GPS + Glonass Using the Best of Both Worlds

Transcription

1 GPS + Glonass Using the Best of Both Worlds Jupiter SL869 Jupiter JN3 Jupiter SE880

2 IMPROVE TIME-TO-FIRST-FIX GET MORE ACCURATE POSITIONING ENHANCE TIME IN NAVIGATION COLLECT MOST RELIABLE PROBE-DATA TABLE OF CONTENTS: EXECUTIVE SUMMARY 1. GPS and GLONASS Technology - Background Information 2. Restrictions of GPS-Only 3. Combining GPS & GLONASS 3.1. Test studies in Los Angeles, London and Johannesburg 3.2. Central Findings 4. The Telit difference 4.1. Telit Jupiter SL Telit Jupiter JN Telit Jupiter SE About Telit

3 EXECUTIVE SUMMARY At the end of 2011 the Russian government announced that GLONASS, the Russian Global Navigation Satellite System (GNSS), is fully operational and has global coverage. Experts at Telit decided to test what impact this has on satellite navigation and positioning. They conducted tests in Los Angeles, London and Johannesburg to see the relevance of GLONASS for the whole world. The results clearly showed that the combination of GPS and GLONASS improves positioning tremendously. Especially in urban canyons with huge skyscrapers the receiver had the ability to track at least four satellites and thus calculate a fix which was impossible to guaranty using only GPS. Thanks to the SL869, a newly released Global Navigation Satellite System (GNSS) module from Telit that has access to both GLONASS and GPS, blind spots were reduced and navigation performance was radically improved. This white paper shows the test set-up and examines the results. For the future further tests are planned. 3

4 1. GPS AND GLONASS TECHNOLOGY Radio-based Global Navigation Satellite Systems (GNSS) are part of our daily life for navigation, surveying and mapping. Although there are several GNSS like the European Galileo or the Chinese Beidou, the US GPS is the most popular one providing global coverage and used widely in navigation systems. Today there are 31 GPS satellites that are operational, plus 3-4 decommissioned satellites that can be reactivated if needed. the more accurate the fix will be. In theory this is possible with GPS-only as there should always be at least 5 satellites visible anywhere on the Earth s surface. If there is an unobstructed view of the sky even 12 satellites can be visible. But often there are buildings, trees, mountains or clouds blocking some of the GPS signals, and the GPS receiver is unable to obtain a position fix. Since October 2011 the Russian GLONASS has been fully operational with 24 satellites in orbit plus four in reserve and one currently undergoing trials. This is not only an alternative to GPS but, even more, the completion of a combined GPS/GLONASS system where there are in total 55 fully operational satellites in outer space in different orbits (see picture 1). For satellite navigation at least 4 satellites are needed to determine a position solution: three to provide the data for each space axis (x, y and z) and one to provide the time sent. The more satellites that can be tracked, 4

5 EXECUTIVE SUMMARY At the end of 2011 the Russian government announced that GLONASS, the Russian Global Navigation Satellite System (GNSS), is fully operational and has global coverage. Experts at Telit decided to test what impact this has on satellite navigation and positioning. They conducted tests in Los Angeles, London and Johannesburg to see the relevance of GLONASS for the whole world. The results clearly showed that the combination of GPS and GLONASS improves positioning tremendously. Especially in urban canyons with huge skyscrapers the receiver had the ability to track at least four satellites and thus calculate a fix which was impossible to guaranty using only GPS. Thanks to the SL869, a newly released Global Navigation Satellite System (GNSS) module from Telit that has access to both GLONASS and GPS, blind spots were reduced and navigation performance was radically improved. This white paper shows the test set-up and examines the results. For the future further tests are planned. 3

6 3. COMBINING GPS & GLONASS 3.1. Test studies in Los Angeles, London and Johannesburg In February 2012 the Telit GNSS engineers decided to run a field test comparing the navigation accuracy of GPS only receivers and GPS+GLONASS receivers. The team did seven test tracks between 11:00 a.m. and 3:00 p.m. in Downtown Los Angeles. They tested several standard GPS only units in comparison to the Jupiter SL869, Telit s new GNSS module which processes both GPS and GLONASS signals. The results were always very similar: Combining GPS and GLONASS provided much more accurate and better positioning possibilities instead of GPS only see picture 2. to determine a position solution. With a GPS+GLONASS receiver this didn t happen the receiver never lost the signal. Furthermore there is a huge difference in the accuracy of ground track. With GPS there were several meters tracked off-road, means the track was not on the street but next to it. With GPS+GLONASS the positioning was very accurate and it didn t happen at all. The picture shows a single test track. The red line represents GPS only. It shows that during the test track there were several instances where GPS was not able Tracked way in Los Angeles. Picture 2: Tracked way in Los Angeles. Green shows the route which was driven with GPS & GLONASS receiver, red the same route with a standard GPS-only receiver. 6

