GNSS Output Plotting Help.

I have an output variable in cell array format (TC_NORM 24x1 cell). It is divided in 24 hours/day. It is divided in 3.600 seconds/hour. Total of 32 GPS Satellites.

For each hour the cell unity is 6 x 3.600 Double.

I have thought in formating the lines, four types to fit the 32 satellites with the eight colors for each satellite.

SV1(Line(*) Y); SV2(Line(*) M) SV3(Line(*) C) SV4(Line(*) R) SV5 (Line(*) G) SV6(Line(*) B) SV7 (Line(*) W) and SV8 (Line(*) K);

The second 8 satellite group the line (-);

The third 8 satellite group the line (.);

The forth 8 satellite group the line (+);

I wish to plot the entire TC_NORM 24x1 cell in only one figure.

Considering that sll satellites may appear in some hours and changing as hours increase. I will have a the Satellites on the Axis Y and the second of the entire day in the Axis X.

I appreciate and thank in advance any help I receive.

Best Regards,

Gilberto Fernandes

Answer 1

[sanidhyak]

Hi @Gilberto Santos,

I understand that you want to plot “GNSS” data from a “24x1 cell array” (“TC_NORM”), where each cell represents an hour with a “6x3600” double matrix. You also want to visualize all 32 GPS satellites over a 24-hour period with distinct colors and line styles.

Kindly refer to the following steps to achieve the same:

1. Initialize the figure to plot all data in one graph.
2. Define colors and line styles. Use 8 colors for groups of 8 satellites and use 4 different line styles (-, --, :, -.) to differentiate them.
3. Loop through each hour (1-24). Extract the 6x3600 double matrix from “TC_NORM”{hour} and compute the time range (in seconds) for the current hour.
4. Loop through all 32 satellites and assign row indices (modulo 6) to fetch data. Also, assign color and line style based on satellite index.
5. Now plot the data and set appropriate plot styling.

You can also go through the below code which implements the above approach:

clc; clear; close all; 

% Assume TC_NORM is already loaded as a 24x1 cell array 

colors = {'y', 'm', 'c', 'r', 'g', 'b', 'w', 'k'}; 
lineStyles = {'-', '--', ':', '-.'}; 

figure; 
hold on; 

total_seconds = 24 * 3600; % Total seconds in a day 

yticks(1:32) = 1:32; 
for hour = 1:24 
    if isempty(TC_NORM{hour}) 
        continue; 
    end 
    
    data = TC_NORM{hour}; % 6 x 3600 matrix per hour 
    start_time = (hour - 1) * 3600; % Starting second for the hour 
    
    for sv = 1:32 
        row = mod(sv-1,6) + 1; % Select row in 6x3600 matrix 
        time_values = start_time + (1:3600); 
        
        color_index = mod(sv-1, 8) + 1; 
        line_index = floor((sv-1) / 8) + 1; 
        
        plot(time_values, data(row, :), 'Color', colors{color_index}, 'LineStyle', lineStyles{line_index}); 
    end 
end 

ylabel('Satellite PRN'); 
xlabel('Time (seconds of the day)'); 
title('GNSS Output Plot'); 
ylim([1, 32]); 
set(gca, 'YTick', 1:32); 
grid on; 
hold off; 

For further reference on MATLAB’s plotting functions, kindly refer to:

• https://www.mathworks.com/help/matlab/ref/plot.html

Cheers & Happy Coding!