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Datalink Communications

The AH-64D utilizes a secure, modem-based datalink (SMDL) to send and receive targeting data, tactical reports, text messages, and mission files amongst other AH-64D’s within the team. The modem traffic is relayed as discreet microbursts of data across the helicopters’ radios, which allows multiple datalink networks to be tuned simultaneously; one network across each radio.

As envisioned for use on the modern battlefield, AH-64D teams are employed as tactical maneuver units in a combined arms scenario alongside friendly infantry, armor, and artillery echelons. In such scenarios, communications are not only critical to the success of the mission but are also multi-tiered to coordinate with the various other air and ground forces operating in the same area of operations. This can impose significant command and control challenges on unit commanders when coordinating the movements and actions of large formations of attack helicopters; the challenges of which are exacerbated when performed by aircrews that are simultaneously operating at extremely low altitudes, especially at night.

These challenges in command and control can be mitigated by employing semi-automated and direct exchanges of data between AH-64D team members to reduce voice traffic and increase the efficiency of distributing tactical information. Several tactical report formats are available to AH-64D aircrews in exchanging targeting data, fires distribution, battle damage assessments, position updates, and status of onboard fuel and munitions. In addition, individual points or entire mission files may be transmitted across the datalink to synchronize information displayed on the TSD of each AH-64D as battlefield conditions evolve or as changes in mission occur in real-time.

Datalink messages may be transmitted between AH-64D Team members and Primary members within a datalink network. Up to 16 aircraft may be present within a network, with 15 network members in each aircraft’s network list and the 16th aircraft being the ownship.

Team members. Team members receive text messages and mission files. These messages coordinate team actions and movements and distribute mission updates across the entire team of AH-64D’s on a datalink network.

Primary members. Primary members receive tactical reports, targeting data, fires distribution, and individual TSD points. These messages coordinate tactical actions of individual companies and platoons of AH-64D’s.

A datalink network consists of multiple AH-64D network members transmitting and receiving data messages between each aircraft by assigning unique identification numbers within each data message, one for the message originator and one for the message subscriber.

When a data message is transmitted across the radio frequency that all network members are tuned, the modems onboard each aircraft receive the data message and compare the message’s subscriber ID(s) with those that are assigned to their aircraft. If the subscriber ID within the message matches their ownship ID number, the modem stores the message within the modem buffer and notifies the crew via advisories on the EUFD. The originator ID within the message is correlated with the matching ID number of a network member and the corresponding callsign of the sender is displayed to the crew receiving the message. If the subscriber ID within the message does not match their ownship ID number, the modem rejects the message without crewmember interaction.

Datalink network between members of “Darkhorse” company

Each network may consist of 16 network members, containing 15 subscribers in addition to the ownship. Any of the 15 subscribers may be set as a Team member, a Primary member, or both; however, a maximum of 7 subscribers within each network may be designated as a Primary member. The designation of a subscriber as Team or Primary determines the type of data messages the member may receive from the ownship.

Team Messages (COM page)

Command and control, and mission updates.

  • TEXT Text messages
  • CURRENT MISSION Mission files residing in
    the aircraft memory
  • MISSION 1 Mission 1 files residing on the DTC
  • MISSION 2 Mission 2 files residing on the DTC
    (Data Transfer Cartridge)

Primary Messages (TSD and FCR pages)

Targeting, fire control, and status reports.

  • BDA Battle Damage Assessment reports
  • TGT FCR Target reports
  • PP Present Position reports
  • FARM Fuel/Ammo/Rockets/Missiles reports
  • PFZ/NFZ Priority Fire Zones/No Fire Zones
  • POINT Individual TSD Point transmissions
  • RFHO FCR RF Target Handover

The designation of network subscribers as Team or Primary members are uniquely defined by each individual network member, and only affect outgoing data messages from the ownship. For example, the aircrew in DH06 may designate each of the remaining three aircraft as Team members within their cockpit for sending text messages to the entire flight platoon, but each of the other three aircrews may have designated DH06 as the sole Team member within each of their respective cockpits for sending text messages back to the flight leader.

