Telit Wireless Solutions JF2 Technical specifications

JF2 Product Description
80403ST10103A Rev.7 – 2013-04-18

JF2 Product Description
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APPLICABILITY TABLE
PRODUCT
JF2

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SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
Notice
While reasonable efforts have been made to assure the accuracy of this document, Telit
assumes no liability resulting from any inaccuracies or omissions in this document, or from
use of the information obtained herein. The information in this document has been carefully
checked and is believed to be entirely reliable. However, no responsibility is assumed for
inaccuracies or omissions. Telit reserves the right to make changes to any products described
herein and reserves the right to revise this document and to make changes from time to time
in content hereof with no obligation to notify any person of revisions or changes. Telit does
not assume any liability arising out of the application or use of any product, software, or
circuit described herein; neither does it convey license under its patent rights or the rights of
others.
It is possible that this publication may contain references to, or information about Telit
products (machines and programs), programming, or services that are not announced in your
country. Such references or information must not be construed to mean that Telit intends to
announce such Telit products, programming, or services in your country.
Copyrights
This instruction manual and the Telit products described in this instruction manual may be,
include or describe copyrighted Telit material, such as computer programs stored in
semiconductor memories or other media. Laws in the Italy and other countries preserve for
Telit and its licensors certain exclusive rights for copyrighted material, including the
exclusive right to copy, reproduce in any form, distribute and make derivative works of the
copyrighted material. Accordingly, any copyrighted material of Telit and its licensors
contained herein or in the Telit products described in this instruction manual may not be
copied, reproduced, distributed, merged or modified in any manner without the express
written permission of Telit. Furthermore, the purchase of Telit products shall not be deemed
to grant either directly or by implication, estoppel, or otherwise, any license under the
copyrights, patents or patent applications of Telit, as arises by operation of law in the sale of a
product.
Computer Software Copyrights
The Telit and 3rd Party supplied Software (SW) products described in this instruction manual
may include copyrighted Telit and other 3rd Party supplied computer programs stored in
semiconductor memories or other media. Laws in the Italy and other countries preserve for
Telit and other 3rd Party supplied SW certain exclusive rights for copyrighted computer
programs, including the exclusive right to copy or reproduce in any form the copyrighted
computer program. Accordingly, any copyrighted Telit or other 3rd Party supplied SW
computer programs contained in the Telit products described in this instruction manual may
not be copied (reverse engineered) or reproduced in any manner without the express written
permission of Telit or the 3rd Party SW supplier. Furthermore, the purchase of Telit products
shall not be deemed to grant either directly or by implication, estoppel, or otherwise, any
license under the copyrights, patents or patent applications of Telit or other 3rd Party supplied
SW, except for the normal non-exclusive, royalty free license to use that arises by operation
of law in the sale of a product.

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Usage and Disclosure Restrictions
License Agreements
The software described in this document is the property of Telit and its licensors. It is
furnished by express license agreement only and may be used only in accordance with the
terms of such an agreement.
Copyrighted Materials
Software and documentation are copyrighted materials. Making unauthorized copies is
prohibited by law. No part of the software or documentation may be reproduced, transmitted,
transcribed, stored in a retrieval system, or translated into any language or computer language,
in any form or by any means, without prior written permission of Telit
High Risk Materials
Components, units, or third-party products used in the product described herein are NOT
fault-tolerant and are NOT designed, manufactured, or intended for use as on-line control
equipment in the following hazardous environments requiring fail-safe controls: the operation
of Nuclear Facilities, Aircraft Navigation or Aircraft Communication Systems, Air Traffic
Control, Life Support, or Weapons Systems (High Risk Activities"). Telit and its supplier(s)
specifically disclaim any expressed or implied warranty of fitness for such High Risk
Activities.
Trademarks
TELIT and the Stylized T Logo are registered in Trademark Office. All other product or
service names are the property of their respective owners.
Copyright © Telit Communications S.p.A. 2013.

