BARNARD MICROSYSTEMS LIMITED

helping you keep an eye on things...

unmanned air ...

avionics

Flight Management  Unit peripherals: GPS

from http://www.u-blox.com/

• X, Y, Z position location
• precision timing

If you have information on any new products in this area, we would be pleased to add your contribution and credit you for the information.

• Qinetiq Q20 high sensitivity GPS unit
• SiRF III GPS IC
• u-Blox high sensitivity GPS chipset
• u-Blox LEA-4T ANTARIS^® 4   Module with Precision Timing
• NMEA codes

Download a 138 page, 516 kByte,  pdf document ICD-GPS-200C on the details of the  GPS system implementation.

from http://www.qinetiq.com/home/commercial/gps_and_rfid/gps/GPS_Products/high_sensitivity_gps.html

Until recently GPS positioning relied on direct satellite view, excluding many environments from the advent of GPS. Many GPS enabled devices in the market are simply unable to meet customer requirement due to these limitations. In response QinetiQ has developed a high sensitivity module which continues to provide position information where conventional GPS fails.

QinetiQ High Sensitivity GPS brings the advantages of satellite navigation to a whole range of new applications. Using a dedicated baseband processor with massive parallel correlation and frequency search capability, our Q20 receiver is much more sensitive and faster to fix than other GPS engines.

In urban and indoor environments our technology provides greatly increased availability of position and timing solutions. In many cases even the GPS antenna can be eliminated saving cost and improving the form factor of customers products. We supply a range of Q20 GPS receiver products to support the developer from demonstration kits and integration boards to Q20 modules in high volume. Please also talk to us about your requirements for custom modules and 'zero' antenna solutions.

The Q20 HS is a complete GPS receiver module with very fast acquisition and very low signal strength tracking capability. Proprietary low level data demodulation capability allows the Q20 HS to provide sustained operation indoors without network assistance. The Q20 HS is available now in quantity for use in embedded applications.

The Q20 Integration Board has been designed to make prototyping and integration into customer solutions as easy as possible. It comprises a Q20 receiver module mounted onto a carrier board with all the peripheral components and connectors required to get you up and running.

The Q20 High Sensitivity GPS Demonstration Kit is for developers who want to explore the advantages that a highly sensitive GPS receiver can provide in their positioning applications. The kit contains a small battery powered demonstration unit based on the Q20 module and all the accessories and software required to start with high sensitivity GPS.

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Above and below from http://www.sirf.com/products/GSC3LPProductInsert.pdf

from http://www.sirf.com/products/GSC3LPProductInsert.pdf

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from http://www.u-blox.com/products/Product_Summaries/UBX-G5010_Prod_Summary(GPS.G5-X-06042).pdf

UBX-G5010, UBX-G5000 u-blox 5 GPS Single Chip and Chipset for Mobile Terminal Applications

Preliminary Data – Chipset scheduled for Q2 2007

Overview

The u-blox   5   chip   family   is   the   latest GPS   technology generation from u-blox that   redefines the boundaries of GPS performance, integration and cost efficiency.

A   dedicated   acquisition   engine   with   over   1 million effective   correlators   is   capable   of   massively   parallel searches across the time/frequency space. This enables satellite acquisition   in under 1 second and acquisition sensitivity   reaching   –160 dBm. Acquired   satellites   are passed on to a power-optimized tracking engine. This setup   simultaneously   allows   the   tracking   of   16 satellites   and   the   search   for   additional   ones.   The computed position is available within seconds. The   on-chip   power   management   unit   features   a switch-mode   DC/DC   converter   that   optimizes   power efficiency and enables having a single voltage source.

Power needs   lower   than 50 mW ensure   long battery times. The   UBX-G5000   baseband   IC   will   be   capable,   via   a simple   software   upgrade   into   external   Flash   EPROM, of   receiving   and   processing   L1   Galileo   signals   once they become available. The   ability   to perceive   Galileo satellites   will   bring   higher   coverage,   improved reliability and better accuracy. Its   advanced   jamming   suppression   mechanism automatically   filters   signals   from   interfering   sources, thus maintaining high GPS performance.

