Swarm M138 User manual

Swarm M138 Modem
PRODUCT MANUAL
Revision 1.20 · February 2022
©2022 Swarm Technologies, Inc.

Legal Notices
This User Manual provides user information and is provided “as is.” Swarm Technologies and its affiliated
companies, directors, officers, employees, agents, trustees or consultants (“Swarm”) assume no
responsibility for any typographical, technical, content or other inaccuracies in this User Manual. Swarm
reserves the right to revise this User Manual or withdraw it at any time without prior notice. You can find
the current version of this Swarm Modem User Manual at www.swarm.space.
SWARM MAKES NO GUARANTEES, CONDITIONS, WARRANTIES, OR REPRESENTATIONS, EITHER
EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION, ANY IMPLIED REPRESENTATIONS,
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USAGE, OR TRADE PRACTICE, USE, OR RELATED TO THE PERFORMANCE OR
NONPERFORMANCE OF ANY PRODUCTS, ACCESSORIES, FACILITIES, SERVICES OR USER
INFORMATION, EXCEPT AS EXPRESSLY STATED IN THE LIMITED WARRANTY. ANY OTHER
STANDARDS OF PERFORMANCE, GUARANTEES, CONDITIONS AND WARRANTIES ARE HEREBY
EXPRESSLY EXCLUDED AND DISCLAIMED TO THE FULLEST EXTENT PERMITTED BY LAW. THIS
DISCLAIMER AND EXCLUSION SHALL APPLY EVEN IF THE EXPRESS LIMITED WARRANTY
PROVIDED IN THE LEGAL INFORMATION BOOKLET FAILS OF ITS ESSENTIAL PURPOSE.
FURTHER, THE LIMITED WARRANTY COVERS THE SWARM M138 MODEM (INCLUDING
HARDWARE, SOFTWARE AND/OR FIRMWARE) AND ACCESSORIES ONLY, AND NO WARRANTY IS
MADE AS TO USER INFORMATION AND/ OR COVERAGE, AVAILABILITY OR GRADE OF SERVICE
PROVIDED BY SWARM SEPARATELY FOR SWARM SATELLITE SERVICES.
IN NO EVENT SHALL SWARM BE LIABLE, WHETHER IN CONTRACT OR TORT OR ANY OTHER
LEGAL THEORY, INCLUDING WITHOUT LIMITATION STRICT LIABILITY, GROSS NEGLIGENCE OR
NEGLIGENCE, OR IMPLIED WARRANTY, FOR ANY DAMAGES IN EXCESS OF THE PURCHASE
PRICE OF THE SWARM M138 MODEM (INCLUDING HARDWARE, SOFTWARE AND/OR FIRMWARE)
AND/OR ACCESSORIES AND/OR THE COST OF SWARM SATELLITE SERVICES PROVIDED, NOR
SHALL SWARM BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
CONSEQUENTIAL, OR PUNITIVE 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 SWARM MODEM-M138 (INCLUDING HARDWARE, SOFTWARE AND/ OR
FIRMWARE) AND/OR ACCESSORIES AND/OR THE SWARM SATELLITE SERVICES, OR ARISING
OUT OF OR IN CONNECTION WITH THE ABILITY OR INABILITY TO USE THE SWARM
MODEM-M138 (INCLUDING HARDWARE, SOFTWARE AND/OR FIRMWARE) AND/OR
ACCESSORIES AND/OR THE SWARM SATELLITE SERVICES , TO THE FULLEST EXTENT THESE
DAMAGES MAY BE DISCLAIMED BY LAW AND REGARDLESS OF WHETHER SWARM WAS
ADVISED OF THE POSSIBILITIES OF SUCH DAMAGES.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 2

