PDF User Manual

 

 

Owner’s Instructions

 

You have just acquired a high precision instrument, manufac-
tured using the most up-to-date technology.  The Skywatch 

was designed to handle intense use and extreme condi-

tions. Please take the time to carefully read your instructions so
as to understand all the great features this unit has to offer. 

Buttons Uses : 

Turn your

on by pushing either the 

wind

or 

mode

button.
Push the 

wind

button to choose between maximum or average

wind speed. 
Press and hold the 

wind

button to switch the wind speed 

measurement unit : km/h, m/s, knots or mph.
Push the

mode

button to choose between current temperature,

WindChill Factor,  pressure, pressure historical records and 
altitude.
Press and hold the 

mode

button to switch temperature unit: 

˚C or ˚F.
Extreme values of wind speed and temperature can be deleted
by pressing both the

wind

and 

mode

buttons simultaneously.

Push the clock button to set the 

clock

timer.

Current Temperatur e :

The temperature sensor is located on the left corner,  over the 
display.  In the event of severe temperature changes, allow a 
few moments for the sensor to reach the current temperature. 
Select the current temperature with the

mode

button. Current temperature is displayed

at the bottom of the LCD either in ˚C  or ˚F.  To change the unit of measurement, press
the

mode

button for 2 seconds.

Please note that holding the instrument in your hands for a while may influence the
temperature reading. The sensor is very sensitive.

1. Button wind
2. Button clock
3. Button mode

All segments

of the LCD

1 2 3

Owner’s Instructions SKYWATCH

®

Geos

 

Minimum and Maximum Temperature s :

Minimum and Maximum temperatures are permanently displayed.
Extreme values will flash on the bargraph. When your instru-
ment is on standby,  temperature is measured every thirty (30)
minutes, allowing a recording of the extreme values, even when
the instrument is turned off.
Extreme temperature values can be deleted by pressing both the

wind

and 

mode

buttons simultaneously.

Minimum and maximum temperature

measurement displayed 

with flashing lines on the bargraph

Wind-chill Factor :

The wind-chill factor is a calculation of the effect of wind on 
temperature. It portrays an indication of the loss of heat by 
your body in case of temperatures below 37˚C  and the aug-
mentation of the heat with a temperature over 37˚C  and wind.
For instance, with a 0˚C  current temperature and a 40 km/h 
blowing wind, your body will use as much heat as if it would
be exposed to a temperature of -15 ˚C  with no wind. This value
of -15˚C  is called wind-chill factor.  Wind-chill factor can be 
selected by pressing the 

mode

button. The corresponding 

symbol       is then displayed in the bottom of the LDC. 

Pressure :

The pressure sensor is located inside the instrument. The indicated pressure is the
actual pressure at the instrument’s altitude and not the reported pressure at sea level.

Temperature in Celcius and 

Fahrenheit degree

Changing of temperature unit 

(ºC and ºF)

Wind-chill

factor mode

 

The pressure can be influenced by 3 main factors:
1. Altitude. Pressure decreases with altitude. In similar meteorological conditions, if 

pressure is 1013 hPa at the sea level, it will be only 977 hPa at 300m or 794 hPa
at 2,000 m.

2. Meteorological conditions. Atmospheric pressure changes according to the weather.

During nice weather,  pressure at the sea level can reach 1050 hPa and if the 
weather gets bad, it can go down to 980 hPa. 

3. The wind. The wind can exert a pressure on objects that it 

hits. With a 100 km/h wind blowing, this additional pressure
may vary from +/- 10 hPa, depending the position of the 
instrument. However,  for windspeed bellow 30 km/h, this 
influence is insignificant. 

Pressure measurement can be selected by pushing the 

mode

button. Pressure in hPa is then displayed at the bottom of 
the LCD.

Historical Pressure Record :

The instrument automatically records the pressure of the past 3, 6, 9 and 12 hours.
The historical pressure record can be selected by pushing the 

mode

button. Pressure

in hPa is then displayed at the bottom of the LDC. 
The pressure from 3 hours ago is represented by the segment number 3. Pressure from
6, 9 and 12 hours ago are represented respectively by segments 6, 9 and 12.

Altitude :

Altitude is calculated according to barometric pressure. This is why a difference of pres-
sure will influence the indicated altitude. It is necessary to calibrate your instrument
before using this function (for instance before mountain climbing or ballooning).
Altitude can be selected by pushing the 

mode

button. Altitude is then displayed in meters

at the bottom of the LCD.

Current pressure

Historical pressure record with segments 3, 6, 9 and 12 

on the left bargraph

 

Calibration: Calibration can be done only if the instrument is set in altitude mode. To
enter calibration mode, both 

mode

and 

wind

button need to be pushed at the same

time. All other information will disappear
from the LCD. In this mode, the mode 
button increases the altitude and the 

wind

button decreases it.
Once the reference altitude has been 
correctly entered, you can leave the cali-
bration mode by pressing both buttons

mode

and 

wind

at the same time.

