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Stand-Alone Mode

Stand-Alone is the simplest of the four operating modes. The simulator generates NMEA position data entirely from local input - no network ingest, no upstream source - and emits it to one or both of two outputs: a USB-serial device and / or one or more EFB apps over XGPS.

This is the mode you reach for when:

  • You have a single station (one host, maybe one iPad).
  • You want full manual control of position, altitude, speed, and heading from the web UI.
  • You don't need another simulator or external script feeding position in.

Stand-Alone vs Sender

Stand-Alone and Sender Mode both generate NMEA from manual input. The only difference: Sender additionally publishes the position to one or more network receivers. If you're not going to have a receiver downstream, Stand-Alone is the cleaner choice.

When to use Stand-Alone

Use case Why Stand-Alone fits
Driving a single iPad with ForeFlight or Garmin Pilot No network protocol needed; XGPS over UDP 49002 is enough.
Driving a single Bad Elf SBK-2500 over USB The simulator generates NMEA-0183, the cable carries it, the avionics consume it.
Driving both a Bad Elf and an iPad from the same station Both outputs run from the same NMEA engine. Enable both blocks.
Classroom demos and single-station tutorials Operator sees the controls; the EFB or avionics see real position.

Reaching Stand-Alone mode

Step Action
1 Log in if BYPASS_AUTH=false.
2 In the mode selector at the top of the dashboard, choose Stand Alone.
3 The Output Settings panel appears with two blocks - USB and EFB.

Stand-Alone is not selectable while the emulator is running. Press Stop first if you need to switch modes.

Output Settings panel

At least one output must be enabled before Start activates.

USB Serial Output

Control Default Valid values What it does
USB Serial Output toggle off on / off Enables NMEA-0183 emission to a USB-serial device.
Device (none) Any path matching the supported serial-device patterns The serial device to open. The Refresh button rescans the host's device list.
Baud Rate 115200 1200 - 115200 Symbol rate on the serial line. Must match the receiving device's expectation.

Wire format is fixed at 8N1. See Serial Output for per-device guidance and USB Serial (Bad Elf) for the Bad Elf SBK-2500 setup end to end.

EFB Output (UDP 49002 - ForeFlight and Garmin Pilot)

Control Default Valid values What it does
EFB Output (Port 49002) master toggle off on / off Enables the EFB block. With this off, neither broadcast nor unicast EFB output is sent.
Broadcast off on / off Sends XGPS frames to the local broadcast address. ForeFlight auto-discovers the source this way.
Garmin Pilot / ForeFlight (IP Address) off on / off Sends XGPS frames to one or more unicast targets. Required for Garmin Pilot.
EFB target IPs (empty) Comma-separated list. See IP Range Parsing. Individual IPs (10.200.50.5), ranges (10.200.50.10-10.200.50.20), or mixed.
Simulator Name (empty) Free text, typically aircraft type (CL350, Ultra) The string that appears in the EFB's GPS-source list. Required when EFB output is enabled.

When to use Broadcast vs IP targeting

Situation Broadcast IP targeting
ForeFlight, same Wi-Fi, no AP isolation Yes Optional
Garmin Pilot, same Wi-Fi No (Garmin Pilot doesn't accept broadcast) Yes
Multiple iPads with mixed apps Both (broadcast covers ForeFlight, IPs cover Garmin Pilot) Both
iPads on a different VLAN with a router between Broadcast won't cross routers Yes

For a complete EFB walk-through including iPad-side configuration, see Connecting ForeFlight and Connecting Garmin Pilot.

Position, altitude, speed, heading

Stand-Alone mode is driven by the Navigation Controls panel - the one with the airport picker, the altitude / airspeed sliders, and the compass dial. It works identically across all four modes, so its detail lives on its own page: Navigation Controls.

Input What it sets
Airport picker Snaps lat / lon to a known airport from the built-in database (4,003 entries). See Airport Lookup.
Altitude slider Target altitude in feet MSL. The engine ramps to it at ALTITUDE_RATE_FT_PER_2SEC (default 1000 ft / 2 s).
Airspeed slider Target airspeed in knots. Ramps at AIRSPEED_RATE_KTS_PER_SEC (default 30 kts/s).
Heading dial Target heading 1-360 degrees. Ramps at HEADING_RATE_DEG_PER_SEC (default 3 °/s).