Each Preset on the COM page may be configured with independent network and modem settings, to include unique frequencies, network subscribers, and Team and Primary designations. If a preset has been configured for network protocols, the network associated with that preset will be designated by a letter indicating the type of protocol, and a number corresponding with the preset number. Only presets 1 through 8 may be configured with DATALINK protocol on the MODEM sub-page, which is indicated by an “L” on the COM page and EUFD.

In the example below, Presets 1, 2, and 3 have been configured for DATALINK protocol, and the networks associated with each preset have been configured with unique lists of network subscribers on the NET sub-page. Preset 1 includes each aircraft within the entire flight platoon, while Presets 2 and 3 only include subscribers from each individual Air Weapons Team (AWT) within the flight platoon; Red Team and White Team.

Network configurations for Presets 1, 2, and 3

Since each preset can include a unique network configuration, and a different preset may be tuned to each radio, it is possible to simultaneously tune different datalink networks for each echelon within the entire flight platoon, with datalink messages being transmitted across the appropriate frequency for the echelon to which it pertains.

In the example below, each aircrew can communicate and exchange datalink messages with the entire flight platoon using a common radio frequency and datalink network on the FM1 radio. However, Red Team and White Team are using their FM2 radios to communicate and exchange datalink messages within their respective AWT’s; with each AWT utilizing a separate radio frequency and datalink network.

Datalink structure across two Air Weapons Teams (AWT) within a single flight platoon

The AH-64D’s datalink modem utilizes the same radio equipment that is used for voice communications to relay data between other aircraft within the AH-64D team. As such, datalink networks are tuned in the same manner as tuning a radio to a communications preset. However, unlike voice transmissions, the datalink can only function when a radio has been tuned to a preset, which allows the modem to send and receive datalink messages across the network associated with that preset. If a radio is manually tuned to a frequency, datalink messages cannot be transmitted or received across that radio, even if tuned to the same frequency of an existing datalink network.

EUFD Controls

The Enhanced Up-Front Display (EUFD) provides the aircrew with a consolidated location for viewing the current configuration and datalink settings of each radio. The modem can receive datalink messages from the VHF, UHF, FM1, and FM2 radios simultaneously, but each crewmember may only transmit datalink messages across a single radio at any given time.

The radio through which each crewmember transmits datalink messages is independent from the radio the crewmember has selected for voice transmissions. The Datalink Transmit Select rocker is used to select a radio for datalink transmissions while the Radio Transmit Select rocker is used to select a radio for voice transmissions. In the example below, the current crewstation is configured to transmit voice over the VHF radio and datalink over the FM2 radio. The opposite crewstation is configured to transmit voice over the UHF radio and datalink over the FM1 radio.

Radio Status Area

The Primary Network List displays which radios are configured to transmit and receive datalink messages, and to which datalink network the radio has been tuned. In the example above, the modem is monitoring the FM1 radio for datalink messages from the network associated with Preset 1 and monitoring the FM2 radio for datalink messages from the network associated with Preset 2.

The Standby Network List displays which datalink networks are associated with the radio presets residing in the standby slots for each radio. When considering the standby slots of each radio, the number of networks that may be readily accessible at any given time is as follows:

  • 8 datalink networks (two for each radio) may be loaded into the VHF, UHF, FM1, and FM2 radios.
  • 4 datalink networks (one for each radio) may be tuned and monitored for data communications.
  • 2 datalink networks (one for each crewmember) may be selected to transmit data communications, independently of the radios selected by each crewmember for transmitting voice communications.

If generator power is lost, crewmembers may still use the radios and the EUFD interface for voice communications while operating on battery power, but datalink communications will not be possible.

(See Enhanced Up-Front Display (EUFD) for more information.)

COM Originator Identification (ORIG ID) Sub-Page

The ORIG ID sub-page allows crewmembers to review or modify the ownship’s identification settings for sending and receiving traffic across the datalink network(s). The ownship’s ID settings may be individually edited from this page, or they may be replaced all at once using pre-planned network member data accessed through the Originator Directory (ORIG DIR) sub-page.