Altitude

Altitude

calibration mode

Relative humidity :

The humidity sensor is located on the left upper side of the display.  In the case of a
severe humidity change, allow a few moments for the sensor to react and display the
new relative humidity level.
The relative humidity range goes from 0 to 100%. (0% meaning that the air is 
completely dry and 100% meaning an air saturated with water.) This limit depends 
on the quantity of water contained in the air and its temperature. Note that you will 
need less water in cold air than in warm air to reach 100% relative humidity.
The following points have to be taken into consideration when measuring humidity :
1. Relative humidity depends on temperature. By moving the instrument from a warm

spot to a cold one, the measured value may differ.

2 Humidity is not homogeneously spread out in the atmosphere so two very close 

measured areas can give two different readings. 

3. The sweat and breath of a person very close to the sensor can influence the results

of the measurement.

Relative humidity can be selected by pushing the 

mode

button. It is then indicated 

in % at the lower corner of the display with the symbol %
Note: Humidity sensor was calibrated during the assembling of
your           . It will be possible to re-calibrate it in our factory
later on.

Relative humidity 

in percent

 

Dew point : 

Dew point is calculated by mixing the humidity rate and current
temperature. It indicates at what temperature condensation will
appear.
Dew point can be selected by pushing the 

mode

button. It is 

then indicated in ˚C  or ˚F  in the lower corner of the display 
with the symbol 

Current Wind Speed :

The impeller at the top is the wind sensor.  For accurate measurements, it is 
necessary for the ball propeller to be wide opened (you can pivot it) and to be aligned
with the axis of the wind. The wind vane will help you to find the wind direction. When
not in use, it is better to twist the ball propeller into the sphere for optimal protection.
Note: if you measure the wind 30˚  off the wind axis, the result will be wrong of only 
by 2%.
Current wind speed is permanently dis-
played in the middle of the LCD.
By pushing on the

wind

button for more

than 2 seconds, you can switch your unit
of measurement. Optional units of mea-
surement include: MPH, KPH, knots, and
m/s
The Beaufort scale on the left of the 
display always indicates the instant wind
speed. The speed displayed is averaged
over 2 seconds.

Average and Maximum Wind Speed :

The average wind speed calculation is based on measurements made over the past
60 seconds. So after 70 seconds of use, measurements taken during the first ten
seconds will not be taken into considera-
tion to calculate the average wind speed.
This balanced measurement mode allows
an accurate display of the windspeed,
without being influenced by the wind speed
irregularities.
Average and maximum wind speed can be
selected by pushing the 

wind

button. These

speeds are displayed in the top of the LCD,

Beaufort scale

Average

windspeed

Maximum

windspeed

Instant windspeed,

here 5.1km/h

Dew point

 

with a

AV

symbol for average wind speed and 

MAX

symbol for maximum wind speed.

Maximum wind speed can be deleted by pressing the 

wind

and 

mode

buttons simul-

taneously.

Standby :

The instrument turns itself to standby after 3 minutes without
touching any buttons. In the stand by mode, only the clock is 
displayed. A pressure on a button and the instrument turns on.

Clock Timer:

The clock is displayed only in standby mode. Press and hold the
middle button for 1-2 seconds to set the clock. The 

mode

button increases minutes

and the

wind

button increases hours. Another push on the middle button sets the 

instrument back in normal mode.
Press and hold the middle button to switch the clock between 24 or 12 hours - with
AM and PM indication displayed.
Note : The clock setting can not be done when the              is in standby.

Ball propeller:

The ball propeller has to be wide opened and aligned with the wind axis in order 
to get accurate windspeed measurement. Use the wind vane for a good alignment
with the wind. 
After using your instrument, twist the ball propeller into the sphere for optimal 
protection.
The ball propeller can be popped out but for replacement only.  This operation may 
affect the strength of the plastic so we do not recommend it.

Compass :

The              features a high precision, Swiss needle compass.

Wind Vane :

The Wind vane is located just below the ball propeller.  Turn the instrument so that the
wind blows on the wind vane and indicates wind direction. Then align your instrument
with the axis of the wind for an accurate reading. Wind direction can be determined 
by using the compass in conjunction with the wind vane.
A turning wind vane means that it is not well aligned with the wind axis. Be aware that
holding the instrument in front of you may disturb the airflow through the wind vane.

Standby mode

 

Batteries :

The             is powered by a 3V type CR2032 Lithium battery,. The   

features

an extra battery that allows for convenient replacement at any time and place.

