NAL A3LA-R User manual

Copyright © 2021 by NAL Research Corporation
11100 Endeavor Ct., Suite 300
Manassas, Virginia 20109 USA
Phone: [phone]
Email: [e-mail]
Powered by
Model A3LA-R User Guide
Version A
April 1, 2022
451-93156-001A

A3LA-R User Guide Version A
Document Number: 451-93156-001A 2 of 158
LEGAL DISCLAIMER AND CONDITION OF USE
This document contains information for the Iridium A3LA-R modem and accompanying
accessories (“Product”), which are 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, 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 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.

A3LA-R User Guide Version A
Document Number: 451-93156-001A 3 of 158
REVISION HISTORY
Revision
Date
Description
1.1
04/08/2013
Initial version
1.2
07/14/2021
Updated to new template; proofread.
A
04/01/2022
Formal release

A3LA-R User Guide Version A
Document Number: 451-93156-001A 4 of 158
REFERENCE DOCUMENTS
The latest revisions of the NAL documents are available from the NAL Research website at
https://www.nalresearch.com/support/documentation-downloads/.
Reference
Title
Revision/Date
[1]
A3LA-R Product Information
[2]
Getting Started With Model A3LA-R (TN2012-11-V1.0)
Version 1.0, 2012
[3]
SatTerm Software Manual (451-94000-001A)
Version A, 2022
[4]
Additional Information on DirectIP SBD (TN2007-637-
V1.0)
V1.0, 2007
[5]
Additional Information on SBD (AN2012-04-V4.0)
V4.0, 2012

A3LA-R User Guide Version A
Document Number: 451-93156-001A 5 of 158
TABLE OF CONTENTS
1Introduction............................................................................................................. 16
2Multi-Interface Connector ........................................................................................ 17
2.1 RS232 Data Interface (Standard 9-Wire Configuration) ..................................................... 18
2.2 RS232 Data Interface (3-Wire Configuration)..................................................................... 18
2.3 DC Power Input................................................................................................................... 19
2.4 Power On/Off Control......................................................................................................... 20
2.5 Audio Interface ................................................................................................................... 21
2.6 Digital Peripheral Link (DPL)................................................................................................ 22
3Antenna Connector .................................................................................................. 23
4SIM Card Interface.................................................................................................... 25
5LED Display .............................................................................................................. 26
6Configuration Settings.............................................................................................. 27
7Modes of Operation ................................................................................................. 28
8Mounting Recommendations.................................................................................... 29
9Technical Support..................................................................................................... 30
Appendix A: AT Interface ................................................................................................... 31
A.1 Command Types ................................................................................................................. 31
A.2 Basic Commands................................................................................................................. 31
A.3 Extended Commands.......................................................................................................... 31
A.4 Command and Response Characters.................................................................................. 33
A.5 Command Entry .................................................................................................................. 33
A.6 Command Responses.......................................................................................................... 34
A.7 Hardware Failure Reporting................................................................................................ 35
Appendix B: AT Command Set Description.......................................................................... 36
B.1 AT –Attention Code............................................................................................................ 36
B.2 A/ –Repeat Last Command ................................................................................................ 36
B.3 +++ –Escape Sequence....................................................................................................... 36
B.4 En –Echo............................................................................................................................. 36
B.5 On –Online ......................................................................................................................... 36
B.6 Qn –Quiet Mode ................................................................................................................ 36
B.7 Vn –Verbose Mode ............................................................................................................ 37

