What counts as the first GPS device?
The title asks for a single first device, but the history does not offer one. A receiver that could use signals from the Global Positioning System had to exist before the system was complete, because the satellites were being tested on the way to a full constellation. Developers built experimental equipment to test the first satellites, then early military sets, then commercial survey receivers, and only after that portable consumer units. Which of these is “first” depends on whether you mean the first prototype, the first sold to customers or the first small enough to carry. This article is mostly about the earliest hardware; the first portable consumer receivers are covered in our piece on handheld GPS.
Receivers before the satellites
Navigation satellites came before GPS. The Navy’s Transit system, which began operating in the 1960s, already needed shipboard receivers. They were large and slow by later standards: a ship typically had to wait for a satellite to pass overhead and then process the Doppler measurements for a few minutes to obtain a fix. Transit receivers are a useful reminder that the hardware problem of turning faint satellite signals into a position had been tackled before GPS existed.
The first test equipment
When the Navstar program put its first satellites into orbit starting in 1978, the early user equipment was a set of experimental receivers built by contractors for military test ranges. Reports describe sets that filled racks, needed external power and were operated by specialists. The main difficulty was that the signals are extremely weak when they arrive, and the receiver must generate a copy of the satellite’s code and slide it in time until it lines up with the incoming signal. Doing that for four satellites at once, in real time, with 1970s electronics, took a lot of hardware. Early designs often tracked satellites one at a time, switching between them in sequence, which was slow and less accurate for moving vehicles.
Over the following years the designs moved toward receivers with several channels, each tracking its own satellite continuously. That shift is one of the most important improvements in early receiver design, because it allowed a fix to be updated smoothly even when the user was moving quickly, as an aircraft would be.
Survey receivers lead the way
The first customers outside the military were not drivers or hikers but surveyors. Instead of reading the coded navigation message in the way a vehicle receiver does, early survey sets used the carrier wave of the signal, which allows very precise measurements over long baselines, and compared observations at two points. Because surveyors could process the data afterward, they did not need real-time answers, and they were willing to pay high prices. Companies such as Trimble were among those that offered early commercial sets in the 1980s, and the surveying market helped fund later work on cheaper equipment. Dates vary between sources, so treat any exact “first commercial unit” claim with caution.
Military sets: from vehicles to soldiers
Military procurement moved from experimental sets toward fieldable equipment through the 1980s, mounted first in aircraft, ships and vehicles. The satellites were not yet all in orbit, so for years users could receive usable coverage only for part of the day. When the Gulf War began in 1991, the constellation was incomplete but still useful, and units reportedly bought commercial receivers in addition to military sets because there were not enough of the latter. Later the military introduced small hand-held sets designed for individual soldiers. The policy side of that period, including why some signals were restricted, is covered in our article on military positioning.
Getting smaller
The shrinking of receivers depended on three kinds of progress.
- Integrated circuits: custom chips replaced boards of separate components. The wider story is told in our article on integrated circuits.
- Better clocks and oscillators: a receiver does not need an atomic clock, since it gets timing from the satellites, but it does need a stable local oscillator.
- Lower power use: battery-powered operation became practical only as electronics became more efficient.
By the end of the 1980s companies were advertising receivers of a size one could hold in the hand, though early units were still heavy, power-hungry and limited to a few channels. The step from these sets to a mass-market chip is a later chapter, covered in the history of GPS chipsets.
Why the early hardware still matters
Early receivers show that the satellites alone were not enough. Without a way for people to use the signals, there would have been no navigation revolution. The hardware went through familiar stages: laboratory prototypes, specialist military and survey equipment, then products aimed at ordinary buyers. At each stage, cost and size fell while capability rose, a pattern also seen in computers and mobile phones.
For anyone investigating the “first” claim, the safest summary is that several groups produced early receivers within a short period, and the title of first depends on the definition used. Be wary of sources that name a single device and date without saying what they are measuring.