Technical data
ASTi ACE Studio Components Reference Guide Rev. M DOC-01-TELAS-CRG-4
Copyright © 2014 Advanced Simulation Technology inc. 209
14.12. Transceiver
Summary: The Transceiver works in conjunction with an RCU component to
create a simulated radio.
Description: The Transceiver is, as the name suggests, a component used to model
radio transmission and radio reception. Used in conjunction with a Radio Control
Unit (RCU), an Intercom Control Unit (ICU), a Receiver or a Transmitter
component it forms the basis of a Radio, Network Intercom, Receiver or
Transmitter respectively.
Some of the core features of the Transceiver include:
• Host Control of core radio parameters
• Modulation Matching (AM, FM, USB, LSB, etc.)
• RF Propagation Modeling based on world position, frequency, etc.
• Crypto state and sound modeling
• Frequency Hopping modeling
• Jamming support
• Squelch control
• Terrain support (in conjunction with an external Terrain Server)
• Antenna Gain, Cable Loss, RXTuneTone and other advanced radio parame-
ters
• Audio and Tactical Data Link support
• Multi-protocol support including local, ASTiNet, DIS and HLA
The Transceiver provides a generic, high-level radio simulation, which includes
transmit and receive operations, frequency tuning effects, AM and FM modulation
modes, signal-strength variation due to range, transmit power, antenna and receiver
gain, RF and internal noise, and propagation path loss, sidetone signal return, and
support for crypto and frequency hop behaviors, and more.
At the simplest level, the Transceiver component provides a simulation of the
interface between the signal and data flow within a radio, and the simulated radio
frequency (RF) environment. Just as in the real world, the signals passed between a
real transceiver and the remainder of the radio sub-system provide information to/
from the Transceiver, and include the transmit and receive audio signals (voice/
tones), transmit and receive data message signals (including Link-16, IDM,
ACARS, etc), and control signals that determine the behavior of the Transceiver
(such as tuned frequency, modulation mode, bandwidth, etc).
In effect the Transceiver may be regarded as having two bi-directional information
interfaces, and a single (mostly) one-way control interface. One of the bi-
directional information interfaces operates internally, within the simulated radio
and/or vehicle, and operates at base-band, while the other bi-directional interface
operates in the RF bands, and provides wireless transmission and reception. The
control interface determines the translation between the base-band and RF
environments.
A Transceiver component must be used with an RCU object to form an operational
“radio”, with the RCU providing the greater portion of the control interface data
values. Applicable RCU sub-class objects that may be used with the Transceiver
include: RCU, ICU, transmitter, and receiver components respectively. The nature
of the selected RCU will determine the available capabilities of the Transceiver. For
example, selection of a ‘receiver’ RCU object will limit the operation of the
Transceiver to the reception of RF originated signals.
The Transceiver can be used to implement various fidelity levels of RF modeling
from simple frequency matching, through full-fidelity simulation of specific radio
types, including propagation and ranging, bandwidth overlap, antenna gain, etc.
Ranging behavior requires that each radio have a ‘world position’ describing the
location of the radio on or above the Earth’s surface. If a radio is configured to
operate using the DIS networking protocol, another option available is to attach a
radio to an externally simulated entity, using the Entity Attach feature. Once
attached, the Transceiver position will be slaved to the selected entity and all range
calculations will be based on the supplied entity position.
The received signal strength is computed for all in-tune radios based on the power
of the transmitter, the antenna gains of the transmitter and receivers, and the
relative world positions. If the terrain interface is installed, the gain factor for the
in-tune radios is factored in the calculator. If frequency hopping or encryption is
enabled, the parameters of the transmitter and receiver are compared to see if the
audio is received. (In frequency hopping mode, the frequency field is ignored. The
frequency is implied in the selected Net ID hopset). If multiple transmitters are
broadcasting on the same frequency, the Transceiver will typically do one of two
things. For AM signals, the received RF power is combined and the received audio
is a sum of the transmitted signals in proportion to their signal strength. For FM
signals, only the strongest received signal is included.
Once the received power is determined, the RF SNR is calculated. The noise level
is determined by thermal noise, internal radio noise, and other parameters, which
are set in the Transceiver. The RF SNR is then compared to the squelch level. If the
ratio is less than the squelch level, the signal is not received. Setting the squelch to
zero disables the squelch.