September 10, 2011 at 19:14The principle of the digital compass
Due to the widespread use of the android mobile platform and gps chips as part of end products in particular, I became interested in the idea of a digital compass, around which so many questions now arise.
So, the object we are considering is a compass, which is based on the principle of construction on determining coordinates using satellite navigation systems. However, in practice there are cases when the compass incorporates a block of magnetoresistors (the principle of changing the resistance from the position of an object in absolute space) or Hall elements as a receiver. Hall elements, on the other hand, are built on the basis of micromechanical systems that are highly sensitive to changes in the magnetic field in a particular case, changes in the distribution of charges on a silicon wafer under the influence of the Earth's magnetic field. Devices based on magnetoresistors and Hall elements personify the compass in its classical form, as an autonomous measuring tool, in contrast to “collective” type systems, the input information for which comes directly in the form of a satellite signal. As a result, systems tied to an external source of information are essentially devices with an indication of the track angle in the form of a compass.
Since in practice we are most often dealing with determining the location and direction using navigation systems, for example, at least android with its google maps application, the following is the principle of operation of the algorithm of this particular use case:
1. Using satellite signals, we take the coordinates of the receiver satellite navigation systems (and, accordingly, the object)
2. We note the point in time at which the coordinates were determined.
3. We wait a certain time interval, short enough for better results.
4. Re-determine the location of the object.
5. The simplest navigational problem is solved to calculate the motion velocity vector from the obtained coordinates of two points and the size of the time interval, after which, knowing the vector, we can easily get:
a) the direction of motion
b) the speed of motion
6. The transition to step 2 is carried out.
As you can see, the operation of the algorithm is provided cyclically and the starting point for the start of the next vector will be the end of the guide vector for the last time interval.
The disadvantages of this method, in the application of digital compassing:
if the object is motionless in absolute space, you won’t be able to find the direction of movement, the fixation points of the coordinates coincide in this case.
As an exception, rather large objects (for example, large sea vessels), where it is possible to install 2 receivers (for example, on the bow and stern). Thus, the coordinates of two points can be obtained immediately, even if the object is motionless, and go to step 5. We
also need to take into account the accuracy of determining coordinates by satellite positioning systems and its effect on slow-moving objects, due to the scatter of location errors.
So, the object we are considering is a compass, which is based on the principle of construction on determining coordinates using satellite navigation systems. However, in practice there are cases when the compass incorporates a block of magnetoresistors (the principle of changing the resistance from the position of an object in absolute space) or Hall elements as a receiver. Hall elements, on the other hand, are built on the basis of micromechanical systems that are highly sensitive to changes in the magnetic field in a particular case, changes in the distribution of charges on a silicon wafer under the influence of the Earth's magnetic field. Devices based on magnetoresistors and Hall elements personify the compass in its classical form, as an autonomous measuring tool, in contrast to “collective” type systems, the input information for which comes directly in the form of a satellite signal. As a result, systems tied to an external source of information are essentially devices with an indication of the track angle in the form of a compass.
Since in practice we are most often dealing with determining the location and direction using navigation systems, for example, at least android with its google maps application, the following is the principle of operation of the algorithm of this particular use case:
1. Using satellite signals, we take the coordinates of the receiver satellite navigation systems (and, accordingly, the object)
2. We note the point in time at which the coordinates were determined.
3. We wait a certain time interval, short enough for better results.
4. Re-determine the location of the object.
5. The simplest navigational problem is solved to calculate the motion velocity vector from the obtained coordinates of two points and the size of the time interval, after which, knowing the vector, we can easily get:
a) the direction of motion
b) the speed of motion
6. The transition to step 2 is carried out.
As you can see, the operation of the algorithm is provided cyclically and the starting point for the start of the next vector will be the end of the guide vector for the last time interval.
The disadvantages of this method, in the application of digital compassing:
if the object is motionless in absolute space, you won’t be able to find the direction of movement, the fixation points of the coordinates coincide in this case.
As an exception, rather large objects (for example, large sea vessels), where it is possible to install 2 receivers (for example, on the bow and stern). Thus, the coordinates of two points can be obtained immediately, even if the object is motionless, and go to step 5. We
also need to take into account the accuracy of determining coordinates by satellite positioning systems and its effect on slow-moving objects, due to the scatter of location errors.