GLONASS - The Younger Brother or An Adequate Response to GPS?

Determination of the location for many centuries it was a whole art. It is striking how representatives of the ancient civilizations made sea travel, arriving exactly at the destination. They used with the techniques that can sometimes strike a modern man. It was no joke - to make a long voyage, navigating by the sun and the stars "by sight"?

It is believed that the first cards appeared in the IV century BC. Later the invention of the astrolabe, quadrant, sextant, compass and then, then the gyro. Thanks to the efforts of geographers, astronomers and tourists on the cards was applied to an increasing amount of detail.

For many centuries people dedicate their lives to the development of cartography and navigation. And these skills were highly valued. Drastically changed with the advent of all of the space age - navigation became available to everyone anywhere in the world.

Modern navigation

The conquest of a man near-Earth space was the impetus for the development of many areas of science and technology. Every second satellites transmit vast amounts of information of various types: the results of shooting at different ranges of a certain area of the Earth's surface and to satellite television, which has become habitual. Sin does not use this to solve the problem of determining its location.

A few words about the GPS ...

GPS (Global Positioning System) - the satellite navigation system. This system was originally developed by U.S. Department of Defense, through which, incidentally, saw the light of the global Internet.

The first satellite of the 24 needed to cover the entire surface of the Earth, was launched in 1974, the last - in 1993. Now continue launching advanced satellites to replace the defective.

The system is used to provide navigational data of both civilian and military. And the accuracy of data collected by the military, above that provided by the use of additional ranges and immunity encoded signal.

GPS-receivers, whose existence is not only lazy, or have heard the representatives of the African tribes use public channels of navigation information.

... And GLONASS

Lagging behind the Americans, under the auspices of the Ministry of Defense, in 1982 launched the first satellite system GLONASS (Global Navigation Satellite System). Satellites in this system is also 24, and their "park" is also constantly being updated.

Roskartografiya developed appropriate card in Russia and abroad are available GLONASS receivers.

However, the accuracy of the GLONASS coordinate inferior competitor. The cause and the number involved in the system of ground stations, and in coding the signal, and the accuracy of data ephemeris and almanac.

Brothers forever?

The fact that GLONASS should be demonstrated by the fact that some foreign and domestic companies produce hybrid receiver - a device that can operate simultaneously with the GLONASS and GPS satellites at the respective frequencies, using the desired signal format.

One of them - a Russian company Lexand. Navigator Lexand SG-555 - almost the first GLONASS / GPS navigator (after several failed experiments), which anyone can buy at retail.

The main advantages of not only Lexand SG-555, but all hybrids are as follows:

- A higher rate of cold and hot start;

- High positioning accuracy;

- High stability when a signal is received.

Marketing ploy? Not at all. To determine the coordinates on the surface of the earth and GPS, GLONASS, and must establish a connection with at least four satellites! In the GPS receiver in an active 24 satellites, the receiver GLONASS - the same as a hybrid - the same Lexand SG-555 - already 48. Almost fifty!

Not surprisingly, the four-any connection is made quickly enough.

Here we recall and about the stability of the signal. Buildings, topographic features, clouds and even the foliage of trees can temporarily hide one or more satellites. But tune in to the other hybrids easier, again, for the reason indicated in the preceding paragraph.

The same is true and accurate. Numerous sources claim:

- The more satellites the receiver sees, the more accurate will be determined by the coordinate;

- GLONASS satellites in the northern hemisphere are better GPS satellites due to a tilt of the orbit.

No comments.

Alas, the accuracy and incidence of GLONASS devices - so far "younger brother". But he has every chance to become a "proper response". But we, the users still enjoy the smooth running of the hybrid receivers, which combine the best qualities of both.

Short Educational Program on the Work of Navigators. What is The Ephemeris and Almanac?

The processes taking place in modern technology, the user is a mystery. Moreover, the user often they did not care, either not interested or simply do not care. This applies to the navigators. Included - and you know your coordinates. A few finger movements - the route is ready. Sometimes, however, to understand the technical characteristics of the same browser, you must know more than you need just to use it.

So, make a reservation at once: the article will be of interest to those who are not satisfied with the role of an ordinary user "black box with a screen." For those who want to explore all points of the technical characteristics of the device before purchase. For those who enjoy understanding the processes occurring in a variety of devices.

Such people do not say "I do not know" to questions like: "What is on your computer has a processor?". Question-what is essentially an elementary, but you'll be surprised at what percentage of fellow comrades know the answer to it. Try it!

A little about the terms

In every field of science and technology is full of terms. These terms are sound mysterious to the uninitiated, but are, in general, understandable, a closer look.

In theory, satellite navigation system is also a set of terms. Not surprisingly, this sphere of knowledge and is associated with the movement of satellites in near-Earth space, and the reception, processing, signaling, and their coding.

Terms that are useful to be considered is the concept of the almanac and ephemeris. Why are these concepts we are interested in? Yes, because the knowledge of these concepts is based understanding of the "cold" and "hot" start device.

Almanac of modern navigation and not just

Even before the era of satellite navigation concept Almanac already existed. Almanac named directory that contains the basic astronomical data - positions of celestial bodies and their binding to the calendar. One of the oldest almanac is a Chinese book Tong Shin.

Today heralds the appointment has not changed. Only changed the amount of data they contain, and their accuracy. Almanac of satellite navigation - the collection of data on the basic parameters of satellite orbits in the navigation system. The presentation of these data for us, actually, not so important.

Almanac contains six parameters of the satellite's orbit at a particular time. Each satellite system has data on other satellites. Navigator, establishing a link with only one companion, after receiving the almanac has information about the parameters of the orbit, and others. Almanac loaded in the memory of the satellite, valid for 30 days. Nevertheless, these data are specified more often - every few days during a session with one of the ground stations.

Ephemerides

In addition to the basic orbital parameters, the navigator receives from each of their satellites ephemeris, this data, which used to calculate the deviation of the orbit, the perturbation coefficients, etc. That is, with the help of their navigator with high accuracy can locate satellites.

Ephemerides carrying more precise data become obsolete much sooner. Their data are only active for about 30 minutes. They also updated the ground stations.

Without data on the location of navigation satellites can not determine the coordinates of the receiver. Necessary for the entire four satellites. On the singularities of the navigator and the inclusion of a "cold", "warm" and "hot" start, let's talk in the next article.