Wireless sensor network - Smilenet

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Wireless sensor network - image 2

Wireless sensor network


Contents

Method:

Summary:

Smilenetz means Soil Moisture Intelligent Long-Range Environmental Network

Radio frequency used:

868 MHz and 2.4 GHz

Radio protocol used:

Range/Power (line of sight/dBm):

20 km line of sight

300 m wet forest

at 868 MHz with 300 mW and quarter wave antenna


Hop modes:

Point-to-multipoint or Zigbee dependent on radio module


GPRS:

GPRS modem at gateway

Mesh limitations:

Additional information:

Sensor compatibility:

1 Wire

Digital IO

8 channel 10 bit AD converter, 0 to 2.5V

Frequency counter

RS232

Future options: SDI12, I2C, SPI


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

Future option: database

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 high power radio TX: 150 mA


Reliability:

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

Monitoring software for incoming packets including RSSI


Installation underground possible:

yes

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

Support:

Yes, but research institution

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


Software:

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:

Problems/Questions:

Links

Projects that used the above equipment:


Other related web sites:

Technical information: http://www.mx.hs-mannheim.de

Distributors


References

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