NAL RESEARCH CORPORATION A3LA-RG Operating and maintenance instructions

GENERAL DESCRIPTION OF MODEL A3LA-RG
Revision A
May 20, 2020
451-93156-009A
Copyright © 2020 by NAL Research Corporation
11100 Endeavor Court Suite 300
Manassas, Virginia 20109 USA
Phone: [phone]
E-mail: [e-mail]

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LEGAL DISCLAIMER AND CONDITIONS OF USE
This document contains information for the Iridium A3LA-RG modem and accompanying accessories
(“Product”) is provided “as is.” Reasonable effort has been made to make the information in this document
reliable and consistent with specifications, test measurements and other information. However, NAL
Research Corporation and its affiliated companies, directors, officers, employees, agents, trustees or
consultants (“NAL Research”) assume no responsibility for any typographical, technical, content or other
inaccuracies in this document. NAL Research reserves the right in its sole discretion and without notice to
you to change Product specifications and materials and/or revise this document or withdraw it at any time.
User assumes the full risk of using the Product specifications and any other information provided.
NAL Research makes no representations, guarantees, conditions or warranties, either express or
implied, including without limitation, any implied representations, guarantees, conditions or warranties of
merchantability and fitness for a particular purpose, non-infringement, satisfactory quality, non-interference,
accuracy of informational content, or arising from a course of dealing, law, usage, or trade practice, use, or
related to the performance or nonperformance of any products, accessories, facilities or services or
information except as expressly stated in this guide and/or the Product and/or satellite service
documentation. Any other standards of performance, guarantees, conditions and warranties are hereby
expressly excluded and disclaimed to the fullest extent permitted by the law. This disclaimer and exclusion
shall apply even if the express limited warranty contained in this guide or such documentation fails of its
essential purpose.
In no event shall NAL Research be liable, whether in contract or tort or any other legal theory, including
without limitation strict liability, gross negligence or negligence, for any damages in excess of the purchase
price of the Product, including any direct, indirect, incidental, special or consequential damages of any kind,
or loss of revenue or profits, loss of business, loss of privacy, loss of use, loss of time or inconvenience, loss
of information or data, software or applications or other financial loss caused by the Product (including
hardware, software and/or firmware) and/or the Iridium satellite services, or arising out of or in connection
with the ability or inability to use the Product (including hardware, software and/or firmware) and/or the
Iridium satellite services to the fullest extent these damages may be disclaimed by law and whether advised
of the possibilities of such damages. NAL Research is not liable for any claim made by a third party or made
by you for a third party.

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Revision History
Revision
Date
Description
Author
1.3
8/2/16
Initial version
P. Kormendi
A
5/20/20
Added revision history
Updated address
Updated document number
Added AT^VOLB command
P. Kormendi

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TABLE OF CONTENTS
GLOSSARY ....................................................................................................................... 6
1.0 PURPOSE .................................................................................................................... 7
2.0 SPECIFICATIONS ......................................................................................................... 8
3.0 GPS RECEIVER SPECIFICATIONS ................................................................................... 9
4.0 MULTI-INTERFACE CONNECTOR .................................................................................... 9
4.1 RS232 Data Interface (Standard 9-Wire Configuration) .................................................. 10
4.2 RS232 Data Interface (3-Wire Configuration) ................................................................ 11
4.3 DC Power Input ........................................................................................................ 11
4.4 Power On/Off Control ................................................................................................ 12
4.5 Audio Interface ........................................................................................................ 12
4.6 Digital Peripheral Link (DPL) ....................................................................................... 13
5.0 IRIDIUM ANTENNA CONNECTOR .................................................................................... 13
6.0 GPS ANTENNA CONNECTOR .......................................................................................... 14
7.0 SIM CARD INTERFACE .................................................................................................. 14
8.0 LED DISPLAY .............................................................................................................. 15
9.0 CONFIGURATION SETTINGS ......................................................................................... 15
10.0 MODES OF OPERATION .............................................................................................. 15
11.0 AES-256 BIT ENCRYPTION .......................................................................................... 16
12.0 SELF-MONITORING TO PREVENT MODEM-LOCKUP ......................................................... 16
13.0 MOUNTING RECOMMENDATIONS ................................................................................. 17
14.0 TECHNICAL SUPPORT ................................................................................................. 17
APPENDIX A: AT INTERFACE .............................................................................................. 18
APPENDIX B: S-REGISTER DEFINITIONS .............................................................................. 89
APPENDIX C: SUMMARY OF RESULT CODES ......................................................................... 94
APPENDIX D: INFORMATIVE EXAMPLES ............................................................................... 97
APPENDIX E: POWER CONSUMPTION .................................................................................. 102
APPENDIX F: DESCRIPTION OF THE IRIDIUM NETWORK ........................................................ 109
APPENDIX G: STANDARDS COMPLIANCE .............................................................................. 115

