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Radar View#

mwp supports the display of "radar" contacts. This provides a view of adjacent aircraft obtained from a number of sources:

  • Tracked Telemetry. Models tracked by telemetry (CRSF, LTM, MAVLink, Smartport, MPM(Flysky, Smaprtport)). Provided by RX Telemetry Mirroring or dedicated telemetry radios.

  • INAV-radar. INAV radar works in conjunction with INAV flight controllers to broadcast the location of UAS fitted with an ESP32 LoRa module. mwp can listen to one of these modems in ground station mode to display the positions of the rest of the 'swarm' (up to 4 UAS); technical / MSP details.

  • Full size aircraft reported by the MAVLink 'Traffic Report' / 'ADSB Vehicle' message. Examples of available hardware include:

    • uAvionix PingRX, a compact device that receives ADS-B location data from full sized aircraft and publishes the locations as MAVLink. For a ground based installation, this device has around a 40Km detection radius. MAVLink ICD.
    • Aerobits TT-SC1. Untested, but supports the same MAVLink API as the PingRX. Product documentation.

  • Full size aircraft reported using the SBS-1 Basestation streaming TCP protocol. This can be generated by the open source dump1090 application with a SDR receiver, as well as commercial products.

  • Proximity alerts (visual and audible) for manned (ADS-B / SBS-1) aircraft, based on planned or actual home location.

mwp Configuration#

mwp can receive the 'radar' data over one or two connections, either or both may be active, and mwp can receive and display 'own vehicle' telemetry (MSP, LTM or Smartpost), Tracked Telemetry, 'INAV-radar' and 'MAVlink Traffic' data simultaneously. Radar data may be received over:

  • The main serial port device (see caveat for INAV-radar) or
  • device(s) defined by the radar-device CLI or configuration parameter (MAVLink Traffic, INAV-radar)

The radar-device option is defined by the standard mwp naming scheme:

  • A serial device node, with optional baud rate, e.g.:
    • /dev/ttyACM0, /dev/ttyUSB4@567600, /dev/rfcomm3
    • Serial defaults to 115200 baud, but may be set in the device name (@baudrate)
  • A Bluetooth address (for BT bridges)
    • 00:0B:0D:87:13:A2
  • A UDP address, e.g. for simulation, recording replays or serial multiplexer (INAV, mavlink).
    • udp://:30001 local UDP listener.
  • A SBS-1 source, defined by a special URI:
    • sbs://[[host][:port]] Host and port are optional, defaulting to localhost and 30003. So the minimal "URI" is sbs://.

For "Telemetry Tracking", please see its separate article.

The specific (not shared with the main serial port) radar device(s) may be defined on the command line, or in the static command options file (~/.config/mwp/cmdopts):

  • mwp --radar-device udp://:30001
  • $ cat ~/.config/mwp/cmdopts
    # Default options for mwp
# using udev rule to associate a specifc USB-TTL adaptor to a name
--radar-device=/dev/pingRX@57600

Multiple devices may be defined, e.g.

  • As separate options, --radar-device=/dev/pingRX@57600 --radar-device= /dev/inavradar@115200
  • As a comma separated list: --radar-device=/dev/pingRX@57600,/dev/inavradar@115200

Any bespoke radar-device is started automatically on startup (or when it shows up). It is not managed via the serial Connect button.

Using the main serial port#

The main serial port may be used for MavLink Traffic without any further configuration. For INAV-radar, to use the main MSP port for INAV-radar (vice using --radar-device), it is still necessary to add a command option to mwp; it needs to told to relax the default inbound MSP direction check.

This is enabled as

mwp --relaxed-msp

which should be 'mainly harmless' for normal operations. It's entirely acceptable to put this in ~/config/mwp/cmdopts to make it the default, as the protocol check dilution is slight.

Settings#

The following dconf setting affect the radar function:

Setting Usage
radar-list-max-altitude Maximum altitude (metres) to show targets in the radar list view; targets higher than this value will show only in the map view. Setting to 0 disables. Note that ADS-B altitudes are AMSL (or geoid) and SBS-1 altitudes are "Flight Level" (standard atmosphere).
radar-alert-altitude Target altitude (metres) below which ADS-B / SBS-1 proximity alerts may be generated. Requires that 'radar-alert-range' is also set (none zero). Setting to 0 disables. Note that the above altitude datum.
radar-alert-range Target range (metres) below which ADS-B / SBS-1 proximity alerts may be generated. Requires that 'radar-alert-altitude' is also set (none zero). Setting to 0 disables.