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Contents
1.Introduction ..............................................................................................................8
1.1.Scope............................................................................................................................. 8
1.2.Audience........................................................................................................................ 8
1.3.Contact Information, Support.......................................................................................... 8
1.4.Document Organization.................................................................................................. 9
1.5.Text Conventions ........................................................................................................... 9
1.6.Related Documents....................................................................................................... 10
2.General description..................................................................................................11
2.1.SiRFawareTM Technology............................................................................................. 11
3.Technical Description...............................................................................................12
3.1.Product Compatibility................................................................................................... 12
3.2.Receiver Architecture................................................................................................... 13
3.3.Major Components....................................................................................................... 14
3.3.1.ON-OFF.............................................................................................................................14
3.3.2.SYSTEM-ON.....................................................................................................................14
3.3.3.Band pass SAW filter (1.575 GHz):.....................................................................................14
3.3.4.GSD4e Chip .......................................................................................................................14
3.3.5.VDD 18..............................................................................................................................15
3.3.6.NRESET ............................................................................................................................15
3.3.7.Host Port ............................................................................................................................15
3.3.8.MEMS Sensor Interface......................................................................................................15
3.3.9.TCXO ................................................................................................................................15
3.3.10.Memory..............................................................................................................................15
3.4.Physical Characteristics ................................................................................................ 16
3.5.Mechanical Specification.............................................................................................. 16
3.6.External Antenna Connection........................................................................................ 16
3.7.Input/Output and Power Connections ............................................................................ 16
3.8.Environmental.............................................................................................................. 16
3.9.Compliances ................................................................................................................ 16
3.10.Marking/Serialization................................................................................................ 17

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3.11.Active Antenna Gain Requirements ........................................................................... 17
4.Software..................................................................................................................18
4.1.TTFF (Time to First Fix) .............................................................................................. 18
4.1.1.Hot Start.............................................................................................................................18
4.1.2.Warm Start .........................................................................................................................18
4.1.3.Cold Start ...........................................................................................................................18
4.2.AGPS .......................................................................................................................... 19
4.3.Time Mark Pulse (1PPS)............................................................................................... 19
4.4.Power Management...................................................................................................... 19
4.4.1.Hibernate State ...................................................................................................................19
4.4.2.Micro Power Mode .............................................................................................................19
4.4.3.Adaptive Trickle Power (ATP)............................................................................................20
4.4.4.Push to Fix Mode (PTF)......................................................................................................20
4.5.Differential Aiding (DGPS) .......................................................................................... 20
4.5.1.Satellite Based Augmentation Systems (SBAS)....................................................................20
4.6.5Hz Update Rate .......................................................................................................... 20
4.7.Dynamic Constraints .................................................................................................... 21
5.Performance Data ....................................................................................................22
6.Electrical Requirements............................................................................................23
6.1.Power Supply............................................................................................................... 23
6.1.1.VDD 18..............................................................................................................................23
6.1.2.External Antenna Voltage....................................................................................................23
6.1.3.RF (Radio Frequency) Input................................................................................................23
6.1.4.Antenna Gain......................................................................................................................23
6.1.5.Burnout Protection..............................................................................................................23
6.1.6.Jamming Performance.........................................................................................................24
6.1.7.Flash Upgradability (Flash only)..........................................................................................24
6.1.8.Patch Updates (EEPROM only)...........................................................................................24
6.1.9.Reset Input .........................................................................................................................24
6.2.Data Input/Output Specifications................................................................................... 25
6.2.1.Voltages and Currents.........................................................................................................25
6.2.2.Pinout Description ..............................................................................................................27
7.Software Interface....................................................................................................30

