If the remote control range has shortened, is noise the reason?
Noise is only one of the possible causes. When range drops, first check the antenna position, the antenna cable and connector, the receiver supply voltage and the ground quality. A voltage drop exceeding 0.5 V under load on the receiver supply shortens the range on its own; diagnosing noise is meaningful only after these mechanical and electrical causes have been eliminated.
The most common sequence when range drops is as follows:
- Antenna position: has the antenna been placed inside or at the foot of a metal body? A metal surface suppresses the antenna pattern. Move the antenna away from metal, upwards and into the open if possible.
- Antenna cable and connector: a crushed cable and a loose or oxidised connector produce losses. Unplug the connector, clean it and refit it.
- Supply: measure the receiver supply under load. Below 0.2 V is good, 0.2-0.5 V is borderline, above 0.5 V is a fault. A low supply directly affects transmitter power and receiver sensitivity.
- Ground: if the receiver chassis connection is made to a painted surface, the reference is corrupted; clean until the metal shines.
- Noise: if the above are clean, look at the noise sources. Brushed motors, inverters and switching driver outputs radiate broadband noise.
The noise verification test is simple: switch off the suspect loads one by one and measure the range again. If the range recovers when one load is switched off, the source has been found; in that case apply suppression to that load with X/Y capacitors and a ferrite, and route its cable away from the receiver antenna.
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