Scanning
Scanning Guide
Starting a Scan
Press the * key to begin scanning. The radio starts stepping through frequencies or channels depending on the current mode. Press EXIT or * again to stop the scan.
Scan Modes
The scan resume behavior is set via menu 17. Three modes are available:
| Mode | Behavior | Best for |
|---|---|---|
| TO (Time) | Pauses on signal, then resumes after a ~500 ms timeout regardless of signal state | Monitoring busy channels — prevents lockup on persistent carriers |
| CO (Frequency) | Pauses while the signal is present, resumes automatically when the carrier drops | Finding active frequencies — ensures the full transmission is heard |
| SE (Fine) | Stops immediately when a signal is found and stays until manually moved | Searching for a specific signal — use when you want to lock onto a find |
Frequency Scan
In VFO mode, the scanner steps through frequencies within the current band range. The step size is set by menu 42 (Freq Step). Scan direction is UP or DOWN based on the last tuning direction used before the scan started.
- Smaller step sizes (e.g., 5 kHz) provide more thorough coverage but scan more slowly.
- Standard VHF/UHF land mobile step is 12.5 kHz.
- The scan wraps around within the band boundaries.
Channel Scan
In channel mode, the scanner steps through stored memory channels in order. Channels that do not have the scan flag enabled are skipped. This lets you curate exactly which of the 1000 possible channels participate in a scan.
Setting the scan flag
Each channel has a scan-enabled flag stored in its channel data. Enable or disable it per channel using the channel programming menu or via the web configurator before flashing.
Tone Scan (QT Scan)
QT Scan detects CTCSS or DCS tones on an active signal. This is useful for identifying the access tone required by a repeater when you can hear traffic but the squelch is filtered by your own RX tone setting.
- Tune to the frequency carrying the signal.
- Start QT scan. The radio cycles through CTCSS tones and DCS codes one by one.
- When the correct tone is found, the squelch opens and the scan stops.
- The identified tone is displayed. Apply it as the RX tone for this channel.
Scan Timing
The following timing values are hardcoded in the RT-900 firmware:
| Event | Duration |
|---|---|
| Signal found confirmation delay | 100 ms |
| Signal lost timeout (TO mode) | 500 ms |
These values are baked into the firmware and cannot be changed via the menu. Firmware modification is required to adjust them.