Air Traffic Management Testing Solutions for ED-137 and ED-138 Standards

Welcome to GL's latest newsletter, where we discuss our Air Traffic Management (ATM) testing solutions for Analog, TDM, Ethernet, and IP communications networks. Our solutions are adaptable to global standards, making them versatile for various needs.

Air Traffic Management


GL offers innovative solutions for testing next-generation ATM networks. This includes the ability to emulate and load test equipment such as Controller Working Positions (CWP), Ground Radio Stations (GRS), Analog-to-IP converters, Gateways, and more. Components can be accurately evaluated for timing, performance, and functionalities.

The GL test tools for next-generation ATM adhere to the ED-137 standards, providing signaling and traffic emulation. They also monitor the quality of service as per ED-138 and offer call quality statistics such as MOS (Mean Opinion Score), Packet loss, Jitter, Latency and more.

The Timing Measurements within the Air Traffic Management test suite can precisely measure signal, voice delay and voice quality (PESQ/POLQA scores) across the device or ATM network.

GL’s ED-137 and ED-138 Voice over IP Test Tools have been widely welcomed by global Air Navigation Service providers and Voice Communications System (VCS)/Radio/Recorder/Gateway companies. These tools have been recognized as essential during development, functionality testing, performance testing, factory acceptance testing, deployment, and field testing.

Critical Delay Measurements

Measuring delays in hybrid ATM networks is crucial to ensuring clear and quick communication between air traffic controllers and pilots. Recognizing, capturing, timestamping, and correlating events at Analog, TDM, and IP interfaces are essential steps. Conducting repeated delay measurements ensures that the device and network under test perform consistently over time.

GL ‘s Timing Measurements in Air Traffic Management (TM-ATM) test suite precisely emulates endpoints in ATM networks and measures delay for various occurrences in signaling and voice transmission. The suite encompasses all necessary hardware deployed across the Air Traffic Management network and software designed to identify, capture, timestamp, and correlate events at Analog, TDM, and IP interfaces.

This TM-ATM solution is based on GL’s Message Automation and Protocol Simulation (MAPS™) software program. MAPS™ emulates a wide range of telecom protocols, including ED-137 Radio, Telephone, and Recorder. The MAPS™ program runs on the Windows® operating system and utilizes the PC’s network interface card to send and receive traffic.

Key features:

  • Delay measurements for:
    • Push To Talk (PTT), PTT confirmation, PTT release, PTT release confirmation
    • Squelch On/Off
    • End-to-end voice delay for PTT, and Squelch
    • Main/Standby Tx/Rx transfer
    • Main/Standby Tx/Rx transfer confirmation
    • Remote Receiver Mute/ Unmute
    • Remote Receiver Mute/Unmute confirmation
  • Supports for end-to-end voice quality measurement using industry standard ITU algorithms (PESQ and POLQA)
  • Measure consistency and reliability by doing multiple iterations
  • Load test the network to achieve the required Peak Busy Hour and Peak Busy Minute loads
  • Centralized control and reporting of the tests
  • Ability to interface with Analog, TDM and IP based systems
  • Customize test suite to measure delay and voice quality between Analog and IP networks
  • Automated tests to run multiple iterations for accuracy and consistency
  • Timing accuracy using different clock sources - Local clock, GPS, Master, and Slave
  • Supports audio/tone transmission and recording/tone detection
  • Up to 32 hardware-based filters for wirespeed filtering
  • Supports voice detection in IP packets and voice delay calculation
  • Measured delays for every iteration are logged to CSV file
  • Display live measurement and load statistics
  • Test results can be exported to PDF file

Solutions for Air Traffic Management

GL’s solutions include rack-mounted and portable hardware equipment deployed across the Air Traffic Management network.