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7.1.NMEA Output Messages .............................................................................................. 30
7.2.SiRF OSP Output Messages.......................................................................................... 30
7.3.Software Functions and Capabilities.............................................................................. 31
8.Mechanical Drawing.................................................................................................32
9.Conformity Assessments........................................................................................34
9.1.Declaration of Conformity ............................................................................................ 34
9.2.R&TTE Notify Body Opinion....................................................................................... 35
10.Evaluation Kit ......................................................................................................36
11.Product Handling..................................................................................................37
11.1.Product Packaging and Delivery ................................................................................ 37
11.2.Moisture Sensitivity.................................................................................................. 37
11.3.ESD Sensitivity......................................................................................................... 37
11.4.Safety....................................................................................................................... 37
11.5.Disposal ................................................................................................................... 38
12.Ordering Information............................................................................................39
13.Glossary and Acronyms.........................................................................................40
14.Safety Recommendations .......................................................................................42
15.Document History.................................................................................................43

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1. Introduction
1.1. Scope
Scope of this document is to give an overview of new standalone GPS module JF2.
1.2. Audience
This document is intended for customers developing applications using JF2 module.
1.3. Contact Information, Support
For general contact, technical support, to report documentation errors and to order manuals,
contact Telit Technical Support Center (TTSC) at:
[email protected]
[email protected]
[email protected]
[email protected]
Alternatively, use:
http://www.telit.com/en/products/technical-support-center/contact.php
For detailed information about where you can buy the Telit modules or for recommendations
on accessories and components visit:
http://www.telit.com
To register for product news and announcements or for product questions contact Telit
Technical Support Center (TTSC).
Our aim is to make this guide as helpful as possible. Keep us informed of your comments and
suggestions for improvements.
Telit appreciates feedback from the users of our information.

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1.4. Document Organization
This document contains the following chapters:
“Chapter 1: “Introduction” provides a scope for this document, target audience, contact and
support information, and text conventions.
“Chapter 2: “General Description” gives an overview of the features of the product.
“Chapter 3: “Technical Description” describes the features of the product.
“Chapter 4: “Software” describes in detail the characteristics of the product.
“Chapter 5: “Performance Characteristics” shows the performance of the product.
“Chapter 6: “Electrical Requirements” describes in details the electrical characteristics of the
product.
“Chapter 7: “Software Interface” provides some fundamental hints about the conformity
assessment that the final application might need.
“Chapter 8: “Mechanical Drawings” provides info about Hardware interfaces.
“Chapter 9: “Conformity Assessment” provides certifications and assessment of JF2.
“Chapter 10: “Evaluation Kit” provides some fundamental hints about evaluation Kit.
“Chapter 11: “Product Handling” describes the packaging and mounting of the module.
“Chapter 12: “Ordering Information” describes the ordering information for obtaining
product.
“Chapter 13: “Glossary and acronyms” contain the explanation of acronyms used in the
present document
“Chapter 14: “Safety Recommendation” provides some safety recommendations that must be
follow by the customer in the design of the application that makes use of the JF2
“Chapter 15: “Document History” provides the history of the present document.
1.5. Text Conventions
Danger – This information MUST be followed or catastrophic equipment failure
or bodily injury may occur.
Caution or Warning – Alerts the user to important points about integrating the
module, if these points are not followed, the module and end user equipment
may fail or malfunction.
Tip or Information – Provides advice and suggestions that may be useful when
integrating the module.

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All dates are in ISO 8601 format, i.e. YYYY-MM-DD.
1.6. Related Documents
JF2 Hardware User Guide,
JF2 EVK User Guide,
JF2 Serial Interfaces Application Note,
JF2_JN3 Low Power Modes Application Note
JF2_JN3 MEMS Application Note,
JF2 Antenna Sense Application Note

