How to plot time from 0-24?

Dear All,

I have time :

• Description:Time of GPS measurement (GPS seconds)
• Data Type: double
• Units: s
• Valid Range: 0, 99999

How can I plot it from 0-24 UT and LT?

Best,

Ara

Answer 1

[Ayush Singh]

Hello Ara

To plot GPS time in both Universal Time (UT) and Local Time (LT), you need to convert the GPS time to hours and then adjust for the local time zone difference from UT. MATLAB makes these conversions straightforward.

I am assuming you have a vector of GPS times in seconds and want to plot some corresponding data, here's how you could do it:

1. Convert GPS Time to Hours

First, convert your GPS time from seconds to hours to make it easier to plot on a 0-24 hour scale.

gpsTimeSeconds = ...; % Your GPS time data here
gpsTimeHours = gpsTimeSeconds / 3600; % Convert seconds to hours

2. Adjust for Local Time

Determine the offset of your local time zone from UT. For example, if you are in Eastern Daylight Time (EDT), the offset is -4 hours from UT.

localTimeOffset = -4; % Example for EDT
localTimeHours = gpsTimeHours + localTimeOffset;

% Handle wrapping around 24 hours
localTimeHours = mod(localTimeHours, 24);

3. Plotting

Now, you can plot your data against both UT and LT. Assuming you have a vector `data` that corresponds to the measurements taken at the GPS times:

data = ...; % Your data corresponding to the GPS times

% Plot UT
subplot(2, 1, 1); % Create a subplot for UT
plot(gpsTimeHours, data);
xlabel('Time (UT)');
ylabel('Measurement');
title('Measurement vs. Universal Time');
xlim([0, 24]);
grid on;

% Plot LT
subplot(2, 1, 2); % Create a subplot for LT
plot(localTimeHours, data);
xlabel(['Time (LT, offset ' num2str(localTimeOffset) ' hrs)']);
ylabel('Measurement');
title('Measurement vs. Local Time');
xlim([0, 24]);
grid on;

This code will generate a figure with two subplots: one plotting your data against Universal Time and the other against Local Time.

[Ara]

Hi Ayush Singh,

Thank you for the code and your useful explanation. I plotted but it does not work. I divided time to 3600 but still is not correct. In local time the vector appears as a 0-24 but the plot is not correct.Please see atatched.

Would you please provide your advice?

[Ayush Singh]

Please let me know how are you doing the conversions for 'gpsTimeSeconds' and 'data'.

If possible please share the files you are using for conversion!

[Ara]

I have a vector column for S4 and for Time as well. Here is what I plotted.

plot (time/3600,S4);

[Ara]

Please see below the data to provide a picture of my data that I am analysing it.

Here is S4:

NaN

NaN

NaN

NaN

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0632044002413750

0.0612583011388779

0.0612583011388779

Here is Time:

1395965920.00000

1395965921.00000

1395965922.00000

1395965923.00000

1395965925.00000

1395965926.00000

1395965927.00000

1395965928.00000

1395965929.00000

1395965930.00000

1395965931.00000

1395965932.00000

1395965933.00000

1395965934.00000

1395965935.00000

1395965936.00000

1395965937.00000

1395965938.00000

1395965939.00000

1395965940.00000

1395965941.00000

1395965942.00000

1395965943.00000

1395965944.00000

1395965945.00000