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APPENDIX H: MIL-STD-810G CERTIFICATION ....................................................................... 116
APPENDIX I: EXPORT COMPLIANCE INFORMATION ................................................................ 117
APPENDIX J: MECHANICAL DRAWINGS ................................................................................ 118

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GLOSSARY
BIS Bureau of Industry and Security
DAV Data After Voice
DoD EMSS DoD Enhanced Mobile Satellite Services
DTE Data Terminal Equipment
DSN Defense Switch Network
EAR Export Administration Regulations
FDMA Frequency Division Multiple Access
GPS Global Positioning System
ISU Iridium Subscriber Units (Modems, Phones, Trackers)
LBT L-Band Transceiver
NIPRNET Non-Secure Internet Protocol Router Network
NOC Network Operation Center
OFAC Office of Foreign Asset Controls
PSTN Public Switch Telephone Network
RHCP Right Hand Circular Polarization
RUDICS Router-Based Unrestricted Digital Internetworking Connectivity Solution
SBD Short Burst Data
SIM Subscriber Identity Module
SMA Sub-Miniature Version A
SMS Short Message Service
TDD Time Domain Duplex
TDMA Time Division Multiple Access
VSWR Voltage Standing Wave Ratio

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1.0 PURPOSE
This document describes the electrical and mechanical interfaces of the A3LA-RG. Model A3LA-RG is an
Iridium satellite modem comprised of a 9523 L-band transceiver (LBT) and a built-in u-blox MAX-6Q GPS
receiver. The A3LA-RG has an internal micro-controller programmed to monitor the modem‘s connectivity
status to prevent hardware lock-up. It is designed to transmit either AES 256-bit encrypted or unencrypted
data (but not voice) via the Iridium satellite network. Similar to a standard landline modem, the A3LA-RG
can be controlled by any DTE (data terminal equipment) capable of sending standard AT commands via an
RS232 serial port. A DTE can be a desktop computer, a laptop computer, a smart phone, or even a micro-
controller. With the exception of a smaller form-factor, model A3LA-RG is functionally compatible with the
A3LA-XG. Model A3LA-RG-MIL is an A3LA-RG that has been certified to MIL-STD-810G standards and IP67
rating.
Services supported include:
1. Dial-Up Data Switch
2. Direct Internet Connection (or NIPRNET Connection)
3. Direct Internet Connection using Apollo Emulator (only for DoD EMSS Gateway)
4. Short Message Service (SMS)
5. Short-Burst Data (SBD)
6. Router-Based Unrestricted Digital Internetworking Connectivity Solution (RUDICS)
7. Voice when combined with the DPL audio handset
IMPORTANT: User should not disassemble the A3LA-RG for repair or services. The
warranty is voided if the A3LA-RG is disassembled. It should be returned to NAL Research
for any services or firmware upgrade.
IMPORTANT: GPS antenna should only be connected to the A3LA-RG when it is not
powered. Do not connect or disconnect the GPS antenna while A3LA-RG is powered. The
internal GPS receiver calibrates the noise-floor on power-up, and by connecting the GPS
antenna after power-up can result in prolonged acquisition time. To test GPS signal
reacquisition, physically block the signal to the antenna rather than disconnect and
reconnect the antenna is recommended.
Figure 1. Iridium Satellite Modem A3LA-RG.
SIM Reader under the lid
DB25 Multi-Interface Connector
SMA GPS Connector
TNC Iridium Connector

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IMPORTANT: Never feed supply voltage into the active GPS antenna. Always use the bias
voltage supplied by the A3LA-RG SMA antenna connector to power an active GPS antenna.
Feeding voltage to the GPS antenna other than the provided bias voltage will permanently
damage the A3LA-RG.
2.0 SPECIFICATIONS
2.1 Mechanical Specifications
Dimensions: 102 mm x 61 mm x 24 mm (4.0” x 2.43” x 0.95”)
Weight: 201 g (7.1 ounces)
Multi-Interface Connector: 25-Pin Male D-Sub
Iridium Antenna: TNC Female Connector
GPS Antenna: SMA Female Connector
SIM Chip Reader: Located beneath a cover plate on top of the A3LA-RG
Status Display: Four LEDs
Cooling: Convection
Enclosure: Aluminum/EMI shielding
2.2 RF Specifications
Operating Frequency: 1616 to 1626.5 MHz
Duplexing Method: TDD
Multiplexing Method: TDMA/FDMA
Link Margin: 12 dB average
Average Power during a Transmit Slot (Max): 7W
Average Power during a Frame (Typical): 0.6W
Receiver Sensitivity at 50(Typical): –118 dBm
2.3 Electrical Specifications
Main Input Voltage Range: +4.0V to +5.4V or +5.0V to +32.0V
Average Standby Current: ~175mA @ 5.0VDC (with +5.0V to +32.0V setup)
Average Data Call Current: ~420mA @ 5.0VDC (peak of 2A)
NOTE: The power requirements apply to DC power measured at the A3LA-RG multi-
interface connector input. The average data call current may vary depending on the field-
of-view between the modem antenna and the Iridium satellite.
2.4 Environmental Specifications
Operating Temperature Range: –30oC to +70oC (–22oF to +158oF)
Operating Humidity Range: < 75% RH
Storage Temperature Range: –40oC to +85oC (–40oF to +185oF)
Storage Humidity Range: < 93% RH
2.5 Data I/O Specifications
Dial-Up Data/RUDICS: 2.4 Kbits/sec (average)
Direct Internet: 2.4 Kbits/sec (average)