A3LA-R User Guide Version A
Document Number: 451-93156-001A 6 of 158
B.8 Wn –Error Correction Message Control............................................................................. 37
B.9 Zn –Soft Reset .................................................................................................................... 37
B.10 &Cn –DCD Option............................................................................................................... 37
B.11 &Dn –DTR Option............................................................................................................... 37
B.12 &Fn –Restore Factory Settings........................................................................................... 38
B.13 &Kn –Flow Control ............................................................................................................. 38
B.14 &Mn –Asynchronous/Synchronous Mode......................................................................... 39
B.15 &Qn –Sync/Async Mode .................................................................................................... 39
B.16 &Sn –DSR Override ............................................................................................................ 39
B.17 &V –View Active and Stored Configuration....................................................................... 39
B.18 &Wn –Store Active Configuration...................................................................................... 40
B.19 &Yn –Designate Default Reset Profile ............................................................................... 40
B.20 \Kn –Control Break............................................................................................................. 40
B.21 %R –Display Registers ........................................................................................................ 41
B.22 *Pn –Power ........................................................................................................................ 41
B.23 +CBST –Select Bearer Service Type.................................................................................... 41
B.24 +CGMI –Manufacturer Identification ................................................................................ 42
B.25 +CGMM –Model Identification .......................................................................................... 42
B.26 +CGMR –Revision............................................................................................................... 42
B.27 +CGSN –Serial Number ...................................................................................................... 42
B.28 +CMEE –Report Mobile Equipment Error.......................................................................... 42
B.29 +CPAS –Modem Activity Status.......................................................................................... 44
B.30 +CR –Service Reporting Control......................................................................................... 44
B.31 +DS –Set Data Compression Function................................................................................ 45
B.32 +DR –Data Compression Report Level............................................................................... 46
B.33 +CEER –Extended Error Report.......................................................................................... 47
B.34 +CHUP –Hangup call........................................................................................................... 47
B.35 +CMGD –Delete SMS Message .......................................................................................... 47
B.36 +CMGF –SMS Message Format.......................................................................................... 50
B.37 +CMGL –List SMS Messages............................................................................................... 50
B.38 +CMGR –Read SMS Message ............................................................................................. 51
B.39 +CMGS –Send SMS Message.............................................................................................. 52

A3LA-R User Guide Version A
Document Number: 451-93156-001A 7 of 158
B.40 +CMGW –Write SMS Message To Memory....................................................................... 52
B.41 +CMOD –Call Mode............................................................................................................ 53
B.42 +CNMI –New SMS Message Indications to DTE................................................................. 53
B.43 +COPS –Operator Select .................................................................................................... 55
B.44 +CPBF –Find Phonebook Entries........................................................................................ 56
B.45 +CPBR –Read Phonebook Entries ...................................................................................... 57
B.46 +CPBS –Select Phonebook Storage.................................................................................... 58
B.47 +CPBW –Write Phonebook Entry....................................................................................... 58
B.48 +CPIN –Enter PIN................................................................................................................ 59
B.49 +CPMS –Select Preferred SMS Message Storage .............................................................. 60
B.50 +CREG –Network Registration ........................................................................................... 61
B.51 +CSCA –SMS Service Center Address................................................................................. 62
B.52 +CSCB –Select Cell Broadcast Message Types ................................................................... 62
B.53 +CSCS –Select TE Character Set ......................................................................................... 63
B.54 +CSMS –Select SMS Message Service................................................................................ 63
B.55 +CSTA –Select Type of Address.......................................................................................... 64
B.56 +GMI –Manufacturer Identification................................................................................... 64
B.57 +GMM –Model Identification ............................................................................................ 65
B.58 +GMR –Revision................................................................................................................. 65
B.59 +GSN –Serial Number......................................................................................................... 65
B.60 +GCAP –General Capabilities ............................................................................................. 65
B.61 A –Answer .......................................................................................................................... 65
B.62 D –Dial................................................................................................................................ 65
B.62.1D> –Direct Dial From Phonebook...................................................................................... 66
B.63 Hn –Hangup........................................................................................................................ 67
B.64 S0=n –Auto-Answer ........................................................................................................... 67
B.65 Xn –Extended Result Codes ............................................................................................... 67
B.66 +CLVL –Volume Level Control ............................................................................................ 68
B.67 +CMUT –Mute Control....................................................................................................... 69
B.68 +CRC –Cellular Result Codes .............................................................................................. 69
B.69 +CVHU –Voice Hangup Control.......................................................................................... 70
B.70 +CCLK –Real-Time Clock..................................................................................................... 70

