Flytec 6020 * - Manual (Page 48)

Operating Manual Flytec 6020
an altitude limit to be adjusted by the pilot in Main Setup Menu
⇒
User Settings
⇒
Speed
⇒
Stallspeed above which the stall alarm shall not be initiated. In this case naturally, the
landing areas should be located below this limit.
Practice has proven that about half of the otherwise unattractive landings have been rescued
by pushing the steering bar upright when the stall alarm was triggered.
9.3 Navigation
9.3.1 Reception quality of GPS
The GPS-Receiver can follow up to 16 satellites simultaneously. After turning on the unit it is
necessary to receive at least 4 satellites to fix position for the first time. Once logged on,
3 satellites (for 2D positioning) are sufficient for further position finding. However, if altitude
recording is also required (3D positioning), then definitely 4 satellites are required. There is a
table in the receiver, The Satellite Almanac, in which the path, place, and time of all
satellites are kept with reference to the receiver. The Almanac is continuously updated
during signal reception. However, if the signal to the Almanac memory is disrupted
completely or the unit is taken 200 km or more from the last reception point, then the
Almanac has to be re-established. Power is still supplied to the almanac’s memory even
when the unit is turned off.
Normally the instrument recognizes its position under unobstructed view condition after
a few minutes. If the receiver is switched-off for a short time (less than 2 hrs.), the time for
new position finding is less than a minute. Buildings, mountains or thick forest affect
reception quality of the receiver. Therefore, you should always look for the best possible
visibility around you and the antenna in the casing should point upwards if possible.
In particular when mounted on the steering bar of the hang glider, we recommend not to
have the instrument fixed under the pilot’s head on the middle of the basis, but indeed
sideways. In this position the 6020-GPS should not have more than 45° deviation from
horizontal position so that the antenna points upwards.
Due to the fact that receiving strength of the satellite signals is only approx. 1/1000 of mobile
radios, these radio sets and other disruptive factors (like notebooks) should be operated as
far away as possible from the 6020-GPS.
The 6020-GPS is fitted with a 16-channel GPS-Receiver which is featured with
lesser power consumption and also a significantly shorter satellite detection time.
Precision is between 7 to 40m. As an average one may assume approx. 15 m.
9.3.2 Accuracy of GPS altitude
A good explanation of GPS accuracy is found on the following website:
http://www.kowoma.de/en/gps/errors.htm
First of all the term accuracy has to be defined: On the website above you can read:
“The declaration of the accuracy by Garmin GPS receivers sometimes leads to confusion.
What does it mean if the receiver states an accuracy of 4 m? This readout refers to the
so-called 50 % CEP (Circular Error Probable). This means that 50 % of all measurements
may be expected within a radius of 4 m. On the other hand it also means that 50 % of all
measured positions are outside of this radius. If one assumes a standard dispersion, then
95 % of all measured positions are within a circle of twice this radius, thus 8m, and 98.9 %
are within a circle of 2.55 of the radius, thus in this case within 10 m. “
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