Enhanced receiver architectures for processing multi GNSS signals in a single chain : based on partial differential equations mathematical model

The focus of our research is on designing a new architecture (RF front-end and digital) for processing multi GNSS signals in a single receiver chain. The motivation is to save in overhead cost (size, processing time and power consumption) of implementing multiple signal receivers side-by-side on-board Smartphones. This thesis documents the new multi-signal receiver architecture that we have designed. Based on this architecture, we have achieved/published eight novel contributions. Six of these implementations focus on multi GNSS signal receivers, and the last two are for multiplexing Bluetooth and GPS received signals in a single processing chain. We believe our work in terms of the new innovative and novel techniques achieved is a major contribution to the commercial world especially that of Smartphones. Savings in both silicon size and processing time will be highly beneficial to reduction of costs but more importantly for conserving the energy of the battery. We are proud that we have made this significant contribution to both industry and the scientific research and development arena. The first part of the work focus on the Two GNSS signal detection front-end approaches that were designed to explore the availability of the L1 band of GPS, Galileo and GLONASS at an early stage. This is so that the receiver devotes appropriate resources to acquire them. The first approach was based on folding the carrier frequency of all the three GNSS signals with their harmonics to the First Nyquist Zone (FNZ), as depicted by the BandPass Sampling Receiver technique (BPSR). Consequently, there is a unique power distribution of these folded signals based on the actual present signals that can be detected to alert the digital processing parts to acquire it. Volterra Series model is used to estimate the existing power in the FNZ by extracting the kernels of these folded GNSS signals, if available. The second approach filters out the right-side lobe of the GLONASS signal and the left-side lobe of the Galileo signal, prior to the folding process in our BPSR implementation. This filtering is important to enable none overlapped folding of these two signals with the GPS signal in the FNZ. The simulation results show that adopting these two approaches can save much valuable acquisition processing time. Our Orthogonal BandPass Sampling Receiver and Orthogonal Complex BandPass Sampling Receiver are two methods designed to capture any two wireless signals simultaneously and use a single channel in the digital domain to process them, including tracking and decoding, concurrently. The novelty of the two receivers is centred on the Orthogonal Integrated Function (OIF) that continuously harmonies the two received signals to form a single orthogonal signal allowing the “tracking and decoding” to be carried out by a single digital channel. These receivers employ a Hilbert Transform for shifting one of the input signals by 90-degrees. Then, the BPSR technique is used to fold back the two received signals to the same reference frequency in the FNZ. Results show that these designed methods also reduce the sampling frequency to a rate proportional to the maximum bandwidth, instead of the summation of bandwidths, of the input signals. Two combined GPS L1CA and L2C signal acquisition channels are designed based on applying the idea of the OIF to enhance the power consumption and the implementation complexity in the existing combination methods and also to enhance the acquisition sensitivity. This is achieved by removing the Doppler frequency of the two signals; our methods add the in-phase component of the L2C signal together with the in-phase component of the L1CA signal, which is then shifted by 90-degree before adding it to the remaining components of these two signals, resulting in an orthogonal form of the combined signals. This orthogonal signal is then fed to our developed version of the parallel-code-phase-search engine. Our simulation results illustrate that the acquisition sensitivity of these signals is improved successfully by 5.0 dB, which is necessary for acquiring weak signals in harsh environments. The last part of this work focuses on the tracking stage when specifically multiplexing Bluetooth and L1CA GPS signals in a single channel based on using the concept of the OIF, where the tracking channel can be shared between the two signals without losing the lock or degrading its performance. Two approaches are designed for integrating the two signals based on the mathematical analysis of the main function of the tracking channel, which the Phase-Locked Loop (PLL). A mathematical model of a set of differential equations has been developed to evaluate the PLL when it used to track and demodulated two signals simultaneously. The simulation results proved that the implementation of our approaches has reduced by almost half the size and processing time

OGSR: A Low Complexity Galileo Software Receiver using Orthogonal Data and Pilot Channels

To improve localisation accuracy and multipath rejection, the Galileo-OS signal offers a new modulation with efficient power distribution technique between the two data and pilot navigation components. To achieve the full benefits of this modulation, a robust acquisition and tracking methods must be deployed. For example, using two parallel correlation channels to acquire these data and pilot will gain 3dB over using a single channel acquisition correlating with either one of them. However, dual channel SW receivers cost more processing overheads. In this paper, the authors propose to orthogonalise the received data and pilot signals so to enable their acquisition in a single correlation channel bandpass sampling receiver. Our simulation results, using Simulink, prove that OGSR performance is maintained (preserving the 3dB gain) with less processing time while the implementation complexity is reduced by 50%