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Short-Burst Data: 1960 bytes for Mobile-Originated and 1890 bytes for Mobile-Terminated
Short Messaging: 160 Characters (maximum)
Hardware Interface: RS232
Software Interface: Standard AT Commands
Encryption: AES-256 Bit when Enabled
2.6 Related Hardware
Antennas: SYN7391 Series, SAF2040 Series, SAF5340 Series, SAF5350 Series
Data Kit/Connector: HRC-24-7R, HRC-24-8R
Power Adapters: LA-3098, LA-7021
Audio Handset: DPLS0401-X
2.7 Reference Documents
A3LA-RG Product Information
Getting Started With Model A3LA-RG (TN2012-31-V1.0)
SatTerm Software Manual (TN2012-004-V8.6.0)
Additional Information on DirectIP SBD (TN2007-637-V1.0)
Additional Information on SBD (AN2012-04-V4.0)
3.0 GPS RECEIVER SPECIFICATIONS
The standard A3LA-RG hardware configuration has a u-blox MAX-6Q GPS receiver. Below are the
specifications.
Receiver Type: 50-channel u-blox 6 engine
L1 frequency (1575.42 MHz carrier frequency), C/A code
SBAS: WAAS, EGNOS, MASA
Maximum update rate: 5Hz
Accuracy: Horizontal Position 2.5m CEP
SBAS 2.0m CEP
Acquisition (typical): Cold start 27 seconds
Warm start 27 seconds
Hot start 1 second
Sensitivity: Tracking 161 dBm
Cold starts 147 dBm
Hot starts 156 dBm
Operational Limits: Velocity 500 m/sec
Altitude 50,000 m
Dynamics < 4 g
I/O Protocols: NMEA, UBX binary, RTCM
4.0 MULTI-INTERFACE CONNECTOR
The multi-interface connector is a male 25-pin miniature D-Sub type that includes five interfaces—
RS232, DC input power, ON/OFF control line, analog audio and Digital Peripheral Link (DPL). The multi-

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interface connector pin assignments are summarized in Table 1, which is ‘pin-to-pin’ the same as model
A3LA-R, A3LA-RM and A3LA-XG.
Table 1. Pin Assignment for the Multi-Interface Connector.
4.1 RS232 Data Interface (Standard 9-Wire Configuration)
The A3LA-RG supports a standard RS232 data interface to a DTE incorporating hardware handshaking
and flow control. The RS232 data interface comprises of eight standard RS232 data, control and status
signals plus a ground level signal reference as shown in Table 1. This interface allows a connected DTE to
utilize the A3LA-RG’s modem functionality through standard AT and extended sets of AT commands. These
commands are defined in Appendix A. The factory-set baud rate is 19,200 bps and can be changed using the
+IPR command.
Note that the Ring Indicator is used by the A3LA-RG to indicate that a Mobile Terminated SBD (MT-SBD)
message is queued at the gateway. Application developers can monitor this pin and apply appropriate AT
commands to the A3LA-RG to retrieve the MT-SBD message.
PIN #
SIGNAL
DESCRIPTION
INTERFACE
1
EXT_ON_OFF
Power on/off control input
DC Power
2
+12VDC
Output Voltage to Power the DPL Handset
DC Power
3
EXT_GND
External GND input
DC Power
4
EXT_B+
External 4.0V –5.4V or 5.0V –32.0V
DC Power
5
SPKR_AUD
Speaker audio output
Analog Audio
6
DA_TX
PCM digital audio output
Digital Audio
7
RI
RS232 Ring Indicate
RS232 Data
8
RTS
RS232 Request To Send
RS232 Data
9
TX
RS232 Transmit Data (Input)
RS232 Data
10
DCD
RS232 Data Carrier Detect
RS232 Data
11
DA_FS
PCM digital audio frame sync output
Digital Audio
12
DA_CLK
PCM digital 2.048MHz audio clock output
Digital Audio
13
RX
RS232 Receive Data (Output)
RS232 Data
14
SIGNAL GND
Signal ground, 0V signal reference and return
GND
15
MIC_AUD
Microphone audio input
Analog Audio
16
EXT_B+
External 4.0V –5.4V or 5.0V –32.0V
DC Power
17
EXT_GND
External GND input
DC Power
18
DPL_TX
Digital Peripheral Link (DPL) data output
DPL UART
19
DTR
RS232 Data Terminal Ready
RS232 Data
20
DPL_RX
Digital Peripheral Link (DPL) data input
DPL UART
21
DSR
RS232 Data Set Ready
RS232 Data
22
CTS
RS232 Clear To Send
RS232 Data
23
SIGNAL GND
Signal ground, 0V signal reference and return
GND
24
DA_RX
PCM digital audio input
Digital Audio
25
SIGNAL GND
Signal ground, 0V signal reference and return
GND