Note that proximity alerts require that both the radar-alert-altitude and radar-alert-range values are set, and that there is a planned or actual home location.

Usage#

Once the radar interface is open, radar tracks are displayed on the map and in a list available from the "View -> Radar View' menu option.

  • The list view is sort-able on the Id, Status, Last (time) and Range columns.
  • The map visualisation may be toggled by the Hide Tracks (Show Tracks) button.
  • List and map views are updated in (near) real time.
  • Preference for display units are used for positions, altitude and speed.

Name#

Type Usage
INAV-radar Node Id (typically 'A' - 'D')
Traffic Report Callsign if reported, otherwise [ICAO number]
SBS-1 Callsign if reported, otherwise [Mode S hexadecimal code]
Telemetry User defined for automatically allocated, prefixed by TTRK-

Status#

Radar contacts have one of the following status values:

Status Explanation
Undefined ADS-B: Not shown in list or on the map, INAV-Radar not armed / updated
Stale The last contact was more that 120s previous. Displayed in the list and shown on the map with reduced intensity or an INAV-radar node has 'lost' status
Armed An active INAV-radar contact
ADS-B A live MAVLink Traffic report
SBS SBS-1 report
Hidden A MAVLink Traffic /SBS-1 contact is between 5 and 10 minutes old. It remains in the list but is not displayed in the map. MAVLink Traffic Report / SBS-1 tracks are removed from the list (and internal storage) after 10 minutes inactivity. INAV-radar ground station. Stale / 'Lost' INAV-radar contacts do not expire, as they may relate to a lost model.

The number displayed after the status text is:

Type Usage
INAV-radar The link quality
Traffic Report Time since last communication in seconds
SBS-1 Always 0

Columns#

The columns are sortable. Note that since the introduction of Telemetry Tracking, a new column "*" has been added, this contains a single character indicating the source:

Indicator Source
A ADS-B via MAVLink
I INAV Radar
S ADS-B via SBS
T Telemetry Tracker

Telemetry Tracker

Examples#

  • Proximity Alerts
  • Live and stale aircraft
  • Aircraft tooltip
  • Mission Plan
  • List view

Live ADS-B and simulated INAV targets, with proximity alerts (range < 3000m).#

radar-alerts

Local manned aircraft view over Florida (May 2020).#

Florida-may-2020

Simulated INAV radar view#

inav-radar-sim

Simulators#

There are simulators for both INAV-radar and MAVLink 'Traffic Report' (e.g. uAvionix PingRX) in the mwptools/src/samples/radar directory.

There is a replay tool for SBS-1 logs mwptools/src/samples/sbs-test/sbs-player.rb.

Changing the Radar Symbols#

Any map symbol used by mwp can be changed by the user; in the image above, the INAV radar node symbol has been changed from the default stylised INAV multirotor to a smaller version of the mission replay "paper plane" symbol as described in creating your own icon.

Protocol documentation#

The MAVLink implementation is comprehensively documented by the vendor.

INAV radar#

The following is required by a device wishing to act as a ground node (it either masquerades as an INAV FC, or declares itself a GCS)

  • Receive and respond to the following MSP data requests:
    • MSP_FC_VARIANT (responding as INAV or (from 2021/05/06) GCS for generic ground control stations).
    • MSP_FC_VERSION (in INAV and GCS modes)
    • MSP_NAME (in INAV and GCS modes)
    • MSP_STATUS (in INAV mode)
    • MSP_ANALOG (in INAV mode)
    • MSP_BOXIDS (in INAV mode)
    • MSP_RAW_GPS (in INAV mode)
  • Receive unsolicited
    • MSP2_COMMON_SET_RADAR_POS

Note that the device firmware assumes that MSP buffer sizes are "as specification"; exceeding the expected message buffer size may crash the device (mea culpa).

In GCS mode, the node is passive; it does not use a LoRa slot and does not attempt to broadcast a location. In INAV mode, the node takes up a LoRa slot and is expected to reply to the additional MSP queries.

mwp's behaviour is defined by the GCS Location

  • If the GCS Location is defined (when the radar device is initialised, then mwp will respond as INAV and return the GCS Location, which may be driven by gpsd if required.
  • Otherwise, mwp will respond as a passive GCS.

SBS-1#

Protocol description.