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Datalink Analysis System

Overview of ATN Datalink Analysis System

  • The ATN Datalink Analysis System consists of an ATN Data Recorder and Analysis Software which runs on a PC.
  • The ATN Data Recorder is responsible for recording inputs/outputs to/from a CMU. It is intended to be used either while in service or while the CMU is under test at an industry test facility (for instance ARINC or SITA). The ATN Data Recorder may also be used in a typical engineering lab environment on a regular basis as a means to ensure that problems noticed in the engineering lab can be reproduced at a later point in time.
  • The Analysis Software runs on a PC and is enabled by a USB Dongle. A USB Dongle and a copy of the analysis software accompanies each unit purchased. Additional USB Dongles can be purchased to run the Analysis Software on multiple PCs if desired.
  • The user is provided with the ability to view all protocol layers (ATN Stack, AVLC, ACARS, etc.) in a human readable format. This information can be viewed on the ATN Data Recorder itself, or it can be viewed via the Analysis Software after recorded data has been downloaded to a USB thumb drive from the ATN Data Recorder.

ATN Data Recorder Component

  • The ATN Data Recorder is intended to record all communication between a CMU and the VHF Radio(s).
  • Its reception/transmission communication paths are limited as follows: One Ethernet Port for those CMUs communicating (or having listening methods) over Ethernet. 4 ARINC 429 Receivers. 2 ARINC 429 Transmitters (used in test mode only) Two full duplex RS422 ports. One USB Port for downloading recordings.
  • The ATN Data Recorder requires input from an accurate time source. Ideally this would be from a GPS Receiver, but an FMS or Chronometer is a less desirable substitute.
  • The ATN Data Recorder is equipped with 32 Gigabytes of storage capacity. Data on the unit can be manually erased. If not manually erased, 10% of the oldest recordings are automatically erased when storage capacity on the unit reaches 80%.
  • All 429 receivers on the ATN Data Recorder have lightning protection circuitry.
  • The ATN Data Recorder can be configured uniquely for a given CMU and can operate in the cockpit or the EE-bay, depending on availability of a connection between the Data Recorder and the CMU. However, the unit has Function Keys which are useful for tagging events that can only be operated in a cockpit installation.
  • Transfer of information from the Data Recorder is accomplished by inserting a thumb drive (32 Gigabyte or higher capacity) into the unit. Various commands are made available to isolate the data to be transferred the thumb drive, including specification of a time frame and flight leg.
  • Data files are separated in internal storage based on flight id, origin/destination, and potentially other configurable items defined in the Data Recorder Configuration File.
  • Unique Data Recorder Configuration Files may be loaded via a thumb drive by plugging it into the USB port with a properly named file.
  • The ATN Data Recorder has the following 6 function keys:
  • Function Key 1:Event Key. Depressing this key time stamps an event. Once pressed, the operator is provided with a text window allowing a brief explanation of the event.
  • Function Key 2:Pause Key. Pauses message scrolling on the screen, allowing the operator to navigate up and down a page at a time via the page keys (Function Key 3 and Function Key 4) or to navigate by using a finger on the touch screen. This allows the operator the capability of isolating a given message of interest and expanding its content in real time for inspection.
  • Function Key 3:Page Up key, active only after the pause key has been struck.
  • Function Key 4:Page Down Key, active only after the pause key has been struck.
  • Function Key 5:Switches Display to Scripted Test CMU Mode allowing scripting or manual generation of ATN test messages.
  • Function Key 6:Power Switch. Depressing this key for 10 seconds powers the unit down.

Analysis Software Component

  • The Analysis Software provides a means to perform manual analysis of data recorded by the ATN Data Recorder. All recorded information can be displayed in human readable format.
  • Review of recorded data allows an engineer to quickly determine the probable cause of an anomaly. The following are some important connections that can be reviewed and analyzed:
  • VDR <--> CMU communication (ARINC 750), particularly related to VHF Uplinks/Downlinks.
  • GPS -> Consumption of broadcast data which can provide a time source, location, etc.
  • FMS -> Consumption of broadcast data, similar to GPS.
  • Etc.
  • Data pertaining to specific messages from/to a given LRU are presented in human readable format (this includes 429 labels broadcast from LRUs such a GPS or FMS). Configuration files define aircraft specific label content for broadcast data.
  • Images on the following slides provide examples of typical operation of the tool, in the context of VDR<->CMU communication.

The Scriptable Test CMU Option

  • Optional functionality can be enabled on the ATN Data Recorder so that it may serve as a Scriptable Test CMU.
  • In such a mode, the recorder sends ATN messages at specified locations, altitude, time, frequencies, etc. as well as obeying ARINC 631 for multi-frequency operation. It responds to the messages from the ground in a pre-programmed way.
  • Operating in this mode may prove useful when attempting to reproduce failure scenarios. Data such as; frequency, position, altitude, transmit messages, timing between messages, etc. might be important factors in successfully reproducing a previous failure.
  • In order to operate in this mode, the recorder be wired to an ARINC 750 radio.


Nominal Operating Voltage 28V DC
Voltage Operation Range 12V DC -> 30V DC
Power Consumption Less than 4W


Weight 1.3 lbs./0.59 kg
Case EML and water tight


Width Height
Top 5.834" 2.130"
Bottom 5.834" 2.130"
Front 5.825" 4.500"
Rear 5.825" 4.495"
Left 2.130" 4.504"
Right 2.130" 4.504"

"When performance is lacking, go with the alternative: Software Development Alternatives"
David W. Dodson, President and CEO, SDA Inc.