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4.2 RS232 Data Interface (3-Wire Configuration)
A 3-wire RS232 data interface may also be implemented. Because of risk of over-run and data loss
especially at high baud rates, the 9-wire interface is the recommended implementation. Several steps must
be taken to allow 3-wire configuration (i.e. only using S_TX, S_RX, and SIGNAL GND). These steps ensure
the A3LA-RG and DTE to work together without having hardware handshaking.
1. The modem’s DTR line must be held high. Using the modem’s input voltage is fine for this purpose
BUT ONLY if the input voltage is less than 5VDC (see important note below). Looping back the
modem’s DSR line to DTR line will NOT work. The DSR line on the modem should be left
unconnected.
2. Disconnect the CTS, DCD, DSR, DTR, RTS and RI lines between the DTE and modem.
3. AT&Dn must be set to AT&D0 to ignore the DTR input from the DTE.
4. AT&Kn must be set to AT&K0 for no flow control.
5. The setting can be stored on the modem permanently (until another setting overwrites it) so that it
remains after a power cycle. The modem allows two profiles in which settings are stored, and user
can choose either as a default profile. The relevant commands are &Wn and &Yn. &Wn stores the
present configuration in profile <n>, where <n> can be either 0 or 1. &Yn designates which profile
is loaded after reset or power-up, again <n> is either 0 or 1.
6. Any needs of the DTE must be addressed separately.
WARNING: DO NOT use the modem’s input voltage to bring the DTR line high when the
input voltage is higher than 5VDC. Supplying voltage higher than 5VDC to the DTR line will
permanently damage the A3LA-RG.
NOTE: The Iridium’s Direct Internet service when using the Windows-based Apollo client
requires DCD to be present; hence it is incompatible with a 3-wire serial configuration. The
Direct Internet with Apollo client is available only on the EMSS DoD gateway and NOT on
the commercial gateway.
4.3 DC Power Input
The DC power input is through pin 4 & 16 (EXT_B+) and pins 3 & 17 (EXT_GND). Note that two pins are
provided for the external DC input and two pins are also provided for the associated external ground input.
This is done to distribute the current across two wires, and therefore all four pins should be utilized in the
external power connection. Cables used to supply power to the A3LA-RG should be kept as short as possible
to prevent significant voltage drop, which can cause the A3LA-RG to malfunction during a data call, an SMS
session or an SBD session. Power reset by the A3LA-RG during a call is an indicative of the DC power source
unable to sustain voltage above 4.0V at peak current demand. Appendix E provides the electrical power
profile of the A3LA-RG.
The A3LA-RG accepts either +4.0V to +5.4V or +5.0V to +32V input. The A3LA-RG is shipped with
hardware set for +5.0V to +32V input. It can be changed to +4.0V to +5.4V input through an internal
jumper—POWER MUST BE DISCONNECTED BEFORE RESETING THE JUMPER. The jumper can be found by