A3LA-R User Guide Version A
Document Number: 451-93156-001A 8 of 158
B.71 –MSVTS –DTMF Generation in Voice Call.......................................................................... 71
B.72 –MSVTR –DTMF Received in Voice Call ............................................................................. 72
B.73 –MSVLS –Local DTMF Feedback Selection......................................................................... 72
B.74 –MSSTM –Request System Time ....................................................................................... 73
B.75 –MSGEO –Request Geolocation ........................................................................................ 74
B.76 +CCFC –Call Forward Service.............................................................................................. 75
B.77 +CLCC –Request Current Call Status .................................................................................. 76
B.78 +CNUM –Read MSISDN Numbers...................................................................................... 77
B.79 +CSSSC –Supplementary Services Short Code ................................................................... 77
B.80 +WIRLP –Iridium Radio Link Protocol ................................................................................ 77
B.81 +WFRNG –Force IRLP Renegotiation ................................................................................. 79
B.82 +WTM –IRLP Test Mode..................................................................................................... 80
B.83 +WDLDM –IRLP Dynamic Link Delay Measurement.......................................................... 80
B.84 +WDAV –Register or Deregister an RS232 DAV Data Peripheral....................................... 81
B.85 +SBDWB –Short Burst Data: Write Binary Data................................................................. 81
B.86 +SBDRB –Short Burst Data: Read Binary Data ................................................................... 82
B.87 +SBDRT –Short Burst Data: Read Text Message................................................................ 83
B.88 +SBDD –Short Burst Data: Clear SBD Message Buffer(s)................................................... 84
B.89 +SBDC –Short Burst Data: Clear SBD MOMSN................................................................... 84
B.90 +SBDS –Short Burst Data: Status........................................................................................ 85
B.91 +SBDTC –Short Burst Data: Transfer MO Buffer to MT Buffer .......................................... 85
B.92 +CAR –Audio Output Control ............................................................................................. 86
B.93 In –Identification................................................................................................................ 86
B.94 +CIER –Indicator Event Reporting...................................................................................... 86
B.95 +CRIS –Ring Indication Status ............................................................................................ 88
B.96 +CSQ[F] –Signal Quality...................................................................................................... 89
B.97 +CULK –Unlock................................................................................................................... 90
B.98 +CVMI –Voicemail Indication............................................................................................. 91
B.99 +CICCID –Read ICC ID from SIM ......................................................................................... 91
B.100 +CLIP –Calling Line Identification Presentation ................................................................. 91
B.101 +CLIR –Calling Line Identification Restriction .................................................................... 93
B.102 +IPR –Fixed DTE Rate ......................................................................................................... 94

A3LA-R User Guide Version A
Document Number: 451-93156-001A 9 of 158
B.103 +SBDWT –Short Burst Data: Write a Text Message........................................................... 94
B.104 +SBDDET –Short Burst Data: Detach.................................................................................. 95
B.105 +SBDI –Short Burst Data: Initiate an SBD Session.............................................................. 96
B.106 +SBDIX[A] –Short Burst Data: Initiate an SBD Session Extended....................................... 98
B.107 +SBDDSC –Short Burst Data: Delivery Short Code........................................................... 101
B.108 +SBDMTA –Short Burst Data: Mobile-Terminated Alert ................................................. 102
B.109 +SBDREG –Short Burst Data: Network Registration ........................................................ 102
B.110 +SBDAREG –Short Burst Data: Automatic Registration ................................................... 105
B.111 +SBDSX –Short Burst Data: Status Extended ................................................................... 106
B.112 +ADJANT –User Antenna Adjustment Required.............................................................. 108
B.113 +WANTST, +ANTST –Antenna status ............................................................................... 108
B.114 +PCDA –Pending call drop alert ....................................................................................... 109
B.115 +DPLCI –DPL Call Indication ............................................................................................. 109
B.116 +CCWA –Call Waiting service........................................................................................... 110
B.117 +CLCK –Facility Lock ......................................................................................................... 113
B.118 +CPWD –Change Password.............................................................................................. 115
B.119 +CSDT –Sidetone.............................................................................................................. 116
B.120 +CHLD –Call Hold and Multiparty .................................................................................... 117
B.121 +XCSI –Extended Call State Information.......................................................................... 118
B.122 +CDSI –Report SMS status ............................................................................................... 120
B.123 +GPSSTA –Configure GPS status ...................................................................................... 122
Appendix C: S-Register Definitions ................................................................................... 123
C.1 S-Register Commands....................................................................................................... 123
C.1.1 Sr –Direct S-Register Reference....................................................................................... 123
C1.2 Sr? –Direct S-Register Read............................................................................................. 123
C.1.3 Sr=n –Direct S-Register Write.......................................................................................... 123
C.1.4 ? –Referenced S-Register Read ....................................................................................... 123
C.1.5 =n –Referenced S-Register Write .................................................................................... 123
C.2 Standard S-Registers......................................................................................................... 124
C.3 Iridium-Specific S-Register Extensions.............................................................................. 126
Appendix D: Summary of Result Codes............................................................................. 130
Appendix E: Informative Examples................................................................................... 133

