Nomadic NMX920 Assembly Instructions

NOMADIC
COMMUNICATIONS
NMX920
OEM Integrators Guide
Version 1.02
December 1999

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1. Record of Issue
Issue Issued by Date Nature of Amendment(s)
1.0 BH 17.11.1999 Draft release
1.01 BH 26.11.1999 Added PCB layout dimensions for plug in
modem option.
1.02 BH 09.12.1999 Update of Modem I/O for improved performance
1.03 BH 03.01.2000 Added SAR compliance results
Any and all specifications are subject to change by Nomadic Communications Pty Ltd without notice except to the appropriate spectrum management authorities.
The information in this specification is deemed reliable at the time of printing. Nomadic Communications does not assume responsibility for any errors that may
appear in this specification nor any omissions that may have occurred at the time of printing. Interested parties must therefore rely on their own enquires. Nomadic
Communications does not assume liability arising from the application or use of any information contained in this document or the product referred to by this
document. Mobitex® is a registered trademark of Telia AB, Sweden.

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2. Contents
1. Record of Issue........................................................................................................ 2
2. Contents .................................................................................................................. 3
3. Scope ...................................................................................................................... 4
3.1. Standards ......................................................................................................... 4
3.2. Applicability....................................................................................................... 4
4. Interface Notes......................................................................................................... 5
5. Physical Requirements ............................................................................................ 6
5.1. Dimensions....................................................................................................... 6
5.2. System Interface............................................................................................... 6
5.3. RF Port ............................................................................................................. 7
5.4. Power Supply.................................................................................................... 7
5.5. Board to Board Connection............................................................................... 9
6. Modes Of Operation............................................................................................... 10
6.1. Application of power........................................................................................ 11
6.2. Network Contact ............................................................................................. 11
6.3. Mode Change ................................................................................................. 11
6.4. Shutdown........................................................................................................ 12
6.5. Removal of power........................................................................................... 12
7. Notes for Integrators .............................................................................................. 13
7.1. Antenna .......................................................................................................... 13
7.2. Human Exposure Issues................................................................................. 13
7.3. Power Supply.................................................................................................. 14
7.4. Operational Notes........................................................................................... 15
8. Mobitex Compliance............................................................................................... 16
9. Technical Specification .......................................................................................... 18
10. Development Tools............................................................................................. 19
10.1. NMD920 Modem Evaluation Kit.................................................................. 19
10.2. ModmTest ................................................................................................... 19
11. Ordering Information........................................................................................... 20
12. References......................................................................................................... 21

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3. Scope
The NMX920 Radio Packet Modem is a second generation product providing system
integrators access to 900 MHz Mobitex Networks.
This OEM Integrators Guide documents the behaviour and control of the NMX920 to
enable OEM designers to correctly and efficiently interface with the modem. This
document is concerned with the physical, interface and regulatory issues related to the
use of NMX920. It does not address the issues of good wireless application design, or
code generation, though references to these issues can be found in section ……
3.1. Standards
The NMX920 operates in the 900 MHz SMR (Specialised Mobile Radio) Band in
North America.
The NMX920 is designed to comply with established system and RF standards.
The standard documents listed here are for reference only, and are subject to
change or revision at any time.
Mobitex
Approval Standards: Mobitex Operators Association (MOA)
Documents: Mobitex Interface Specification, Revision R4A, October 1998
Approval Authority: BellSouth Wireless Data
USA
Approval Standards: Federal Communications Commission, FCC, USA
Documents: CFR47, Parts 2, 15, 90
Approval Authority: FCC
Canada
Approval Standards: Industry Canada, IC, Canada
Documents: RSS-119
Approval Authority: Industry Canada
3.2. Applicability
The content of this document is valid for the Nomadic Communications NMX920
Mobitex Radio Modem, with firmware versions greater than 2.01

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4. Interface Notes
qPermanent damage can occur to the NMX920 if operated without a properly
connected 50-ohm antenna and cable (eg. RG-174). Care should be taken to ensure
that the antenna and cable are correctly matched to the NMX920.
qNMX920 must be properly subscribed with the approved MOBITEX Network
Operator in the country of intended operation before use. Care should be taken not to
operate an unregistered NMX920.
qWhen power is applied to the NMX920 power pins it will enter POWER-OFF MODE
(see section 6 below) waiting to sense a “power on request” via the correct assertion
of DTR pins (see section 6 below).
qWhen operated for the first time, via the correct assertion of the DTR pin (see section
6 below), the NMX920 may take several minutes as it attempts to become BORN on
its’ registered MOBITEX Network. Once BORN, the NMX920 will enter its default
mode, Battery Save or Express, as programmed at time of manufacture. The Mode
may be changed by the relevant MASC command.
qNMX920 should always be operated as described in this document, special attention
should be given to power handling detailed in section 6.

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5. Physical Requirements
5.1. Dimensions
The overall dimensions of the NMX920 are provided below. It should be noted that
the NMX920 can be ordered with a variety of termination options. It is the
integrator’s responsibility to specify these options as required and maintain
sufficient space around the modem for cable access, if required.
The integrator is also required to maintain adequate ventilation about the NMX920.
The amount of ventilation required will be dependent on the worst case transmit
duty cycle that could be expected from the wireless application. Failure to provide
adequate ventilation will not damage the NMX920, but if power amplifier
temperature exceeds safe operating limits, the NMX920 will perform a controlled
shutdown.
MMCX
RF Connector
Locating pin x 3
NMX920
102 mm
System
Interface
30 Way
(2 x 15)
55 mm
12 mm High
1
2930
2
5.2. System Interface
The System Interface port on the NMX920 provides power, serial communication
and status indicators between the OEM device and the modem. In addition to the
user signals, there are a number of signals that are used for manufacturing
purposes. Only the signals listed below may be used for system interconnection.
All other signals should be ‘no connects’.
The standard system interface connector is a 2 x 15 x 2 mm pitch connector. The
NMX920 may be ordered with this connector mounted on the top for cable
interface, or underneath for board to board connection. Refer to the Ordering
Information.
The NMX920 is available with either a RS-232 serial interface, or a TTL (5V) serial
interface. This is an order time option, and is not retrofitable in the field. Refer to
the Ordering Information

