CC BY
20
with focus on the Xilinx low-cost space-grade FPGA.
The primary or main objective was to implement a software-defined GPS receiver. This was achieved using Matlab. The secondary objective was to improve the primary objective. This was reasonably attained using the Matlab HDL Coder workflow and some of the GPS receiver algorithms could be improve from Matlab floating to fixed-point implementations which making them more
compact, efficient and implementable into a low-cost microcontroller.
The tertiary objective was to implement a firmware and to propose a low-cost space-borne GPS receiver roadmap. Tracking spacecraft can be done by radar stations from the ground, but it's much more expensive and takes longer than an in flight system I think there's a good chance we'll end up being able to use FPGA-Base GPS and save us some of the expense of using ground observations.
REFERENCES
1. Strang G, Borre K (1997) Linear Algebra, Geodesy, and GPS. Wellesley Cambridge Press, Wellesley.
2. Borre, Kai (2003). The GPS easy suite-Matlab code for the GPS newcomer.
3. Kai Borre ,GNSS and positioning for the future
4. K J Parkinson, A G Dempster, P Mumford, C Rizos,FPGA based GPS receiver design considerations
5. Peter J Mumford 1, Nagaraj Shivaramaiah 1, Eamonn Glennon 1, Kevin Parkinson 1 ,The Namuru V3.2A Space GNSS receiver
6. Nganyang Paul Bayendang (2015) , Nano-satellite GPS Receiver Design and Implementation A Software-to-Firmware Approach
7. Yong Li, Eamonn Glennon, Rui Li, Yuanyuan Jiao, Andrew G Dempster ,
8. K J Parkinson , P J Mumford , E P Glennon , N C Shivaramaiah , A G Dempster , C Rizos
9. Eamonn P. Glennon, Joseph P. Gauthier, Mazher Choudhury ,Kevin Parkinson , Andrew G. Dempster,Project Biarri and the Namuru V3.2 Spaceborne GPS Receiver
10. National Aeronautics and Space Administration, Patent No: 7,548,199
УДК 621.396
Fonseca Norena L. A., Cari Siles J.
Samara National Research University, Samara, Russia
ANALYSIS OF THE IMPACT OF BEIDOU NAVIGATION SYSTEM ON VOLGA REGION
This paper analyzes the positioning capability of BEIDOU Navigation Satellite System by visibility of satellites and DOP values. We show the use of BEIDOU system in Volga region and we give a glimpse oof its possible positioning accuracy and its service range. The paper also proves the positioning capability enhancement of the western high attitude area by improved constellation. Also we give a short review of the constellation of BDS and its coverage through the pf. K. Borre's Easy Suite. Thus we give conclusion and possible uses for
Introduction
China has completed the construction of the BeiDou-2 system that consists of 14 BeiDou satellites and 32 ground stations. China is ready to continue the upgrade of the system with the launch of 18 satellites to create global coverage constellation that will be completed by 2020, 35 BeiDou-3 satellites will be sent into the space, providing service to users around the Earth[1].
Nowadays, Beidou-3 or the third phase of the project has been started. It will contain 2 satellites which have already been launched and are operable at the moment, and 18 more satellites which are expected to be launched in July of this year (2017)[1]. The BeiDou system (BDS) currently consists of 7 GEO, 8 IGSO and 7 MEO satellites [2,3]. The figure 1 shows a screenshot of BeiDou satellites by Orbitron 3.71 (FREE tracking software). It is visible that the major concentration of satellites is in the Asia-Oceanic region.
Figure 1 - Screenshot of Orbitron tracking at 18th of April of 2017
The preliminary results of analysis of accuracy for BDS presented in [4,5,6] by the means of simulations show that finished BDS-3 will become a superior navigation system in Asian region and around the globe. In a standalone case or using only BDS, the performance of BDS-3 would be a little better than using GPS on a global scale, whereas the most effective performance is definitely in the Asian region. In fact, the
performance of BDS in Asia is improved significantly compared to GPS alone in terms of visibility, DOP values, and robustness to urban canyon effect. Our goal is to test the current performance of the BDS worldwide and on Volga region using a standalone case.
We analyze what the current performance of the BDS is. We do an analysis that allows us to observe accuracy of the received data of this
1 °Х 1
system outside of China. Taking into account that there is not much information that allows us to give a deep explanation of the subject and the reservation of information on the commercial use of this, we give a glimpse of this system.
