Why is the crane remote control range lower than the catalogue value?
Catalogue range is measured in open, unobstructed ground. The first cause of the drop on site is the receiver antenna staying inside the metal panel.
Catalogue range is measured in an unobstructed open area, with the transmitter and the receiver in sight of each other. The value in the field comes out below that, and the most frequent cause is the receiver antenna staying inside the metal panel. Taking the antenna outside the panel closes most of the complaints on its own.
Factors that reduce range
- Antenna position: If the receiver antenna stays inside a metal panel, the signal is seriously weakened. The antenna should be taken outside the panel, at least 20 cm away from any metal surface, and placed vertically.
- Metal structures: Steel construction reflects the signal and creates shadow zones.
- Interference: Inverters, welding machines and frequency converters generate noise in the same band.
- Weak batteries: As the transmitter battery drops, the output power decreases; loss of range is the first symptom.
These four can be present together on the same site and their effects add up. The effect of concrete walls and steel construction on range is dealt with separately.
Permanent shortening, or a dropout at one spot?
Before you start looking for a fault, split the symptom in two; the cause and the remedy of the two pictures are different.
| Symptom | Possible cause | First check |
|---|---|---|
| Short range everywhere, all the time | Antenna placement, antenna cable, weak battery | Take the antenna outside, fit a fresh battery and repeat the measurement |
| Dropout at a particular spot on the site | Metal shadow, reflection | Change the direction and the height of the antenna at that same spot |
| Dropout while a particular machine is running | Source of interference | Stop that machine and repeat the measurement |
What to do on site, in order
- Fit a fresh battery to the transmitter or charge the remote control fully, and make the measurement again from the start.
- Take the antenna outside the panel, bring it into a vertical position, move it away from metal surfaces.
- Keep the transmitter and the receiver antenna in the same plane; a transmitter held tilted couples poorly with a vertical antenna.
- Stop the suspected sources of interference one by one and repeat the measurement; inverter interference is the item skipped most often.
- Accept the distance you measure with a margin left on top of it, not at the limit of your requirement.
Write these steps down on paper together with the measured values: from which point, with which battery, with the antenna in which position, how many metres. A large part of range complaints arise from the measurement being made under different conditions every time; when no record is kept, there is no telling whether the intervention worked.
When you cannot take the antenna outside
The antenna cannot be taken outside on every site: risk of impact, pressure washing or a closed machine body will not allow it. The solution that first comes to mind in that case is extending the antenna cable, but as the cable gets longer the loss grows and you may end up writing a loss instead of a gain. Installing the receiver as the outdoor type, mounted next to the machine without a panel, removes this constraint from the outset. Another practical solution is to take the receiver behind a plastic cover rather than a metal one; what gets in the way is not the thickness of the metal but the closed metal surface itself.
Set the expectation correctly
The open-area value is approximately 100 m on the SF series and approximately 150 m on the ST series. On an enclosed, metal-dense site, dropping below that value is not a fault but the expected result. The right approach is to measure the real diagonal distance and to leave a range margin on top of it; an installation working at the limit gives its first fault when the season or the layout changes.
Make the acceptance measurement under the worst conditions: with the bridge at the farthest point, the doors closed and the neighbouring machines running. An installation that passes under those conditions will not cause trouble on a good day anyway. If you do the opposite, that is, if you measure and accept in an empty workshop, you will have dropouts on the first busy shift and the cause will be taken for a fault in the remote control.
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