4.2 Checking for RF interference
If you suspect a device may be causing radio frequency (RF) interference you can use your VHF
radio to check.
1. Turn off the suspect device.
2. Tune your VHF radio to a quiet channel such as Channel 13.
3. Adjust your radio’s Squelch control until the radio outputs audio noise.
4. Re-adjust your radio’s Squelch control until the audio is quiet, only slightly above the noise
threshold.
5. Turn on the suspect device.
• If the radio’s audio noise increases then the device is causing RF interference.
• If there is no change in the radio’s audio noise then the device is not causing RF interference.
Note:
If RF interference is present then it is likely that both VHF and AIS reception are being
degraded by the device.
Multiple antenna installations
Important additional considerations when installing multiple antennas.
To prevent potential channel interference when installing two or more VHF radios on the same
vessel, ensure that the antennas are located at least 2.4 m (8 ft.) away from each other.
Audio Troubleshooting (transmission / reception)
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