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2. General description
Building upon the SiRFstarIV™ architecture’s high-performance and micro-power
capabilities, the JF2 devices incorporate innovations such as SiRFaware™, SiRFInstantFix™
and Active Jammer Removal. The JF2 can navigate to -160dBm and track to -163dBm,
providing higher coverage, accuracy and availability. This next generation Jupiter Module
consumes only 10mA (1.8V) in 1-Hz TricklePower™ mode and can maintain hot-start
conditions continuously in SiRFaware™ mode while drawing as little as 50-500uA. The JF2
offers A-GPS support and operate with a 1.8V power supply. JF2 supports a full range of
satellite-based augmentation systems, including WAAS, EGNOS, MSAS and GAGAN.
The GPS module combines the SiRFstarIV™ GSD4e™ GPS engine, TCXO, SAW filter,
RTC and memory (Flash and EEPROM modules only).
2.1. SiRFawareTM Technology
SiRFawareTM maximizes performance of the JF2 without requiring it to maintain full power.
This is achieved by using the following advanced technology to maintain continuous location
awareness while minimizing power consumption:
‐Opportunistic ephemeris decode and advanced power management, which allow the
GPS receiver to stay in hot start conditions nearly continuously while consuming very
little power.
‐Local ephemeris prediction for three days in advance using captured ephemerides,
which boosts sensitivity and performance.
‐Dynamic contextual awareness by monitoring temperature change and by interfacing
with MEMS sensors to detect movement, which conserves power and also boosts
performance.

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3. Technical Description
High-speed Location Engine – Twice the available DSP memory and search speed of
SiRFstarIII architecture for enhanced sensitivity and navigation performance, greater
coverage, reduced time to fix and improved positional accuracy.
Adaptive Micro Power Manager – Advanced power management with integrated LDO
regulation to maintain hot-start conditions with minimal energy. Always ON 1.8V supply
must be used.
MEMS Sensor Interface (I2C DR port) – Static detection is implemented and utilizes an
accelerometer to determine if the module is moving in order to pin position. Additionally, the
SiRFAware/MPM feature utilizes the accelerometer for MEMS wakeup to control the
frequency of wakeup from hibernate for updating data.
Active Jammer Remover – Advanced DSP technology actively identifies and removes
jammers prior to correlation. This feature maximizes GPS performance and helps identify
issues during the design phase. Up to 8 CW jammers can be identified and removed.
External LNA Control – The JF2 SYSTEM-ON signal is available for use to control an
external LNA. When the JF2 is in hibernate/sleep mode, SYSTEM-ON is low. When the JF2
is in full power state, SYSTEM-ON is HIGH.
5Hz Navigation – The JF2 can run with a navigation update rate of 1Hz or 5Hz. This is
controllable in NMEA and OSP mode. Note that the UART baud rate will need to be
increased to support the higher message output (about 38400 baud minimum in NMEA).
High Performance Solution:
‐High sensitivity navigation engine (PVT) tracks as low as -163dBm
‐48 track verification channels
‐SBAS: WAAS, EGNOS, MSAS, GAGAN.
Adaptive Micro Power Controller:
‐Only 50 to 500uA maintains hot start capability
Active Jammer Remover:
‐Removes in-band jammers up to 80 dB-Hz
‐Tracks up to 8 CW jammers
Advanced Navigation Features:
‐Smart sensor I2C interface
‐Interrupt input for context change detection
3.1. Product Compatibility
The JF2 incorporates a new technology far advanced compared to the previous SiRFstarIII
designs. It offers an upgrade path from existing Telit and competitive designs.
JF2 incorporates the same footprint as the Jupiter3 (J3) with the same pad dimensions.
Pinouts are adapted to make use of the SiRFstarIV advanced technology. Please check the
HW User Guide for more details.
Note that the JF2 is not backwards compatible with the J3.

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NMEA version 3.0 protocol is supported as well as the new SiRF ONE SOCKET binary
PROTOCOL (OSP).
3.2. Receiver Architecture
The functional architecture of the JF2 receiver is shown in Figure 1.
Note: The LNA is included in the GPS chip for passive antenna operation.
Note: LNA is included in the GPS chip for passive antenna operation.
Note: LNA is included in the GPS chip for passive antenna operation.
GSD4e
SAW
TCXO
Flash or
EEPROM
VDD 18 NRESET
PSU
capacitors
and inductors
RTC
LNA
O
N
-
O
FF SYSTEM-ON
UART/SPI/I2C/DR_I2
ACTIVE/PASS
IVE
P
OR
SPI Flash
Figure 1 – JF2 Architecture

