shupp / predict Goto Github PK

A partial PHP port of the Gpredict program for real-time satellite tracking and orbit prediction.

PHP 81.71% CSS 0.95% JavaScript 9.89% HTML 7.45%

prediction php satellite orbit gpredict sgp4 sdp4 mechanics

predict's Introduction

Overview

Predict is a partial PHP port of the Gpredict program that allows real-time tracking and orbit prediction of satellites from two line element sets. It supports the SGP4 and SDP4 models for prediction.

Installation

Just clone this repo and try out the tests and examples from the root of the checkout.

Examples/Tests

The tests directory includes a port of the original sgpsdp test files from Gpredict. They are pretty close.

Included in the examples directory is a sample iss.tle (with an update script, which you should run first). There are two examples, the visible_passes.php script and the benchmark.php script. The former is for generating visible pass predictions of the ISS, and its output is similar to what you might get from the Heavens-Above website, and it is heavily commented. The latter just does predictions for benchmarking with xhprof.

You can see an image of a Predict/Google Maps API mash-up I did for fun:

You can also see an example visible pass plotted from the polar view of the observer:

About this port

This port largely maintains the style and organization of the original C code, but scopes methods into classes rather than leaving everything in the global scope. The motivation for this is so that changes upstream can more easily be integrated over time. Only the prediction routines have been ported.

predict's People

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urthecast-alpha earthdaily-analytics imclab ontwikkel sshyran antonjan ty701 mdb473 swipswaps puchol baptistebuvron luislortega bnomei

predict's Issues

Use future time stamp for TLE epoch date

Firstly, many thanks for your work on this, it's been a number of years since you developed it but it's still working well with PHP 7.4 today!

As I understand it the orbit data is derived from the epoch timestamp in the TLE, if I want to run a prediction for orbit data for the next X hours how can I pass in a custom epoch timestamp?

just retrieve a lat long from TLE

Hi there and thanks for your work.
I would like to retrieve the actual position (lat,long,alt) of a satellite using it tle

is there an easy way to achieve this with your library ?

thx

Generate the polar view

Hi,
First of all thank you for your work, it is very useful to me.

I was wondering what tools did you use to generate this polar view? :

Regards,

Baptiste

find_aos

While running the examples, system hangs and never returns. I used benchmark.php to pinout the problem.
in find_aos there is a while loop that never returns as it never meets its exit criteria

            /* coarse time steps */
            while (($sat->el < -1.0) && ($t <= ($start + $maxdt))) {
                $t -= 0.00035 * ($sat->el * (($sat->alt / 8400.0) + 0.46) - 2.0);
                $this->predict_calc($sat, $qth, $t);
	    }

I have logged the values pr. iteration but could not upload the file by some reason, but what I see is that $t does not change much pr iteration, the same goes for $sat->el. Result is that the while never returns

The values below is representative for millions of iterations

Questions is if there is php modules that is needed for this to work other than the default installed.

iterations	sat->el	sat->alt	t	start	maxdt
0	-73,975175626402	-4560,103514259	2459617,4481556	2459617,4481556	10
1	-73,87032519055	-4561,181733378	2459617,44671	2459617,4481556	10
2	-73,464149095807	-4560,5291291953	2459617,4452641	2459617,4481556	10
3	-75,310423177676	-4563,847366679	2459617,443832	2459617,4481556	10
4	-78,015114451347	-4566,4703585768	2459617,442336	2459617,4481556	10
5	-77,516865451781	-4560,4099581754	2459617,4407525	2459617,4481556	10
6	-74,636932324811	-4554,8049470713	2459617,4392032	2459617,4481556	10
7	-73,668009331926	-4557,434459539	2459617,4377549	2459617,4481556	10
8	-74,451387515641	-4561,3075714539	2459617,4363264	2459617,4481556	10
9	-73,65694944637	-4560,7715054378	2459617,4348632	2459617,4481556	10
10	-73,875387357264	-4561,5292445828	2459617,4334248	2459617,4481556	10
11	-76,699016024553	-4565,749786223	2459617,4319777	2459617,4481556	10
12	-78,917294329151	-4565,075014268	2459617,4304351	2459617,4481556	10
13	-76,604863196001	-4557,2245809497	2459617,4288298	2459617,4481556	10
14	-73,886629026637	-4555,2627792388	2459617,4273171	2459617,4481556	10
15	-74,156655017189	-4559,6561184997	2459617,425889	2459617,4481556	10
16	-74,689487120297	-4561,5841579956	2459617,4244395	2459617,4481556	10
17	-73,409089479928	-4560,6666999958	2459617,4229686	2459617,4481556	10
18	-74,876013372407	-4563,4031843497	2459617,4215376	2459617,4481556	10

visible_passes example produces no output

I run the visible_passes.php and it only outputs the execution time. I run the update_iss_tle.php, switched to the Munich coordinates no change. (PHP 7.3.11)

I also run the tests:
test-001:

DEEP_SPACE_EPHEM: 0 (expected: 0)

+-----------+-------+-------------------+----------------+
| step time | label | result            | expected       |
+-----------+-------+-------------------+----------------+
| 0         | X     | 2328.970679894    | 2328.97048951  |
|           | Y     | -5995.2208365303  | -5995.22076416 |
|           | Z     | 1719.970675003    | 1719.97067261  |
|           | VX    | 2.9120722684876   | 2.9120723      |
|           | VY    | -0.98341533361961 | -0.98341546    |
|           | VZ    | -7.0908169591995  | -7.09081703    |
| 360       | X     | 2456.1078185219   | 2456.10705566  |
|           | Y     | -6071.9386872949  | -6071.9385376  |
|           | Z     | 1222.8956529742   | 1222.89727783  |
|           | VX    | 2.6793891170929   | 2.67938992     |
|           | VY    | -0.44828850697443 | -0.44829041    |
|           | VZ    | -7.2287926088171  | -7.22879231    |
| 720       | X     | 2567.5628174962   | 2567.56195068  |
|           | Y     | -6112.5038266594  | -6112.50384522 |
|           | Z     | 713.96223091205   | 713.963974     |
|           | VX    | 2.4402450448499   | 2.44024599     |
|           | VY    | 0.098110705997632 | 0.09810869     |
|           | VZ    | -7.3199594406421  | -7.31995916    |
| 1080      | X     | 2663.089901107    | 2663.0907898   |
|           | Y     | -6115.4828512355  | -6115.4822998  |
|           | Z     | 196.39997365938   | 196.39640427   |
|           | VX    | 2.1961212031747   | 2.19611958     |
|           | VY    | 0.65241593650208  | 0.65241995     |
|           | VZ    | -7.3628241569699  | -7.36282432    |
| 1440      | X     | 2742.5539796449   | 2742.55133057  |
|           | Y     | -6079.6701380186  | -6079.67144775 |
|           | Z     | -326.38990977996  | -326.38095856  |
|           | VX    | 1.9484977623213   | 1.94850229     |
|           | VY    | 1.2110724358902   | 1.21106251     |
|           | VZ    | -7.3561931161315  | -7.35619372    |
+-----------+-------+-------------------+----------------+
Execution time: 1.42ms

test-002:

DEEP_SPACE_EPHEM: 64 (expected: 64)

+-----------+-------+-------------------+------------------+
| step time | label | result            | expected         |
+-----------+-------+-------------------+------------------+
| 0         | X     | 7495.2201411522   | 7473.3706665     |
|           | Y     | 462.94809890153   | 428.95261765     |
|           | Z     | 5835.8349041958   | 5828.74786377    |
|           | VX    | 5.0882603867801   | 5.1071513        |
|           | VY    | 6.443501397454    | 6.44468284       |
|           | VZ    | -0.19471250013834 | -0.18613096      |
| 360       | X     | -3288.9442643066  | -3305.22537232   |
|           | Y     | 32406.513820666   | 32410.86328125   |
|           | Z     | -24698.039221757  | -24697.17675781  |
|           | VX    | -1.3007845995153  | -1.30113538      |
|           | VY    | -1.152411491841   | -1.15131518      |
|           | VZ    | -0.28406152599689 | -0.28333528      |
| 720       | X     | 14274.027501406   | 14271.28759766   |
|           | Y     | 24124.319408041   | 24110.46411133   |
|           | Z     | -4717.544641732   | -4725.76837158   |
|           | VX    | -0.31979616237533 | -0.32050445      |
|           | VY    | 2.6780090133369   | 2.67984074       |
|           | VZ    | -2.083730161548   | -2.08405289      |
| 1080      | X     | -9974.2370793588  | -9990.05883789   |
|           | Y     | 22705.004307077   | 22717.35522461   |
|           | Z     | -23620.751174898  | -23616.890662501 |
|           | VX    | -1.0168297875949  | -1.01667246      |
|           | VY    | -2.2917181849532  | -2.29026759      |
|           | VZ    | 0.72887185127627  | 0.72892364       |
| 1440      | X     | 9796.1208521507   | 9787.86975097    |
|           | Y     | 33758.707410724   | 33753.34667969   |
|           | Z     | -15022.996600166  | -15030.81176758  |
|           | VX    | -1.0932750515211  | -1.09425966      |
|           | VY    | 0.92249936983212  | 0.92358845       |
|           | VZ    | -1.5229952073342  | -1.52230928      |
+-----------+-------+-------------------+------------------+
Execution time: 1.82ms

I also tried with a well known tle&qth location with a valid pass in ~1 hour in the feature, same result.

shupp / predict Goto Github PK

predict's Introduction

Overview

Installation

Examples/Tests

About this port

predict's People

Contributors

Stargazers

Watchers

Forkers

predict's Issues

Use future time stamp for TLE epoch date

just retrieve a lat long from TLE

Generate the polar view

find_aos

visible_passes example produces no output

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