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removing the modem’s bottom plate. With the A3LA-RG held in the position shown in Figure 2 (DB25
connector to the left), the A3LA-RG is set for 4.0V to +5.4V when the red jumper is on the middle and left
pins and is set for +5.0V to +32V when the jumper is on the middle and right pins. Each pin is also labeled
with 5V and 32V to the left and right pins, respectively.
NOTE: User MUST remember the input voltage setting on the A3LA-RG and not to apply
voltage above the maximum limit (of either 5.4V or 32V). The A3LA-RG will be damaged
beyond repair with warranty voided if this were to occur.
IMPORTANT: User can remove the A3LA-RG’s bottom plate to set the jumper but not for
repair or services. The warranty is voided if the A3LA-RG is disassembled for any reason
other than to set the jumper.
4.4 Power On/Off Control
With the EXT_ON_OFF pin is left unconnected, the A3LA-RG will automatically turn on or off when
external DC power is applied or removed. Prior to turning the A3LA-RG off, command AT*P0 should be
issued to ensure all memory write activity is completed. When the A3LA-RG is powered off, its internal
power-on-reset circuit requires two seconds for voltages to decay. Users should not re-apply power until this
time has elapsed. If the two-second wait time is not adhered to, the reset circuit may not operate and the
A3LA-RG could be placed in a non-operational state. The state is not permanent and can be rectified by the
above procedure.
The A3LA-RG will automatically turn on/off when external DC power is applied/removed via the EXT_B+
and EXT_GND inputs. The EXT_ON_OFF (pin 1) control input is used to turn a powered A3LA-RG on and off
in a toggle fashion. The EXT_ON_OFF control input is normally “floating” (i.e. high). When it is pulled to GND
level (i.e. low) for at least 270 ms and released, the A3LA-RG will alternate from its current on/off state. The
current drawn on the external load used to pull the A3LA-RG to GND is no more than 0.5mA. The signal on
pin 1 is considered GND when it is at 0.5V or less.
4.5 Audio Interface
The A3LA-RG supports both digital and analog audio I/O. The digital audio is in PCM format. In such
format, digital audio cannot travel far (less than one foot); this is why the analog is chosen for the A3LA-RG
audio handset. The analog audio input is a single-ended, unbalanced input with a minimum impedance of
Figure 2. Power Input Setting for the A3LA-RG.
Red jumper used
to set input
voltage range

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10kto ground. The A3LA-RG accepts a maximum input level of 2.0V peak-to-peak without signal
distortion. The analog audio output is also a single-ended, unbalanced output capable of driving an
impedance of 600or more to ground. The A3LA-RG delivers undistorted audio up to 2.0V peak-to-peak.
The combined analog I/O audio interface (pins 5 and 15) and the DPL UART I/O interface (pins 18 and
20) enable an analog audio handset to be connected to the A3LA-RG. With the DPL audio handset model
DPLS0401-X and DB25 data kit model HRC-24-8R, the A3LA-RG can be used both as a data modem and a
satellite phone. This setup as shown in Figure 3 can be an extremely useful developmental tool since the
modem status can be seen on the handset LCD similar to a 9555 Iridium phone.
4.6 Digital Peripheral Link (DPL)
The DPL interface is composed of two ports—a full duplex asynchronous serial link for control messages
and a PCM digital audio link for audio traffic. The protocol used on these ports is made available to
application developers only on a case-by-case basis and after appropriate Non-disclosure Agreements and/or
License Agreements are executed.
5.0 IRIDIUM ANTENNA CONNECTOR
The A3LA-RG modem uses a single TNC female 50-ohm connector for both transmit and receive (see
Figure 4). Cable loss between the modem and the antenna is critical and must be kept less than 3dB at the
operating frequency of 1616 to 1626.5 MHz. The minimum link margin of 12 dB must also be maintained.
General RF parameters are listed in the table below.
NAL Research offers several types of antennas for use with the A3LA-RG modem. These antennas
include the fixed mast, mobile magnetic/permanent mount and portable auxiliary. For low-cost and
applications where small form-factor and light-weight are required, NAL Research recommends model
SYN7391-C. If the specific application requires a custom antenna, it must meet the specifications below.
TYPE
DESCRIPTION
Frequency Range
1616 to 1626.5 MHz
Input/Output Impedance
50 Ohms
Oscillator Stability
1.5ppm
DPL Handset
A3LA-RG Modem
HRC-24-8R Data Kit
Figure 3. A3LA-RG Connected to a DPL Handset via the HRC-24-8R.