This article proposes to check the current accuracy of BeiDou through the visibility of satellites and Dilution of Precision using the adapted Kai Borre's Easy suite. Being exact, we use the Easy11 and Easy4 to check the visibility of satellites around the world and consider the DOP in Penza. The used data has been taken from the FTP NASA's service which daily collects the Navigation data of BeiDou satellites around the world.
Satellite visibility analysis
The Easy-11 creates a stereographic plot of GPS satellite orbits from an ephemerides or almanac file. The plot is as seen from the position (phi, lambda). All (parts of) orbits with elevation angle lower than a given cut-off angle are omitted [3]. The satellite visibility analysis is made by changing the latitude and longitude (phi, lambda), using a static elevation angle and checking its coverage out. Moreover, we create a heatmap for to illustrate the hot points that mean an amount of satellites. And finally, we do an analysis focused on the Volga region of the General Service area and generating an overall estimate over Penza by means of Dilution of Precision. The measurement given in this article is based on Navigation data and the configuration is as follows:
satellite Constellation configuration: BeiDou system, CGCS2000 datum.
simulation time length setting: 2 days.
and 0.2x0.2° for
grid resolution : Regional analysis.
satellite observation cut-off angle : 20°. The days of study day (87) and (88) of the year 2017.Then we have 48 hours of satellite visibility divided into 10 periods. The emulation consists of average of amount of satellites that is divided in 5 time periods and represented by global heatmaps.
00 05 10 15 20
to 05:00
10 15 20 00
00 00 00 00
With Easy-11, we calculated the number of visible satellites every 5 minutes, then we averaged it over every 5 hours (except the last period of 4 hours). The time reference for the BDS uses the BeiDou navigation satellite system Time 86400secs measurement
seconds, thus 24^ours *60„
. * 60_____ —
BDT) in
This means that every 900 seconds the of data is taken. Table 1 contains visibility data, obtained in the days 87 and 88 of 2017 during a 24h observation taken every 15 minutes and averaged over different periods. This is necessary since a single average would not give us a more effective visibility of the satellites.
The table 1 shows the number of visible satellites at a certain point of the map. It is worth noting that it has divided in five periods, and each period has a comparison among day 87 and day 88. So, it can be seen that the BeiDou system has not yet a global coverage.
the simulation step length setting: 15 min ;
Spatial variation of the number of the actual BeiDou constellation
Table 1
Time Period
Day 87
Day
First Period (00:00 -05:00)
Second Period
(05:00 -10:00)
i' f . J «?Ьсг; " ^ J
>*,- * • -4 ..'".--J
V.
^^ЖрЦ-^. ï'Çjt \-H
- , j,
Third Period (10:00 -15:00)
Fourth Period
(15:00 -20:00)
Fifth Period (20:00 -00:00)
First period: Between 0:00 to 5:00 hours, BeiDou has no satellites around part of Canada and U.S and Latin America, but the vast majority of the satellite are visible in the region of Asia, like Philippines, Malaysia, Vietnam and Thailand, the satellites count reach more than 10 satellites; It can be seen that 9 satellites are around China and India; Between 7 and 8 satellites cover the north and south part of the region of Asia; more less that 6 and 5 cover the region of Europe. Second Period: it is almost the same as the first one, the difference is found in the north of the American continent, can have the visibility of 1, 2 and up to 3 satellites. Third period: The visibility of the satellites in the American continent is increased from 3 to 4 satellites and decreases the number of satellites in the region of Asia between 8 to 9 satellites. Fourth period: It can be seen that from 15:00 until 20:00 hours, the northern and southern hemisphere in the eastern part the vast majority visibility of satellites above the 7 satellites and in South America can be observed between 3 to 4 satellites. Fifth period: Again BeiDou has not any satellite around part of Canada and U.S until the Patagonia - Argentina, and almost come to be similar to the first period.
Relative positioning accuracy factors and the positioning error
We focus on the Volga region for an analysis and give a perspective of using BDS in this part of the world. In standalone case, one of the relative positioning error come from a few visible satellites due to the pseudorange observations are obtained from a matrix A that basically consists of the distances between satellite location and receiver location. Following the IERS (International Earth Rotation and Reference System Service), The origin is located at the mass center of the Earth; The Z-axis is in the direction of the IERS Reference Pole (IRP); The X-axis is directed to the intersection of IERS Reference Meridian (IRM) and the plane passing the origin and normal to the Z-axis; The Y-axis, together with Z-axis and X-axis, constitutes a right handed orthogonal coordinate system [7].