A3LA-R User Guide Version A
Document Number: 451-93156-001A 10 of 158
E.1 Unit Identification ............................................................................................................. 133
E.2 Setting the Default Configuration..................................................................................... 133
E.3 Power on to Send an SBD Message .................................................................................. 134
E.4 SBD Automatic Notification Registration.......................................................................... 135
E.5 SBD Automatic Notification Message Reception.............................................................. 135
E.6 SBD Automatic Notification Automatic Registration........................................................ 136
E.7 Originate a Data Call ......................................................................................................... 136
E.8 Answer a Data Call ............................................................................................................ 137
E.9 Disconnect a Data Call ...................................................................................................... 137
E.10 Coordinate +CLCC and +CPAS Responses ......................................................................... 138
Appendix F: Power Consumption ..................................................................................... 140
Appendix G: The Iridium Network .................................................................................... 146
G.1 Iridium Network Data Capabilities.................................................................................... 147
G.2 Dial-up Data Service.......................................................................................................... 148
G.3 Direct Internet Connection ............................................................................................... 150
G.4 Short Burst Data................................................................................................................ 151
G.5 Short Messaging Service ................................................................................................... 151
G.6 RUDICS .............................................................................................................................. 152
G.7 Iridium Geolocation .......................................................................................................... 152
Appendix H: Standards Compliance.................................................................................. 153
Appendix I: Certificate of Compliance............................................................................... 154
Appendix J: Export Compliance ........................................................................................ 155
Appendix K: Design Specifications.................................................................................... 156
K.1 Mechanical Specifications................................................................................................. 156
K.2 RF Specifications ............................................................................................................... 156
K.3 Electrical Specifications..................................................................................................... 156
K.4Environmental Specifications ........................................................................................... 157
K.5 Data I/O Specifications...................................................................................................... 157
K.6 Related Hardware ............................................................................................................. 157
Appendix L: Mechanical Drawing ..................................................................................... 158

A3LA-R User Guide Version A
Document Number: 451-93156-001A 11 of 158
TABLE OF FIGURES
Figure 1: Iridium Satellite Modem A3LA-R ................................................................................... 16
Figure 2: Power Input Setting for the A3LA-R............................................................................... 20
Figure 3: Location of the SIM Reader ........................................................................................... 22
Figure 4: Location of the SIM Reader ........................................................................................... 25
Figure 5: Iridium Satellite Modem A3LA-R ................................................................................... 26
Figure 6: Average Current Drawn During Standby ..................................................................... 141
Figure 7: Average Power Consumption During Standby ............................................................ 141
Figure 8: Average Current Drawn During a Data Switch Call...................................................... 142
Figure 9: Average Power Consumption During a Data Switch Call............................................. 142
Figure 10: Average Current Drawn During an SBD Transmission............................................... 143
Figure 11: Average Power Consumption During an SBD Transmission...................................... 143
Figure 12: Average Current Drawn During an SMS Transmission .............................................. 144
Figure 13: Average Power Consumption During an SMS Transmission ..................................... 144
Figure 14: Average Current Drawn During a Voice Call Using DPL Handset .............................. 145
Figure 15: Average Power Consumption During a Voice Call Using DPL Handset ..................... 145
Figure 16: Iridium Network Major Components ........................................................................ 146
Figure 17: Iridium Network Data Capabilities............................................................................. 148
Figure 18: PSTN Dial-up Connectivity ......................................................................................... 149
Figure 19: Iridium Dial-up Data Service ...................................................................................... 150
Figure 20: Certificate of Compliance .......................................................................................... 154
Figure 21: A3LA-R Mechanical Drawing...................................................................................... 158

