Erwan Motte / GLORI Documentation

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source/INS/INS_ancillary.rst
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1 1 **********************
2 2 Ancillary measurements
3 3 **********************
  4 +
  5 +Reference of Figure 1 is in the :ref:`Ins_intro`
  6 +
  7 +As shown in (Figure 1), the following ancillary data are measured and recorded:
  8 +
  9 +--The aircraft’s distance from the ground, using a 4.2–4.4 GHz Thomson ERT 900 Radio Altimeter with an accuracy of approximately 2%.
  10 +
  11 +--Attitude and position information using the aircraft’s integrated Inertial Navigation System (Ixblue AirINS [36])
  12 +(GPS time, GPS altitude, latitude and longitude, heading, pitch, roll, and 3-axis speed).
  13 +
  14 +--GPS Position derived from a Ublox Neo6T receiver [37] connected to the Zenith RHCP antenna, which records the aircraft’s
  15 +position and GPS information (relative elevation and azimuth, code phase, Doppler frequency, signal to noise ratio, pseudo-range) at a frequency of 5 Hz.
4 16 \ No newline at end of file
... ...
source/INS/INS_backend.rst
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1 1 ***************
2 2 Back end
3 3 ***************
  4 +
  5 +The back end unit is an industrial PC running Windows 7, with 8 GB of RAM and an Intel core i7 processor.
  6 +The system hard drive is a single Solid State Drive (SSD), whereas the data hard drive consists of two 1 TB SSDs, allowing
  7 +more than 20 h of continuous raw data to be recorded at the nominal 10 Mbps sampling frequency.
4 8 \ No newline at end of file
... ...
source/INS/INS_data_format.rst
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1 1 ***************
2 2 Raw Data format
3 3 ***************
  4 +
  5 +Output data format values
  6 +=========================
  7 +
  8 +There are many types of data values notably the unsigned, signed ans 2s complements.
  9 +In the case of GLORI the output format values is a type of unsigned, where the values are represented in the table below.
  10 +
  11 ++------+------+
  12 +| 00 | -3 |
  13 ++------+------+
  14 +| 01 | -1 |
  15 ++------+------+
  16 +| 10 | +1 |
  17 ++------+------+
  18 +| 11 | +3 |
  19 ++------+------+
  20 +
  21 +
  22 +Output data format
  23 +==================
  24 +
  25 +Output data of GLORI is a 32 bits ibyte format. Which means that we have an I & Q series of data.
  26 +This series of 32 bits data is composed of 2 samples S0 and S1, meaning that every sample contains 16 bits. Since there are
  27 +4 channels in GLORI, the 16 bits series is therefore divided by 4 and results to 4 bits of information for each channel.
  28 +These 4 bits correspond to the I & Q mentionned previously, where the first 2 bits are for I and the second two are for Q.
  29 +The channels 0,1,2 and 3 are respectively in this order for both samples as illustrated in the figure below.
  30 +
  31 +.. figure:: /img/raw_data_format.png
  32 + :align: center
  33 + :alt:
  34 +
  35 + Output data format
  36 +
  37 +
  38 +Compressing data
  39 +================
  40 +
  41 +In the case that not all channels are being used, a conversion_2bits code can be used to save space while keeping informative data intact.
  42 +for example if only channel 0 is being used, the other channels will only collect noise data. This code eliminates data in
  43 +other channels and keeps only data from channel 0 transforming the output data format into 8 bits instead of 32 bits.
  44 +
  45 +conversion_code:` http://tully.ups-tlse.fr/erwan/stage_ray/blob/master/Conversion_code/raw_IQ_to_2bit_packed_3ch_skip500kS.c `
  46 +
  47 +You first need to build the code then use the expression below:
  48 +``./raw_IQ_to_2bit_packed_3ch_skip500kS /home/glori/GLORI/test_lake_flight3_sdr/GLORIE_2015-06-24-233029.dat``
  49 +
  50 +Where ``raw_IQ_to_2bit_packed_3ch_skip500kS`` is the name of the built target and,
  51 +``/home/glori/GLORI/test_lake_flight3_sdr/GLORIE_2015-06-24-233029.dat`` is the file to compress.