Thus, we take a sample of the BeiDou navigation satellite system Time (BDT), one epoch and take pseudorange of viewed satellites [7].
The figure 2 shows a spatial variation of the number of visible BeiDou satellites in regional scale. It is interesting due to the amount of satellites is uneven. This figure shows a mean between all 48 hours of test. Focusing on Volga Region we can see that the concentration of satellites is different in Samara and Penza, the variation is approximately one satellite. This paper focuses on the Penza city and analyses the DOP that could be the worst case of visible satellites and the most interesting to analyse.
Figure 2 - Spatial variation of the number of visible satellites
Analysis visibility of satellites day
of 2017
Table 2
Green Lines Indicate Visible Satellites
Elevation Mask 20°
BDT [hours]
Skyplot for the position (ф, А) = (53°, 45°) Elevation mask 20° 00
All PRNs except 1 3 4 15 16 17 18 19 20 21 22 23 24 25
Total number of Visible Satellites
Number of Visible Satellites
We take as reference the address ul. Suvorova, 111, лит. А, Penza, Penzenskaya oblast' with geographic coordinates °10,54.5"N 4 5°00,13.6"E corresponding to Penza State University. the regional analysis starts using the Easy-11.
The table 2 shows the result of visibility of satellites on Penza by Easy-11 using Rinex-file of day 88 of 2017. The results show that the system is not a 100% functional, however, the receiver can observe the minimal number of satellite for positioning into long periods of day. The skyplot allows to see that the regional satellites as IGSO and GEO reach to cover this part of Russia with an approximation of 3 satellites a little greater to the 60 ° over cut-off angle and the passage of a satellite by zenith. With a mask (cut-off angle) of 20° the visibility of satellites is not stable and it creates a sort of use strips, where between 20 hours and 01 hour is the best visibility.
The visibility of satellites is just part of the computation of positioning accuracy.
To analyze the DOP, we based on the satellite geometry; given the parameters ephemerides data and BDT, then to calculate satellite locations by satpos function (Easy Suite) ; the navigational solution observation allows to determine the A matrix [8].
(obsX — satXX (obsY — satY)- (obsZ — satZ)-
A =
Pi
obsX — satX2
Pi
obsX — satXn
Pn
Pi
(obsY -- satY)i Pi
(obsY — satY)n
Pi
(obsZ — satZ)i
Pi
(obsZ — satZ)n
—1 —1 —1
With the A matrix, we calculate the cofactor matrix Q which is the inverse of the normal
equation matrix the components:
Q matrix has the following
■Чхх 4xY 4xz 4xt
4yx 4yy 4yz 4Yt
4zx 4zY 4zz 4zt
\-4tx 4tY 4tz 4tt
Q = inv(A' *A) =
Therefore we compute the DOP in Matlab by:
GDOP = sqrt(trace(Q)); PDOP = sqrt(trace(Q(1: 3,1:3))); TDOP = sqrt(Q(4A));
The whole DOP values are dimensionless, it allows that the DOP values are especially useful when planning the observational periods. They multiply the range errors to give the positioning errors (approximately). Moreover it is important to remark that good observations are achieved when PDOP is smaller than 5 and when the measurements come from at least five satellites [3].
The DOPs were computed using matrix Q showed before. The figure 3 shows in 24 hour the dilution of precision. The DOP is divided in 5 derivations of DOP. The Geometrical DOP describes a slight variation with a mean 6.0084. It means an acceptable observation the service area in Penza is, but has a significant error, that peak had a high value of 25 that we assume as a wrong observation. GDOP values are mainly distributed in the 5 ~ 10m range, and the change is relatively stable; the individual time point DOP value of the jump is due to the selection of the Satellite is changed, the observation point and the satellite geometry changed greatly, resulting in DOP appear hopping. In the end the Horizontal and vertical DOP show a variation that can assume as an error produced by the possible variations of the terrain and the deformity of the prism between the receiver and satellites.
As part of this report, we compare our result of Penza with any point of Chinese region to illustrate the differences. It was chosen a random point in china 53° 10' 54.5'' N and 45° 00' 13.6'' resulting in a point in Beijing.