  • Central Administrative System:
    • Controls all the components of TM-ATM test suite and runs the tests to perform measurements
    • Calculates the time difference between posted events and reports the precise one-way delay at different points in the network
  • ED-137 Radio Emulator:
    • Emulates Air-Ground calls (as per ED-137), and multiple CWPs or GRSs
    • Can emulate PTT/Squelch, send and record audio to perform end-to-end voice delay and quality measurement
    • Emulates all radio events such as Main/Standby Tx Rx switching, Mute/Unmute Receiver etc.
  • Packet Filter System:
    • Deployed in-line on an Ethernet network
    • Provides 32 hardware filters to filter and timestamp the packets of interest at wirespeed
    • Packet filtering can be based on Layer 2 (Ethernet), Layer 3 (IP), and Layer 4 (UDP/TCP) headers
    • Can generate TTL triggers (1 Microsecond pulse) for each filter passed
  • Analog VCS/Radio Emulator:
    • Emulates PTT/Squelch and Audio; generates TTL triggers based on PTT On, PTT Off, Audio Start and Audio Detect (On or Off)
    • Inject and record analog signals at the VCS and Radio
  • Event Decoder:
    • Receives filtered packets from Packet Filter System and Control Signal Detector with timestamping
    • Processes received packets, sends notifications to the Controller Administrative System
    • Detects audio in RTP packets to identify the beginning of voice in the stream
  • Control Signal Detector:
    • Monitors IO channels of the Sensoray for low-to-high and high-to-low transitions
    • Used to filter and forward desired events/frames
    • Monitors TTL output from the Analog Radio Controller and Packet Filter System and generates a corresponding IP packet to send to the Event Decoder
  • Voice Quality Testing Software:
    • Performs end-to-end voice quality assessment using industry standard ITU algorithms (PESQ and POLQA) across the ATM network

Air Traffic Management Network

Below is a typical Air Traffic Management network showing the role of emulators and analyzers. GL emulates air-to-ground, ground-to-ground, and recorder interfaces as per ED-137 standards. All IP traffic can be monitored using the IP analyzer - PacketScan™ and analyzed either locally or remotely using web based - NetSurveyorWeb™ applications.

Air Traffic Management Network

The sections below provide a brief discussion of GL’s emulators and analyzers used for testing VoIP-based ATM networks and equipment.

MAPS™ ED137 Radio emulates air-to-ground calls by simulating either CWP or GRS. The ED-137 Radio emulator supports both versions B and C of ED-137 Volume 1 Radio. Hundreds of CWPs or Radios can be emulated, generating bulk Air-to-Ground calls using a single instance/license. It can be used to test the functionality and performance of CWP, GRS, and Radio Gateways. The ED-137 Radio emulator is validated against VOTER versions and volumes for GRS and VCS Radio ED137/1C compliance. The application has adopted ED-137/1C Change 1 and Change 2. Supports IPv6 addressing.

MAPS™ ED137 Telephone emulates ground-to-ground calls by simulating a CWP. It supports both versions B and C of ED-137 Volume 2 Telephone. Hundreds of CWPs can be emulated, generating bulk ground-to-ground calls using a single instance/license. It can be used to test the functionality and performance of CWP and is validated against VOTER_4.1.33.3 for VCS-Telephony-Interface-Test cases. The application has adopted ED-137/2C Change 1 and supports IPv6 addressing.

MAPS™ ED137 Recorder emulates the recorder interface at CWP, GRS and Recorder server as per version B and C of ED-137 Volume 4 Recorder. It can be configured as either a CWP, GRS, or Recorder to emulate the recorder interface at that node. Hundreds of CWP/GRS/Recorders can be configured to emulate bulk recording sessions. The application has adopted ED-137/4C Change 1 and supports IPv6 addressing.

PacketScan™ is a protocol analysis software (as per ED-138) that captures Air-to-Ground and Ground-to-Ground calls in the ATM network. The application can capture, segregate, monitor, and collect statistics such as packet loss, delay, jitter, and MOS on all the captured calls. It can also act as a probe in the network, sending Call Detailed Records to a centralized database to facilitate centralized monitoring of the probes/network.

NetSurveyorWeb™ is a web-based dashboard for centralized monitoring of ATM network. Users can navigate through real-time and historical records, filter VoIP traffic, and graphically analyze calls, generate reports to view the MOS, Packet Loss, Failed Calls, Post Dial Delay, and more. Users also have the ability to generate alarms and receive email notifications to report configured failures in the network.

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