sat-alert

sat-alert is a small service oriented to be execute by the computer cronetab. It takes a date, a satellite name and url to post as CLI arguments. It returns a list of all the satellite passes above the ground station that PREDICT is configured to use.

The package is composed by:

1. sat-alarm.c. It retrieves data from PREDICT in server mode.

2. updateTLE.sh. This script only updates the local TLE's for PREDICT or GPREDICT to use. It does so by downloading the last published TLE'S at celestrak.com.

This code is intended to be run on a server where PREDICT is running in server mode. Also, both codes are inteded to be added into a UNIX cronetab. sat-alarm.c should run once per day, while updateTLE.sh once per hour.

External libraries

sat-alarm.c uses several libraries that need to be installed before compilation. Two of those need to be added dinamically while compiling. These are:

1. curl.h
2. json-c.h Therefore, after installing all the libraries, to compile:

gcc sat-alarm.c -ljson -lcurl

Crontab for periodic execution:

crontab -e

In crontab file add the follwoing line to run in an hourly basis, for example.

0 * * * * ./path/to/scheduled/code

PREDICT configuration

NOTE: By default, PREDICT uses socket port 1210 for communicating with client applications. First, install PREDICT.

sudo apt install predict

Now configure your QTH information and perform a first manual update of its TLE's. Finally, start it in server mode.

predict -s

Example of manual usage

After follwoing the previous steps just run the code like:

sat-alert -s ISS -d 20/06/2017 -u https://hooks.slack.com/services/xxxxx

This would POST to the given URL information about the ISS passing above the ground station, the 20th of June of 2017.

Date and Time (UTC)	El	Az	Ph	Lat	Lon	R	Orbit
1493799554 Wed 03May17 08:19:14	0	159	192	23	65	2304	5477 +
1493799624 Wed 03May17 08:20:24	2	147	195	26	62	2080	5477 +

Its raw format in JSON would be:

{
    "attachments": [
        {
            "color": "#36a64f",
            "pretext": "SAT NAME + DATE",
            "title": "Date and Time (UTC)  | El   |  Az  | Ph   | Lat  | Lon  | R    | Orbit",
            "text": "1493828443 Wed 03May17 16:20:43    0  305  242   50   99   2313   5482 *"
        }
    ]
}

If date is not given, then the current date is taken. For automatic usage the command is the same but run by cronetab.

Thanks

We would like to thank the PREDICT developers for the great CLI tool for Satellite tracking that they have generated. https://github.com/koansys/predict