Manual for MiniBSV 10k
MiniBSV 10k is a low price fog sensor for visibility measurement, suitable forwarning system for a dense fog.

* acrylic panel is attached.
The sensor is sensitive for fog particles in a zone about 25 cm ahead of the locationof the sensor who limit the visibility in the air. These particles are normally themicroscopic water particles constituting fog, but they may also be snowflakes,
raindrops or air pollutants.
The sensor is heated to a few degrees above ambient temperature in order to keep
moisture away.
In order to keep the electronics dry, a membrane ventilator that keeps the pressure
inside at the same level as outside. This prevents liquid water from sucking into thesensor through micro cracks etc. at falling temperature – a creative solution to a bigproblem.
The sensor produces analog and digital signals:

About the analog output:
The microprocessor controls the analog output giving the visibility directly(vis=01000 meters gives 0.5 Volt, and vis=00500 meters gives 0.25 Volt etc up to 5
Volt at 10000 meters).

About the RS232 output:
The calculated data is presented in digital form as an ASCII string on the RS232
output, 1,200 baud 8N1, that is transmitted "streaming" every 30 seconds the fixedlength data. This string can be received by many loggers with RS232 inputs but
also by a PC via the serial port and with a terminal program like Hyper Terminal(part of WINDOWS).
This is an example of an output string:
amb=+100 alfa=+0.00120 vis=02500
The first figure – the amb parameter is uncalibrated measure of the ambient solar
irradiance in W/m2. The sensitivity depends strongly on how the sensor is aimed.
The sensor can, when mounted, be calibrated by comparing it with an irradiancesensor. But a simple method is to take data from a clear day at noon. If the sun is
60 deg or more above the horizon the irradiance is not far from 1,000 W/m2. The
measurement is not very accurate- but it may be useful for instance for telling if it isday or night.
The second figure is the so-called extinction coefficient often called alfa. The
relation between the extinction and visibility is alfa=3/vis.* The alfa parameter canbe used for monitoring trends in visibility when the visibility is larger than 10,000
meters. But note that the absolute accuracy in alfa is limited in such cases and notguaranteed. Visibility between 2~10km is as well output but the absolute accuracy
for this range is not guaranteed.
The third figure – the vis parameter - is the measured visibility in meters calculated
based on the value of alfa.
If the optical receiver is saturated by for instance sunlight or reflections from an
object in the sensitive zone like an insect or fallen snow covering the front, thevisibility displayed visibility value will be 00000 and the output can be:
amb=+050 alfa=+0.00000 vis=00000

MiniBSV 10k Specifications
Size(W*D*H)

68*34*45 mm

WeightApprox. 170 g

Heating time

Approx. 1 min.

Power consumption<50 mA DC12 Volt ( 8-14)

OutputAnalog：0-5 V

Measurement time

30 sec.

Operational temperature-20…+50 ℃

Projector output

Approx. 3 mW(NIR LED), Eye safe class 1 M

Light source wavelength

850 nmHousing

Aluminum Oxide, O-ring sealing

Visibility calculation range

10 m…10 km

Digital：RS232 1200 bps8N1Guaranteed absoluteaccuracy±30 %（Visibility calculation range : up to 2 km）

Mounting and connecting MiniBSV 10k

The sensor should be mounted so that it "looks" horizontal and roughly north (southon the southern hemisphere) – eliminating direct sunlight into receiver. There mustnot be anything in the sightline closer than 5 meters.

The outer dimensions are 68*45*34 mm and four M3 holes for fastening are locatedon the top surface.
We deliver the sensor with a mounting bracket made of PMMA plastic, seen in thepicture above, so the sensor is electrically isolated when using the bracket.
When the sensor is mounted on the roof or the wall of a multistoried building, it ispreferable that the sensor is kept a few meters apart from the surface of the building.
The visibility can be measured higher than the actual value at a building surface
where the ambient temperature is heated by the heat emitted by the building itself
and water vapor is more likely to evaporate.
The sensor is delivered with a 6 meter 5-wire cable connected.
The wire colors are chosen as follows:

redblack
whitegreen
yellow

12 Volt DC Power inPower ground
Signal ground
Digital signal out
Analog out