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3.3. Major Components
All power supply components are on board including capacitors and additional Power-On-
Reset (POR) for the 1.8V supply.
A 1.8V always ON supply with noise and ripple characteristics mentioned in section 5.1 is
critical for reliable operation. This can be a 1.8V supply that is backed up by a very low
current 1.8V LDO that will supply the 14uA typical when the GPS has been shut down into
Hibernate mode. Refer to the HW User Guide for additional details. If the 1.8V supply is
inadvertently cut off the GPS 1.8V POR will shut it down into Hibernate with loss of data. It
is important that the GPS has sufficient bulk capacitance to enable the GPS to shut down
gracefully into Hibernate mode. In addition this would only be possible if a 1.8V battery
backed supply is also provided to retain the GPS in Hibernate mode ready to accept an ON
pulse once the main 1.8V supply is available again.
3.3.1. ON-OFF
This control 1.8V to 3.6V input signal is used to turn ON and turn OFF the GPS receiver.
Main 1.8V power must be already available and stable.
There is a minimum time period before the receiver will accept an ON pulse once the 1.8V
power has been first applied, 3 seconds typical. It is suggested the SYSTEM-ON line is
monitored as it will indicate when the GPS can accept an ON pulse after the first 1.8V power
application. If a 1.8V battery back-up system is used and the GPS has already been powered
up, shut down should be done via the ON-OFF line. The SYSTEM-ON line will not indicate a
READY state if the main 1.8V supply is re-applied. The battery back-up supply has kept the
system ready and valid and an ON pulse can be applied as soon the main 1.8V supply is
stable. Note, clean application of this 1.8V supply is required.
3.3.2. SYSTEM-ON
This is an active high (1.8V) indication that the system is ready to receive an ON pulse or that
the system is ON and running. A short duration active high pulse occurs on this line if the
main 1.8V supply has been connected (if no 1.8V battery back-up is used) and is valid. Note,
that noisy or unstable application of the 1.8V power will cause the 1.8V POR monitor to shut
the GPS down and lose data.
3.3.3. Band pass SAW filter (1.575 GHz):
This filters the GPS signal and removes unwanted signals caused by external influences that
would corrupt the operation of the receiver. The filtered signal is fed to the RF input of
GSD4e chipset for further processing. The filter has a bandwidth of 2 MHz.
3.3.4. GSD4e Chip
This single chip GPS device includes an integrated Baseband and RF sections. The LNA
amplifies the GPS signal and provides enough gain for the receiver to use a passive antenna.
A very low noise design is utilized to provide maximum sensitivity. This LNA is internal to
the GPS baseband and can be switched between low and high gain mode.

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3.3.5. VDD 18
This is the primary, always-ON supply voltage for the module. A very low noise 1.8V
always-ON source must be used.
3.3.6. NRESET
This is the user Reset input, however it is recommended not be used. The module has two
internal POR devices. One POR for the 1.2V core and a POR for the 1.8V supply. No user
POR is required.
3.3.7. Host Port
The JF2 has a single HOST port. The user can select between UART, I2C and SPI ports
through the use of external pull-up and pull-downs resistors. See the HW User Guide for
more details.
The UART port is the preferred serial communications port, most popular and easiest to
utilize.
3.3.8. MEMS Sensor Interface
The DR I2C port is used for MEMS sensor interface. Reference the HW User Guide for more
details on how to connect to an accelerometer and/or magnetic sensor.
3.3.9. TCXO
This highly stable 16.369 MHz oscillator controls the down conversion process for the RF
block.
3.3.10. Memory
Two versions of the JF2 are available with internal memory, Flash or EEPROM.
The Flash version includes a 16MB Flash storage device for operational software and satellite
data.
The EEPROM version includes a 512KB EEPROM storage device for patch code, satellite
data, and client generated predicted ephemeris.
The ROM-only does not include on-module memory. External Host memory or SPI flash may
be used to store patch code, satellite data, and predicted ephemeris.

