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SPx Server (Tracking & Distribution)

Products » Tracking, Fusion & Distribution » SPx Server (Tracking & Distribution)

Radar Target Tracking

An advanced radar distribution, target extraction and tracking server application.

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SPx Server (Tracking & Distribution)
SPx Server (Tracking & Distribution)

Video and Track Distribution

Supports network distribution of radar video and track reports to remote clients in SPx, ASTERIX or NMEA-0183 formats.

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Key Features

The software is highly configurable and may be used to identify target-like shapes according to defined rules.

High Performance Multi-Hypothesis Tracker

The SPx Tracker uses multi-hypothesis association. As measurements from radars are imperfect, the ability to simultaneously consider multiple interpretations offers significant improvements in performance over simpler single-hypothesis trackers.

Configurable Target Extraction Parameters

The behaviour of the tracker may be configured through a set of tracking parameters that control many aspects of the tracker's performance, including min/max speed of target, multi/single hypothesis association, fixed/adaptive gain and more.

Secondary Surveillance Radar Extraction

SPx Server supports target tracking from secondary surveillance radar (SSR) transponder video, including decoding of the interrogation mode information. If the SSR/IFF transponder video is sampled with sufficient resolution, codes from interleaved mode 1, 2, 3/A and C responses can be extracted. This information then forms part of the plot and is passed onto the tracker to assist with tracking.

Integrated Radar Processing

The SPx Tracker incorporates radar processing modules for pre-processing video prior to plot extraction and target tracking. User-defined processing can be accommodated with plug-in modules.

Comprehensive User-interface for Configuration

A full range of display tools are provided, including a browser interface, for visualisation of radar video, plots and tracks, for configuration of the processing prior to deployment and monitoring during operation.

SPx Server (Tracking & Distribution)

SPx Server (Tracking & Distribution) Details

Extra Info

Host Systems

SPx Server is application software, designed to run on standard Intel PC or SBC hardware.

The software is simple to install and the following minimum specificiation is suggested:

  • Intel Core i5 or better CPU
  • 8GB or more of RAM
  • Windows 10 or 11 / Linux (mainstream distribution such as Red Hat, CentOS, Fedora and Ubuntu) less than 2 years old

Target Extraction

The SPx Extraction process examines the processed video to search for target-like returns that form a connected target-like shape. A set of configurable parameters define the target size of interest, allowing small noise returns or larger clutter or land masses to be eliminated early in the processing.

The extraction process begins by creating a set of spans that represent intervals of video above a threshold for each processed return. These spans are then combined across returns to form connected two-dimensional shapes. The weighted centre of gravity, bounding box and total weight of the plot shape are calculated and entered into a plot database, along with a timestamp. At this stage of the processing, no merging occurs of close plots that are likely to be derived from the same target. This allows partial plots to be reported on the network, if desired, and allows the tracking process to consider the merits of merging in the context of the local tracks.

Secondary Surveillance Radar Extraction

Interrogation mode tags may be embedded at the start of the IFF video stream as P1/P3 pulses or a specific mode specified, telling SPx Server which responses to expect. The processing includes de-FRUITING and de-garbling to remove typical noise from an IFF video.

The IFF video handling capabilities provide a viable, highly cost-effective alternative to traditional hardware-based IFF decoding systems.

Track Creation

The tracker maintains an active track database, updated with new plot data from the data extraction stage. New tracks are added automatically or from a manual request (operator input or external process).

The automatic track creation occurs when plots entered into the database are uncorrelated, or ungated, with any existing known target. A new preliminary track is created and is updated with future detections until confidence is established that the track is likely to be a target of interest.

The time a track is held in the preliminary stage is a programmable option and needs to be set to balance the speed of detection with the likelihood of a false alarm. In a low clutter environment, where extracted plots are likely derived from real targets, the acquisition time may be as short as 2 detections. For noisy situations, where the plot extractor is reporting false detections, the integration time in the preliminary stage may be extended.

Model Based Tracking (MBT)

The MBT extensions to SPx Server (V1.72 onwards) can handle a larger number of provisional tracks than the standard MHT's initiation process. This allows specific target models to be created, meaning that different parameter configurations can process the same radar video. The ability to detect small targets and support multiple tracking modules may offer new opportunities for tracking. Click here for further details on the MBT extensions.

Track Filter

For each hypothesis, the tracker updates the current estimated position with the new measurement. If the measurement were known to be completely accurate, the update process would believe the measurement and the new estimate would be exactly the measured value. For various reasons, the measurement is inaccurate so the update process must take a weighted combination of the expected position and the measured position. This is the track filtering. SPx offers a number of track filtering modes. The simplest mode uses fixed gains in the components of the measurement. This can be successful for tracking applications where the target is clearly identified and relatively clutter free.

