Hemisphere GPS SBX-4 Assembly Instructions

875-0176-000
Integrator Guide
SBX-4
OEM Board
Revision: B2
January 12, 2018

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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.
ThisproductcomplieswiththeessentialrequirementsandotherrelevantprovisionsofDirective2014/53/EU.Thedeclarationofconformitymaybe
consultedathttps://hemispheregnss.com/About‐Us/Quality‐Commitment.
Copyright Notice
Copyright Hemisphere GNSS, Inc. (2017). All rights reserved.
No part of this manual may be reproduced, transmitted, transcribed, stored in a retrieval system or
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miniEclipseTM, PocketMax3 PCTM, PocketMax3TM, PocketMax3TM, S320TM, SBX-4TM, VectorTM,
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properties of their respective owners.
Patents
Hemisphere GNSS products may be covered by one or more of the following patents:
U.S. Patents
Australia Patents
6111549 6876920 7400956 8000381 8214111 2002244539
6397147 7142956 7429952 8018376 8217833 2002325645
6469663 7162348 7437230 8085196 8265826 2004320401
6501346 7277792 7460942 8102325 8271194
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6549091 7292186 7808428 8140223 8311696
6711501 7373231 7835832 8174437 8334804
6744404 7388539 7885745 8184050 RE41358
6865465 7400294 7948769 8190337
Other U.S. and foreign patents pending.
Notice to Customers
Contact your local dealer for technical assistance. To find the authorized dealer
near you:
Hemisphere GNSS, Inc
8515 East Anderson Drive
Scottsdale, AZ 85255 USA
Phone: [phone]
Fax: [phone]
[e-mail]
www.hgnss.com
Technical Support
If you need to contact Hemisphere GNSS Technical Support:
Hemisphere GNSS, Inc.
8515 East Anderson Drive
Scottsdale, AZ 85255 USA
Phone: [phone]
Fax: [phone]
[email protected]
Documentation Feedback
Hemisphere GNSS is committed to the quality and continuous improvement of our products and
services. We urge you to provide Hemisphere GNSS with any feedback regarding this guide by writing
to the following email
address: [e-mail].

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Table of Contents

Copyright Notice ............................................................................................................................................. i
Trademarks .................................................................................................................................................... i
Patents ........................................................................................................................................................... i
Notice to Customers ....................................................................................................................................... i
Technical Support .......................................................................................................................................... i
Documentation Feedback .............................................................................................................................. i
Terms and Definitions .................................................................................................................................. iii
Chapter 1: Introduction .................................................................................................................................. 1
Product Overview ........................................................................................................................................ 2
Chapter 2: Integrating the SBX-4 .................................................................................................................. 3
Mechanical Layout ....................................................................................................................................... 4
LED Indicators ............................................................................................................................................. 7
SBX-4 Block Diagram .................................................................................................................................. 8
SBX-4 Connector Pin Assignments ............................................................................................................. 9
Signal Lock Indicator Pin ........................................................................................................................... 10
Reset Pin ................................................................................................................................................... 11
Antenna Interface ...................................................................................................................................... 12
Radio Frequency Immunity and Emissions ............................................................................................... 12
SBX-4 Dual Serial Port Overview .............................................................................................................. 13
Single Serial Port Operation ................................................................................................. 1 3 
Dual Serial Port Operation .................................................................................................... 13
Factory Default Settings ............................................................................................................................ 14
SBX-4 Integration Summary ...................................................................................................................... 14
Chapter 3: SBX-4 Operation ....................................................................................................................... 16
Introduction .................................................................................................................................................. 1
Beacon Information ..................................................................................................................................... 1
Operating Modes ......................................................................................................................................... 2
Automatic Beacon Search (ABS) Mode ................................................................................. 2
ABS Global Search ................................................................................................................. 2
ABS Background Search ........................................................................................................ 3 
Manual Mode .......................................................................................................................... 3
Database Mode ...................................................................................................................... 3
NEW SBX-4 Commands ............................................................................................................................. 4
Evaluating Performance .............................................................................................................................. 6
Appendix A: Troubleshooting ........................................................................................................................ 7
Appendix B: Technical Specifications ......................................................................................................... A1
SBX-4 Specifications ................................................................................................................................. B2