Third Party Information
This User Manual might refer to third party sources of information, hardware or software, products or
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responsible for, any third party information, including without limitation the content, accuracy, copyright
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Swarm of the third party information. ANY THIRD PARTY INFORMATION THAT IS PROVIDED WITH
SWARM’S FACILITIES, SERVICES, PRODUCTS OR USER INFORMATION IS PROVIDED “AS IS.’’
SWARM MAKES NO REPRESENTATIONS, GUARANTEES OR WARRANTIES IN RELATION TO
THIRD PARTY INFORMATION AND SWARM SHALL NOT BE LIABLE FOR ANY LOSSES, DAMAGES,
LIABILITIES, JUDGMENTS, FINES, AMOUNTS PAID IN SETTLEMENT, EXPENSES OR COSTS OF
DEFENSE SUSTAINED IN RELATION TO ANY SUCH THIRD PARTY INFORMATION.
Intellectual Property, Trade Secret, Proprietary or Copyrighted Information
To protect Swarm proprietary and confidential information and/or trade secrets, this User Manual may
describe some aspects of Swarm technology in generalized terms. Swarm products may include
copyrighted Swarm and third party software. Any such copyrighted software contained in Swarm products
may not be modified, reverse engineered, distributed or reproduced in any manner to the extent provided
by law. The purchase of any Swarm products shall not be deemed to grant either directly or by implication
or otherwise, any license under copyrights, patents, or patent applications of Swarm or any third party
software provider, except for the normal, nonexclusive, royalty free license to use that arises by operation
of law in the sale of a product.
Content Copyright
You are exclusively responsible for the use of the Swarm Modem-M138, including proper use of third
party copyrighted materials. If you violate these terms you agree to defend, indemnify and hold Swarm
harmless with respect to any claims or actions by third parties related to your improper use of copyrighted
materials and to pay all costs, damages, fines and other amounts incurred by Swarm, or on its behalf, in
the defense of any such claims or actions.
Export Compliance
The Swarm Modem-M138 is controlled by the export laws and regulations of the United States of
America. The U.S. Government may restrict the export or re-export of this product to certain individuals
and/or destinations. For further information, contact the U.S. Department of Commerce, Bureau of
Industry and Security or visit www.bis.doc.gov
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 3

Revision History
Revision
Date
Comment
Firmware
Version
1.00
11/11/21
Swarm M138 Modem Product Manual - Initial Release
1.01
12/01/21
Corrected pinout table
Updated $GN and $GS descriptions
Updated Modem status message structure
Updated date/time format to reflect YYYY-MM-DDTHH:MM:SS
1.02
12/07/21
Updated Table 6 to reflect Figure 4
1.10
01/12/22
Updated transmit current measurements
Removed section 3.3
Updated T/R pin notes
Updated $GP command description
Updated M138 Modem images
Updated regulatory information
1.11
01/20/22
Added antenna guidance to Section 6
1.20
02/15/22
Updated power characteristics for all M138 operating modes
Updated RSSI_bkgnd operating range
Updated GPIO1 mode description
GPS Cold/Warm start flowchart and timings
1pps pin removed
$MT L=U command option removed
Updated capacitance and inductance table
2.0.0
Additional Resources:
Please visit our developer tools webpage for quickstart guides and other helpful resources:
https://swarm.space/developertools
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 4