The filter works by computing a dynamic filter gain, K, based on estimated system noise and measurement noise models. The system noise is used to model uncertainty in the known dynamics of the target, including its ability to manoeuvre. As system noise increases, or equivalently as measurement noise decreases, the filter places more weight on the measurement so the filter gains increase. As system noise decreases or as measurement noise increases, the filter gains decreases causing less emphasis to be placed on the new measurement. The filter gains are continually changing and provide, under certain assumptions of the noise characteristics and linearity, an optimal estimation of the true target position.

Tracking Parameters

The tracking behaviour parameters may be set initially from a configuration file and may be adjusted during operation of the tracker using either a customer GUI or network interface. Parameters include:

  • Min/max speed of target to be tracked
  • Multi or single hypothesis association modes
  • Fixed gain or adaptive gain
  • Expected target dynamics
  • Size limitations on targets to be tracked
  • Measurement noise estimates

Redundant Operation

Dual instances can be run simultaneously to provide redundant operation for high reliability systems, with the secondary instance automatically taking over if the first instance fails, providing an uninterrupted stream of radar and target track data.

Additionally, SPx Fusion Server can support redundant operation, providing a consistent set of track IDs to clients in the event of failover, and SPx Monitor provides monitoring and diagnostics, showing which instance is active and automatically restarting applications that have stopped.


New Features Added

Web Interface for control and graphical monitoring

In-built AIS association

Doppler Video support

Sidelobe suppression

ARM support

  • Multi-function primary and secondary (IFF) radar processor
  • Radar video from HPx cards or network
  • Radar processing
    • Filtering
    • CFAR Thresholding
    • Area-based video filtering/masking
    • Clutter map generation
  • Plot Extraction and merging
  • AIS track display and recording
  • Multi-hypothesis target tracking
  • Model-based tracking extension
  • Fully configurable tracking
  • Area-dependent tracking parameters
  • Full auto track initiation
  • Redundant operation, with automatic failover
  • Built-in world coastline database
  • Static or moving platform
  • NMEA navigation input for ship systems
  • Radar network distribution
  • Radar, NMEA and AIS record/replay
  • Comprehensive configuration GUI
  • Windows or Linux versions
  • Network remote control
  • Receipt and tracking from plot data
  • Receipt and distribution of lidar data
  • Video, plot and track output to network
  • Fully configurable for:
    • Vessel traffic systems (VTS)
    • Surface movement radars
    • Air defence
    • Security (personnel, vehicles etc.)
    • Military naval
SPx Server Brochure
SPx Server Datasheet
Cambridge Pixel Product Summary Brochure
New MBT Extensions to SPx Server App Note
Tracking from Video in SPx Server App Note
Radar Solution
SPx Server
Radar Solution
SPx Server

System Requirements

Processor: X86 architecture
Recommended processor is Intel Core i5 or higher. Minimum 4GB system memory recommended.
Operating System: Windows 10 or 11
Linux (Fedora, Ubuntu, RHEL)
For other operating systems consult factory
Graphics: Requires 1024 x 768 graphics display or higher for maintenance and configuration. Recommended PCIe or XMC graphics card. GUI is not needed for operational system.
Disk: Disk storage is optional for radar video recording.
Network: 100 Mbit or 1 Gbit Ethernet adaptor recommended.
Expansion Slot: PCI, PCIe or PMC expansion slot required if using a HPx radar interface cards. Refer to the user manual for these cards for full details.

Software Licensing

Licensed Functions: Radar video distribution
Plot extraction
Target extraction
Record and Replay
Moving platform
Licence Protection Method: USB Dongle
MAC-address licence file
(other schemes are possible, consult factory for details)

Radar Interface

Radar Input: Hardware interface card: HPx200/200e/250/400e/346
Network input from supported radar types
Radar Trigger: PRF: up to 10kHz with HPx cards
Amplitude: Up to 30V. Single-ended (opto-coupled) or differential (RS422)
Impedance: 75R or high impedance
Radar Video: Amplitude: 5V (positive or negative)
Impedance: 75R or high impedance
Azimuth - ACP/ARP: Single ended signal up to 30V or differential RS422

ACP count: 60, 180, 300, 360, 1024, 2048, 4096, 8192, 16384 pulses per ARP.
Software automatically detects ACP count.
ACP Interpolation supported for low counts.

ARP: 1 pulse per scan

Rotation rate: up to 240rpm
Azimuth - Parallel: 12 bit RS422 differential azimuth value with data strobe
Azimuth - Synchro/Resolver: 115V reference voltage, 90V synchro (3 wire) or resolver (4 wire) input. Reference voltage is standard 115V input. (Other synchro voltages on request)
Note: Synchro/resolver input requires use of HPx-180 synchro/resolver to parallel converter PCI card.
Plot Inputs: Option to receive plot data from proprietary radars. Consult factory for details.