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Terms and Definitions
The following table lists the terms and definitions used in this document
Term Definition
DGPS/DGNSS Differential GPS/GNSS refers to a receiver using Differential
Corrections.
Firmware Firmware is the software loaded into the receiver that controls
the functionalit
y
of the receiver and runs the GNSS en
g
ine.
GNSS Global Navigation Satellite System (GNSS) is a system that
provides autonomous 3D position (latitude, longitude, and
altitude) along with very accurate timing globally by using
satellites. Current GNSS providers are: GPS, GLONASS and
Galileo. BeiDou is expected to have
g
lobal covera
g
e b
y
2020.
GPS Global Positioning System (GPS) is a global navigation
satellite s
y
stem implemented b
y
the United States.
NMEA National Marine Electronics Association (NMEA) is a marine
electronics organization that sets standards for
communication between marine electronics.
RTCM Radio Technical Commission for Maritime Services (RTCM) is
a standard used to define RTK message formats so that
receivers from an
y
manufacturer can be used to
g
ether.
SBAS Satellite Based Augmentation System (SBAS) is a system that
provides differential corrections over satellite throughout a
wide area or re
g
ion.
Signal-to-Noise Ratio Signal-to-Noise Ratio (SNR) is the ratio of the message
content of the si
g
nal a
g
ainst the noise of the si
g
nal.
Subscription A subscription is a feature that is enabled for a limited time.
Once the end-date of the subscription has been reached, the
feature will turn off until the subscription is renewed.

SBX-4 Integrator Guide Chapter 1 - Introduction Page 1 of 22
Chapter 1: Introduction
Product Overview

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Chapter 1: Introduction
Product Overview
Welcome to the SBX-4 Integrator Manual and thank you for considering Hemisphere GNSS for
your differential GPS requirements. The purpose of this manual is to familiarize you with the
proper installation, configuration and operation of the SBX-4 beacon receiver module and to
introduce you the mechanical, electrical and communication properties of this OEM receiver.
This document provides instructions and recommendations related to a successful integration of
the SBX-4 engine.
The SBX-4 is an extremely sensitive 300 kHz minimum shift keying (MSK) demodulator. It obtains
differential GPS corrections broadcast by radio beacons adhering to standards such as
International Telecommunications Union M.823 and various broadcast standards in the frequency
range of 283.5 to 325.0 kHz.
This document is intended to assist a systems designer with the integration of the SBX-4.
Successful integration of this module within a system will require significant electronics expertise,
such as power supply design, serial port level translation, reasonable radio frequency
competency, an understanding of electromagnetic compatibility and circuit design and layout.
The SBX-4 engine is a low-level module intended for custom integration with the following
general integration requirements:
 Regulated power supply input (3.3 VDC +/- 3%) and 70 mA continuous
 Low-level serial port communications (3.3 V CMOS)
 The beacon antenna is powered with a separate regulated voltage source of 5 VDC
 The antenna input impedance is 50 ohms
The chapters that follow provide detailed information on the SBX-4 module, including the
hardware and software interface, in addition to various descriptions of technologies and features
that it supports.
Some notable features of the SBX-4 module are:
 Dual channel tracking for increased robustness
 Dual serial ports accommodate both NMEA and RTCM communications
 Certified IEC 61108-4 compliant
 Patented ceramic filter blocks out-of-band signals, optimizing reception
 Low power and lock status LEDs permit visual verification of receiver status
 Reverse compatibility ensures operation in existing SBX-2 and SBX-3 integrations
 Boot loader for firmware upgrade reliability

SBX-4 Integrator Guide Chapter 2
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Integrating the SBX-4 Page 3 of 22
Chapter 2: Integrating the SBX-4
Mechanical Layout
LED Indicators
SBX-4 Block Diagram
SBX-4 Connector Pin Assignments
Signal Lock Indicator Pin
Reset Pin
Antenna Interface
Radio Frequency Immunity and Emissions
SBX-4 Dual Serial Port Overview
Factory Default Settings
SBX-4 Integration Summary

