ADREL ALT-USB, Manual, Page: 3 / 11

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1. Introduction
In accordance with the FAI recommendations, the measurement of altitude in the categories S1
and S5 is to be measured electronically with the use of altimeters. According to these guidelines
altimeter has been developed, which in addition to measuring the maximum altitude, stores
measurement results for the entire flight. Its parameters were adjusted to the recommendations of
the FAI. Altimeter’s size (9.5 x 24 x 7) and weight (1.2 g) allow for its inclusion in all types of
space models. Altimeter may also prove useful when setting F1B model category (eg, choice of
propeller).
2. Overview of altimeter
In the described altimeter height measurement is made
on the basis of pressure changes depending on altitude.
Measuring sensor is an electronic system, which measures
the absolute pressure. This sensor is factory calibrated. In
the program, which reads data from altimeter, follows the
conversion of pressure to altitude based on the formula,
which takes into account the current pressure, pressure
changes, temperature, vertical temperature gradient, change
of the density of the atmosphere, depending on altitude..
Model Altimeter AL-01 is used for measuring the height
of the model and the analysis of the flight. Measurements are
stored in nonvolatile memory so they are saved when device
is disconnected from power. Frequency of measurement is set
in the range of 50 measurements per second to 1
measurement every 5 seconds
The readout of the altimeter’s measurements and
parameters is possible when cable is connected to the USB
connector on your computer. The chart shows the entire
flight of a rocket. The graph can be zoomed. For the purposes of competitions altimeter is able to
store the starting numbers of competitors. In addition, each altimeter has a recorded permanent
unique serial number. For archiving the results of
competitions, the measurements can be saved to
disk and retrieved any time.
Adapter - Charger used to connect the altimeter to
a computer using a standard USB cable with the
tip of a type B.
Adapter has a built-
in complete control
system of battery
recharge (single-cell
Li-Pol).
3. Some theory
With the increase in altitude at which it measurement shall be taken the amount column of
the atmosphere decreases, as well as the pressure measured. Pressure changes with altitude within
the first 2000m above the sea are fast - with an increase of altitude about 8m atmospheric pressure
decreases about 1 hPa (see further - bar degree). As a result, measurements made at the same point
and at the same time at different heights, give different pressure values. In addition the changes in
pressure at the same point will be affected by the changes in air temperature.