The dilution of precision shows that the stability and the positioning accuracy is better in Beijing. Although the media in figure 4. GDOP is higher than figure 3, the line shows a constant value below average, whereas the GDOP is constantly changing.
p
p
n
n
Geometrical Dilation of Precision
Observations of day 87 and 88
Figure 3 - DOP in Penza at the days 87 and 88 of 2017
Geometrical Dilation of Precision
Observation of day 87 and 88 Positional Dilution of Precision
Observation of day 87 and 88 Time Dilution of Precision
Time of day 87 and 88 Horizontal Dilution of Precision
Observations of day 87 and 8 Vertical Dilution of Precision
Observations of day 87 and 88
Figure 4 - DOP in Beijing (China) at the days 87 y
of 2017
On the other hand, the PDOP and TDOP remain close to their mean, it allows to see a constant stability that appear over china that as we showed before, it was the completion of phase one and two of the system. Finally, the vertical dilution of precision is better in Beijing with a difference of 15 over the both averages.
Conclusion
It is evident that the coverage is not worldwide yet, however, it is expected to increase the coverage in 2017 with the launch of new satellites.
It is important to mention that is used the conventional method of positioning that also used in Easy-11 and all its library of Easy Suite provide by pr. Kai Borre at Samara Research University. The details of these methods are given in [3].
The future of BDS and all GNSS is bright. More satellites and more signals will be available to whole kind of users. However, the challenge will be how to solve interoperability issues between them. Interoperability and compatibility of all GNSSs would ensure the benefits of satellite-based Positioning, Navigation and Timing are far
greater than what any individual system can provide.
The preliminary results presented in this article indicate BDS-2 can provide 4 to 8 additional satellites with superior performance over the greater Asia region with the use of its unique GEO/IGSO/MEO combined satellite constellation. With the standalone case, the performance of Compass would get little better than that of GPS on a global scale, whereas a significant performance improvement is in the Asia region. In fact, the performance of Compass in Asia is improved significantly compared to GPS alone in term of visibility.
On the other hand, the regional analysis in Penza. The BDS shows that in the entire service area 4 or more satellites are visible and it is the key of the service. The area of visible number reaches an insufficient performance, the visibility and the coverage is not enough too.
In Penza, DOP values distributed in the range 5~10 , focusing on the service area with reference to the DOP grade distribution are up to acceptable, but not in whole time. However, the position changes more stable. For a civilian purpose, it is the expected result and it would
be thought to use the BDS as part of a combined system with GPS and Glonass. Thus it is possible to increase the accuracy of mapping and Topology in a considerable way.
There are many factors of positioning error, we focus on geometrical analysis because it allows you to take a look and be able to understand if it is worth to enter fully into the positional analysis on the Volga region. As a conclusion of this report we give advice on beginning to enter into analysis of this constellation and improve any positioning use of it
The analysis of satellites visible it shows the BDS is not yet completed and therefore it is just a close approximation of real use. As can be seen in the graphs, also the BDS has a poor coverage in the American continent, and depending on the time periods, it can observe a vast majority of the satellites in the region of middle of the continent of Asia, reaching its coverage almost up to the northern and southern hemispheres, and it is advantage that should be taken.
REFERENCES
1. Gibbons Media & Research LLC, "China to Launch First BeiDou-3 Navigation Satellite this Summer," 16 Febrary 2017. [Online]. Available: http://www.insidegnss.com/node/535 6.
2. 2016 Gibbons Media & Research LLC, "China Launches New MEO BeiDou Satellite; 18 More to Come by End of 2018," 5 January 2016. [Online]. Available: http://www.insidegnss.com/node/4 8 37.
3. G. Strang and K. Borre, Algorithms for Global Positioning, 2012.
4. C. He-Chin, H. K.-W. C. Yu-Sheng, Y. Ming and R. Ruey-Juin, "The performance comparison between GPS and BeiDou-2/compass: a perspective from Asia," National Cheng-Kung University,, Tainan 701, 2009.
5. T. Weiming, C. H. Jian and H. Meng, "Analysis of the Impact of BeiDou Regional Constellation on Relative Positioning Accuracy," Technology Research Center, Hubei Wuhan, 2015.
6. C. Yu Cong and X. Wang, "Positioning Accuracy of BeiDou regional Navigation Satellite System," Ministry of water resources public welfare industry research special of china, 2014.
7. China Satellite Navigation Office, "BeiDou Navigation Satellite System Signal In Space Interface Control Document," 2016.
8. A. Ranganathan, "github," 2011. [Online]. Available: https://github.com/aanjhan/cu-hw-gps. [Accessed April 2017].
9. M. Bhuiyan, S. Soderholm, L. Ruotsalainen and H. Kuusniemi, "Implementation of a Software-Defined BeiDou Receiver," Lecture Notes in Electrical Engineering •, May 2014.