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Chapter 2: Integrating the SBX-4 OEM Board
Mechanical Layout
Figures 1-1 to 1-3 provide the physical layout of the SBX-4 beacon receiver, including dimensions
and key components.
Note: Figure 1-1 to Figure1-3 dimensions are in inches.
Figure 1-1: Top-side view of SBX-4

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Figure 1-2: SBX-4 bottom view

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Figure 1-3: SBX-4 side view

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LED Indicators
The SBX-4 engine has two surface-mounted LED indicators located on the opposite side of the
board in relation to the header connectors. The red LED is for signaling the power-on status of
the receiver, labeled with “PWR” silk-screening. The green LED is for indicating signal acquisition,
labeled with “LOCK” silk-screening.
When power is applied to the SBX-4, the power LED illuminates and when the SBX-4 achieves
signal acquisition on a valid DGPS beacon, the lock LED illuminates.
Figure 1-4 shows the front and back of the SBX-4, including the illumination of the power and lock
LED indicators.
Figure 1-4: SBX-4, front and back

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SBX-4 Block Diagram
The SBX-4 accepts an analog input signal between 283.5 kHz and 325.0 kHz from an antenna into its front
end where it is filtered and converted to a digital output.
The Digital Signal Processor (DSP) demodulates GPS correction information from the digital stream. The
output of the SBX-4 is RTCM SC-104 DGPS correction data at a 3.3V CMOS interface level. Figure 1-3
provides a view of the block diagram. Figure 1-5 displays the block diagram.
Figure 1-5: Block diagram

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SBX-4 Connector Pin Assignments
The SBX-4 has two header connectors designated as J200 and J300, labeled with on-board silk-
screening. The J200 connector is a 1 x 4 pin header with 0.1 in (2.54 cm) spacing that provides
antenna power input, and signal distribution. The J300 connector is a 2 x 12 pin header with 0.1
in (2.54 cm) spacing that provides access to antenna power input, receiver serial ports, receiver
power, external reset and external lock indicator functions.
Table 1-1 provides pin-out information for connector J200:
Table 1-1: SBX-4 connector J200 pin-out (Samtec TSW-10407-G-S)
Pin Signal Description
1, 3 Ground Analog ground
2 RF signal input Antenna RF signal input
4 Antenna power output Antenna power supply 5 VDC
Table 1-2 provides pin-out information for connector J300:
Table 1-2: SBX-4 connector J300 pin-out (Samtec TSW 11207-G-D)
Pin Signal Description
1, 2 Antenna power in Antenna power supply input: 5
VDC
3, 4 SBX-4 power in Receiver power supply input:
3.3 VDC
14 TXD0 output, 3.3 V
CMOS
NMEA, RTCM and status output
15 TXD1 output, 3.3 V
CMOS
NMEA and status output
16 Lock Lock indicator (active high)
17 RXD0 Input, 3.3 V CMOS Command/query input
18 RXD1 Input, 3.3 V CMOS Command/query input
19 External reset input External reset input (active
low)
21, 22
23, 24
Ground Digital ground

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Note: In order to maintain backwards hardware compatibility with the SBX-3, it is possible to
power the SBX-4 with 5 V. The serial data output level will track the input voltage when greater
than 3.3 V is supplied. The serial data inputs will be tolerant to voltages up to the level of the
supplied input voltage.
Signal Lock Indicator Pin
Pin 16 of connector J300 may be used to drive an LED or sensor to indicate that the SBX-4 is
locked to a beacon signal and is demodulating RTCM SC-104 data. The maximum current
available from this pin is 5 mA at an input voltage 3.3 V. The output of this signal may be
transistor buffered within your integration if greater current is required.
Figure 1-6 illustrates an example lock indicator circuit.
Figure 1-6: Lock indicator circuit

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Reset Pin
Pin 19 of connector J300 may be used to reset the SBX-4. Activating the reset circuit of the SBX-
4 results in the same effect as cycling the input power to the receiver. The operating configuration
of the receiver before reset is maintained, including operating mode, baud rate, frequency and
MSK rate of the last tuned station.
Figure 1-7 illustrates an example reset switch circuit.
Figure 1-7: Reset switch circuit

