PREMO & Wireless Technology through “Witech” radio module

19th January 2011

Premo

ES Admin

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Massive use of wireless devices in the 2.4 GHz band is producing what has been called the ISM Revolution. ISM mean: Industrial, Scientific and Medical. ISM bands are frequency bands of free use (portions of the radio-electric spectrum, for which no license is required). It doesn´t mean that the devices operating on ISM bands are exempt from the regulations governing the use of those bands, both from the standpoint of radio (power, channel, duty cycle, etc.) and Electromagnetic Compatibility (emission and immunity).

Wireless technologies are being extended in exponential way, especially in the 2.4 GHz, which is nearly saturated with standards like Zigbee, Bluetooth and Wi-Fi. The presence of numerous devices in this band, including microwave ovens, makes the likelihood of interference is high and that the devices have to be designed with high frequency selectivity and very good quality at link level. This is also the reason because of new spread spectrum techniques (FHSS and DSSS) be needed to increase the immunity to electromagnetic noise.

Another of the handicaps from the use of 2.4 GHz band is that it is coincident with the resonant frequency of water, and therefore tends to be absorbed more quickly by structural elements (walls, ceilings, etc..), which makes difficult a good and big cover .

Choose the Sub-1GHz band, largely help to solve the problems of the 2.4 GHz although we must also take into account the limitations on restrictions on the duty cycle, no interoperability with other systems, and geographical limitation such as different frequency operation bands, 868MHz can no operate in USA or 915MHz can no operate in Europe, for example.

There are a variety of models available, from the front-end (external CPU) to the radio module integrated broadband or narrow band, with different CPU capabilities, and RF hardware interface: micro-strip antenna, ceramics, whip or SMA connector for external antenna, they can be adapted with total flexibility to design the final product.

From a hardware point of view the differences offers by modules of broadband and narrow band are: Narrowband: Sensitivity: Ultra-High (-114dBm), Link-budget: Extreme (until 2km, free-space), Average data speed: 25kbps/s, Ultra-low consumption (50uA, in Rx with 1s latency). Broadband:

Sensitivity: High (-105dBm), Link-budget: High (until 1,5km, free-space), High data speed: 500 kbps, Ultra-low consumption (20uA, in Rx with 1s latency).

In general, the broadband module is suitable for most of the applications and the narrow-band one, is recommended when you need a link-budget extremely high, as is the case of transmission between network nodes for Remote Metering Applications, where is essential to ensure coverage between nodes in the network even when they are installed in basements and should communicate with adjacent building.

Some of the most important features of Witech radio module are:

• Power supply voltage: 2.8 a 3.6V

• Storage temperature range: -40 a 85ºC

• Operating temperature range: -30 a 75ºC

• Firmware options for several applications

• Remote firmware update (wireless WBOOTLOADER)

• Complete interface and easy programming in “C” language

Main applications of the PREMO Witech Radio Module are: Automatic Meter Reading Networks, AMR) for water, electricity and gas, General Purpose Ad-Hoc Sensor Networks, Wireless Domotic Systems, Industrial Control, Solar Panel Monitoring Networks, Marinas Dock Pedestals, Real Time Location Systems (RTLS), Indoor Navigation and Access Control, Healthcare and Wellness Networks, Weather Stations, and Watering and Irrigation Control Networks.