WRX2C
9Pages

The WRX2C is a low cost wide band FM receiver with quasi-DC data slicer in a Radiometrix SIL standard pin out and footprint. It offers an economical and reliable low power data link without compromising the receiver performance. WRX2C receiver and the matching TX2A or TX2S transmitter enable the simple implementation of a wireless data link at up to 12 kbps at distances up to 75 metres inbuilding and 300 metres open ground. Figure 1: WRX2C-433-12 Features Conforms to ETSI EN 300 220-3 (radio) and EN 301 489-3 (EMC) Standard frequencies: 433.92MHz Custom frequencies available in 433.05-434.79MHz (EU) band Data rates up to 12kbps Usable range over 300m Applications Handheld terminals EPOS and inventory tracking Sensor nodes Data loggers Industrial telemetry and telecommand In-building environmental monitoring and control High-end security and fire alarms Technical Summary Single conversion FM superhet SAW band pass filter, image rejection: 45dB Supply range: +3V or 2.9V - 15V (regulator version) @ 10mA Data bit rate: 12kbps max. Receiver sensitivity: -115dBm (for 12dB SINAD) Local Oscillator (LO) re-radiation: <-65dBm Adjacent Channel: -65dBm Blocking: -75dB Size: 47 x 19 x 6 mm Evaluation platforms: Universal Evaluation Kit (UNIEK) Narrow Band Evaluation Kit (NBEK)

Figure 2: WRX2C block diagram

Figure 3: WRX2C pin-out and dimension (with can) User interface WRX2 pin 1 2 Function 50Ω RF input from the antenna RF Ground is internally connected to the module screen and pin 4 (0V). These pins should be directly connected to the RF return path - e.g. coax braid, main PCB ground plane etc. Received Signal Strength Indicator with >60dB range. DC level between 0.3V and 1.5V Open collector with weak pullup to Vcc Ground (0V) 2 2.9V – 15V DC power supply 500mVpk-pk audio. DC coupled, approx 1.4V bias Received Data output from the internal data slicer, which is not a simple 'average and...

Absolute maximum ratings Exceeding the values given below may cause permanent damage to the module. Operating temperature Storage temperature Vcc, RXD (pins 5, 7) RSSI, AF (pins 3, 6) RF in (pin 1) Performance specifications (Vcc = 3V / temperature = 20°C unless stated) pin DC supply Supply voltage Supply current RF/IF RF centre frequency IF Bandwidth Frequency stability Channel spacing RF sensitivity @ 12dB SINAD RSSI range CD threshold Blocking Image rejection Adjacent channel rejection Spurious response rejection LO re-radiation Baseband Baseband bandwidth @ -3dB AF level DC offset on AF...

Applications information Power supply requirements WRX2C modules have built-in regulator which deliver a constant 2.8V to the module circuitry when the external supply voltage is 2.9V or greater, with 40dB or more of supply ripple rejection. This ensures constant performance up to the maximum permitted rail, and removes the need for external supply decoupling except in cases where the supply rail is extremely poor (ripple/noise content >100mVpk-pk). WRX2C Received Signal Strength Indicator (RSSI) The WRX2C receiver incorporates a wide range RSSI which measures the strength of an incoming...

Antennas The choice and positioning of transmitter and receiver antennas is of the utmost importance and is the single most significant factor in determining system range. The following notes are intended to assist the user in choosing the most effective antenna type for any given application. Integral antennas These are relatively inefficient compared to the larger externally-mounted types and hence tend to be effective only over limited ranges. They do however result in physically compact equipment and for this reason are often preferred for portable applications. Particular care is...

0.5 mm enameled copper wire close wound on 3.2 mm diameter former RF Feed point 15% to 25% of total loop length RF-GND wire, rod, PCB-track or a combination of these three RF Figure 5: integral antenna configurations External antennas These have several advantages if portability is not an issue, and are essential for long range links. External antennas can be optimised for individual circumstances and may be mounted in relatively good RF locations away from sources of interference, being connected to the equipment by coax feeder. Helical. Of similar dimensions and performance to the...

Module mounting considerations The module may be mounted vertically or bent horizontal to the motherboard. Good RF layout practice should be observed – in particular, any ground return required by the antenna or feed should be connected directly to the RF GND pin at the antenna end of the module, and not to the GND pin which is intended as a DC ground only. All connecting tracks should be kept as short as possible to avoid any problems with stray RF pickup. If the connection between module and antenna does not form part of the antenna itself, it should be made using 50 microstrip line or...

Radiometrix Ltd Hartcran House 231 Kenton Lane Harrow, Middlesex HA3 8RP ENGLAND Tel: +44 (0) 20 8909 9595 Fax: +44 (0) 20 8909 2233 sales@radiometrix.com www.radiometrix.com Copyright notice This product data sheet is the original work and copyrighted property of Radiometrix Ltd. Reproduction in whole or in part must give clear acknowledgement to the copyright owner. Limitation of liability The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd reserves the right to make changes or improvements in the design, specification or manufacture of...