Highlights

• Massively parallel GPS engine
• 50 channels
• Over 1 million correlators
• Cost and space efficiency
• Optimized silicon architecture
• Miniature footprint  
• Small bill of material
• No external LNA and Flash EPROM needed
• SuperSense®: deep indoor performance
• -160 dBm acquisition, reacquisition and tracking sensitivity
• Ultra-low power consumption: 50 mW
• Long battery times
• Galileo ready

Features

• 32 channel acquisition engine
• 18 channel tracking engine
• Assisted GPS and Autonomous GPS operation
• Supports AssistNow® Online and Offline
• Supports RRLP, RRC, OMA/SUPL and proprietary protocols
• Wide clock frequency range
• XTAL: 19-26 MHz, TCXO 19-40MHz
• Coverage of all cellphone reference frequencies
• Integrated DC/DC converters enable power-efficient applications with single voltage supply  
• Supports SBAS: WAAS, EGNOS and MSAS
• Connectivity: USB, 2 UARTs, SPI, DDC
• RoHS compliant (lead-free)

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from http://www.u-blox.com/products/lea_4t.html

The LEA-4T, supporting precision GPS timing and raw measurement data for demanding positioning applications, provides high sensitivity, exceptionally low power consumption and USB connectivity.

The LEA-4T features a Time Mode function whereby the GPS receiver assumes a stationary 3D position, whether programmed manually or determined by an initial self-survey. Stationary operation enables GPS timing with only one visible satellite and eliminates timing errors which otherwise result from positioning errors. The accuracy of the time pulse is as good as 50 ns, synchronized to GPS or UTC time. An accuracy of 15 ns is achievable by using the quantization error information to compensate the granularity of the time pulse. The built-in 2-channel time mark and counter unit provides precise time measurement of external signals (EXTINT0 and 1).

The LEA-4T also supports raw measurement data (carrier phase with half-cycle ambiguity resolved, code phase and Doppler measurements) which can be used in external applications that offer precision positioning, real-time kinematics (RTK) and attitude sensing.

Above: part of the u-blox LEA-4T evaluation kit we ordered in March 2007.

• Stationary Mode for GPS timing operation
• 15 ns timing accuracy (error compensated)
• 1-Satellite GPS timing
• 10 Hz raw measurement data output
• Flash EPROM: programmable and configurable
• SuperSense Indoor GPS, -158 dBm

• 16 channel ANTARIS 4 positioning engine
• Supports DGPS, WAAS, EGNOS and MSAS
• 4 Hz position update rate
• Configurable time pulse: 0.1 Hz - 1 KHz
• Ultra low power consumption
• 2 channel precision time mark / counter
• A-GPS and autonomous mode, supports AssistNow™
• 1 USB and 1 UART ports
• Configurable I/O and UART voltage levels
• Supports passive and active antennas
• Antenna short and open circuit detection and protection
• Power brown-out protection: No external reset hardware needed
• Operating temperature range: -40 to 85°C
• RoHS compliant (lead-free)

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The National Marine Electronics Association (NMEA) has developed a specification that defines the interface between various pieces of marine electronic equipment. See http://www.nmea.org/ to purchase a copy of the NMEA 0183 Standard. We have derived the information for  the u-Blox NMEA codes from http://www.gpsinformation.org/dale/nmea.htm#ZDA and from the http://home.mira.net/~gnb/gps/nmea.html#gprmc web sites. The folowing is an example of a section of data that is output each second to a logging text file created by the u-Blox evaluation module:

The meaning of this information, as derived from the above mentioned web sites,  is as discussed next.

Each sentence begins with a '$' and ends with a carriage return/line feed sequence and can be no longer than 80 characters of visible text (plus the line terminators). The data is contained within this single line with data items separated by commas. The data itself is just ASCII  text and may extend over multiple sentences in certain specialized instances but is normally fully contained in one variable length sentence. The data may vary in the amount of precision contained in the message. For example time might be indicated to decimal parts of a second or location may be show with 3 or even 4 digits after the decimal point.

Programs that read the data should only use the commas to determine the field boundaries and not depend on column positions. There is a provision for a checksum at the end of each sentence which may or may not be checked by the unit that reads the data. The checksum field consists of a '*' and two hex digits representing an 8 bit exclusive OR of all characters between, but not including, the '$' and '*'. A checksum is required on some sentences.

- from http://www.gpsinformation.org/dale/nmea.htm#ZDA

The satellite PRN number per ICD-GPS-200. This is a required data item as it is the GPS user's primary means of identifying GPS satellites. It is equivalent to the space vehicle identification (SVID) number of the satellite. The PRN number lies in the range from 01 to 32.

- from http://celestrak.com/GPS/almanac/SEM/definition.asp

RMC

VTG

GGA

GSA

GSV

GLL

ZDA

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