Accept "Disable Sub-band Recommendation" (but retain transmission of sub-band), without affecting communication and allowing you to know the channel status.
In 430Test at 440 MHz, or move away from electrical devices (especially battery chargers and HDMI cables, which are sources of high-speed data signal radiation) before testing.
If the firmware has a field strength table (like Sxx), observe the noise floor at S0.S4 internal processing can be used, S1The S2 measurement is excellent. Typical background noise in urban areas ranges from S3, with variations over time (lower in the morning and noon, higher in the afternoon and evening). If the background noise fluctuates significantly when a specific location (including antenna angle) is fixed, it indicates interference.
If you have SDR or spectrum analyzer software, check for interference.
In addition to troubleshooting interference, you can also set the noise level to 0. If there is white noise, it should be fine. However, if there are clicking or buzzing sounds, or sounds like those from Star Wars or a woodpecker, then…Coffee! Audio indicates interference.
The hand-held radio receiver in the V-band operates almost flawlessly, but I have only seen one instance where the U-band sensitivity was significantly lower (around 7 dB). Therefore, it is important to investigate and rule out environmental factors.
If there's a video available, please share it. Many of these sounds can be easily identified with just one ear.
Finally, there is interference from adjacent frequencies, which means other business or pirate radio stations operating in the vicinity of 144 MHz (potentially separated by tens of MHz) interfering with the receiver. This type of interference is very rare, but it cannot be ruled out. A simple troubleshooting method is to use a TV to search for DTMB signals and check the frequency; 100Any signal between 250 MHz should be treated with suspicion. Strong or very poor-quality black broadcasts can also interfere, so it's best to first check using a radio receiver.
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