As the basic concepts on which the cold start function is based, ephemeris and almanac are used. The essence of these terms will be discussed below. Users of modern technology have little interest in the internal processes of its work. The navigator, which today is widely used for various purposes to obtain accurate coordinates, is no exception.
The mechanism of action of this device is very simple. Due to a couple of finger movements, you can sketch a future route in a minute. After switching on, the device determines the exact coordinate location of its owner in seconds.
To understand the characteristics of the technical side that 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 necessary for use. It is necessary to dig deeper both in the terminology itself and in the structure of the apparatus and the action of its functional side.
To understand how the cold and hot start of GPS works, you should understand the basic terminology. Each area of technology and science is full of terms. Despite the relative mystery of the first word heard, when parsing the meaning it acquires a completely understandable and conscious meaning.
The theory of space navigation considers:
- satellite movement;
- signal reception, processing, transmission;
- signal coding.
As mentioned earlier, hot and cold start depend on the terminology. Let us consider in more detail the concepts of almanac and ephemeris.
How is used in navigation almanacs
The term "almanac" is familiar to many. And for the first time this word could be heard at school. In fact, a kind of reference book is considered an almanac, 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 considered the book "Tong Sin" from China.
By the time the navigators, who have a hot and cold start, appeared, nothing had changed in the appointment of the almanacs. Only the data itself has undergone changes, or rather its quantity. Given the development of modern technologies, as well as the features of the operation of sophisticated equipment, the data in the almanacs have become more extensive and accurate.
The almanac used in modern space navigation is a data set that includes information about all the main orbital parameters, within which the movement of satellites through the navigation system is carried out.
Almanac has six orbital parameters belonging to satellites. Moreover, each of them is valid for a certain period of time. Each satellite in this system has data about other satellites. As a result of this, the navigator, establishing a connection with only one of them, upon receiving the almanac “learns” data about all their other orbits.
When loading the almanac into the navigator’s memory, the user can apply this information for 30 days. Despite this, data refinement is much more common. This process is carried out during the connection with one of the existing ground stations once every few days.
Specificity of ephemeris
A cold start is also guided by data such as ephemeris. They are used to calculate orbital deviations, perturbation coefficients, and more. In other words, ephemeris not only helps determine the location of satellites, but also makes it possible to do this with high accuracy.
Those ephemeris that carry the most accurate data are most likely to become obsolete. The activity of this information lasts only 30 minutes. This data is also updated 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 about the location of the navigation satellites, you cannot determine the coordinates of the receiver. This requires four satellites.
The algorithm used in the work of the navigator
It’s easy to understand the general principles by which a cold start in the navigator takes place. But if we talk about the algorithm operating in the device itself, then it can only be general. Only the navigator developers themselves can have in-depth knowledge.
In general, the action of this device is as follows:
- The included navigator attempts to contact one of the existing navigation satellites.
- The first satellite with which it was possible to successfully establish a connection starts transmitting an almanac to the device. It usually contains all the basic orbital information about one satellite constellation within a specific navigation system.
- Since communication with one satellite to obtain exact coordinates is not enough (the minimum number is 4), the remaining ones begin to transmit their ephemeris. There is a refinement of their placement.
Cold Start Features
When you turn on the navigator for the first time or after a long break in work, a cold start is triggered. The user has to wait some time until their own coordinates are received. This will be the time of the 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 in sight;
- from atmospheric features;
- from the indicator of electromagnetic noise, which is at operating frequencies.
In general, a cold start is a navigator state in which its memory does not have any ephemeris and almanac at all. In some cases, this data may be present, but it will be considered obsolete.
To obtain new data, you will have to start a cold start of GPS and perform all necessary manipulations.
Cold start action algorithm
To get new data, the navigator needs to go through a full cycle.
A cold start includes the following actions:
- search for the first satellite and attempt to establish communication with it;
- receiving an almanac and storing this data;
- receipt and preservation of ephemeris;
- attempt to communicate with three other satellites;
- receiving ephemeris from three satellites and storing these data;
- the use of ephemeris to calculate its own coordinates.
Given how many actions are taken to “warm up” the navigator, it becomes clear why the device needs time during a cold start.
In general, if we draw analogies, such a launch of the navigator resembles the cold start of the engine in terms of time.
Features of warm and hot starts
The navigator’s hot start is characterized by the presence of relevant data in its memory - an active almanac and ephemeris. Action time has already been considered. It is 30 days on the almanac, half an hour on the ephemeris.
The possibility of performing a hot start exists if the power was turned off for a short time. This means that to obtain the coordinates, the inclusion algorithm will be significantly reduced.
It will only be required:
- try to establish communication with all satellites;
- if necessary, update the ephemeris and preserve them;
- Using ephemeris, calculate the coordinates of your own location.
With a warm start, the work is greatly simplified. In this state, the navigator has an up-to-date almanac, however, it needs to receive updated ephemeris.
Features of the Navitel Navigator
Navitel is a navigation type software. It is designed for various types of devices, the equipment of which includes an external or built-in GPS-receiver. This program provides downloading maps of various countries in a detailed form.
Such cards contain:
- house numbering;
- street names;
- names of subway stations and more.
The cold start of Navitel implies that the unknown indicators are time, ephemeris, position, almanac. The shutdown threshold at which data is lost by the navigator is 70 hours or more. This can 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 previously. Cold start times can last more than 20 minutes.
Many drivers purchase Webasto cold start kits for their cars. After all, the car engine during idle time in the cold season also needs to be warmed up, like the navigator.
If we talk about the warm and hot start of the Navitel navigator, it should be noted that the action scheme is similar. Only with a warm start, the device is activated after a few minutes. When hot, the coordinates are calculated in less than a minute.
Advantages of Navitel Navigator
There are many similar programs. But in comparison with them, Navitel has many advantages.
Advantages of the device:
- fast zooming and scrolling system;
- the switching process is automated;
- the ability to select the orientation of the map based on the direction in which the movement is carried out, or based on the location of the north;
- full-screen perception of information;
- 2D and 3D modes;
- tooltip feature .
The functional side of the device supports many features, including determining the current position on the map, displaying it, plotting a route (manually or automatically), etc.