... ...
source/INS/INS_frontend.rst
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... ... @@ -7,4 +7,9 @@ Front-End
7 7 :align: center
8 8 :alt:
9 9  
10   - GLORI Front-End
11 10 \ No newline at end of file
  11 + GLORI Front-End
  12 +
  13 +The GLORI front-end (figure) filters and amplifies the received signals, and ensures channel switching for calibration purposes,
  14 +as well as basebandmixing and D/A conversion through the use of a SDRNav40 v2 receiver.
  15 +The latter is is a multi-frequency, quad-channel, tuneable receiver using synchronized MAX2112 tuners and MAX19505 A/D Conerters,
  16 +which ensure direct down conversion and sampling of the signals.
12 17 \ No newline at end of file
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source/INS/INS_intro.rst
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  1 +.. _Ins_intro:
  2 +
1 3 ***************
2 4 Introduction
3 5 ***************
  6 +
  7 +The GLORI instrument is derived from the cGNSS-R family. It is a highly versatile, low-cost, 4-channel GNSS-R receiver,
  8 +built using mainly commercial off-the-shelf components. Direct and reflected GNSS signals are received by two hemispherical GPS dual-frequency
  9 +(L1 and L2) dual-polarization active antennas: the Zenith RHCP antenna, hereafter referred to as ZR, mounted on the upper
  10 +part of the aircraft fuselage, and the Nadir dual polarization (LHCP and RHCP) antenna, hereafter referred to as NL and NR, mounted
  11 +on the lower fuselage of the aircraft. One of the main advantages of the instrument is its ability to simultaneously record
  12 +both LHCP and RHCP polarizations, allowing it to analyse depolarization effects produced by the land surface.
  13 +The received signals are filtered to reduce out-of-band noise, which could saturate the front-end. Channel cross-calibrations
  14 +are performed during each flight, in order to assess the channel-to-channel gain imbalance possibly caused by differences
  15 +in cable losses or digitizer amplification.
  16 +The RF signals are fed into three of the four available channels of the L-band front-end, which ensures direct in-phase and
  17 +quadrature (IQ) down-conversion, 2-bit signal decimation, and serialization to a USB 2.0 interface.
  18 +A standard PC is used to acquire the raw data signals. Signal acquisition, tracking and observable computations are performed
  19 +during post-processing, following the flights. The main technical specifications of the instrument are presented in Table 1,
  20 +and an instrument block diagram is shown in Figure 1.
  21 +
  22 +.. figure:: /img/Block_GLORI_instrument.png
  23 + :align: center
  24 + :alt:
  25 +
  26 + Block diagram of the GLORI instrument.
  27 +
  28 +
  29 +
  30 +.. figure:: /img/table_instrument_specification.png
  31 + :align: center
  32 + :alt:
... ...
source/VAL/VAL_ins_frontend.rst
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... ... @@ -10,11 +10,57 @@ Oscillator stability
10 10  
11 11 Oscillator frequency
12 12 ====================
  13 ++----------------+------------+
  14 +| Oscillaor type | QUARTZ |
  15 ++================+============+
  16 +| Model |501- 04538F |
  17 ++----------------+------------+
  18 +| Frequency | 10 MHz |
  19 ++----------------+------------+
  20 +| Input | +15 VDC |
  21 ++----------------+------------+
  22 +| S.N. |8499 - 0930 |
  23 ++----------------+------------+
13 24  
14 25  
  26 +GLORI Oscillator
  27 +----------------
  28 +
  29 +.. figure:: /img/GLORI_oscillator.png
  30 + :align: center
  31 + :alt:
  32 +
  33 + GLORI oscillator
  34 +
15 35 Channel to channel phase stability
16 36 ==================================
17 37  
  38 +A splitter 3 channels was used to test phase stability between channels. At the other end of the splitter
  39 +was connected an antenna capable of intercepting L1 band frequencies.
  40 +This test will allow us to know the errors on altimetry that can be produced from this device.
  41 +After measurements and data processing, we started by visualizing the phase variation of each channel in the picture below.