The "ramp" behavior is what makes Stand-Alone output look like a real aircraft instead of a teleporting cursor. See Navigation Controls for the underlying math and the per-rate env vars.

NMEA sentence selection

Stand-Alone honors the sentence selections from the NMEA panel. GPGGA and GPRMC are always emitted; everything else is opt-in. See NMEA Sentences for the per-sentence detail.

Starting and stopping

Action What happens
Start The NMEA engine arms with current sliders / airport. The serial port opens (if USB enabled). The EFB sender opens its socket. NMEA output begins at 1 Hz.
Stop All outputs close. The engine releases. Slider / heading values are preserved in memory for the next start.
Adjust a slider while running The new value becomes the target the engine ramps toward. The transition rates govern how fast it gets there.
Container restart All in-memory state is discarded. If AUTO_START_MODE=standalone is set, the simulator re-arms on the next boot with the env-var defaults.

Persistent state

Setting UI control Env var Survives restart?
Mode (set to standalone at boot) Mode selector AUTO_START_MODE=standalone Only if env var set
Default position Airport picker / lat-lon DEFAULT_LAT, DEFAULT_LON Yes (env var, used at boot)
Default altitude / airspeed / heading Sliders / dial DEFAULT_ALT_FT, DEFAULT_AIRSPEED_KTS, DEFAULT_HEADING Yes (env var, used at boot)
Transition rates (no UI control) ALTITUDE_RATE_FT_PER_2SEC, AIRSPEED_RATE_KTS_PER_SEC, HEADING_RATE_DEG_PER_SEC Yes (env var, applied always)
USB enabled Output Settings AUTO_START_USB_ENABLED Only if env var set
USB device Serial picker AUTO_START_USB_DEVICE Only if env var set
Serial baud Serial picker SERIAL_BAUDRATE Yes (env var, host-wide default)
EFB enabled Output Settings AUTO_START_EFB_ENABLED Only if env var set
EFB broadcast Output Settings AUTO_START_EFB_BROADCAST Only if env var set
EFB IP targets Output Settings AUTO_START_EFB_TARGET_IPS Only if env var set
EFB simulator name Output Settings AUTO_START_EFB_SIM_NAME Only if env var set

See Environment Variables for the authoritative reference.

Worked scenarios

Scenario 1 - Single iPad with ForeFlight, no USB

A pilot at their desk wants ForeFlight on their iPad to think the aircraft is at KCRQ, taking off west at 450 knots, climbing to 45,000 feet.

Setting Value
Mode Stand Alone
USB output off
EFB output on
Broadcast on
IP targeting off (broadcast is enough for ForeFlight on the same Wi-Fi)
Simulator name CL350
Airport KCRQ
Altitude 45000 ft (ramps from 0)
Airspeed 450 kts (ramps from 0)
Heading 270

Pressing Start begins XGPS broadcast immediately. ForeFlight picks CL350 from its GPS-source list within ~5 s. The altitude rolls from 0 to 45,000 over ~90 s.

Scenario 2 - Bad Elf SBK-2500 driving cockpit avionics

A maintenance bench is testing a panel that consumes serial NMEA-0183 at 9600 baud (a common legacy rate). The Bad Elf is wired host-USB to RS-232 into the panel's GPS-in port.

Setting Value
Mode Stand Alone
USB output on
Device /dev/ttyUSB0
Baud rate 9600
EFB output off
Airport KORD
Altitude 0 ft
Airspeed 0 kts
Heading 360

The panel sees a stationary aircraft at KORD. Adjust heading on the compass dial to confirm the panel's HSI follows.

Scenario 3 - Both outputs at once

The same maintenance bench, but the technician also wants a Garmin Pilot iPad to corroborate what the avionics is seeing.

Setting Value
Mode Stand Alone
USB output on, /dev/ttyUSB0 at 9600
EFB output on
Broadcast off
IP targeting on, target 10.200.40.198 (the iPad)
Simulator name BENCH

Both outputs run from the same NMEA engine, so whatever the iPad sees is what the panel sees.

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