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Satellite signal strength reported by the A3LA-RG when issuing an AT+CSQ command indicates the
signal strength of the ring channel. Care should be taken when using this signal reading for comparisons
between devices. Of particular notes are the followings:
1. There is a 0.5 dB tolerance on the calibration.
2. Each bar represents a 2 dB increment.
3. Multiple ring channels can be present at the same time so units can lock to different signals.
4. If the reading is near the decision threshold it would be easy to see a 1 bar difference.
6.0 GPS ANTENNA CONNECTOR
The A3LA-RG modem uses an SMA female connector for the GPS antenna (Figure 4). Any active antenna
required a bias voltage of ~3.3VDC with <50mA is appropriate. NAL Research offers a magnetic mount GPS
antenna as well as dual Iridium/GPS antenna for use with the A3LA-RG. For low-cost and applications where
small form-factor and light-weight are required, NAL Research highly recommends model SAF7352-IG.
7.0 SIM CARD INTERFACE
The A3LA-RG modem contains an integrated SIM reader. The modem uses and requires an Iridium SIM
chip for operation. The SIM chip is inserted into the opening located on top of the modem as shown in Figure
4. A plastic locking mechanism is used hold the SIM in-place. Place the SIM chip (facing down) into the SIM
reader’s bracket. Make sure that the cut-off on the SIM chip aligns with the SIM reader.
PARAMETER
VALUE
Operating Temperature Range
–40oC/+85oC without loss of function
Measurement Frequency Range
1616 to 1626.5 MHz
VSWR
< 1.5 : 1
Maximum Gain
3 dBic
Nominal Impedance
50 Ohms
Polarization
Right Hand Circular (RHCP)
Basic Pattern
Omni directional and hemispherical
Figure 4. Location of the SIM Reader.
Iridium Antenna Connector
GPS Antenna Connector
SIM Reader under the lid

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8.0 LED DISPLAY
The A3LA-RG has four status LEDs depicted as P for power indicator, I for Iridium satellite signal
strength, G for GPS signal strength and S for status (see Figure 5). They offer users a quick visual check to
ensure proper modem operations as well as a way to optimize antenna locations during field installation.
These LEDs provide the following information:
P: LED lights up when power is provided to the A3LA-RG.
I: LED stays solid when the signal strength is between 3–5, blinks when the signal strength is
between 1 and 2 and is off when signal strength is 0. The LED also stays solid when the carrier
detect (CD) line on the RS232 goes high during a data call.
G: LED stays solid when there is a valid GPS position fix (usually with at least 4 satellites), blinks
when there is only 2D fix or using dead reckoning (usually with 3 satellites or less), and stays off
when unable to obtain a position fix.
S: LED lights up when the A3LA-RG is in data mode.
9.0 CONFIGURATION SETTINGS
The A3LA-RG allows users to configure its data port communication parameters. The three configuration
types are active, factory default, and stored. The active configuration is the set of parameters currently in
use. They can be changed by the users individually via specific AT commands. The factory default
configuration is stored in permanent memory. This configuration can be recalled at any time through use of
the AT&Fn command.
Two groups of settings, or “profiles”, can be stored as user-defined configurations. Users first create
desired active configurations and then write them to memory using the AT&Wn command. These profiles can
be designated to be loaded as the active configuration upon A3LA-RG power-up through use of the AT&Yn
command. The A3LA-RG can be reset without loss of power to these profiles through use of the ATZn
command. The configuration settings are stored in “S-register” locations and are detailed in Appendix A.
10.0 MODES OF OPERATION
The A3LA-RG serial data port is always in one of two modes: command mode or data mode. When the
data port is in command mode, AT commands can be entered to control the A3LA-RG. In command mode,
flow control has no effect, with the RTS input ignored and the CTS output driven ON (low). When in data
mode, the A3LA-RG transfers data over the Iridium network. In data mode:
1. All characters from the DTE are sent over the Iridium network to the remote side of the connection.
P, I, G, S LEDs
Figure 5. Iridium Satellite Modem A3LA-RG.

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2. No unsolicited result codes are issued.
3. RTS/CTS flow control, if enabled, is active. When RTS is OFF (high), the A3LA-RG suspends transfer
of data to the DTE; when CTS is OFF, the A3LA-RG expects the DTE to suspend transfer of data.
Transitions between the modes of operation are performed automatically by the A3LA-RG in response to
AT commands; the DTE has no other control over the mode.
11.0 AES-256 BIT ENCRYPTION
The A3LA-RG modem has a built-in AES-256 encryption software module. It can transmit either
encrypted or unencrypted data in all modes—dial up, direct Internet, RUDICS, SBD and SMS. The A3LA-RG
does not support encrypted voice calls. All voice calls are made in the ‘clear’ unless an external encryption
module is hooked to it such as the General Dynamics® Sectéra. When encryption is enabled and for non-
packetized data transmission modes including dial-up, direct Internet and RUDICS, the A3LA-RG sends data
in NAL Research’s proprietary format called packet send mode. Packet send mode is implemented to handle
AES-256 frame synchronization between the A3LA-RG and a connected device. The encryption and
decryption keys are matched in each frame to ensure NIST FIPS 140-2 compliance.
Instructions on how to use encryption can be found in manuals AT Command Reference in Appendix A.
List of AT commands used to set encryption include ^CCOP, ^KD, ^KE, ^KZ, ^STR, and ^UE. The
encryption algorithm implemented into the A3LA-RG complies with NIST FIPS 140-2 as defined in the
following documents:
1. Security Requirements for Cryptographic Modules, FIPS PUB 140-2, US Department of
Commerce, National Institute of Standards and Technology, May 25th, 2001.
2. Security Requirements for Cryptographic Modules, Annex A: Approved Security Functions
for FIPS PUB 140-2, US Department of Commerce, National Institute of Standards and
Technology, February 19th, 2003.
12.0 SELF-MONITORING TO PREVENT MODEM LOCK-UP
The 9523 RF board can sometimes ‘lock-up’ when being inactive over a long period of time (a day or
longer). The only way to recover is to power cycle the ISU. The A3LA-RG has safeguards put in place with a
watch-dog timer to keep the 9523 RF board from locking up. These were done by having another micro-
controller in-line with the serial communications, monitoring the communications and making sure the 9523
is responding correctly. Each of the safeguards is enabled by default. Below is a description of each of the
four safeguards. These safeguards are also employed on the A3LA-RM and A3LA-XM.
Check When Not in a Data Call: The micro-controller has a timer that is reset every time a character
arrives from the 9523 board. The timer is set to end every 2 minutes. When the timer expires the micro-
controller will check to make sure the 9523 is still responding by sending it an AT command. If the 9523
responds it starts the counter over again. If there is not response it power cycles the 9523. This can be
enabled or disabled with the ^MPTNC command.
Check When in a Data Call: The micro-controller has a timer that is reset every time a character arrives
from the 9523 board during data calls. The timer is set to end every 4 minutes during data calls. When the
timer expires the micro-controller will check to make sure the 9523 is still responding by sending it the +++
sequence. If the 9523 responds it returns to the data connection and starts the counter over again. If there