  1. DL sub-page. Displays the Datalink sub-page.

  2. Ownship Callsign. Activates the KU for inputting the originator callsign for the ownship. A minimum of 3 and a maximum of 5 alphanumeric characters may be entered.

    Note

    The originator callsign is for reference only and will not affect the function of the datalink networks.

  3. Datalink Originator ID. Activates the KU for inputting the originator identification (ID) number which identifies the ownship on the datalink network. The alphanumeric character ranges that are valid for entry are 0-39 (with no leading zeros), A-Z, 1A-1Z, 2A-2Z, and 3A-3I; for a total of 127 unique network ID numbers.

    Note

    Each network member, to include the ownship, must have a unique ID number. If two or more members on the same datalink network are assigned the same identification number, erroneous behavior may be observed when using the datalink, or when using functions within the cockpit that are associated with the datalink.

  4. Digital ID Select. Selects a page format for configuring digital ID settings for each type of protocol.

    • DATALINK/TACFIRE. Displays digital ID settings for DATALINK or TACFIRE protocols.
    • INTERNET. Not implemented.
    • FIRE SUPPORT. Not implemented.

  5. TACFIRE ID Settings. Not implemented.

  6. ORIG ID sub-page. Displays the Originator Directory sub-page.

  7. Ownship Status Window. Displays the current digital ID settings of the ownship.

  8. MSG sub-pages. Displays Message sub-pages for sending or receiving digital messages.

    • MSG – REC. Displays the Message Receive sub-page. If no messages are present on the receive list, this sub-page option will not be displayed.
    • MSG – SEND. Displays the Message Send sub-page.

COM Originator Directory (ORIG DIR) Sub-Page

The ORIG DIR sub-page allows crewmembers to set their ownship identification settings to a pre-planned network member entry. This directory facilitates efficient and rapid configuration of the ownship’s originator ID to correspond to a pre-planned network identification.

  1. Replace Ownship. Replaces the ownship’s digital ID settings with those of the directory member that has been selected for review.

  2. Directory Members. Selects a directory member for review within the Directory Member status window.

  3. Directory Member Status Window. Displays the callsign and digital ID settings of the selected directory member.

  4. Paging Controls. Cycles forward and back through multiple pages of the directory.

  5. Search Directory. Activates the KU for inputting alphanumeric characters to search for a specific member within the directory. Displayed members will be filtered accordingly based on the results.

COM Network (NET) Sub-Page

The NET sub-page allows crewmembers to review or modify the callsign and identification settings of each member within the datalink network of the selected preset. The callsign and subscriber ID settings for each network member may be manually edited from this page, or they may be replaced altogether using pre-planned network member data accessed through the Member Directory (MBR DIR) sub-page.

  1. SUFFIX sub-page. Not implemented.

  2. MEMBER EDIT. Displays options for editing the digital ID settings of the selected network member.

    • MEMBER EDIT – DEL. Deletes the network member from the preset.

    • MEMBER EDIT – TEAM. Designates the network member as a Team member. Any of the 15 members within a network may be designated as a Team member.

    • MEMBER EDIT – PRI. Designates the network member as a Primary member. No more than 7 members within a network may be designated as a Primary member.

    • MEMBER EDIT – C/S. Activates the KU for inputting the network callsign of the member. A minimum of 3 and a maximum of 5 alphanumeric characters may be entered.

    • MEMBER EDIT – SUB. Activates the KU for inputting the subscriber identification (ID) number, which identifies the member on the datalink network. The alphanumeric character ranges that are valid for entry are 0-39 (with no leading zeros), A-Z, 1A-1Z, 2A-2Z, and 3A-3I; for a total of 127 unique network ID numbers.

      Note

      Each network member, to include the ownship, must have a unique ID number. If two or more members on the same datalink network are assigned the same identification number, erroneous behavior may be observed when using the datalink, or when using functions within the cockpit that are associated with the datalink.

  3. Preset Status Window. Displays the unit ID and modem protocol of the preset network, along with the callsign of the selected network member.