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3.4. Physical Characteristics
The JF2 receiver has advanced miniature packaging and a LGA footprint and is smaller than
the Jupiter 32 and similar in size to the Jupiter3 (J3). It is a surface mount device packaged on
a printed circuit board, with a metallic RF enclosure on one side. There are 32 surface mount
connection pads with a base metal of copper and an Electroless Nickel Immersion Gold
(ENIG) finish.
3.5. Mechanical Specification
The physical dimension of the JF2 is as follows:
‐length: 11.0 mm ± 0.1 mm
‐width: 11.0 mm ± 0.1 mm
‐thickness: 2.8 mm max
‐weight: 1 g max
Refer to Figure 2 for the JF2 mechanical layout drawing.
3.6. External Antenna Connection
The RF connection for the external antenna has a characteristic impedance of 50 ohms.
3.7. Input/Output and Power Connections
The I/O (Input / Output) and power connections use surface mount pads.
Note that GPIO and UART/SPI/I2C/DR_I2C are 1.8V signals.
3.8. Environmental
The environmental operating conditions of the JF2 are as follows:
‐temperature: –40oC to +85oC (measured on the shield)
‐humidity: up to 95% non-condensing or a wet bulb temperature of +35oC
‐shock (non-operating): 18 G peak, 5 ms
3.9. Compliances
The JF2 complies with the following:
‐Directive 2002/95/EC on the restriction of the use of certain hazardous substances in
electrical and electronic equipment (RoHS)
‐Manufactured in an ISO 9000: 2008 accredited facility
‐Manufactured to TS 16949 requirement (upon request)

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3.10. Marking/Serialization
The JF2 supports a 2D barcode indicating the unit serial number below. The Telit
13-character serial number convention is:
‐characters 1 and 2: year of manufacture (e.g. 12 = 2012, 13 = 2013)
‐characters 3 and 4: week of manufacture (1 to 52, starting first week in January)
‐character 5: manufacturer code
‐characters 6 and 7: product and type
‐character 8: product revision
‐characters 9-13: sequential serial number
3.11. Active Antenna Gain Requirements
LNA Gain Setting LNA Gain
(dB) Noise Figure (dB) Recommended External Gain Range (dB)
Low 6.0 – 10.0 8.5 – 9.5 16-30
High (default) 16.0 – 20.0 4.0 8-18
Table 1 – Active Antenna Gain Requirements
Notes:
1. Recommended external gain range is total any external gain, such as antenna or
external LNA and any passive loss due to cables, connectors, filters, matching
network, etc.
2. In the High Gain setting an external LNA is not recommended.
3. In the Low Gain setting, the noise figure of the external LNA or active antenna must
be chosen to ensure that the total cascaded noise figure is sufficiently low to meet
overall system design requirements.

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4. Software
4.1. TTFF (Time to First Fix)
TTFF is the actual time required by a GPS receiver to achieve a valid position solution. This
specification will vary with the operating state of the receiver, the length of time since the last
position fix, the location of the last fix, and the specific receiver design.
4.1.1. Hot Start
A hot start results from a software reset after a period of continuous navigation, or a return
from a short idle period (i.e. a few minutes) that was preceded by a period of continuous
navigation. In this state, all of the critical data (position, velocity, time, and satellite
ephemeris) is valid to the specified accuracy and available in memory. Requires always ON
1.8V main supply.
4.1.2. Warm Start
A warm start typically results from user-supplied position and time initialization data or
continuous RTC operation with an accurate last known position available in memory. In this
state, position and time data are present and valid but ephemeris data validity has expired.
Requires always ON 1.8V main supply.
4.1.3. Cold Start
A cold start acquisition results when either position or time data is unknown. Almanac
information is used to identify previously healthy satellites.
Please refer to section 3.6 for performance data.