A3LA-R User Guide Version A
Document Number: 451-93156-001A 12 of 158
TABLE OF TABLES
Table 1: Pin Assignments for the Multi-interface Connector....................................................... 17
Table 2: General RF Parameters ................................................................................................... 23
Table 3: Custom Antenna Specifications ...................................................................................... 23
Table 4: Numeric and Verbose Modes ......................................................................................... 35
Table 5: Standard S-Registers ..................................................................................................... 124
Table 6: Iridium-Specific S-Register Extensions.......................................................................... 126
Table 7: V.25ter/Hayes Result Codes.......................................................................................... 130
Table 8: GSM 7.07 Result Codes ................................................................................................. 131
Table 9: GSM 7.05 Result Codes ................................................................................................. 132
Table 10: Iridium-Specific Result Codes...................................................................................... 132
Table 11: Unit Identification ....................................................................................................... 133
Table 12: Default Configuration.................................................................................................. 133
Table 13: Power on to Send an SBD Message ............................................................................ 134
Table 14: SBD Automatic Notification Registration.................................................................... 135
Table 15: SBD Automatic Notification Message Reception........................................................ 135
Table 16: SBD Automatic Notification Automatic Registration.................................................. 136
Table 17: Originate a Data Call ................................................................................................... 136
Table 18: Answer a Data Call ...................................................................................................... 137
Table 19: Disconnect a Data Call................................................................................................. 137
Table 20: Coordinate +CLCC and +CPAS Reponses..................................................................... 138

A3LA-R User Guide Version A
Document Number: 451-93156-001A 13 of 158
GLOSSARY
ASCII ...........................American Standard Code for Information Interchange
AT ...............................Two-letter sequence starting a string of terminal commands. The AT is
intended to get the terminal’s attention prior to executing a command.
BIS...............................Bureau of Industry and Security
bps..............................bits per second
CE ...............................Conformité Européenne
CEP .............................circular error probability
CTS..............................Clear To Send
DAV.............................Data After Voice
DC...............................Direct Current
DCD ............................Data Carrier Detect
DCS.............................Distributed Control Systems
DoD.............................Department of Defense
DP...............................Data Peripheral
DPL .............................Digital Peripheral Link
DSN.............................Defense Switch Network
DSR.............................Data Set Ready
DTE.............................Data Terminal Equipment
DTMF..........................Dual-Tone Multi-Frequency
DTR.............................Data Terminal Ready
EAR.............................Export Administration Regulations
EMI .............................Electromagnetic Interference
EMSS ..........................Enhanced Mobile Satellite Services
ETSI.............................European Telecommunications Standards Institute
FCC .............................Federal Communications Commission
FDMA..........................Frequency-Division Multiple Access
GMT............................Greenwich Mean Time
GND............................Ground
GPRS...........................General Packet Radio Service

A3LA-R User Guide Version A
Document Number: 451-93156-001A 14 of 158
GPS.............................Global Positioning System
GSM............................Global System for Mobile Communications
GSS .............................Gateway SBD Subsystem
IMEI ............................International Mobile Equipment Identification
I/O ..............................Input / Output
IRLP.............................Iridium Radio Link Protocol
IP ................................Internet Protocol
IP67 ............................Ingress Protection 67
ISU ..............................Iridium Subscriber Unit (modems, phones, trackers)
kbps............................kilobits per second
LAN.............................local Area Network
LBT..............................L-Band Transceiver
LCD .............................Liquid-Crystal Display
LED .............................Light-Emitting Diode
MOMSN......................Mobile-Originated Message Sequence Number
ms...............................millisecond
MS ..............................Mobile Station
MTMSN ......................Mobile-Terminated Message Sequence Number
NIPRNet......................Non-classified Internet Protocol Router Network
OFAC...........................Office of Foreign Asset Controls
PDU ............................Protocol Data Unit
PIN..............................Personal Identification Number
PPP .............................Point-to-Point Protocol
PSTN...........................Public Switched Telephone Network
PUK.............................Personal Unblocking Key
RF................................Radio Frequency
RHCP...........................Right-Handed Circular Polarization
RI ................................Ring Indicator
RP ...............................Relay Protocol
RTS..............................Request To Send