Revision History 4
Additional Resources: 4
1 Safety Information and Compliance 7
1.1 FCC Compliance 7
1.2 ISED Compliance 8
1.3 RF Exposure Guidance 8
1.4 EU RED Certification 9
1.5 Transceiver Regulatory Certification 9
2 Product Overview 10
3 Mechanical Specification 11
3.1 Modem Dimensions 11
3.2 Environmental 12
4 Electrical Interfaces 13
4.1 User Host Device 13
4.2 Modem Pin Allocation 14
4.3 DC Power Interface 16
4.4 Power On/Off Control 19
4.5 Serial Data Interface 19
4.6 LED Indicators 20
5 Design Guidance 21
5.1 Input Connections 21
5.2 Decoupling and Feed-through Capacitors 21
5.3 Input Voltage Examples 22
5.4 Communications 24
5.4.1 Level Shifting 25
5.5 Example Power Regulation Design 26
6 RF Interfaces 28
6.1 RF Connectors 28
6.2 RF Antenna 28
6.2.1 Antenna Characteristics 29
6.2.2 Ground Plane Requirements 30
6.3 Antenna Debugging 32
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7 Software interface 33
Message types 33
General command structure 33
Command timing 34
Command responses 34
Boot-up sequence 35
GPS Date/Time Reference 35
Messages 36
Table of Commands and Messages 37
$CS - Configuration Settings 38
$DT - Date/Time Status 39
$FV - Firmware Version Read 42
$GJ - GPS Jamming/Spoofing Indication 43
$GN - Geospatial Information 45
$GP - GPIO1 Control/Status 48
$GS - GPS Fix Quality 52
$MM - Messages Received Management (2-way operation) 55
$MT - Messages to Transmit Management 59
$PO - Power Off 62
$PW - Power Status 63
$RD - Receive Data Unsolicited Message 65
$RS - Restart Device 66
$RT - Receive Test 67
$SL - Sleep mode 70
$M138 - Modem Status Unsolicited Message 73
$TD - Transmit data 74
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 6

1 Safety Information and Compliance
The Swarm M138 Modem is designed to comply with the standards for Radio Emissions
Compliance and Electromagnetic Compatibility in the United States, Canada, Australia, New
Zealand, United Kingdom, European Union, Brazil, as well as worldwide.
1.1 FCC Compliance
1.1.1 FCC Interference Statement (Part 15.105 (b))
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with
the instructions, may cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one of the
following measures:
● Reorient or relocate the receiving antenna.
● Increase the separation between the equipment and receiver.
● Connect the equipment into an outlet on a circuit different from that to which the receiver
is connected.
● Consult the dealer or an experienced radio/TV technician for help.
This device complies with part 15 of the FCC Rules. Operation is subject to the condition that
this device does not cause harmful interference.
1.1.2 FCC Part 15 Clause 15.21:
Changes or modifications not expressly approved by the party responsible for compliance could
void the user's authority to operate the equipment.
1.1.3 FCC Part 15.19(a):
This device complies with part 15 of the FCC Rules. Operation is subject to the following two
conditions: (1) This device may not cause harmful interference, and (2) this device must accept
any interference received, including interference that may cause undesired operation.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 7

1.1.4 FCC ID:
The FCC ID for the Swarm M138 Modem is 2AVE9-M138. All manufacturers integrating the
Swarm M138 Modem into their products are required to provide a physical or e-label stating
“Contains FCC ID: 2AVE9-M138”.
1.1.5 Part 15 Subpart B Disclaimer:
The final host product requires Part 15B compliance testing with the modular transmitter
installed.
1.2 ISED Compliance
1.2.1 ISED RSS-Gen Notice CAN ICES-3 (B)NMB-3(B):
This device complies with Industry Canada’s license-exempt RSSs. Operation is subject to the
following two conditions:
(1) This device may not cause interference; and
(2) This device must accept any interference, including interference that may cause undesired
operation of the device.
Le présent appareil est conforme aux CNR d’Industrie Canada applicables aux appareils radio
exempts de licence. L’exploitation est autorisée aux deux conditions suivantes :
1) l’appareil ne doit pas produire de brouillage;
2) l’appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est
susceptible d’en compromettre le fonctionnement.
1.2.2 IC ID:
The IC ID for the Swarm M138 Modem is 25817-M138. All manufacturers integrating the Swarm
M138 Modem into their products are required to provide a physical or e-label stating “Contains
IC ID: 25817-M138”.
1.3 RF Exposure Guidance
In order to comply with FCC / ISED RF Exposure requirements, this device and antenna must
be installed to provide at least 36 cm separation from the human body at all times.
Afin de se conformer aux exigences d'exposition RF FCC / ISED, cet appareil doit être installé
pour fournir au moins 36 cm de séparation du corps humain en tout temps.
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1.4 EU RED Certification
1.4.1 Declaration of Conformity:
Currently under review
1.4.2 Article 10(2)/(10):
Currently under review
1.5 Transceiver Regulatory Certification
The Swarm Modem is a regulatory approved modular transmitter that is designed to be
integrated into an enclosed host system. With appropriate external connections, the host can be
designed to meet full regulatory tests and sold as a regulatory certified product that meets FCC,
IC, and CE requirements. Table 1 below is a partial list of regulatory approvals.
Regulatory
Approvals
Radio Tests
EMC Tests
Safety Tests
FCC
FCC CFR47 Parts 2, 15, and 25
IC
Industry Canada RSS170 Issue 2 - March 2011
CE
ETSI EN 301 721
V2.1.1 (2016-05)
ETSI EG203 367
V1.1.1
CISPR 16-23:2010/A1:2010
EN 55032:2012
EN 6100-4-2/EN55024:2010
EN 6100-4-3/EN55024:2010
EN 6100-4-8/EN55024:2010
EN 62368-1:2014/A11:2017
Table 1: Overview of the Swarm M138 Modem regulatory approvals.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 9