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Antenna Interface
Power may be supplied to the antenna externally through the SBX-4 OEM beacon receiver in one
of two ways:
 Connect Pin 4 of J200 to the antenna power supply (+5 VDC) and connect pin 1 and 3
to ground
 Connect Pin 1 and 2 of SBX-4 connector J300 to the associated power supply (+5 VDC)
and connect pin 1 and 3 of J200 to ground
Pin 4 of connector J200 is internally connected to Pins 1 and 2 of connector J300. Antenna signal
input to the receiver is provided via Pin 2 of J200.
Note: The antenna input voltage is not current limited on the SBX-4 board. If current limiting is
required, the circuitry must be provided within your integration.
Note: External power applied to the SBX-4 for powering the antenna is internally coupled to the
signal input pin (Pin 2 of J300). You do not have to provide this circuitry within your integration.
If you intend to use a 4-pin connector (for example, Panduit CE100F22-4) and a length coaxial
cable to interface the antenna to the SBX-4, follow these instructions:
1. Connect the center conductor of the coaxial cable to Pin 2 of J200.
2. Connect the shield of the coaxial cable to Pin 1 or Pin 3 of J200.
Radio Frequency Immunity and Emissions
When integrating the SBX-4, ensure that complete integration does not emit significant noise
within the 283.5 to 325.0 kHz beacon band. In-band interference incident upon the SBX-4 or its
antenna can influence the reception enough that its quality may be degraded, resulting in a lower
SNR measurement with reduced GPS correction data throughput.
Beacon antennas are designed to pick up any radio frequency energy within the 283.5 to 325.0
kHz beacon band. Both beacon signals and environment noise will be picked up by the antenna
and amplified before going to the receiver. Eliminating the majority of noise within the beacon
band is crucial to achieve optimal system performance.
It is very important to consider the overall performance objectives of the system design with
respect to radio frequency emissions.
Certain nations and industries around the world require positioning and navigation electronics to
achieve certain levels of electromagnetic emissions.

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SBX-4 Dual Serial Port Overview
The SBX-4 features two full duplex serial ports (Port 0 and Port 1). Use of the second serial port
is an option as the SBX-4 supports identical functionality as its predecessor, the SBX-3 on Port 0.
The main purpose of the second serial port is to allow the continuous flow of RTCM data from
Port 0 to a GPS receiver while allowing monitoring of SBX-4 performance via NMEA response
messages on Port 1. Separating RTCM differential data from NMEA status data when output via
the same serial port poses software integration challenges and potential GPS RTCM reception
conflicts.
Single Serial Port Operation
Some integration designs using the SBX-4 beacon receiver include a micro-controller between
the beacon and GPS receiver to provide enhanced communication and data parsing capability.
Within this type of integration, it is possible for the micro-controller to command and query the
beacon receiver and to parse NMEA response strings from RTCM data without impeding the
continuous flow of RTCM data to the connected GPS sensor.
To separate NMEA messages from RTCM data output by Port 0 through a parsing routine,
without causing a parity failure of the RTCM, it is necessary to take advantage of the fact that “$”
and “<LF>” are not supported within the RTCM specification, provided there are no bit errors in
the RTCM stream to start with. Therefore, if a “$” is received, then it should be considered as the
beginning of a NMEA sentence and a “<LF>” should be expected within a window of certain
length. If the parsing routine does not receive one, due to an unlikely communication line error,
after a window of a particular number of bits has passed, re-synchronization to the RTCM data
must occur.
Note: If port 1 is not being used, pin 18 should be connected to the input power supply through a
10 Kohm resistor.
Dual Serial Port Operation
Although an integration may be designed with a microprocessor between the SBX-4 and the GPS
receiver to tune and monitor SBX-4 status, the second serial port of the SBX-4 eliminates the
requirement to develop a NMEA message parsing algorithm.
With this type of architecture, the SBX-4’s main serial port may be interfaced to the GPS
receiver’s receive line to provide RTCM correction data. The secondary serial port interfaces to
the microprocessor for NMEA configuration and querying. This ensures that NMEA response
messages do not interrupt the continuous flow of RTCM data to the GPS receiver.