7 A similar study was conducted in London on March, 20th 2012 monitoring the number of satellites used by a GPS-only receiver and by a GPS+GLONASS receiver. The findings were the same as in Los Angeles: Because of signal blockages in London caused by five story buildings, the number of tracked GPS satellites dropped below four (picture 3). Thus the GPS-only receiver lost its fix point. This happened three times, of which the time around 3:00 p.m. was the most critical one. At that time the receiver had no track for app. 20 minutes. Number of Satellites Tracked satellites :00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00 Picture 3: The same test tracking was done with GPS+GLONASS. It showed that there are always more than 4 satellites in track. A fix is virtually guaranteed (picture 4). In addition even up to 15 satellites were tracked in the middle of London were it wasn t possible to track more than 8 satellites with GPS-only. That nearly doubled the available satellites. The third test was conducted in Johannesburg, South Africa to verify the availability and advantages of GPS and GLONASS in the southern hemisphere. The results in South Africa were similar to the results in London and Los Angeles: With approximately 18 satellites used for the fix with GPS and GLONASS in comparison to 6-8 satellites with GPS-only, not only does the number of visible satellites double, time in navigation improves and a fix is virtually guaranteed. Number of Satellites Tracked satellites :00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00 The picture shows the number of satellites that were in track in London March, 20. Dark green shows times where the number of satellites drops below 4. Picture 4: The picture shows the number of satellites that were in track in London March, 20 with GPS +GLONASS. The number never drops below 6. 7

8 3.2. Central Findings Thanks to the addition of GLONASS, the number of tracked satellites never drops below six in the tested environments, and the problem of lost satellite coverage, especially problematic in urban canyons with tall buildings, is dramatically reduced. Furthermore the test showed that also the accuracy of positioning is significant improved. In addition the team noticed an improved time-to-fix which is for example vital for Stolen-Vehicle-Recovery where it is crucial to locate the vehicle no matter where it is. Accessing the combined GPS/GLONASS constellations is thus a major step forward in navigation, providing the best satellite geometry to obtain the most accurate position possible more often not only in Russia but all over the world. Finally, this enables a more accurate positioning, a better pinning of a person, a car or an asset s true location on a digital map. GNSS Satellites Used Number of Satellites GPS Satellites Used Number of Satellites Minutes Minutes Picture 5: Number of satellites used for the position fix with GPS-only receiver during one hour in Johannesburg, South Africa. Picture 6: Number of satellites used for the position fix with GPS and GLONASS during the same hour in Johannesburg, South Africa. The visible satellites doubles, positioning is significantly improved. 8

9 4. THE TELIT DIFFERENCE 4.1. Jupiter SL869 GNSS modules In Los Angeles the Telit team tested the Jupiter SL869, a new series of GNSS modules from Telit. These tests clearly showed that the SL869 maximizes the performance over GPS alone by utilizing both the GPS satellites plus the GLONASS. The results are: Higher percentage in navigation, faster acquisitions and more precise and accurate position. The Jupiter SL869 is a state-of-the-art 32-channel global navigation module able to receive, track and navigate using the entire spectrum of GNSS systems available in the world: GPS, GLONASS and QZSS, furthermore it is Galileo and Beidou ready. The extreme low profile and small size of the LCC package enables the design of ultra-compact applications. The solution cost and required space is significantly reduced. With its ultra-compact design and extended temperature range, the Jupiter SL869 is a multi-constellation receiver that is ideal for low, medium and high-volume M2M combined applications and mobile/tracking data devices. The results are: Higher percentage in navigation etc. Equipped with a powerful yet power saving processor, the module provides all the GNSS information via NMEA standard protocol on a serial interface. The Telit Jupiter SL869 can efficiently retrieve the correct position in harsh environments using multiple GNSS constellations and SBAS as well as real-time ephemeris data Jupiter JN3 GNSS module Although the combination of GPS and GLONASS provides huge advantages, there are also price differences. So in cases where a very accurate position is not needed, but cents make a difference to a competitor, a GPS-only module would be sufficient. Therefore Telit provides the Jupiter JN3 which is pin-to-pin compatible to the SL869. So customers need only one design for the two alternatives and can migrate whenever needed to one or the other without any problems. The Jupiter JN3 is a state-of-the-art 48-channel GPS module with high sensitivity, extremely low power consumption, and extended ephemeris predictions for fastest TTFF. Coupled with a Telit GSM/GPRS module, the Jupiter JN3 represents the ideal wireless+gps solution in terms of total cost effectiveness and Jupiter SL869 GPS GLONASS 16 x 12.2 x 2.4 mm Jupiter JN3 GPS 16 x 12.2 x 2.4 mm 9