2 Product Overview
The Swarm (Model: M138) satellite data modem transmits and receives data to and from
Swarm’s space network and is designed to be embedded into a third-party product. Swarm
backend systems support the delivery of customer data via a REST API or Webhook to the
cloud service of each user’s choice.
The Swarm Modem is a module suitable for a variety of low-bandwidth use cases: from
connecting people and tracking vehicles, ships, or packages to relaying sensor data for
agriculture, energy, and industrial IoT applications.
The Swarm Modem is a Mini-PCI Express Card that can be easily integrated into any new or
existing PCB design. The Swarm Modem communicates via a standard 3.3V CMOS serial
UART interface or a PC interface with a USB-to-serial converter.
Category
Description
Components
GPS, VHF radio with integrated T/R switch, U.FL connector for GPS and
VHF antenna, indicator LEDs, 3.3V serial interface, 3.3V GPIO
Onboard
Sensors
uBLOX GPS (lat/lon/alt), CPU Temperature
Dimensions
and Mass
51.0 mm x 30.0 mm x 5.3 mm, 9.6 g
See detailed description in the Mechanical Specification section.
Power
Mode
Typical
Peak
3.3V
5V
3.3V
5V
Sleep
-
-
80μA
110μA
Receiver Active
26mA
25mA
40mA
45mA
Transmitter On
850mA
550mA
1000mA
600mA
Protocol
Modified NMEA two-letter command set
Bit rate
1 kbps. Maximum packet size is 192 bytes
Table 2: Overview of the Swarm Modem.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 10

3 Mechanical Specification
3.1 Modem Dimensions
The overall dimensions of the Modem and its weight are summarized below.
Parameter
Value
Length
51.0 mm
Width
30.0 mm
Height
5.3 ±0.1 mm
Weight
9.6 g
Table 3: Modem Mechanical Dimensions and Weight.
Figure 1: Modem front and back views.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 11

3.2 Environmental
The environmental specifications of the Modem are summarized below. The Swarm Modem is
not conformally coated, and as such the user needs to provide any weatherproofing for their
application.
Parameter
Value
Operating Temperature Range
-40 °C to +85 °C
Storage Temperature Range
-40 °C to +85 °C
Operating Humidity Range
0% to 95%, non-condensing
Storage Humidity Range
0% to 95%, non-condensing
Table 4: Environmental Specifications.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 12

4 Electrical Interfaces
The following subsections contain information for the electrical interfaces of the Modem.
4.1 User Host Device
The user host device provides the following connections to the Modem:
● DC power supply input: 3.0V to 5.0V, (1000 mApeak at 3.3V)
○ EMI/RFI shielding CAN is required if using a switching DC power supply in order
to contain radiated emissions
○ Additional filtering of the power supply is highly recommended
■ See Design Guidance for best practices
● Data interface
○ 3.3V Serial Data Interface
● Satellite signal (Use the provided U.FL connector labeled VHF)
● GPS signal (Use the provided U.FL connector labeled GPS)
● GPIO1 (optional)
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4.2 Modem Pin Allocation
The pin numbering scheme of the Swarm Modem is shown in Figure 4. All pins are located on
the card edge of the Swarm Modem and are designed to fit in a standard mPCIE card
connector. The pin function assignment is given in Tables 6 and 7. Multiple supply grounds are
provided and all power pins / supply grounds are required to be connected to the power supply
in order to limit the current on any one pin. Multiple signal grounds are provided to reduce
cross-talk. Many pins are intentionally left empty, and must be left unconnected.
Figure 4: Modem pinout and pin number
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 14