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Factory Default Settings
Table 1-3 presents the factory default SBX-4 operating mode, while Table 1-4 lists the default
SBX-4 communication settings. These operation and port settings are valid upon initial power-up.
The SBX-4 maintains any changes made to its operating or port settings in non-volatile memory
for subsequent power cycles.
Table 1-3: Default SBX-4 operating mode
Tune mode
Automatic
Table 1-4: Default SBX-4 port settings
Baud Rate Data Bits Parity Stop bit Interface level
4800 8 None 1 3.3 V CMOS
SBX-4 Integration Summary
The following steps summarize the general requirements for integrating the SBX-4 and identifies
the command and control features provided:
1. SBX-4 Power Input - Apply a 3.3 VDC power input to Pin 3 of J300 with the power-
return connection at Pin 21 of J300.
2. Antenna Power Input - Apply +5 VDC to either
• Pin 4 of J200 with an antenna power ground connection on Pin 1 of J200
-or-
• Pin 1 of J300 with an antenna power ground connection to Pin 1 of J200
3. Antenna Signal Input to SBX-4 - Connect the coaxial cable center conductor to Pin 2
of J200 and the shield to Pin 3 of J200.
4. SBX-4 Serial Ports - The SBX-4 serial ports communicate at a 5 V CMOS interface
level. You must provide level translation circuitry to connect to a standard RS232/422
type device. Pin assignments for the communication ports of the SBX-4 are as
follows:
• Pin 14 of J300 - TXD0, this is the Port 0 transmit data output from the SBX-4
• Pin 15 of J300 - TXD1, this is the Port 1 transmit data output from the SBX-4
• Pin 17 of J300 - RXD0, this is the Port 0 receive data input to the SBX-4
• Pin 18 of J300 - RXD1, this is the Port 1 receive data input to the SBX-4
• Pin 23 of J300 - Signal return, Port 0
• Pin 24 of J300 - Signal return, Port 1

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5. The following events occur when the SBX-4 is powered-up, or reset:
• Receiver serial number is output
• Configuration and beacon tables are verified and defaulted if required
• Software identification and version are reported
• Channel status information is reported
The following strings are output by the SBX-4 during power up or following receiver reset:
$PCSI,DGPS,P0
$PCSI,S/N:00019001
$PCSI,FCFGcrc,CBF8,CCFGcrc,CBF8,Pass
$PCSI,FGLBcrc,448A,CGLBcrc,448A,Pass
$PCSI,FLSHcrc,1C12 Pass
$PCSI,FSTAcrc,FBEA User,FFFF,FFFF
$PCSI,SBX~4 P030-0 2 Channel DGPS Version 001
$PCSI,F2835,0,R100,0,C0,0
$PCSI,F2835,0,R100,0,C1,0
6. When powered for the first time, the SBX-4 will operate in the default ABS mode and
will conduct a Global Search (GS) to identify the highest quality beacon signal.
Following the signal acquisition phase of the GS and when the primary receiver
channel has acquired a beacon, the receiver’s second channel will conduct a
background search.
7. When the SBX-4 receives a valid RMC message on Port 0, it will switch to database
mode.
8. You may tune the receiver to a specific beacon using the $GPMSK Manual Tune
command referred to in Hemisphere GNSS’ Technical Reference Manual.
9. When tuned to a valid beacon, the SBX-4 monitors RTCM SC-104 message lock,
parity check and outputs RTCM corrections through its primary communications port.
The SBX-4 asserts the lock signal on pin 16 of J300 (active high).
10. When input power to the SBX-4 is cycled, or the receiver reset circuit is activated, the
SBX-4 will attempt to reacquire the last station to which it was tuned. In Automatic
mode, the SBX-4 will try to lock to this station for 10 seconds before initiating a fresh
GS to identify valid beacons. If set to Manual mode, the receiver will attempt to lock
to the last known beacon indefinitely, or until commanded to a new frequency and bit
rate. In Database mode, the SBX-4 will try to lock to the closest station using the last
valid position.

SBX-4 Integrator Guide Chapter 3
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SBX-4 Operation Page 16 of 22
Chapter 3: SBX-4 Operation
Introduction
Beacon Information
Operating Modes
New SBX-4 Commands
Evaluating Performance