A3LA-R User Guide Version A
Document Number: 451-93156-001A 15 of 158
RUDICS .......................Router-based Unrestricted Digital Internetworking Connectivity Solution
SatTerm......................Satellite Terminal emulator software
SBD.............................Short Burst Data
SIM .............................Subscriber Identification Module
SM ..............................Short Message
SME ............................Short Message Entity
SMS ............................Short Message Service
SMS-PP .......................Short Message Service—Point to Point
TCP .............................Transmission Control Protocol
TDD.............................Time-Division Duplex
TDMA .........................Time-Division Multiple Access
TE................................Terminal Equipment
TNC.............................Threaded Neill–Concelman (RF connector)
TPDU...........................Transfer Protocol Data Units
TP-PID.........................Transfer Protocol–Protocol Identifier
UART...........................Universal Asynchronous Receiver-Transmitter
VDC.............................Volts (Direct Current)
VSWR..........................Voltage Standing Wave Ratio

A3LA-R User Guide Version A
Document Number: 451-93156-001A 16 of 158
1INTRODUCTION
This document describes the electrical and mechanical interfaces of the A3LA-R. Model A3LA-R
is a satellite modem comprising a 9523 L-band transceiver (LBT) with an extended input voltage
range. It is designed to operate with the Iridium network. Similar to a standard landline modem,
the A3LA-R can be controlled by any data terminal equipment (DTE) capable of sending
standard AT commands via a serial port. A DTE can be a desktop computer, a laptop computer,
a smart phone, or even a microcontroller. The A3LA-R is functionally compatible with models
9522, 9522A, 9522B, A3LA-D, A3LA-R, and A3LA-RS. It is approximately 60% smaller in volume
and 50% lighter than the 9522B.
Services supported include:
1. Dial-up data switch
2. Direct internet connection (or NIPRNet connection)
3. Direct internet connection using Apollo Emulator (only for Department of Defense
(DoD) Enhanced Mobile Satellite Services (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
Figure 1: Iridium Satellite Modem A3LA-R
IMPORTANT: Do not disassemble the A3LA-R for repair or services. The warranty is voided if the
A3LA-R is disassembled. Return to NAL Research for any services.
DB25 Multi-Interface Connector
TNC Antenna Connector
SIM Reader Under the Lid

A3LA-R User Guide Version A
Document Number: 451-93156-001A 17 of 158
2MULTI-INTERFACE CONNECTOR
The multi-interface connector is a male 25-pin miniature D-Sub type (see Figure 1) that includes
five interfaces—RS232, DC input power, ON/OFF control line, analog audio, and Digital
Peripheral Link (DPL). The multi-interface connector pin assignments are summarized in Table
1, which is ‘pin-to-pin’.
Table 1: Pin Assignments for the Multi-interface Connector
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 4.0 V –5.5 V or 5.0 V –32.0 V
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 2.048 MHz audio clock output
Digital Audio
13
RX
RS232 Receive Data (Output)
RS232 Data
14
SIGNAL GND
Signal ground, 0 V signal reference and return
GND
15
MIC_AUD
Microphone audio input
Analog Audio
16
EXT_B+
External 4.0 V –5.5 V or 5.0 V –32.0 V
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, 0 V signal reference and return
GND