Navigation Information

Platform Navigation: NMEA-0183 input
GPRMC, GPHDT, GPHDM sentences used, interpreted by server.
Physical Interface: Standard serial port on PC or single board computer
Network input (uses NMEA-0183 sentences in network packets)
Navigation Reporting: Optional network distribution of NMEA sentences received on serial port
Programmable IP and port address for output
North Offset Adjustment: Incoming azimuths may be ship or North referenced, with automatic conversion to North referenced from navigation data, as required.


Video Processing with HPx Radar Interface cards

Video Bandwidth: 25 MHz
(When used with HPx-200, HPx-200e or HPx-250 radar interface cards)
A-to-D Conversion: Programmable 2 to 50 MHz sampling rate. 12-bit high-performance capture.
Data is reduced to 8-bits through a programmable LUT.
Threshold Detection: Adaptive threshold CFAR technique with geographical area thresholding
Clutter Processing: Software-based scan-to-scan correlation
Clutter subtraction
Land mass blanking


Land Mask: Static mask: complex polygon of any shape or size, optionally containing holes.
World vector shoreline: land masking using built-in database of world shoreline data (static or moving platforms supported).
Polygon set is defined in world x,y coordinates and is automatically converted into polar space. Typical azimuth resolution is 0.18 degree and range resolution matches input data resolution.
Area Dependent Processing: Tracker parameters can be assigned different values in different areas (static platforms only).
Polygon set is defined in world x,y coordinates and is automatically converted into polar space. Typical azimuth resolution is 0.18 degree and range resolution matches input data resolution.
Automatic Initiation Areas (ATI): Static mask. Complex polygons defined in x,y coordinates. Can be any shape or size.
Independent areas can be configured for radar processing, track initiation and tracking.
Optional automatic suppression of plots over land areas using world vector shoreline database (supplied as standard).
Plot Extraction: Configurable plot geometry (min/max range and azimuth)
Optional plot merging (multiple modes)

Digital Video Distribution

Network Distribution: Distribution onto LAN of radar video data in polar format
Compression: ZLIB or ORC (Open Radar Coding)
Data Rates: Highly dependent on input data and configured resolution.
Typical figures from 2 Mbits/sec for processed video to 10 Mbits/sec.
Network Protocol: UDP - Unicast or Multicast distribution
Video Store for Distribution: Raw input data
Processed data
Clutter map
(One of above with standard server. Multiple channels of distribution are supported with customised server variants, including options for multi-resolution data)

Target Tracking

Maximum number of targets: 500 (typical, but not limited by software)
Track Initiation: Automatic, with programmable extraction areas defined as polygons or range-azimuth segments (static radar only)
Automatic wake area elimination (configurable geometry)
Shadow area elimination from known targets
Manual track initiation from remote system
Configurable min/max initiation speeds, which may be area dependent
Max initiation speed: 1000 m/s
Minimum initiation range at maximum speed:

10NM for targets moving tangential to radar
3 NM for targets moving radially towards or away from radar
Programmable initiation time from 2 scans upwards using M:N or SPRT integrator. Initiation criteria may be area dependent.
Signal to Clutter: Typically 8 dB or higher expected
Target Speeds: Programmable minimum and maximum target speed for initiation in the range 0 to 1000 m/s
Programmable minimum and maximum target speed for tracking in the range 0 to 1000 m/s
Tracking Performance: Figures are highly dependent on sensor, operating conditions and configuration data.
Sample configuration - sea state 1, 100m2 RCS target:
For radar range 200NM, target at 100 NM
  • Position accuracy: σ = 90m
  • Range accuracy: σ = 90m
  • Azimuth accuracy: σ = 10 secs arc
  • Speed accuracy: σ = 5% of true speed for speeds above 5 m/s, σ = 10% of true speed for speeds below 5 m/s
  • Course accuracy: σ = 1 degree
For radar range 70NM, target at 35NM
  • Position accuracy: σ = 25m
  • Range accuracy: σ = 25m
  • Azimuth accuracy: σ = 10 secs arc
  • Speed accuracy: as above
  • Course accuracy: as above
For radar range 35NM, target at 18NM
  • Position accuracy: σ = 20m
  • Range accuracy: σ = 20m
  • Azimuth accuracy: σ = 10 secs arc
  • Speed accuracy: as above
  • Course accuracy: as above
Notes: Performance figures are typical, but depend on exact characteristics of radar and target. Target assumed to be moving in straight line. If server is applying North offset compensation, timely updates of ship's heading are critical for good tracking performance. Quoted values of σ are standard deviations of errors.
User Manual

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Real-World Application

Thales used SPx Server in Royal Navy Minehunter Combat Management System Upgrades, to supply the Thales TACTICOS CMS system with ASTERIX CAT-240 format radar video and NMEA format target track data.