Pin Number
Name
Type
Description
1,3,5-8,10,12,
14,16,19-20,
22-25,28,30-33,
36,38,44-49, 51
NC
NC
No Connection
2,39,41,52
VDD
Power
3.3V/5V at up to
1000mA/600mA
4,9,15,18,21,26,
27,29,34,35,37,
40,43,50
GND
Ground
Ground
11
UART_RX
Comms
3.3V serial receive
13
UART_TX
Comms
3.3V serial transmit
17
T/R
OUTPUT
Digital Output
Transmit/Receive indicator
*leave unconnected if not
used
42
GPIO1
Digital Output/Analog
Input
General purpose
input/output
Table 6: Modem pin numbers and descriptions.
Additional Notes
Pin Number
Note
42
Connection is unbuffered and connected directly to a GPIO on the Modem
processor. Configuration will be provided via serial commands. GPIO1 pin
is 3.3V tolerant and open drain, with a sink current limit of 8 mA (20 mA
with a relaxed VOL/VOH)
2, 39, 41, 52
The VDD connection points are in parallel with one another and power the
Modem. If the designer wants to enable a complete power off mode, a load
switch can be provided here
17
HIGH when transmitting
LOW when receiving
The state will not change faster than 500μs prior to the Modem beginning
to transmit and 500μs after the Modem has finished transmitting.
*leave open if not used
Table 7: Additional notes on pin numbers.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 15

