Wireless sensor network - Smilenet

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Wireless sensor network



Radio frequency used:

Radio protocol used:

Range/Power (line of sight/dBm):

20 km line of sight

300 m wet forest

868 MHz

300 mW TX power

l/4 antenna

Hop modes:


Zigbee (not reliable)


Yes, with Autossh and tunneling

Mesh limitations:

number of sensors:

8 temperature and moisture sensors,

8 analog inputs or digital, 1 RS232

number of nodes per router:

several hundreds

Additional information:

Sensor compatibility:

1 Wire

Digital IO

8 channel 10 bit AD converter, 0 to 2.5V

Frequency counter

Future: I2C, SDI12 ?

Data reading frequency:

Adjustable, e.g. 30 s, 1 min, 15 min

Storage of data/backup:

SD card on node (e.g. 2 GByte)

CF card on Gateway (4 GByte)

Server with database on Internet

Data format: plain ASCII text file

Power consumption:

Sleep mode: about 40 uA

Active mode without radio/sensor: 8 mA

Active mode with soil moisture sensor: 50 mA for 400 ms

Active mode with radio RX: 50 mA

Active mode with radio TX: 150 mA


Years in service: 1 year

Failure rate instrument (years):

Packet failure (%): Depends on environment

Installation procedure:

Configuration in lab

Power on

Range test in field, handheld radio for communication

Installation underground possible:


Battery life:

1 min interval: 2 weeks

90 min interval: approx. 2 years

Battery type

4x AA, 6V (5.2 V)

Sanyo Eneloop NiMh rechargeable, 2000 mAh, self discharge about 15% in 1 year

Alkalines as well (solar power optional in future)

Maintenance required /Ease of maintenance:

Change of battery required


Yes, but research institution

Software debug: Monitor mode to see all raw data, over the air programming in future


Web friendly interface:

Yes, Webpage with graphics based on Gnuplot

Data base:

No, future optional

Scripting language:

No, future optional

Update in the field:

Yes, but only with wired connection, wireless update is future option

Open source:

Yes (Linux, gnuplot, mysql)

Cost (non profit):

30 Euro microcontroller board

15 to 50 Euros radio (depending on frequency and power)

Gateway: 135 Euro embedded pc +30 to 65 Euro for radio modem

GPRS: 150 Euro

Communication costs: 0.2 Euro for 1 MByte

What to watch out for:



Projects that used the above equipment:

Other related web sites:

Technical information