Asked 14th May, 2019

How the GPS devices send messages on internet without internet connection ??

For Hikers/riders, they carry a GPS device which is connected to satellite and they can send messages to their family and friends ..
If I want to build a system to host all kinds of these devices and receive data from them related to their position.
WHAT kind of information or identification I need to know about these devices??
for example, for wireless or ethernet connection TCP/IP is the way to address .. what about the satellite devices ?

Most recent answer

14th Feb, 2020
Javad Farhani
Many devices like Garmin inReach handheld GPS allow the user to send SMS, some other Iridium satellite modem also has the same function but it required a monthly fee.

All Answers (7)

14th May, 2019
Abdelhalim abdelnaby Zekry
Ain Shams University
Dear Akram,
Such devices are built around a microcontroller where all devices including the GPS receivers are operating as a peripheral under the microcontroller. There is also wireless transceiver serving as an internet connection to the wireless LAN access point or an ADSL modem. All these modules are operating under the a local microcontroller.
Best wishes
2 Recommendations
15th May, 2019
Kgs Venkatesan
MEGHA Institute of Engineering and Technology for Women
In today’s time safety and security is what every individual wants whether you are working or staying at home whether it’s for your safety or about your loved one for that you can find a portable GPS device to track them at all time. One thing you should know about GPS trackers is to find the kind that does not permit others to track you. Picking up Letstrack GPS device can be a key to know where your loved one is and where to go when driving.
Global Positioning System (GPS) is the basic global positioning system that allows you to locate areas you need to know before going. If you go to other places, you will get the help of a GPS device. The directions can be direct to the exact location you want to know. If you get an audible GPS, it can tell exactly where to go. Although a lot of trackers be a bit off on the turns, that can be fixed with the help of Internet updates.
Letstrack GPS devices contain a wireless Internet that keeps them updated time to time with the latest traffic and new construction in that particular area. When you decide to get a GPS, you must look into the trend that just comes out.
You will get to know about the modern technology and will get exactly what you looking for. The modern traveling gear starts with the GPS tracking solution. When you get your very own, you can put them on your belt or even on the steering wheel, which offers you easy access to the GPS tracker.
15th May, 2019
Akram el
Yea but what I mean is that in marathons the participants use GPS trackers, meanwhile they can send messages to their relatives without any kind of sim card or network coverage .. so what I guess is that maybe they are accompanied with GPRS card?
How this communication works?
And if I want to track a specific device, what kind of info. I need about a particular device? IP number?
15th May, 2019
Pavel Petrov
University of Economics - Varna
Hi Akram,
My knowledge about GPS satellite tracking is based only on my personal experience. About 7 years ago (in the summer of 2012) me and around 10 my friends (scientists, journalists and crew members) were lost in the Chukchi Sea during an Arctic expedition. We were on the high-speed inflatable boat far away from the mother vessel (ESPY, GP). The main way of communication between the boat and the vessel was VHF marine radio. But it was completely useless, because we were around 30 miles away and the communication could not be established (the VHF capabilities is good for up to 10-15-20 miles depending on both antennas altitude). So the big problem was that we knew our GPS coordinates, but we didn't know the actual vessel coordinates in order to calculate our course and distance to salvation. We didn't even know the general direction where the vessel could be - is it North, South, East or West. The nearest land was about 80 miles to the East, but the fuel was not enough. We were desperately, completely lost in the middle of nowhere and some people started to get crazy...
And then a small device called "Yellow Brick" saves us (I believe it was some pre-version of this one: This small device has GPS receiver but also was capable to send and receive short emails (like SMS) to/from Inmarsat or Iridium satellites. So we on the lost boat could send email to the radio officer on the vessel and he could respond to us. This device could also periodically sent the GPS coordinates by email to someone so he could constantly track your location.
In conclusion - depending on the desired geographic coverage and the application needs you should subscribe to a Satellite Communication Service. The major global providers are Inmarsat, Iridium and VSAT. If you don't need a global coverage then satellites on geostationary orbit could be used and may be the expenditure will be lower.
2 Recommendations
17th May, 2019
C K Gomathy
Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya University
Hello Akram, ,
Google Maps and any other mapping apps on your device has the ability to track your location without needing an internet connection. GPS radio can still get a fix from the satellites and the cached ‘memory’. It will take a little longer, and the accuracy of the fix will depend on a few things outside of your control.Example terrain .
Best Wishes..
14th Feb, 2020
Javad Farhani
Many devices like Garmin inReach handheld GPS allow the user to send SMS, some other Iridium satellite modem also has the same function but it required a monthly fee.

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