Cold start in the navigator

As the basic concepts on which the cold start function is based, ephemerides and almanacs are used. The essence of these terms will be considered below. Users of modern technology are not very interested in the internal processes of its work. The navigator, which is widely used today for various purposes to obtain accurate coordinates, is no exception.

The mechanism of operation of this device is very simple. Due to a pair of finger movements, you can sketch a future route in a minute. After turning on the device in seconds determines the exact location of its owner.

To understand the characteristics of the technical side, which are inherent in this type of technology, and even more so to understand how to make a cold start on the navigator, it is not enough just to get acquainted with the basic information needed for use. It is necessary to dig deeper both in the terminology itself, and in the structure of the apparatus and the operation of its functional side.

Basic terminology

To understand how the cold and hot start of GPS operates, you should understand the main terminology. Each sphere of technology and science is full of terms. Despite the relative mystique of the first time a word is heard, when parsing the meaning, it acquires a completely understandable and conscious meaning.

The theory of space navigation deals with:

• Movement of satellites;
• Signal reception, processing, transmission;
• Coding of signals.

As mentioned earlier, the hot and cold start depends on the terminology. Let us consider in more detail the concepts of the almanac and ephemeris.

How to use the navigation almanac

With the term "almanac" many are familiar. And for the first time this word could be heard at school. In fact, an almanac is a kind of reference book containing the basic information data of astronomical significance. Such data include the positions of celestial bodies in outer space, the specificity of the binding of their movement to calendar days. The oldest almanac on Earth is the book "Tun Sin" from China.

By the time navigators appeared, which have a hot and cold start, nothing has changed in the appointment of almanacs. Changes have undergone only the data itself, or rather their number. Taking into account the development of modern technologies, as well as the features of the operation of the most complicated equipment, the data in the almanacs became more extensive and accurate.

The almanac used in modern space navigation is a set of data that includes information about all the main orbital parameters within which satellite navigation is carried out by the navigation system.

Almanac has six orbital parameters belonging to satellites. And each of them is valid for a certain period of time. Each satellite of this system has data on other satellites. As a result of this, the navigator, establishing a connection with only one of them, gets an "almanac" of data about all their other orbits.

When the almanac is loaded into the navigator's memory, the user can apply this information for 30 days. Despite this, the specification of data is much more frequent. This process is carried out during connection with one of the existing ground stations once every few days.

Specificity of ephemeris

Cold start is guided by such data as ephemeris. They are used to calculate orbital deviations, perturbation coefficients, and so on. In other words, ephemeris not only helps to determine the locations of satellites, but also makes it possible to do this with high accuracy.

Those ephemerides that carry the most accurate data are the fastest becoming obsolete. The activity of this information lasts only 30 minutes. Updating of this data is also carried out at the expense of ground stations.

The importance of this data in order to make a hot or cold start in the navigator is obvious. Without information on the position of the navigation satellites, it is not possible to determine the coordinates of the receiver. This requires four satellites.

Algorithm used in the work of the navigator

Understand the general principles by which a cold start occurs in the navigator is not difficult. But if we talk about the algorithm that operates in the device itself, then it can only be general. In-depth knowledge can be enjoyed only by the developers of the navigator.

In general, the operation of this device is as follows:

1. The included navigator makes attempts to communicate with one of the existing navigation satellites.
2. The first satellite, which succeeded in establishing a connection, starts transmitting the almanac to the device. It usually contains all the basic orbital information about one constellation of satellites within a certain navigation system.
3. Since the links with one satellite are insufficient for obtaining the exact coordinates (the minimum number of them is 4), the remaining ones start transmitting their ephemerides. There is a clarification of their placement.

Features of cold start

When you turn on the navigator for the first time or after a long break in operation, a cold start is triggered. The user has to wait for some time until his own coordinates are received. This will be the time of cold start of GPS.

The length of the waiting period depends on various reasons:

• From the quality level of the receiving unit installed in the navigator;
• On how many satellites are located in the visibility zone;
• From atmospheric features;
• From the index of electromagnetic noise, which is at the working frequencies.

In general, a cold start is a state of the navigator, in which its memory has no ephemerides and an almanac. In some cases, these data may be present, but they will be considered obsolete.

To obtain new data, you will have to start the cold start of GPS and perform all the necessary manipulations.

Cold Start Action Algorithm

To obtain new data, the navigator requires a complete cycle.

Cold start at the same time includes the following actions:

• Search for the first satellite and an attempt to establish communication with it;
• Obtaining an almanac and storing this data;
• Receipt and preservation of ephemeris;
• An attempt to establish communication with three other satellites;
• The receipt of three ephemeris satellites and the preservation of these data;
• Use ephemeris to calculate your own coordinates.

Given how many actions are performed in order to "warm up" the navigator, it becomes clear why the device requires time at a cold start.

In general, if you draw analogies, such a launch of the navigator reminds of the time consuming cold start of the engine.

Features of warm and hot starts

The hot start of the navigator is characterized by the presence in its memory of actual data - active almanac and ephemeris. The time of action has already been considered. It is 30 days on the almanac, half an hour - on the ephemeris.

The possibility of a hot start exists if the power was disconnected for a short time. This means that to obtain coordinates, the inclusion algorithm will be significantly reduced.

It will only be required:

• Try to establish a connection with all the satellites;
• If necessary, to update the ephemerides and save them;
• Using ephemeris, calculate the coordinates of your own location.

With a warm start, the work is much simpler. In this state, the navigator has an up-to-date almanac, but it needs to receive updated ephemeris.

Features Navigator "Navitel"

Navitel is a navigation software. It is designed for various types of devices, which are equipped with an external or built-in GPS-receiver. This program provides loading of maps of different countries in detailed form.

Such cards contain:

• Numbering of houses;
• Street names;
• Names of subway stations and so on.

The cold start of Navitel implies that unknown indicators are time, ephemeris, position, and almanac. The trip threshold, at which data is lost by the navigator, is 70 hours or more. This can also contribute to the transportation of the navigator over long distances in the off state. The process of obtaining data in this case has already been described earlier. Cold start time can last more than 20 minutes.

Many drivers purchase for their cars a set for cold start Webasto. After all, the car engine during idle time during the cold season also needs to be warmed up, like a navigator.

If we talk about the warm and hot start of the navigator Navitel, it should be noted that the scheme of action is similar. Only with a warm start the device is activated in a few minutes. When hot, the coordinates are calculated in less than a minute.

Advantages of navigator "Navitel"

There are many similar programs. But in comparison with them, "Navitel" has many advantages.

Advantages of the device:

• Fast scaling and scrolling map;
• The switching process is automated;
• The possibility of choosing the orientation of the map based on the direction in which the movement is carried out, or on the basis of the location of the north;
• Full-screen perception of information;
• 2D and 3D modes;
• Function of tooltips.

The functional side of the device supports a variety of possibilities, including determining the current position on the map, displaying it, plotting the route (manually or automatically), etc.