Passive GPS tracking occurred sometime before the real-time tracking.
Actually, it is a very simple solution which could be explained in a couple of words. So, a GPS receiver collecting data from GPS/GLONASS/ GALILEO and other systems satellites. The passive tracking device is able to record these data and replay on demand of the user. That is it, no rocket science. Connect flash card or USB stick to the computer and whole picture of past trails and other data as fuel consumption, speeding, GeoFence trespassing and more is before your eyes.
Slightly running ahead, I would like to say that the real-time tracking without cellular network is available. Just such option is more expensive, even unavailable for domestic use, than a conventional GPS tracking method and for the long range tracking mode generally not the GPS signal is used.
To be clear, for active GPS tracking you need to have some kind of transmission option as GPS receiver cannot transmit signal by itself, so it somehow needs to be forwarded to the user.
For the full GPS tracking system performance, the cellular signal is required. Not always and everywhere cellular reception is available as in the mountains, open ocean and behind the clouds.
In marine traffic, this shortcoming is partly offset by the implementation of AIS (Automatic Identification System) and satellite AIS. You can read about it in my post about AIS (Automatic Identification System)
Another tracking solution for ships and aircraft is EPIRB (Emergency Position Indicating Radio Beacon).
In short, it is distress radiobeacon to be activated in a life-threatening emergency.
After emergency activation of buoy, the COSPAS-SARSAT system satellites (not GPS or other navigation system satellites) receiving a signal and forwarding it to Local user terminal, then to Mission control center and Rescue coordination center.
EPIRB is compulsory emergency equipment for all SOLAS vessels and every unit has a unique identification number to be recognized by rescuers. It is very important to properly organize a rescue mission.
EPIRB, as every SOLAS equipment, has a very strict maintenance schedule and never can be expired inspection date.
Well, let’s go back to the title question, how to do real-time GPS tracking without GSM signal?
The short answer is yes. There are some other GPS data transmission ways like WIFI, Bluetooth, VHF or UHF. All of them have one significant drawback a small transmission range. How to cope with it?
Unfortunately without a possibility to send a GPS data no way to obtain the GPS receiver device position. Consequently no real opportunities for real time GPS tracking without mobile network assistance.
I assume that the military has some solutions regarding the topic but until now when you are about to climb high mountains keep the passive GPS tracker or Bluetooth tracker as TrackR bravo in your backpack.
Luckily, a wide range of different kind of such devices available on the market.
LandAirSea LAS-1505 Tracking Key Vehicle GPS Tracking System is a popular one.
Take care and remember You are waiting at home.
Fortunately, I have to admit that I was wrong when claimed that no way to be tracked in remote areas where cellular network not available. It is publicly available by IRIDIUM-GPS and other satellite systems communication-based solution.