10 time-to-market readiness. The extreme low profile and small size of the LCC package enables the design of ultra-compact applications. The solution cost and required space is significantly reduced. With its ultracompact design and extended temperature range, the Telit Jupiter JN3 is the perfect module for low, medium and high-volume M2M combined applications and mobile/tracking data devices. Thus Telit can always provide the perfect module for every need. DE910-DUAL Also Telit s DE910-DUAL features a GPS and GLONASS receiver that improves time for navigation and tracking performance in limited sky environments as well as additional benefits descripted in this White Paper. The DE910-DUAL is a 3G CDMA 1x EV-DO Rev A module with built in GNSS receiver that is part of the Telit s xe910 Family. The family features a single, compact form factor that is interchangeable on any regional cellular network and across technologies, delivering ubiquitous, cost-effective coverage for m2m applications. For more information about the Telit xe910 family please visit or check the QR-code. Original size 4.7 x 4.7 mm 4.3. Jupiter SE880 the smallest GPS receiver in the market Telit offers the smallest GPS receiver in the market, the SE880, which is ideally suited for applications in the commercial, industrial, and consumer segments including wearable and handheld devices. The miniature 4.7x4.7mm LGA (Land Grid Array), SiRFstarIV -based receiver module employs leading 3-D component embedding technology to achieve best-in-class performance in all dimensions critical for regular or size-constrained GPS applications. Because of this extreme sensitivity with -148dBm, the 48-channel receiver can reduce cold start Timeto-First-Fix (TTFF) by more than 3 minutes. In addition it allows class-unique achievements such as a one-satellite acquisition of UTC (typically 4 are required) and fix acquisition with minimal sky-visibility garages, urban canyons, etc. Even indoor fixes are possible in less than 200 seconds. Jupiter SE880 GPS 4.7 x 4.7 x 1.4 mm 10 DE910-DUAL CDMA 1xEV-DO Rev.A 28.2 x 28.2 x 2.4 mm

11 Telit s Jupiter SE880 includes all components necessary for a fully functioning receiver design requiring only a 32 KHz external crystal for its time-base and TCXO to complete the design, along with antenna, power and data connections adequate to the integrator s needs. The SE880 receiver module was conceived to shorten Time-to-Market and to make the chipset-versus-module decision an easy one to make for device integrators. Integrators can attain a working SE880-based design in as little as a week versus several months when starting from a chipset reference design. In addition the Jupiter SE880 has a multi-filter system which includes not only the traditional SAW filters typical in GPS receiver designs but also a 2.4 GHz notchfilter capable of nullifying the jamming effects of highenergy radio devices such as Wi-Fi hot-spots, Bluetooth systems, and others, which greatly affect a GPS receiver s ability to resolve timid satellite signals in the hostile radio environment where they need to operate. Other distinguishing features of the Jupiter SE880 include an extended operating temperature range wherein noise-versus-gain performance is linearly balanced throughout the range with class-leading sensitivity stability particularly at the extremes of -40 and +85 C critical for applications such as sports watches and OEM automotiv navigation systems. For more information about the Telit SE880 please visit or check the QR-code. 5. ABOUT TELIT Telit Wireless Solutions is a brand of Telit Communications PLC (AIM: TCM), an enabler of machine-to-machine (M2M) communications worldwide providing wireless module technology, M2M managed services and value added services, including connectivity. Exclusively dedicated to M2M with more than 12 years of experience in the market, the company constantly enhances its technology leadership with six R&D centers across the globe. Telit offers an extensive portfolio of the highest quality cellular, short-range RF, and GNSS modules, available in over 80 countries. By supplying scalable products that are interchangeable across families, technologies and generations, Telit is able to keepdevelopment costs low and protect customers design investments. In addition, Telit is the only module provider in the market today to offer a value added services bundle including connectivity dedicated to simplifying the deployment of M2M applications. Telit provides unmatched customer support and premier design-in expertise through its 25 sales and support offices, a global distributor network of wireless experts with more than 30 Telit-designated Competence Centers, and its online Telit Technical Support Forum. Telit technology enables organizations to wirelessly collect, process and respond to real-time data creating new efficiencies and revenue opportunities as well as societal and personal benefits. Further information about Telit and its products can be found at 11