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4.2. AGPS
GPS aiding comes in several forms, for the purposes of this document we will focus on
extended ephemeris data as a form of assisted GPS data.
InstantFix (SGEE and CGEE) is a method of GPS aiding that effectively reduces the TTFF by
making every start a Hot or Warm start, through the use of ephemeris predictions.
Client Generated Extended Ephemeris (CGEE) captures ephemeris data from satellites locally
and predicts ephemeris for those visible satellites for up to 3 days.
Server Generated Extended Ephemeris (SGEE) does not require local ephemeris collection
from satellites; it receives the extended ephemeris data from a server and has ephemeris
predictions for all available satellites in the sky.
The module supports AGPS as standard. TELIT provides a server for customers to mirror
with their own servers for download of the SGEE file. Contact TELIT for support regarding
this service.
Note: Due to memory size constraints, modules with EEPROM do not support SGEE.
Note: The ROM-only module does not support CGEE or SGEE. External Host memory can
be used to enable both these features. See HW User Guide for more details on how to
interface with external Host memory.
4.3. Time Mark Pulse (1PPS)
A 1PPS time mark pulse is provided as an output with a width of 200ms. This signal has not
been verified or characterized for all operational conditions.
Note: The GPS will only provide 1PPS when a 3D fix has been obtained using 5 SVs. When
the fix degrades below a 3D solution, the 1PPS will be blanked. Once the fix quality improves
back to a 3D FIX the 1PPS will again be output.
4.4. Power Management
The following paragraphs describe the power management modes and power states supported
by the JF2.
Note that power consumption will be lower if AGPS is used.
4.4.1. Hibernate State
This is the lowest power consumption state (14uA typical) and allows a Hot Start within 2-4
hours of last shut down. The GPS receiver must have had a valid fix with sufficient visible
satellites before having been shut down via the ON-OFF line or serial command.
Note: If AGPS is used there will be no time limit as long as the AGPS data is still valid.
4.4.2. Micro Power Mode
Micro Power mode is a very low power maintenance mode implementing SiRFawareTM
technology. In this mode the JF2 remains predominantly in the Hibernate state, but exits this
state only as needed to maintain location awareness and valid ephemeris data. Thus high

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sensitivity hot start conditions are always present when the ON-OFF signal is used to wake up
the JF2 and obtain a navigation update.
4.4.3. Adaptive Trickle Power (ATP)
Trickle Power mode is a duty-cycled power management mode that reduces average current
consumption by the JF2 while retaining a high quality of GPS accuracy and dynamic motion
response. The duty cycle and navigation update rate are specified by the user to best fit in the
operating environment. This mode adapts to weak or blocked satellite signals by transitioning
the JF2 in and out of full power mode as needed in order to maintain GPS performance.
4.4.4. Push to Fix Mode (PTF)
Push to Fix mode is designed for applications that do not require frequent navigation updates.
In this mode the JF2 remains in the hibernate state most of the time, but wakes up periodically
to perform a hot start acquisition (up to once every two hours) and provide a quality
navigation solution. The JF2 also wakes up when requested by a signal on the ON-OFF line.
4.5. Differential Aiding (DGPS)
4.5.1. Satellite Based Augmentation Systems (SBAS)
The JF2 is capable of receiving WAAS and EGNOS, MSAS, GAGAN differential corrections
which are regional implementations of SBAS. SBAS improves horizontal position accuracy
by correcting GPS signal errors caused by ionospheric disturbances, timing and satellite orbit
errors.
4.6. 5Hz Update Rate
The JF2 defaults to an update rate of 1Hz. The JF2 can be configured to operate in 5Hz
through NMEA or SiRF Binary OSP command (v4.1.0 firmware or later). In UART mode, it
is necessary to increase the baud rate to meet the higher rate of message output from the
receiver.
For example, in NMEA, an output of RMC, GGA, and GSA at five times per second, and
GSV at once per second will require at least a baud rate of 19200. This will ensure that the
messages are outputted within about 0.75 seconds.
Note that the JF2 will continue to run in 1Hz navigation until it gets a navigation fix. Once a
navigation fix is attained, it will transition into 5Hz navigation.
Utilize $PSRF103 for control in NMEA and MID136 in SiRF Binary OSP.