What was gps first used for

By , NRL demonstrated single-satellite position fixes, accurate to about 0. Easton, p. To calibrate ionospheric group delay, the satellite broadcast on two frequencies very similar to the technique pioneered by the Transit program. Its quartz oscillator was expected to be somewhat more stable, about one part in Again, a large frequency shift was observed in the clocks that was finally traced to a solar proton storm. NRL was able to demonstrate ranging accuracies of approximately feet to a fixed location.

Timation NTS The last satellite in the original Timation series was launched in July Bill Huston , to the Program Director Col. Bradford Parkinson. The gross weight had been increased to pounds with a power requirement of watts.

This satellite, developed by Pete Wilhelm of NRL, was placed at an orbital altitude of 7, nautical miles. Timation NTS-1 carried two slightly modified commercial rubidium clocks.

Unfortunately, attitude-stabilization problems induced temperature variations that masked any quantitative performance evalulation. The atomic clocks were not useful as prototypes for GPS.

The NTS satellites were strictly technology-testing satellites. For many reasons, they had no role in the development of the operational satellites by the JPO and Rockwell. They were the only ones used in the operational testing during phase I of GPS. NTS-1 included two small, lightweight rubidium oscillators as clocks. A German commercial company called Efratom had independently developed these models. Amazing at the time, they only consumed about 13 watts of power and weighed some four pounds each.

Further Efratom involvement will be pointed out later. While NRL made some electronic modifications, the modified clocks were not in any sense able to withstand the radiation of the GPS orbits. NRL tests showed that the modified rubidium clocks had an unacceptable level of sensitivity to temperature variations. Bartholomew, p.

This apparently occurred because the satellite used a two-axis gravity gradient stabilization system that does not function well at these altitudes. NTS-1 carried other space technology demonstrations including highly efficient solar cells. The vehicle included two modified cesium beam oscillators developed by Frequency and Time Systems Inc.

FTS of Danvers Massachusetts. The key atomic clock developer was the engineer and creative entrepreneur Robert Kern. This clock showed great initial promise but it was not yet a space prototype in terms of radiation hardening and parts life. It could then have supplemented the satellites being developed by Rockwell, providing another passive ranging signal for the user equipment tests at Yuma Proving Ground.

As a result of these failures, the cesium clock tests were inconclusive. Beard, p. For the next step, NRL defined a radiation-hardening program and contracted with FTS to develop a hardened cesium clock. Unfortunately, the clock suffered a premature failure of the power supply after only 12 hours of operation. FTS soon found the root cause and fixed the design. Beginning with NDS 5, the on-board cesium clocks performed well and were equal or better in stability to the Rockwell rubidium oscillators.

By , a few Pentagon authorities had recognized that a new satellite-based navigation system would be a valuable asset with multiple military applications. Literally hundreds of positioning and navigation systems in use by the DoD were expensive to maintain and upgrade. Obviously, a single replacement system offered significant cost savings.

Unfortunately, the two competing concepts from B and NRL apparently confused the decision-makers. Discussions grew very acrimonious at times. As a result of this inter-service competition and a reluctance to commit the necessary monies, the Pentagon put off making any decision. In November of , Col. Bill Dunn , who led the advance planning group XR , identified Parkinson as a potential candidate to head the floundering B program.

Parkinson had a very relevant background in navigation, guidance, and control that included a Ph. He had been chair of the Astronautics Department at the U.

Air Force Academy, spent three years as a guidance analyst at the Central Inertial Guidance Test Facility, and was operationally oriented with 26 combat missions in AC gunships.

The background was a match, but Parkinson expressed an unwillingness to volunteer for the assignment if he were not assured that he would be the program director. Schultz said he could not yet make that promise. However, immediately after Parkinson left his office, the general reassigned him to the B program and effectively made him the director. Beginning in December, immediately after he assumed control of B, Parkinson instituted a series of 7 a.

At these gatherings, the program staff reexamined every aspect of the proposed B program, including alternatives. This educational process was a key to having everyone in the Program Office completely understand the technical issues they faced. During this period Gen. Schultz supported the program in every way that he could. In particular, Parkinson was allowed to recruit Air Force officers whose background and experience were aligned with the needs of the fledgling program.

All had advanced engineering degrees from the very best universities in the country including MIT, Michigan, and Stanford.

In addition, virtually every officer had experience in developing real hardware or in testing inertial guidance systems. In addition there was a small, carefully-selected group of Aerospace technical support personnel led by Walt Melton from to This fine group of Aerospace engineers and scientists was experienced in an all technical aspects of space navigation programs and particularly skilled at issues relating to signal modulation, satellite position prediction, and building long-life satellites.

