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Smart antenna or modular receiver?

Consolidating your GNSS positioning components

Cast a glance at any 3D grade control system and it is immediately apparent that what's on top of the mast(s) may differ quite a bit in size between systems.

If the item in question has a hefty bulk, it's probably a 'smart antenna', -a GNSS antenna and receiver in the same housing.

This is in contrast to a modular system which has only the GNSS antenna on top of the mast and the receiver is located elsewhere on the machine.

GNSS smart antenna or modular

The smart antenna sends digital data over a CAN connection directly to the 3D grade control system's computer whereas the modular system sends analog data first to the GNSS receiver where it is processed and digitized for then to be send to the computer.

Some of the benefits of using a smart antenna are fewer system components, quicker installation and easier removal at night for theft protection. (One item and one connector versus two items and several connectors).

There is also a benefit to using smart antennae when it comes to changing the system configuration. A grader can quickly and easily be converted from a 3D grade control set-up to a conventional laser and cross slope system by simply replacing the GNSS smart antenna with a laser receiver.

Leica PowerGrade 3D and Caterpillar
                              AccuGrade GPS
Similarly, converting between GNSS and a robotic total station only requires swapping the smart antenna for a robotic target. The smart antenna is subsequently available to be used on a different machine.

Critics of smart antennae state that the value of the equipment on top of the mast is much higher compared to a modular system and since the mast is very exposed, an accident has the potential to be much more costly.

Smart antennae are also considerably heavier than their counterpart and can put quite a bit of stress on the mast. It is important to adhere to the
Leica GNSS antenna (left) and Caterpillar's smart antenna

manufacturer's recommendations when it comes to mast design and material.

The two systems do not differ when it comes to positioning performance. They are equally accurate.

If the system will be employed mainly on a single machine and you do not expect to change between GNSS, robotic and laser very often, then perhaps a modular system should be considered.

But, if you have a need to reconfigure the system frequently, you should look into the smart antenna system.

At the time of this writing, Trimble and Caterpillar are the only companies offering ruggedized smart antennae for all machine types. Their 3D grade control systems are sold under the brand names GCS900 and AccuGrade, respectively.

Leica's PowerDigger 3D also offers a smart antenna, but currently only as a supplement to a modular GNSS receiver and only when configured as a dual-antenna system on an excavator.

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