A Global Positioning System (GPS) comprises how many satellites?

A Global Positioning System (GPS) comprises how many satellites?

گلوبل پوزیشننگ سسٹم کتنے سیٹلائٹس پر مشتمل ہے؟
Explanation
The GPS system consists of a constellation of at least 31 active satellites orbiting Earth.
A minimum of 4 satellites is required at any time to determine a precise 3D location (latitude, longitude, altitude).