Many of their names will be highlighted in Part Two of this story. The Aerospace contingent continued to enjoy the strong support of the president of the Aerospace Corporation, Ivan Getting. Malcolm Currie , formerly of Hughes Aircraft, who had just been appointed to the number three position in the DoD, found himself flying between Washington, D. His secondary purpose was to oversee the relocation of his family, but he needed an official reason to travel to Los Angeles.

After a few weeks, his host Gen. Schultz ran out of subjects to present, and instead invited Currie to spend an afternoon with his new program director, Col. This informal meeting was held in private, in a very small cubicle within the JPO offices. With a Ph. After that meeting, Currie became a good friend to and a sponsor of the new satellite-based navigation program.

DSARC 1. It was held at the Pentagon, and attended by senior officers of all services, with Mal Currie presiding. Currie immediately invited Parkinson into his private office to tell him he wanted a new system proposal developed that would incorporate the best features of all the technical alternatives. He emphasized the need for a joint program involving all services.

Lonely Halls Meeting. Parkinson immediately called a meeting in the Pentagon over Labor Day weekend, September The light at end of those tunnels, both figuratively and literally, came from a small conference room on the top floor, seating about a dozen attendees, all Air Force officers except for three Aerospace Corporation engineers. Parkinson wanted the isolation to ensure unfettered creativity in defining the new proposal.

Leading to this, the Analytical Sciences Corporation TASC under the guidance of Gaylord Green had completed a new systems study, a review and update of the earlier systems study directed by Jim Woodford and Hideyoshi Nakamura for project B in — Dual Use.

One aspect should be strongly pointed out. Civilian users were to be given free access to the signal specification and were expected to use the so-called clear acquisition signal for navigation and other purposes.

In fact, Parkinson highlighted civilian use when he testified before Congress on the proposed new system. GPS Approval. That Labor Day weekend of September had been a very busy three days. Over the next two-and-a-half months there was a flurry of activity as Parkinson made presentations and defended the concept before all those who could block the proposal in the Pentagon. This effort was culminated with the approval to proceed on December 14, This recognition that radio signals from a satellite, or "artificial star" could determine distinct positions on the ground was truly the launching pad of the GPS system.

Even before that, however, the seeds for the GPS technology were being planted. In , Dr. In response to this request, Dr. Getting developed the first three-dimensional, position-finding system based on time difference of arrival. This system became the basis for the future GPS. The deployment portion of the GPS history began in with the decision to develop a satellite navigation system based on existing technology of the U.

Air Force and the U. The system went through extensive testing during the next three years. In the first transmitters were installed on the surface of the Earth and tested--even though no satellites have been launched yet.

The transmitters were dubbed Pseudolites pseudo satellites. Between and , eleven satellites were launched into space and put into position. In , the decision was made to increase the number of satellites to In , the first Block I satellite was launched. This "bird' had sensors specifically designed to detect atomic explosions, and was placed in orbit as a means of monitoring the Soviet Union's compliance with the agreement with the United States to refrain from nuclear testing.

Also in , the onboard atomic clocks, the most accurate timepieces in the world, were activated. Developed by physicists, atomic clocks measure time by the change in energy levels of electrons. These clocks are stable, continuous, and accurate to a nanosecond, or one-billionth of a second.

In , the GPS ceased being solely a military system and was made available for public use. President Ronald Reagan declassified the GPS system in response to a tragedy involving a civilian airplane. Korean Airline flight got lost over Soviet territory and was shot down by Soviet fighters. In , the Challenger space shuttle tragedy halted space shuttle launches, and thereby delayed the GPS system, because shuttles were supposed to transport the new Block II satellites.

Eventually, Delta rockets, the original transport, were put back into use to launch the satellites, and in , the decision was made to increase the number of satellites to 24, because functionality with 18 satellites was still limited. Though the GPS system was available for public use, the first Gulf War in saw temporary deactivation of use by the public, because the military needed more receivers.

Public use returned in along with the decision that the GPS system would be available free of charge to the entire world. Full Operational Capacity FOC was achieved in July of with the placement and activation of the last of the 24 satellites.

Since , GPS history has seen considerable technological advancement. Richard B. They discovered that, because of the Doppler Effect, the frequency of the signal being transmitted by Sputnik was higher as the satellite approached and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion.

The first satellite navigation system , Transit, was used by the United States Navy and was first successfully tested in Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In , the U. Navy developed the Timation satellite which proved the ability to place accurate clocks in space, a technology the GPS system relies upon. In the s, the ground-based Omega Navigation System, based on signal phase comparison, became the first world-wide radio navigation system.

President Ronald Reagan announced that the GPS system would be made available for civilian uses once it was completed.