  4. Member Status Window. Displays the digital ID settings of the selected network member.

  5. Network Members. Selects a network member for review within the Member Status Window.

  6. MBR DIR sub-page. Displays the Member Directory sub-page.

  7. MODEM sub-page. Displays the Modem sub-page.

  8. Ownship Status Window. Displays the digital ID settings of the ownship.

  9. Paging Controls. Cycles forward and back through multiple pages of the network member list.

  10. PRESET EDIT sub-page. Displays the Preset Edit sub-page.

COM Member Directory (MBR DIR) Sub-Page

The MBR DIR sub-page allows crewmembers to add new members to the network or replace existing member entries in the network member list. This directory facilitates efficient and rapid configuration of the network member list using pre-planned network identification data.

  1. STORE Method. Inserts the selected directory member into the selected datalink network.

    • STORE – REPLACE. Displays the REPLACE format of the Member Directory sub-page.

    • STORE – ADD. Adds the selected directory member into the first network entry is that is available. If the datalink network already contains 15 network members, this option will be disabled and “barriered” unless an existing network member is deleted from the selected datalink network.

  2. Directory Members. Selects a directory member for review within the Directory Member status window.

  3. Directory Member Status Window. Displays the digital ID settings of the selected directory member.

  4. Paging Controls. Cycles forward and back through multiple pages of the directory.

  5. Search Directory. Activates the KU for inputting alphanumeric characters to search for a specific member within the directory. Displayed members will be filtered accordingly based on the results.

    Member Directory – Replace Format

    That Replace format of the Member Directory sub-page allows crewmembers to select an existing network member within the current datalink network to replace with the selected directory member.

  6. Preset Status Window. Displays the unit ID and modem protocol of the preset network, along with the callsign of the selected directory member that will replace a selected network member.

  7. Directory Member Status Window. Displays the digital ID settings of the selected directory member that will replace a selected network member.
  8. Network Members. Selects an existing network member for replacement by the directory member displayed within the Preset Status Window, using the information displayed within the Directory Member Status Window.

COM Modem (MODEM) Sub-Page

The MODEM sub-page allows crewmembers to configure the settings the modem will utilize when sending or receiving data through any radios tuned to the selected preset.

  1. Modem Protocol. Selects the type of protocol the modem will utilize for the selected preset.

    • DATALINK. DATALINK-protocol digital messages may be sent using any radio tuned to the selected preset. The modem will monitor any radios tuned to the selected preset for incoming digital messages compatible with AH-64D-only DATALINK protocols.

    • TACFIRE. Not implemented.

    • INTERNET. Not implemented.

    • FIRE SUPPORT. Not implemented.

    • NONE. Radios tuned to the selected preset cannot send digital messages. The modem will not monitor any radios tuned to the selected preset.

  2. Modem Automatic Acknowledgement. Enables/disables automatic acknowledgements by the modem. If a digital message is received, the modem will transmit a discreet acknowledgement to the originator ID of the sender that the digital message has been received by the ownship. NOTE: When a request for data is transmitted to a network subscriber, an “acknowledgement” from the subscriber’s modem only confirms the request for data was received. An acknowledgement does not contain the requested data, which is transmitted within a “reply”.

  3. Modem Retries. Selects the number of subsequent attempts the modem should transmit digital messages if an acknowledgement of reception is not received from any intended message recipients. If an acknowledgement is not received from all intended recipients following the number of selected retries, a “XMIT NAK” (No acknowledgement to transmission) advisory message will be displayed on the EUFD, indicating which radio through which the modem failed to receive all required acknowledgements. This advisory will be removed if the modem successfully receives acknowledgements from all intended recipients from a subsequent digital message transmission.

      1. The modem will not make additional attempts to transmit a digital message.
      1. The modem will make one additional attempt to transmit a digital message to any subscribers that did not return an acknowledgement.
      1. The modem will make two additional attempts to transmit a digital message to any subscribers that did not return an acknowledgement.

  4. Modem Baud Rate. Not implemented.

  5. Preset Status Window. Displays the unit ID, callsign, and modem protocol of the selected preset network.

  6. NET sub-page. Displays the Network sub-page.

Mission creators may configure the datalink settings for each aircraft within the Mission Editor. These settings are located on the Aircraft Additional Properties and Datalinks tabs.