  42 +
  43 +.. figure:: /img/Phase_variation_sdrnav_ti_20.png
  44 + :align: center
  45 + :alt:
  46 +
  47 +We can see in this picture 3 patches, each one appropriate to a channel. Even though some points are further away from
  48 +the patch, errors are predctable to be small because the width of the patch is reasonably small, and the phase shifting
  49 +can be calibrated so we can have all the patches centered to zero.
  50 +
  51 +Channel 0 is our reference so calculating phase and module residuals should be firstly between channel 1 and channel 0, and secondly between channel 2 and channel 0. This provides us with these images below.
  52 +
  53 +.. figure:: /img/GLORI_phase_residuals.png
  54 + :align: center
  55 + :alt:
  56 +
  57 +.. figure:: /img/GLORI_module_residuals.png
  58 + :align: center
  59 + :alt:
  60 +
  61 +Errors, as predicted, are relatively small, and we can see that residuals of channel 1 are smaller than those of channel
  62 +2.
  63 +
18 64  
19 65 Data transmission
20 66 =================
... ... @@ -23,5 +69,42 @@ Data transmission
23 69 Suggestions / Improvements
24 70 ==========================
25 71  
  72 +Nut4nt is a possible canidate for replacing GLORI. It's physically more compact and lighter than GLORI. Plus Nut4nt uses
  73 +a signle configuration file to start measurments as for GLORI needs 5.
  74 +the comparison of these front-ends is represented in the figure below.
  75 +
  76 +.. figure:: /img/Nut4nt_Glori.PNG
  77 + :align: center
  78 + :alt:
  79 +
  80 + Comparison between Nut4nt and GLORI
  81 +
  82 +It is clear in this picture that nut4nt is easiest to use, but we still have to validte its phase stability with the same test done
  83 +on GLORI. As mentionned in the picture above, Nut4nt uses a low quality internal oscillator, so to appropriately compare these two front-ends,
  84 +some minor modifications were made so that the new front-end uses the same oscillator as GLORI.
  85 +
  86 +.. figure:: /img/Nut4nt_external_osc.png
  87 + :align: center
  88 + :alt:
  89 +
  90 + New and improved Nut4nt
  91 +
  92 +
  93 +
  94 +Like the steps above, the splitter test was done on the new front-end and the phase diagram was generated.
  95 +
  96 +.. figure:: /img/Phase_variation_nut4nt_crystal_ti_20.png
  97 + :align: center
  98 + :alt:
  99 +
  100 +Although phase patches are not as satisfying as those of GLORI, we can see in this new device that we do not have phase values far from the patch.
  101 +
  102 +Phase residuals represented in the figure below, show that GLORI provides less errors in altimetry domain because the width of phase
  103 +patches in GLORI are signficantly thinner than those of Nut4nt.
26 104  
  105 +.. figure:: /img/nut4nt_glori_phase_residu.png
  106 + :align: center
  107 + :alt:
27 108  
  109 +But the difference between these two front-ends is tolerable and keep in mind that Nut4nt is physically lighter than GLORI,
  110 +which means that measurements on drone could be done with the new front-end.
28 111 \ No newline at end of file
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source/blocks.rst
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... ... @@ -25,7 +25,7 @@ blocks where identified:
25 25 - **Analysis routines (ANA)**: Routines used to explore and analyse
26 26 measurements.
27 27  
28   -- **Validation routines (VAL)**: Routines used to validate processed data
  28 +- :ref:`Validation` **(VAL)**: Routines used to validate processed data
29 29 versus modeled data.
30 30  
31 31 - **Inversion Model (INV)**: Description of the model to be used
... ...
source/conf.py
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... ... @@ -118,8 +118,8 @@ todo_include_todos = True
118 118  
119 119 # The theme to use for HTML and HTML Help pages. See the documentation for
120 120 # a list of builtin themes.
121   -html_theme = 'alabaster'
122   -#html_theme = 'sphinx_rtd_theme'
  121 +#html_theme = 'alabaster'
  122 +html_theme = 'sphinx_rtd_theme'
123 123  
124 124 # Theme options are theme-specific and customize the look and feel of a theme
125 125 # further. For a list of options available for each theme, see the
... ...
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