Advanced Simulation Technology inc.
HLA FAQs

Can a single DACS, running Model Builder simulated radio software and connected to a Telestra running HLA software, support two or more independent and concurrent exercises?

In the HLA world, federations are analogous to exercises. A single DACS, running Model Builder simulated radio software and connected to a Telestra running HLA software, supports radios operating in multiple / concurrent federations.
The recommended way to implement flexible assignment of radios to various federations is to provide a host-driven federation number to each radio. The Telestra routes radio traffic based on of federation number values:
Federations 1-8: HLA Networking
Receiver, transmitter and signal traffic is routed over the HLA network, through the RTI.
Federations 9-127: Backchannel Networking
Signal traffic is routed over the physical HLA network, but not through the RTI. Receiver and transmitter traffic is routed through the RTI. See Application Note #54 for more information about backchannel comms.
Federations 128-255: Local Networking
Receiver, transmitter and signal traffic is routed to all DACS located on the local network, behind the Telestra.
For example, let's say that you want:
  • Radios 1-3 in their own federation and locally networked (not routed over the HLA network)

  • Radios 4-9 in their own federation and locally networked (not routed over the HLA network)

  • Radios 10-15 in their own federation and routed over the HLA network
Do this:
  • Radios 1-3: host sets these radio Federation Numbers to 128

  • Radios 4-9: host sets these radio Federation Numbers to 129

  • Radios 10-15: host sets these radio Federation Numbers to 1
For reference, a typical configuration with four DACS connected to an HLA Telestra and a host controller is shown here:

Telestra HLA with DACS diagram
ASTi does not recommend reconfiguring federations during runtime. Although the ASTi DACS and Telestra HLA products are capable of doing this, some RTIs are not so capable. From experience, we have found that some RTIs require that radios be configured to a specific federation prior to the time that the Telestra joins the federation. These RTIs do not support (or perform badly) under "late joiner" conditions. Use the Telestra remote control feature to resign one federation and join another then restart the Telestra comms application.