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Rotator Control

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Rick de N8SDR edited this page Apr 6, 2026 · 1 revision

Rotator Control

SDRLogger+ can control your antenna rotator directly from the browser interface, with support for both PstRotator (UDP) and HamLib rotctld. Point your beam at the DX with a single click.

Supported Protocols

Protocol Software Notes
PstRotator PstRotator by YO3DMU UDP-based, widely used, supports hundreds of rotator controllers
HamLib (rotctld) HamLib project CLI daemon, supports many rotator interfaces

PstRotator Setup

PstRotator is the most popular rotator control software on Windows and has robust UDP support for external applications.

In PstRotator

  1. Open PstRotator.
  2. Go to Setup → Program (or the gear icon).
  3. Find the UDP section.
  4. Enable UDP Control or Remote UDP.
  5. Note the UDP port (default is typically 12000 but may vary by PstRotator version).
  6. Click OK and ensure PstRotator is connected to your rotator controller.

In SDRLogger+ Settings

  1. Open Settings → Rotator Control.
  2. Set Host to 127.0.0.1 (or the IP of the machine running PstRotator if on a different PC).
  3. Set Port to the UDP port configured in PstRotator (e.g., 12000).
  4. Set Protocol to PstRotator.
  5. Check Enable Rotator.
  6. Click Save Settings.

Tip: Verify PstRotator is running and connected to your rotator hardware before enabling rotator control in SDRLogger+. SDRLogger+ can only issue commands if PstRotator is up and listening.

HamLib rotctld Setup

HamLib provides the rotctld daemon for CLI-based rotator control.

Starting rotctld

rotctld -m <model_number> -r <device_port> -t 4533

Replace <model_number> with your rotator's HamLib model number (find it with rotctld --list) and <device_port> with your serial/USB port (e.g., COM3 on Windows or /dev/ttyUSB0 on Linux).

In SDRLogger+ Settings

  1. Open Settings → Rotator Control.
  2. Set Host to 127.0.0.1.
  3. Set Port to 4533 (or whatever port you started rotctld on).
  4. Set Protocol to HamLib.
  5. Check Enable Rotator.
  6. Click Save Settings.

Azimuth Display

When the rotator is connected and enabled:

  • The current azimuth (bearing in degrees) is displayed in the SDRLogger+ header area.
  • The azimuth updates in real time as your rotator moves or as the polling interval fires.
  • The display shows 0–360° with North being 0°/360°.

Note: Azimuth is polled at a fixed interval rather than streamed continuously. If the display seems slightly behind your actual rotator position, this is normal — the next poll will catch up.

Auto-Track

When Auto-track is enabled, SDRLogger+ will automatically send a rotate command to your rotator whenever you click a spot in the DX Cluster panel.

  • Click a spot → radio tunes to the frequency → rotator turns to the bearing of the spotted station's country.
  • Bearing is calculated from your station's grid square (set in your QRZ/HamQTH profile or estimated from your callsign location).

Tip: Auto-track works best when you have a good callsign-to-country database loaded and your grid square is accurate. Without a grid square reference, bearing calculations may be approximate.

To enable:

  1. Check Auto-track in Settings → Rotator Control.
  2. Click Save Settings.

Manual Azimuth Entry

You can manually send your rotator to any bearing directly from the interface:

  1. Find the azimuth input field in the rotator section of the main interface (or header).
  2. Type the desired bearing (0–360).
  3. Press Enter or click Go.

This is useful when you know the bearing to a target without using a cluster spot.

Troubleshooting

Choppy or delayed azimuth updates

  • The rotator display updates on a polling interval. Some rotator controllers respond slowly to position queries.
  • Verify PstRotator is responding quickly by checking its own azimuth display.
  • If using HamLib, try increasing the poll interval or checking rotctld responsiveness.

UDP not reaching SDRLogger+

  • Check that PstRotator's UDP output is enabled and pointed at the correct port.
  • Verify Windows Firewall allows UDP traffic on the configured port.
  • Try netstat -an | find "12000" in a command prompt to confirm the port is open and listening.

Wrong port

  • Cross-check the port number in both PstRotator and SDRLogger+ Settings. A single digit difference is the most common cause of rotator control failures.

Rotator moves to wrong bearing

  • Verify your grid square or QTH location is set correctly — bearing calculations depend on your location.
  • Check that the DX station's country prefix is being correctly identified.

HamLib rotctld not connecting

  • Confirm rotctld is running before enabling the SDRLogger+ rotator. Check with tasklist | find "rotctld" on Windows.
  • Verify the model number with rotctld --list and ensure it matches your hardware.

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