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is no response it power cycles the 9523. This can be enabled or disabled with the ^MPTDC command.
Registrations Every 23 Hours: The micro-controller will force manual registration by implementing the
command AT+COPS=1 every 23 hours to make sure the 9523 stays registered. Registration will not occur
during a data/voice call. This can be enabled or disabled with the ^MPTFR command.
Forced Power Cycles Every 24 Hours: The micro-controller will force a power cycle of the 9523 board
every 24 hours. Power cycle will not happen during a data/voice call. This can be enabled or disabled with
the ^MPTFP command.
13.0 MOUNTING RECOMMENDATIONS
The A3LA-RG has four features on its bottom surface that can aid in its mounting (see Appendix J).
These four features are pre-drilled at a minimum depth of 0.25 inch to accept 6-32 thread type.
14.0 TECHNICAL SUPPORT
FOR TECHNICAL SUPPORT, PLEASE CONTACT US AT
Phone: [phone]
FAX: [phone]
E-mail: [email protected]
Technical documents are also available to download on NAL Research’s website
www.nalresearch.com

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APPENDIX A: AT INTERFACE
A.1 Command Types
The A3LA-RG employs two principal types of AT commands: basic and extended. The two types have
differing syntax used to query and adjust their settings. They also have unique reference standards. A
specific basic AT command is used to reference S-registers and query and adjust their settings. Its syntax is
similar to that of extended AT commands.
A.2 Basic Commands
Basic commands are industry standard and originally developed for Hayes-compatible PSTN modems. In
many cases, basic commands consist of a single ASCII alpha character. In other cases, a special character
precedes the alpha character. Prefix characters used in A3LA-RG basic commands include &, \, %, and *.
Most alpha characters in basic commands are followed by a numeric parameter, n. To adjust its setting,
a basic command is entered with the appropriate numeric value of n. Note that if the numeric parameter n is
omitted from the basic command entry, a value of zero is assumed for n. For example, ATXn is set to a
value of 4 by entering ATX4, whereas it is set to value of 0 by entering either ATX0 or ATX.
To query a basic command setting, the AT&V command is entered to view the active configuration of a
group of basic commands. Some basic commands listed in this document are marked with “No action,
compatibility only”. In these cases, the basic command is accepted in the same fashion as is with other
modems, but has no effect on the operation of the A3LA-RG, since it has no meaning in the Iridium
environment.
A.3 Extended Commands
Extended commands perform actions or set parameters that extend the capability of the A3LA-RG
beyond that which is allowed by basic commands. In some cases, they were designed for the GPS receiver,
encryption, lock-up monitoring and non-PSTN networks such as the GSM network.
Most extended commands include a prefix of + followed by a single alpha character. Prefixes used in
A3LA-RG extended commands include +C, +D, +G, +I, and +S. Extended commands designed specifically
for Iridium products include a –MS prefix. Most extended commands include three alpha characters after the
prefix, but some commands include just one or two alpha characters after the prefix.
Some extended commands have a single execution mode. No further syntax is added after the prefix
and body of the command. For example, AT+GSN is entered as shown to query the A3LA-RG for its assigned
serial number (i.e. IMEI). Some extended commands incorporate a test mode to query their range of valid
responses. Some extended commands incorporate set, read, and test modes. For example, AT–MSVTR is
entered as AT–MSVTR=n in set mode to enable/disable receipt of DTMF messages. It is entered as AT–
MSVTR? in read mode to query its current setting and is entered as AT–MSVTR=? in test mode to query its
range of valid settings. Extended commands are grouped as shown below.
Extended Cellular Commands:
+C prefix
Used for GSM cellular phone-like functions
Standards: ETSI specifications GSM 07.07 [2] and GSM 07.05 [3]
Extended Data Compression Commands:

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+D prefix
Used for data compression
Standard: V.25ter [1]
Extended Generic Commands:
+G prefix
Used for A3LA-RG issues such as identities and capabilities
Standard: V.25ter [1]
Extended Interface Control Commands:
+I prefix
Used to control the DTE interface
Standard: V.25ter [1]
Extended Short Burst Data Commands:
+S prefix
Used for Short Burst Data messaging
Iridium Satellite Product Proprietary Commands:
–MS prefix
Proprietary to the Iridium product line
A.4 Command and Response Characters
The execution of a command string follows a left-to-right execution of each command followed by the
reporting of a result code for the entire string. The ASCII character set (CCITT T.50 International Alphabet
5, American Standard Code for Information Interchange) is used for the issuance of commands and
responses. Only the low-order 7 bits of each character are used for commands or parameters; the high-
order bit is ignored. Upper case characters are equivalent to lower case characters.
A.5 Command Entry
An AT command is a string of characters sent by the DTE to the A3LA-RG while it is in command mode.
A command string has a prefix, a body, and a terminator. The prefix consists of the ASCII characters AT or
at. The body is a string of commands restricted to printable ASCII characters. The default terminator is the
<CR> character. AT command entry syntax is critical, and the following rules apply:
All commands (apart from A/ and +++) begin with a prefix of AT or at.
The commands in a command string (apart from A/ and +++) are executed only after the
return or enter key is pressed.
Use of upper or lower case letters is allowed.
The maximum number of characters in a command string is 128.
If the numeric parameter n is omitted from the basic command entry, a value of zero is
assumed for n.
If an optional parameter is omitted from an extended command, the current value is implied.
Optional parameters are enclosed by square brackets ([...]) in this document.

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Spaces entered into a command string for clarity between the AT prefix and the body of the
command are ignored. Likewise, spaces entered for clarity within the command body between
alpha characters and decimal parameters are ignored.
The backspace or delete keys can typically be used to edit commands.
Characters that precede the AT prefix are ignored.
Ctrl-x can be used to abort a command line input.
Consider the following six commands to be entered in a single command line:
ATX0 (set basic command ATXn to n=0)
AT&V (execute basic command AT&V)
AT+GSN (execute extended command AT+GSN)
AT+CMEE=? (query the valid range of responses of extended command AT+CMEE)
AT+CPBR=1,12 (execute extended command AT+CPBR with parameters 1 and 12)
AT–MSVTR? (query the current setting of extended command AT–MSVTR)
The following are valid single command line entries of above six commands:
at x 0 &v +gsn +cmee=? +cpbr=1,12 -msvtr? (all lower case)
AT X 0 &V +GSN +CMEE=? +CPBR=1,12 –MSVTR? (all upper case)
ATX 0 &V +GSN +CMEE=? +CPBR=1,12 –MSVTR? (space omitted between AT and X)
ATX0 &V +GSN +CMEE=? +CPBR=1,12 –MSVTR? (space omitted between ATX and 0)
ATX &V +GSN +CMEE=? +CPBR=1,12 –MSVTR? (0 omitted from ATX0)
ATX;&V;+GSN;+CMEE=?;+CPBR=1,12;–MSVTR? (semicolon separators)
ATX&V+GSN+CMEE=?+CPBR=1,12–MSVTR? (no separators)
A.6 Command Responses
A result code is sent to the DTE in response to the execution of a command. It may also occur
unsolicited from other conditions such as an incoming call (e.g. RING). Responses returned as a result of a
query are called information responses.
Result codes can be represented by text if the A3LA-RG is in verbose mode or with numbers if in
numeric mode. The command ATVn informs the A3LA-RG whether to respond in verbose or numeric mode.
Further note that responses can be suppressed by setting the command ATQn to ATQ1. Table below shows
the difference in format between these modes.
Numeric Mode
ATQ0 ATV0
Verbose Mode
ATQ0 ATV1
Result codes
<NUMERIC_CODE><CR>
<CR><LF><VERBOSE_CODE><CR><LF>
Information Responses
<TEXT><CR><LF>
<CR><LF><TEXT><CR><LF>