Aircraft Additional Properties. Allows the mission creator to configure any remaining properties that are unique to the aircraft type.

  • Datalink Originator ID. The originator ID will be how the datalink modems of other AH-64D’s within the mission will recognize the aircraft when sending or receiving datalink messages. The alphanumeric character ranges that are valid for entry are 0-39 (with no leading zeros), A-Z, 1A-1Z, 2A-2Z, and 3A-3I; for a total of 127 unique network ID numbers.

    Note

    Each network member, to include the ownship, must have a unique ID number. If two or more members on the same datalink network are assigned the same identification number, erroneous behavior may be observed when using the datalink, or when using functions within the cockpit that are associated with the datalink.

  • Ownship Call Sign. This data field will determine how the aircraft is annotated within the cockpit of other AH- 64D’s within the mission when sending or receiving datalink messages. A minimum of 3 and a maximum of 5 alphanumeric characters may be entered.

(See ORIG ID sub-page for more information.)

Datalinks – SETTING tab. Allows the mission creator to configure the details of each preset on the COM page.

  • Unit ID. This data field determines how the preset is displayed on the COM page and on the EUFD Preset list. Up to 8 alphanumeric characters may be entered.

  • Call Sign. This data field determines how the preset is displayed on the EUFD when assigned to a radio. Up to 5 alphanumeric characters may be entered.

  • Primary Freq. Displays options for designating a primary frequency and radio for the preset. The corresponding entries on the COM Preset format will be displayed in white to highlight the intended radio and net with which the preset is intended to be utilized during the mission. The primary designation does not affect the function of any radio equipment or how the preset is assigned to a specific radio.

  • DL Net. When checked, DATALINK protocols will be enabled on the MODEM sub-page for the preset.

(See PRESET EDIT sub-page in the Radio Communications chapter for more information.)

Datalinks – NETWORK tab. Allows the mission creator to configure the network and modem settings for each preset on the COM page.

  • Preset Buttons (1-10). Selects the corresponding preset with which to edit the network and modem settings in the table below.

  • Auto Acknowledgement. When checked, automatic acknowledgements will be transmitted by the modem when a digital message is received across the datalink network associated with this preset.

  • No Acknowledgement Retries. Selects the number of subsequent attempts the modem should transmit digital messages if an acknowledgement of reception is not received across the datalink network associated with this preset.

  • MBR #. Displays the index of each network member associated with this preset. A maximum of 16 members may be present within each network. The ownship will always occupy the first entry; entries 2-16 will correspond with network subscribers.

  • PILOT NAME. Displays the name of each network member, which corresponds to how their entries will be annotated within the ORIG DIR and MBR DIR sub- pages.

  • C/S. Displays the Call Sign of each network member.

  • ID. Displays the subscriber ID of each network member.

  • PRI. When checked, the member will be designated as a Primary member within the datalink network associated with this preset. A maximum of 8 Primary members may be present within each network, with the ownship always included as the first entry.

  • TM. When checked, the member will be designated as a Team member within the datalink network associated with this preset. A maximum of 16 Team members may be present within each network, with the ownship always included as the first entry.

  • Del. When the red “trash can” icon within this column is selected, the member will be removed from the datalink network associated with this preset. The ownship cannot be deleted from the network.

  • Groups Selection/ADD Button. Displays options for selecting other AH-64D BLK.II Helicopter Groups within the mission. Only AH-64D BLK.II Helicopter Groups that are of the same coalition and not already present within the displayed network will be available for selection. When the ADD button is pressed, all AH-64D’s within that Helicopter Group will be added to the member list of the displayed network.

  • Units Selection/ADD Button. Displays options for selecting individual AH-64D BLK.II helicopters within the mission. Only AH-64D BLK.II helicopters that are of the same coalition and not already present within the displayed network will be available for selection. When the ADD button is pressed, the AH-64D will be added to the member list of the displayed network.

(See NET and MODEM sub-pages for more information.)