A3LA-R User Guide Version A
Document Number: 451-93156-001A 18 of 158
Table 1: Pin Assignments for the Multi-interface Connector
Pin #
Signal
Description
Interface
24
DA_RX
PCM digital audio input
Digital Audio
25
SIGNAL GND
Signal ground, 0 V signal reference and return
GND
2.1 RS232 DATA INTERFACE (STANDARD 9-WIRE CONFIGURATION)
The A3LA-R supports a standard RS232 data interface to a DTE incorporating hardware
handshaking and flow control. The RS232 data interface comprises 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-R’s modem functionality through standard
AT and extended sets of AT commands. These commands are defined in Appendix A: AT
Interface. The A3LA-R automatically adjusts to the DTE baud and overrides the +IPR setting
when dissimilar. Autobaud occurs on the following characters: ‘a’, ‘A’, and CR (carriage return).
Autobaud also occurs on the escape sequence character, provided this is an odd number of
characters. Normally this is set to ‘+’ in register S2 (see Appendix A: AT Interface for details).
Note that the Ring Indicator is used by the A3LA-R 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-R to retrieve the MT-SBD message.
2.2 RS232 DATA INTERFACE (3-WIRE CONFIGURATION)
A 3-wire RS232 data interface may also be implemented. Because of risk of overrun and data
loss, especially at high bauds, the 9-wire interface is the recommended implementation. Take
the steps below to allow 3-wire configuration (i.e., only use S_TX, S_RX, and SIGNAL GND).
These steps ensure the A3LA-R and Data Terminal Equipment (DTE) to work together without
having hardware handshaking.
1. Ensure the modem’s Data Terminal Ready (DTR) line is held high. Using the modem’s
input voltage is fine for this purpose BUT ONLY if the input voltage is less than 5 VDC
(see important note below). Looping back the modem’s DSR line to DTR line will NOT
work. Leave the Data Set Ready (DSR) line on the modem unconnected.

A3LA-R User Guide Version A
Document Number: 451-93156-001A 19 of 158
2. Disconnect the (Clear To Send) CTS, (Data Carrier Detect) DCD, DSR, DTR, Request To
Send (RTS), and Ring Indicator (RI) lines between the DTE and modem.
3. Set AT&Dn to AT&D0 to ignore the DTR input from the DTE.
4. Set AT&Kn to AT&K0 for no flow control or AT&K4 for XON/XOFF software 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; choose either as a default profile. The relevant commands are &Wn
and &Yn.
a. &Wn stores the present configuration in profile <n>, where <n> can be either 0 or
1.
b. &Yn designates which profile is loaded after reset or power-up; <n> is either 0 or 1.
6. Address any needs of the DTE separately.
WARNING: DO NOT use the modem’s input voltage to bring the DTR line high when the input
voltage is higher than 5 VDC. Supplying voltage higher than 5 VDC to the DTR line will
permanently damage the A3LA-R.
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.
2.3 DC POWER INPUT
The DC power input is through pins 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 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. Keep cables used to supply power
to the A3LA-R as short as possible to prevent significant voltage drop, which can cause the
A3LA-R to malfunction during a data call, an SMS session, or an SBD session. Power reset by the
A3LA-R during a call indicates the DC power source is unable to sustain voltage above 4.0 V at

A3LA-R User Guide Version A
Document Number: 451-93156-001A 20 of 158
peak current demand. Appendix F: Power Consumption provides the electrical power profile of
the A3LA-R.
The A3LA-R accepts either +4.0 V to +5.5 V or +5.0 V to +32 V input. The A3LA-R is shipped with
hardware set for +5.0 V to +32 V input. It can be changed to +4.0 V to +5.5 V input through an
internal jumper—DISCONNECT POWER BEFORE RESETING THE JUMPER. Find the jumper by
removing the modem’s bottom plate. With the A3LA-R held in the position shown in Figure 2
(DB25 connector to the left), the A3LA-R is set for 4.0 V to +5.5 V when the red jumper is on the
middle and left pins, and it is set for +5.0 V to +32 V when the jumper is on the middle and right
pins. Each pin is also labeled with 5 V and 32 V to the left and right pins, respectively.
Note: You MUST remember the input voltage setting on the A3LA-R and not to apply voltage
above the maximum limit (of either 5.5 V or 32 V). The A3LA-R will be damaged beyond repair
with warranty voided if this were to occur.
Figure 2: Power Input Setting for the A3LA-R
IMPORTANT: You can remove the A3LA-R’s bottom plate to set the jumper but not for repair or
services. The warranty is voided if the A3LA-R is disassembled for any reason other than to set
the jumper.
2.4 POWER ON/OFF CONTROL
With the EXT_ON_OFF pin left unconnected, the A3LA-R automatically turns on or off when
external DC power is applied or removed. Prior to turning the A3LA-R off, issue command
AT*P0 to ensure all memory-write activity is completed. When the A3LA-R is powered off, its
internal power-on-reset circuit requires two seconds for voltages to decay. Do not reapply
power until this time has elapsed. If the two-second wait time is not followed, the reset circuit
Red jumper used to
set input voltage
range