Battery replacement :

Unscrew the cover on the back of the instrument.
Insert the battery on the bottom, positive side (+) facing you. A second
replacement battery HAS to be put on the top of first battery and HAS 
to be inserted with negative side (-) facing you - the + side against the
+ side.
Screw the cover back with the 2 screws M2,5 x 5.

Maintenance advises :

We have used only electronic components that resists to high temperature but we 
still strongly recommend that you do not expose your instrument to temperatures 
above 65˚C.
This instrument is weatherproof but not waterproof. Do not submerge it.
In order to avoid dirt around the impeller axis, we strongly recommend to twist the 
ball propeller into the sphere when not in use.
Despite the rugged casing, avoid dropping your instrument and exposing it to 
shock. This limited warranty shall be in effect for one year after the date of purchase
by the original consumer purchaser.  During this limited warranty period, JDC Elec-
tronic SA will repair or replace without charges any defective product with a 
comparable product. This limited warranty will not apply to any instrument that has 
been misused, improperly installed, repaired, altered or which has been the subject 
of any negligence or accident.
The speed measurement principle of the SKYWATCH

®

Geos is based on magnetic

transmission. The turning impeller creates a magnetic field that is detected by the
SKYWATCH

®

Geos (JDC Electronic SA patent). If the SKYWATCH

®

Geos is close to

another magnetic field (from a computer,  electronic appliance, etc...), it may display
unexpected values but only if the impeller is not turning. This is not effecting the
normal use of the SKYWATCH

®

Geos.

 

Hygrometer part

Temperature

Response

use

Precision

Resolution Minimum Maximum Sampling

time

-10°C...50°C

±3 %rH

1 %rH

0 %rH

99 %rH

1,5 sec

5 min

Technical Specifications

Response

Accuracy

Resolution Minimum

Maximum

Sampling

time

Current

0.1 knots

108 knots

wind

±4%

0.1 mph

0

125 mph

1 sec

3 sec

speed

0.1 km/h

202 km/h

0.1 m/s

56 m/s

Average

0.1 knots

108 knots

wind

±4%

0.1 mph

0

125 mph

—

—

speed

0.1 km/h

202 km/h

0.1 m/s

56 m/s

Current

±0.5 °C

1 °C

-30 °C

50 °C

1 sec

5 min

1)

temperature

±(0.9 °F)

1 °F

-22 °F

122 °F

Wind-chill

- 

2)

1 °C

—

—

1 sec

—

factor

1 °F

Pressure

3)

±2 mbar

1 mbar

300 mbar

1100 mbar

1 hour

—

Altitude

±2 m

4)

1 m

-500m

8000m

—

—

1)

measured in still air

2)

based on a formula provided by the Midwestern Climate Center, USA:
wc = 91.4 - (0.474677 - 0.020425 v + 0.303107 sqrt(v)) (91.4-T)
where wc = wind-chill factor (°F), v = wind speed (mph) and T = temperature (°F)

3)

absolute pressure. (Pressures 3, 6, 9, 12 hours ago are displayed.)

Beaufort

knots

km/h

mph

m/s

fps

1

1 -

3

1 -

5

1 -

3

1 -

2

1 -

4

2

4 -

6

6 -

11

4 -

7

2 -

3

5 -

10

3

7 - 10

12 -

19

8 - 12

4 -

5

11 -

17

4

11 - 16

20 -

28

13 - 18

6 -

7

18 -

25

5

17 - 21

29 -

38

19 - 24

8 - 10

26 -

34

6

22 - 27

39 -

49

28 - 31

11 - 13

35 -

44

7

28 - 33

50 -

61

32 - 38

14 - 16

45 -

55

8

34 - 40

62 -

74

39 - 46

17 - 20

56 -

67

9

41 - 47

75 -

88

47 - 55

21 - 24

68 -

80

10

48 - 55

89 - 102

56 - 64

25 - 28

81 -

92

11

56 - 63

103 - 117

65 - 73

29 - 32

93 - 106

12

>64

>118

>74

>33

>107

Conversion table of several Measurement Units

 

 

Limited warranty :

This limited warranty shall be in effect for one year after the date 

of purchase by the original consumer purchaser. During this limited warranty period, JDC
Electronic SA will repair or replace without charges any defective product with a comparable
product. This limited warranty will not apply to any instrument that has been misused,
improperly installed, repaired, altered or which has been the subject of any negligence or
accident. The speed measurement principle of the SKYWATCH

®

Geos is based on magnetic

transmission. The turning impeller creates a magnetic field that is detected by the 
SKYWATCH

®

Geos (JDC Electronic SA patent). If the SKYWATCH

®

Geos is close to another

magnetic field (from a computer, electronic appliance, etc...), it may display unexpected values
but only if the impeller is not turning.