RX2A

EW N Radiometrix Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233 Issue 2, 20 October 2005 RX2A UHF FM receiver module with RSSI The RX2A is a miniature PCB mounting UHF radio data receiver. It is an updated version of the Radiometrix RX2 incorporating a received signal strength indicator (RSSI). It allows the simple implementation of data links at speeds up to 64kb/s and distances up to 75 metres in-building or 300 metres over open ground. Features Figure 1: RX2A-433-10 and TX2-433-40 Designed to comply with harmonised radio standard EN 300 220-3 Designed to comply with harmonised EMC standard EN 301 489-3 Data rates up to 64kb/s Usable range up to 300m Versions available on 433.92MHz and 434.42MHz Fully screened Available for operation at 433.92MHz or 434.42MHz in the UK and Europe, the RX2A combines full screening with internal filtering to ensure EMC compliance by minimising spurious radiation and susceptibility. The module suits one-to-one and multi-node wireless links in applications including car and building security, EPOS and inventory tracking, remote industrial process monitoring and computer networking. Because of the small size and low power requirements, the RX2A is ideal for use in portable, battery-powered applications such as hand-held terminals. Technical Summary Single conversion FM superhet SAW front end filter gives >50dB image rejection Operation from 2.7V to 16V @ 12mA Built-in regulator for improved stability and supply noise rejection -101dBm sensitivity @ 1ppm BER, 64kb/s version -108dBm sensitivity @ 1ppm BER, 10kb/s version RSSI output with 60dB range Extremely low LO leakage, 10k // -20dBm and above) For received signal with ±40kHz FM deviation. Typical figures are for signal at centre frequency, max. figures are for ±50kHz offset. For 50:50 mark to space ratio (i.e. square wave). Average over 30ms (10kb/s version) or 3ms (64kb/s version) at maximum data rate. page 3 Radiometrix Ltd, RX2A Data Sheet Power supply requirements The RX2A incorporates a built-in regulator which delivers a constant 2.8V to the module circuitry when the external supply voltage is 2.85V or greater, with 40dB or more of supply ripple rejection. This ensures constant performance up to the maximum permitted supply rail and removes the need for external supply decoupling except in cases where the supply rail is extremely poor (ripple/noise content >0.1Vp-p). Note, however, that for supply voltages lower than 2.85V the regulator is effectively inoperative and supply ripple rejection is considerably reduced. Under these conditions the ripple/noise on the supply rail should be below 10mVp-p to avoid problems. If the quality of the supply is in doubt, it is recommended that a 10µF low-ESR tantalum or similar capacitor be added between the module supply pin (Vcc) and ground, together with a 10Ω series feed resistor between the Vcc pin and the supply rail. Received Signal Strength Indicator (RSSI) The module incorporates a wide range RSSI which measures the strength of an incoming signal over a range of approximately 60dB. This allows assessment of link quality and available margin and is useful when performing range tests. Please note that the actual RSSI voltage at any given RF input level varies somewhat between units. The RSSI facility is intended as a relative indicator only - it is not designed to be, or suitable as, an accurate and repeatable measure of absolute signal level or transmitter-receiver distance. The output on pin 3 of the module has a standing DC bias of 0.15V-0.45V (0.25V typ.) with no signal, rising to 0.9-1.3V (1.15V typ.) at maximum indication. The RSSI output source impedance is high (~50kΩ) and external loading should therefore be kept to a minimum. To ensure a fast response the RSSI has limited internal decoupling of 1nF to ground. This may result in a small amount of ripple on the DC output at pin 3 of the module. If this is a problem further decoupling may be added at the expense of response speed, in the form of a capacitor from pin 3 to ground. For example, adding 10nF here will increase RSSI response time from 100µs to around 1ms. The value of this capacitor may be increased without limit. Typical RSSI characteristic is shown below (this is for indicative purposes only and is not a guarantee of actual RSSI characteristics): 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 -130 -120 -110 -100 -90 RSSI output (V) -80 -70 -60 -50 RF level (dBm) Figure 4: Typical RSSI response Radiometrix Ltd, RX2A Data Sheet page 4 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 OV 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 50Ω microstrip line or coax or a combination of both. It is desirable (but not essential) to fill all unused PCB area around the module with ground plane. The module may be potted if required in a viscous compound which cannot enter the screen can. Warning: DO NOT wash the module. It is not hermetically sealed. optional solder joint for extra mechanical strength recommended horizotal mounting method vertical mounting method Figure 5: Module mounting options Radiometrix Ltd, RX2A Data Sheet page 5 Variants and ordering information The RX2A receiver is manufactured in several variants: Data rate: Slower version: (suffix -10) Faster version: (suffix -64) 433.92MHz 434.42MHz (suffix -433) (suffix -434) 7.8kHz baseband B/W, 50kHz baseband B/W, data rate up to 10kb/s data rate up to 64kb/s Frequency: The following variants are standard: RX2A-433-10 RX2A-433-64 433.92MHz, 10kbps 433.92MHz, 64kbps For other variants please contact Sales department. Radiometrix Ltd, RX2A Data Sheet page 6 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 its subassembly products without notice. Radiometrix Ltd does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. These radio devices may be subject to radio interference and may not function as intended if interference is present. We do NOT recommend their use for life critical applications. The Intrastat commodity code for all our modules is: 8542 6000 R&TTE Directive After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of the R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance to the essential requirements specified in Article 3 of the Directive, as appropriate to the particular equipment. Further details are available on The Office of Communications (Ofcom) web site: http://www.ofcom.org.uk/radiocomms/ifi/licensing/licensing_policy_manual/ Information Requests Ofcom Riverside House 2a Southwark Bridge Road London SE1 9HA Tel: +44 (0)845 456 3000 or 020 7981 3040 Fax: +44 (0)20 7783 4033 information.requests@ofcom.org.uk European Radiocommunications Office (ERO) Peblingehus Nansensgade 19 DK 1366 Copenhagen Tel. +45 33896300 Fax +45 33896330 ero@ero.dk www.ero.dk