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v7.3
Smartphone detection
Meshlium
X
treme
The scanning time is more important in Bluetooth as the devices need some time to reply to the queries.
Device name is not always obtained, as some devices take some time to reply to the name queries. Nevertheless,
the device can be easily identified by its MAC address.
How can I calculate the total number of people from the number of detected devices?
It depends. Not all the people have a smartphone. Also, not all the people switch WiFi and/or Bluetooth radios on
their smartphones. It all depends on so many economic, social and cultural factors. The percentage of people with
WiFi or Bluetooth on depends on the scenario where they are too. For example, if a Meshlium Scanner is installed
in a college campus which provides free WiFi service, many students will be detected because they will probably
keep their smartphones, tablets or notebooks with WiFi on. The same would happen in a mall, airport or hotel
with free WiFi.
Besides, consider that not all the people who could be detected will remain enough time inside of the coverage
area of Meshlium Scanner.
Also, keep in mind that some people can carry several WiFi or Bluetooth devices. For example, a driver with
smartphone in his pocket and a Bluetooth device in his car can be detected as 2 different users by Meshlium.
To sum up, in Libelium we consider that the total number of people can be approximated multiplying the number
of detected devices by a factor, from 3 or 5:
3*Detected devices < Total people < 5*Detected devices
It all depends on a number of variables. The administrator of Meshlium Scanner can perform real tests in order
to find the exact value of this factor in the specific scenario under study.
14.2. WiFi Scanner
14.2.1. Concepts
The additional 2nd WiFi radio integrated in Meshlium Scanner allows to scan WiFi devices in a range of action up
to 200 m depending on the line of sight conditions.
The idea is to search for WiFi devices in a defined interval which can be configured. Meshlium will get the
MAC
address
, information about the detected
Device
. Regarding these devices, we can distinguish Access Points
and Clients
.In the case of each client, Meshlium gets which Access Point the device is connected to (if any).
Also, the signal strength (
RSSI
) of the devices along with a
timestamp
which identifies when the scan detects it.
For this reason, it is important to set the correct time in the System before starting with the storage of the data.
See the Time Synchronization in the System section.
As extra information, the System also identifies the
Vendor
of the WiFi devices using its MAC address and if the
information is synchronized to the external database (
Sync
).
Example of information scanned:
B ID
Sync Timestamp
MAC
Device
RSSI Vendor
53483
0
2012-04-24 07:56:25
C4:2C:03:96:0E:4A
(not detected) 69
Apple
53482
1
2012-04-24 09:11:26
D8:2A:7E:10:1E:63
libelium_wsn1
60
Nokia Corporation
We can select the Scanning Time from a drop-down list. This time specifies how many seconds the scanner will
spend searching. After each scanning process, the system performs a pause of one second before starting again.
The Scanning Time must be trimmed in order to avoid that a temperature of 70 ºC is reached in the Meshlium’s
microprocessor. See chapter “Internal temperature sensors” to know how to monitor the microprocessor’s
temperature.