4.3 DC Power Interface
The DC power interface consists of the DC power inputs as summarized below. The power
requirements apply to DC power measured at the Swarm Modem user connector input and not
at the output of the power supply. It is required that users incorporate the required bypass
capacitors for the supplied power input as can be seen in Design Guidance.
Name
Description
Min
Typ
Max
Unit
VCC
Module supply voltage
3.00
3.30
5.00
V
VCC Ripple
Module supply voltage ripple
-
-
75
mVpp
VCC Limits
Module supply voltage absolute limits
3.00
-
5.00
V
ICC (3.3V)
Current consumption - Sleep Mode
-
-
80
μA
Current consumption - Receiver Active
23
26
40
mA
Current consumption - GPS Acquisition Mode*
40
45
55
mA
Current consumption - Transmitter on
750
850
1000
mA
ICC (4.2V)
Current consumption - Sleep Mode
-
-
100
μA
Current consumption - Receiver Active
23
26
40
mA
Current consumption - GPS Acquisition Mode*
40
45
55
mA
Current consumption - Transmitter on
640
700
800
mA
ICC (5.0V)
Current consumption - Sleep Mode
-
-
110
μA
Current consumption - Receiver Active
23
26
45
mA
Current consumption - GPS Acquisition Mode*
40
45
55
mA
Current consumption - Transmitter on
500
550
600
mA
Table 8: Power supply characteristics for 3.3, 4.2, and 5.0V supplies to the Modem.
*Includes satellite receiver active current with GPS in acquisition mode. The Modem enters into GPS acquisition
mode for approximately 30 seconds after exiting from sleep mode, on powerup, or when the Modem needs to
re-acquire a GPS fix (approximately once every 4 hours) while the Modem is continuously powered on and not in
sleep mode.
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An example power profile for a Modem powered with 3.3V can be found below in Figure 5.
Figure 5: Example current use for a Modem with a 3.3 V input from wake-up, GPS acquisition, Transmit, Receive
mode, and then sleep mode. Note the two breaks in the y-axis scale.
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Transmissions from the Modem consist of short periods of high current draw conforming to the
following characteristics:
Parameter
Value
Note
Transmission
Length
3.7 s
Length of transmission for sending a 192 byte packet to
space. Actual length may be shorter with a smaller packet
size
Transmission
Energy
3.4
mW-hrs
(12.24 J)
Total amount of energy required for 1 transmission to
space (192 bytes), when using 3.3V
Recovery
Time
0.4s
When sending multiple messages, this is the minimum
amount of time that will pass before the Modem will
attempt another transmission
Table 9: Sample Modem transmission characteristics for sending a user payload of 192 bytes. Modem provided with
3.3V input.
Other electrical characteristics of the Modem can be found below:
Parameter
Value
Maximum power at antenna connector
1.122 W
Sum total of all capacitance
255 μF
Sum total of all inductance
16790 nH
Largest capacitor
47 μF
Largest inductor
15000 nH
Total Input Capacitance
57 μF
Table 10: Other electrical characteristics for the Modem
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4.4 Power On/Off Control
The Modem can be powered down with the use of the $PO*1F command. Once powered down,
it can be externally switched on/off by a user-supplied load switch on the VDD power rail.
After power to the Modem has been removed, power should not be restored until at least 1
second has elapsed.
If a Modem does not respond to software commands, remove power from the module, wait for
at least 1 second, and then power it back on. If the 1 second minimum wait time is not adhered
to, the reset circuit may not operate and the Modem could be placed in a non-operational state.
The state is not permanent and can be rectified by the above procedure.
4.5 Serial Data Interface
The serial data interface is a CMOS serial UART 3-wire (serial Rx, serial Tx, and ground)
interface at 3.3V digital signal levels over which the Modem transfers commands, responses,
and message data. The serial communication parameters can be found below.
Parameter
Value
Baud Rate
115200
Data Bits
8 Bits
Parity
None
Stop bits
1 Bit
Flow Control
None
Table 11: Serial communication parameters.
In addition, the electrical characteristics for SERIAL_RX, SERIAL_TX, and GPIO1 can be found
below.
Symbol
Parameter
Min
Typ.
Max
Unit
VIL
I/O input low level voltage
-0.3
-
0.3*3.3V
V
VIH
I/O input high level voltage
0.7*3.3V
-
3.3V
V
RPU/RPD
Weak pull up/down equivalent resistor
(for GPIO1)
25
40
55
kΩ
Table 12: Electrical characteristics for SERIAL_RX, SERIAL_TX, and GPIO1.
© 2022 SWARM TECHNOLOGIES SWARM M138 MODEM PRODUCT MANUAL · REV 1.20 · FEBRUARY 2022 PAGE 19

All customer messages, data, and settings are stored in non-volatile memory. As such, after a
power cycle, customer settings as well as any messages that have not yet been transmitted
over the Swarm network will be retained on the Modem. The read/write lifetime of the Modem
memory exceeds 20 years.
4.6 LED Indicators
The Modem contains three indicator LEDs, whose function is described below. All LEDs are off
when the Modem is placed into sleep mode.
LED
Function
Green
During the bootup sequence the green LED will be on solid for 3 seconds.
During normal operation after bootup and before shutdown, the green LED will blink
100ms every 5 seconds while the Modem is powered on. This is a “heartbeat”
indication that the Modem is working as expected.
Red
After power is applied until the Modem begins booting, the red LED will be on solid
for 10 seconds.
After bootup and while the Modem is acquiring a GPS fix, the red LED will flash
quickly until a valid GPS fix has been found. Then the red LED will shut off during
normal operation.
After waking up from sleep, and before a fresh GPS fix has been acquired, there
will be a single red LED flash every 5 seconds (following the green LED flash) until
a fresh GPS fix has been found. Then the red LED will again shut off during normal
operation.
During the shutdown sequence, the red LED will be on solid until 3.3V power is
removed from the board.
Blue
The blue LED will be on solid when the Modem is actively receiving from a Swarm
satellite
Table 13: LED functions.
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