10. O.M. Montenbruck, A. Hauschild, P. Steigenberger, U. Hugentobler, P. Teunissen and S. Nakamura, "Initial Assessment of the COMPASS/BeiDou-2 Regional Navigation Satellite System".
11. J. Prakash and A. Khandelwal, "Development of Open Source Compass SDR," p. 50, 2012.
12. H. Riebeek, "NASA Earth Observatory," 4 September 2009. [Online]. Available: http://earthobservatory.nasa.gov/?eocn=topnav&eoci=logo. [Accessed 3 March 2017].
13. Y. Tsui and J. Bao, Fundamentals of Global Position System Receivers a Software Approach, New York: John Wiley & Sons, Inc., 2000.
УДК 674.8(075.8)
Левин А.Б., Афанасьев Г.Н.
ФГБОУ ВО «Московский государственный технический университет имени Н.Э. Баумана»
(МГТУ им. Н.Э. Баумана), Мытищинский филиал, Московская обл., Мытищи, Россия
ЭНЕРГЕТИЧЕСКИЙ И МАТЕРИАЛЬНЫЙ БАЛАНС ПРОЦЕССА ПРОИЗВОДСТВА ЖИДКОГО ТОПЛИВА ИЗ ДРЕВЕСНОЙ БИОМАССЫ МЕТОДОМ БЫСТРОГО ПИРОЛИЗА
Рассмотрен тепловой и материальный баланс получения жидкого моторного топлива в процессе быстрого пиролиза древесины. Предложены условные интегральные химические формулы древесины и моторного топлива из нее. Определен расход сухой измельченной древесины для производства 1 т моторного топлива. Приведены результаты эксплуатации действующих установок по производству жидкого моторного топлива из древесины методом быстрого пиролиза. Выполнена оценка себестоимости жидкого биотоплива, получаемого этим методом. Показано, что в современных экономических условиях производство из древесины жидкого моторного топлива неэффективно
Ключевые слова:
древесина, быстрый пиролиз, жидкое моторное топливо, экономическая эффективность
Введение
В связи с ограниченностью земных запасов ископаемых энергоресурсов и желанием в минимально возможной степени зависеть от их импорта заметно возрос интерес к проблеме вовлечения различных видов биотоплива в топливно-энергетический баланс. Этот интерес поддерживается также требованиями сокращения антропогенных выбросов в атмосферу парниковых газов, предположительно приводящих к глобальному изменению климата.
Поскольку газообразное и жидкое топливо более востребовано, исследования в области технологий производства жидкого, в частности моторного, биотоплива весьма интенсивны. Успешно развивалось в период высоких цен на нефть производство такого топлива из растительного пищевого сырья. Так в 2011 году в Бразилии было произведено 26 млрд. литров этилового спирта из сахарного тростника для использования его в качестве компонента моторного топлива. В США производится примерно 4 0 млрд. литров такого топлива из маиса и пшеницы [1]. Известны примеры масштабного производства биодизеля - жидкого топлива, применяемого в смеси нефтяным дизельным топливом в одноименных двигателях внутреннего сгорания [18]. В качестве сырья для производства биодизеля используется рапсовое или пальмовое масло [2, 19].
Начато перспективное производство биодизеля из водорослей.
В то же время производство жидкого моторного топлива из лигноцеллюлозного сырья, в том числе из биомассы древесины развивается менее интенсивно. Хорошо известны и десятки лет используются две технологии - гидролизное производство и технология Фишера-Тропша.
Гидролиз состоит в расщеплении полисахарида целлюлозы древесины слабым раствором серной кислоты на более короткие молекулы - монозы и полисахариды. После нейтрализации и очистки гид-ролизат сбраживается, и последующей ректификацией слабого раствора получают товарный этиловый спирт. Это экологически небезопасное производство, и оно не выдерживает конкуренции с производством синтетического спирта из ископаемых углеводородов - нефти и газа.
Способ Фишера-Тропша, известный с 1927 года, состоит в получении из углеводородного сырья методом пиролиза так называемого сингаза, смеси СО и Н2, и последующего синтеза из этой смеси жидкого топлива или масел. Наилучшие результаты были достигнуты при переработке таким способом каменных углей в странах, не имеющих собственных месторождений нефти, например, в ЮАР.
