More satellites often means a faster lock and a steadier position.
"Band" means a radio frequency the receiver listens to. Single-band units, like the Here3+, listen on one frequency. Dual-band units, like the Here4, listen on two. The second frequency helps the receiver fix a small delay caused by the atmosphere. This delay is one of the biggest sources of GPS error.
Here3+ Overview
The Here3+ is CubePilot's main GPS and compass module. It uses a single-band chip. It tracks several satellite systems at once. It has a built-in compass.
It connects to a Cube or Pixhawk-style flight controller over DroneCAN. This makes setup simple. It can also share the bus with other DroneCAN parts.
For most FPV builds and camera drones, the Here3+ gives a fast lock. It holds a steady position in modes like Loiter and Return to Launch. It can also work as an RTK rover with a base station. This helps on light mapping jobs.
Here4 Overview
The Here4 is the newer, more accurate option. Its main upgrade is dual-band GPS tracking. This cuts lock time. It also cuts position drift caused by the atmosphere.
This helps most in tricky spots. Think of flying near tall buildings, under trees, or near anything that can bounce a signal.
Like the Here3+, the Here4 connects over DroneCAN. It also has a compass built in. It works as an RTK rover too. Its better tracking helps it lock a fixed RTK solution faster. It also holds that lock more often.
RTK Support Compared
RTK stands for real-time kinematic positioning. It uses data from a fixed base station. This can bring GPS accuracy down to a few centimeters, instead of a few meters. Both the Here3+ and Here4 can act as the rover in an RTK setup. Both can get correction data over the DroneCAN bus.
The real difference is speed and stability. The Here4's dual-band tracking locks faster. It stays locked better once you move under cover. This matters on real survey jobs. For a deeper look at planning accuracy, read RTK vs PPK for drone mapping.
Mounting and Physical Differences
Both modules mount above the frame. Keep them away from motors and power wires. The compass inside is sensitive to magnetic noise from those cables. Mounting patterns are similar between the two. Upgrading from a Here3+ to a Here4 rarely means a new GPS mast.
| Factor | Here3+ | Here4 |
|---|---|---|
| GNSS bands | Single-band | Dual-band |
| Connection | DroneCAN | DroneCAN |
| Compass included | Yes | Yes |
| RTK rover support | Yes | Yes |
| Typical lock time | Good | Faster |
| Best use case | General flying, light mapping | Precision mapping, tricky signal areas |
Setting Up Either Module in ArduPilot
Both modules follow a similar setup path in Mission Planner:
- Plug the module into the flight controller's CAN port with the right cable.
- Turn on the CAN driver and DroneCAN GPS in Mission Planner's setup screen.
- Reboot the flight controller so it can find the new device.
- Run the compass calibration away from metal objects and other magnets.
- Check satellite count and lock quality before your first flight.
If you plan to run RTK, you will also need a base station or a correction service. The setup steps are covered in ArduPilot sensor setup.
Which One Should You Buy?
Pick the Here3+ for a general drone, an FPV rig with GPS rescue, or light mapping. Centimeter accuracy is not the main goal. It costs less and covers most everyday needs.
Pick the Here4 for real mapping or survey work. It also suits areas with a partial view of the sky, like near buildings or under trees. The dual-band tracking is the whole reason to pay more, so only choose it if the job needs that speed and accuracy.
Think about how often you fly in tricky spots, not just how the drone flies on a clear, open field. A survey pilot who works mostly in open farmland may never notice the Here4's edge. A pilot who maps construction sites boxed in by tall buildings will notice it on almost every flight.
Budget and Long-Term Value
The Here4 costs more up front, but it can also save time on site. A faster, steadier lock means less standing around waiting for a fix before a mission starts. On a job billed by the hour, that time adds up fast. For a hobby build flown mostly for fun, the Here3+ still gives you almost all of the everyday benefit for less money.