A Single Acquisition Channel Receiver for GPS L1CA and L2C Signals Based on Orthogonal Signal Processing

The GPS L1CA and L2C signals are transmitted from the same GPS Satellite Vehicles constellation. It is desirable, especially in commercial GNSS receivers, to have both of these signals acquired by a single receiver so to assure better signal acquisition and improved reliability at wider operating areas. To achieve this in an efficient process, we propose to integrate the GPS L1CA and L2CM signals orthogonally and acquire them in a single processing channel. After removing the Doppler frequency, our receiver first adds the quadrature components of the L2CM signal and the L1CA signal. This new signal is then shifted by 90o. This is then added to the remaining components of these two signals; thus resulting in an orthogonal form of the combined signals. Secondly, the FFT of this orthogonal signal is then mixed with the complex conjugate of the FFT of a locally generated replica of the CA code combined with a 90o-shifted replica of the CM code. Finally, the output signal is then converted back to the time domain to acquire the signal’s peak. The complexity of our dual-signal receiver implementation is half of that used in dual acquisition methods. Furthermore, MATLAB Simulation results show that our acquisition method compares favorably with other approaches in terms of detection of low sensitivity signals and false alarm probability

Galileo Signals Acquisition Using Enhanced Subcarrier Elimination Conversion and Faster Processing

To solve multipath and to enhance the localisation accuracy in a harsh environment, BOC modulation has been adopted in modern GNSS transmission, such as GPS-M-code and Galileo-OS-code signals. The designers of the BOC technique have pointed out that the correlation function becomes ambiguous when the received signal is correlated with the reference BOC signal at code phase resolutions of 0.5 Chip. This has motivated many contributions to resolving this ambiguity, for example, by processing each side of the BOC lobes as a BPSK signal. Our literature survey concluded that solutions claiming to have mitigated this ambiguity actually have resulted in a more complex receiver implementation. The Enhanced Subcarrier Elimination (ESCE) method detailed in this paper proposes combining the two side lobes into a single lobe centered at the main frequency, thus gaining 2dB more signal power as well as reducing the correlation requirements (signal’s mixing and transforming operations) to the half; i.e. accelerating the acquisition process. HaLo-430 platform generated signals used for testing the MATLAB model of ESCE proves that we outperform three of the most used unambiguous methods

Blood Chemistry and Balance Study in Tansurethral Resection

1) Blood chemistry and balance study of water and sodi u m chloride were performed before and after TUR prostate, bladder neck and bladder tumor, and interesting results were obtained. 2) Blood chemistry (51 cases) : Significant changes were not found in cases of TUR bladder neck and bladder tumor. On the contrary, in TUR prostate were noted transient post-operative decrease of sodium and chloride and transient increase of potassium, nonprotein nitrogen and glucose. Coy combining power changed in somewhat opposite direction to the change of chloride. Protein and hematocrit also showed some decrease temporarily. 3) Balance study of water and sodium chloride (42 cases): Marked changes were not found in cases of TUR bladder neck and bladder tumor. On the contrary, in cases of TUR prostate, as in retropubic prostatectomy, post-operative balance of both water and sodium chloride was followed by negative balance, and then normal balance was regained toward the third post-operative day. Degree of positive balance in TUR prostate as well as intake and output was greater than in open prostatectomy, indicating more important effect on the circulatory system and the kidney. 4) Absorption of irrigating fluid, ine v itable specific factor in TUR prostate, together with the stress in common in any surgery are considered to cause those changes during and after resection. 5) The results described above lead to the following conclusions. 1. TUR bladder neck and bladder tumor gives little i n fluence on the general condition of patients and can be considered a minor surgery. 2. TUR prostate, on the contrary, shou l d be considered a major surgery comparable with the open prostatectomy and may give a greater influence on the circulatory system and the kidney. Selection of cases for TUR prostate must be done with more caution than for open prostatectomy

Typic Xerofluvents. Área de estudio: Sevilla. Localización: Vega

3 páginas.-- Este perfil se ha generado en uno de los informes técnicos realizados en el Curso Internacional de Edafología y Biología Vegetal, patrocinado por la UNESCO-AECI y CSIC, que desde 1963 hasta 2007 se ha venido impartiendo en el CEBAC, actual IRNAS.-- Este pertenece al XIX Curso, 1982.-- El informe original se encuentra en el IRNAS para su consulta.CEBAC-CSICPeer reviewe