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Host Interface Connector
Pin# Pin Name Type/Direction1Description
1-4PWR VBAT Main power supply input
5-8GND
GND Ground (Reference ground for all host interface signals)
9RXD TTL/RS232 output Main serial data receive (optional 5V TTL or
RS-232 DCE compatible output)
10 TXD TTL/RS232 input Main serial data transmit (optional 5V TTL or
RS-232 DCE compatible input)
11 DTR TTL/RS232 input System power-on control (optional 5V TTL or
RS-232 DCE compatible active edge triggered
input)
12 RFU No Connect2Reserved for Future Use
13 RFU No Connect Reserved for Future Use
14 RFU No Connect Reserved for Future Use
15 /RADIO_LED Output Radio-on indicator (active low 5V TTL output)
16 /RX_LED Output Receive packet indicator (active low 5V TTL
output)
17 /MODE_LED Output Network mode indicator (active low 5V TTL
output)
18 /TX_LED Output Transmit packet indicator (active low 5V TTL
output)
19 /NET_LED Output Network contact indicator (active low 5V TTL
output)
20 /PWR_LED Output Power-on indicator (active low 5V TTL output)
21 NC No Connect
22 NC No Connect
23 SYSON
+5V_IN System power-on indicator (active high, high impendence digital output)
24 EXTBAT -(Optional) Standby power supply input (4.75-
5.5VDC @ 100mA maximum)
25 NC No Connect
26 NC No Connect
27 NC No Connect
28 NC No Connect
29 NC No Connect
30 NC No Connect
1Direction with respect to the Modem
2All No Connects must be left Open Circuit
5.3. RF Port
The NMX920 is designed to operate with a 50 ohm antenna system. It is fitted with
a MMCX miniature RF connector. As an order time option, the RF connector may
be a straight connector mounted on the bottom of the modem for board to board
connection, or a right angle connector on the top of the board pointing out, or
sideways. See Ordering Information for details.
5.4. Power Supply
Careful consideration must be given to the power supply design for the NMX920.
Whilst receive current is in the order of 100 mA, the transmitter requires 1.7 A

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during transmission. This current must be available instantly; the modem has less
than 15 msec to change from receive mode to transmit mode, and at this point the
power amplifier has finished its startup sequence. Additionally, the power supply
must be able to provide this current without voltage sag for a maximum length
transmission, about 980 msec. The OEM power supply should fall within the
following template for reliable modem operation.
7.5v
6.5v
2000mA OUTPUT
CURRENT
OUTPUT
VOLTAGE
The output voltage must stay within these limits for any transient load change
greater than 10uS.

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5.5. Board to Board Connection
The NMX920 is available in a direct board to board configuration. In this
configuration, the NMX920 mates directly with system interface and RF connectors
in on the OEM system. This configuration eliminates all modem cabling, resulting
in significant cost savings, and ease of assembly. This option is available at time
of ordering.
The dimensions of the required layout on the host unit are shown below.
Additionally electronic versions of this layout in CADINT format ise available from
Nomadic Communications for import into the system integrator’s CAD system.
Recommend Interface Connectors for Board to Board configuration
RF connector is a PCB surface mounted MMCX male, Part No. Johnson 135-3801-
201 straight plug receptacle or equivalent.
System Interface Connector is a surface mounted 2 x 15 x 2mm plug, Part No.
Samtec TMMH-115-01-S-DV-ES, or equivalent.

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6. Modes Of Operation
The NMX920 is a microprocessor controlled, hybrid electronic device with special
requirements for power quality and application. The NMX920 is designed to operate with
power applied to the External Interface at all times, and provides the ability to power
itself on and off under software and hardware control. Because of the nature of radio
transmissions, and the MOBITEX network, the NMX920 needs to be able to control its
own powering down to ensure that certain time–critical processes are completed and the
system is left in a known state. If possible, OEM designers should provide for this
behaviour by powering the NMX920 from a constant power source, or the same source
as the OEM equipment.
IMPORTANT!
Care should be taken not to remove power from the External
Interface without properly shutting down the NMX920 via the
MASC FO command. For further information see section “Power
Sequencing”
If power is removed from the External Interface, without correctly shutting down the
NMX920, the MOBITEX network will become unaware of the modem’s Active/Inactive
state. This situation is recoverable, however the sudden loss of power could result in loss
of buffered messages. This section outlines the procedures necessary to properly power
and control the NMX920.
The following diagram outlines the relationship between the three power modes and the
mechanisms for changing between them.
The NMX920 operates in one of three distinct power modes while power is applied to the
External Interface; POWER-OFF MODE, BATTERY SAVE MODE and EXPRESS
MODE. To provide control over the operational state, and power consumption of the
NMX920, the OEM can change between these modes by issuing certain MASC
commands and/or electrically activating the DTR line on the External Interface.
NO
POWER POWER-OFF MODE
Removal
of power
BATTERY
SAVE MODE
EXPRESS
MODE
Mode
change Mode change
Shutdown
"Power-on
request"
Application
of power
Network Contact
Operational
Shutdown
"Power-on
request"