radiometrix ltd., NTR2 transceiver data sheet page 1 features conforms to etsi en 300 220-3 (radio) and en 301 48 9-3 (emc) standard frequencies: 434.075mhz, 434.650mhz and 45 8.700mhz custom frequencies available in 433mhz (eu) and 458 mhz (uk) band data rates up to 10kbps usable range over 500m 25khz channel spacing longer range compared to wide band fm modules available for licence-exempt operation in the 433mh z (eu) and 458mhz (uk) bands, the NTR2 modules combine effective screening with internal filtering to minimise spurious radiation and susceptibility thereby ensuring emc compliance. they can be used in existi ng low data rate (<10kbps) applications where the operating range of the system using wide band trans ceivers need to be extended. because of their small size and low power consumption, NTR2 is ideal for u se in battery-powered portable applications. applications epos equipment, barcode scanners data loggers industrial telemetry and telecommand in-building environmental monitoring and control high-end security and fire alarms dgps systems vehicle data up/download technical summary 3 stage crystal controlled vcxo data bit rate: 10kbps max. transmit power: +10dbm (10mw) double conversion fm superhet saw band pass filter, image rejection: 50db rx sensitivity: -118dbm (for 12db sinad) rx adjacent channel: -70dbm supply 2.9v - 15v @ 18ma (internal 2.8v voltage reg ulator) size: 57 x 24 x 8mm evaluation platforms : nbek + ntr carrier the NTR2 transceiver offers a low power, reliable data link in a radiometrix sil standard pin out and footprint. this makes the NTR2 ideally suited to those low power applications where existing single frequency wideband uhf modules have insufficient range. uhf narrow band fm transceiver hartcran house, 231 kenton lane, harrow, middlesex, ha3 8rp, england tel: +44 (0) 20 8909 9595, fax: +44 (0) 20 8909 223 3, www.radiometrix.com issue 1, 30 july 2012 NTR2 figure 1: NTR2-434.650-10
radiometrix ltd., NTR2 transceiver data sheet page 2 functional description the transmit section of the NTR2 consists of a freq uency modulated voltage controlled crystal oscillat or (vcxo) feeding a frequency multiplier with two stag e amplifier and rf filter. final power amplifier st age is factory pre-set to appropriate band power level. op eration can be controlled by the txe line. the tran smitter achieves full rf output typically within 5ms of thi s line being pulled low. the rf output is filtered to ensure compliance with the appropriate radio regulations a nd fed to the 50 antenna pin. the rf output is filtered to ensure compliance with the appropriate radio reg ulations and fed via a fast tx/rx changeover switch to the 50 antenna pin. the receive section is a double conversion nbfm sup erhet with if at 21.4mhz and 455khz fed by a low noise amplifier (lna) on the rf front-end. quadratu re detector output is available as audio frequenc y (af) output and transmitted digital data is regener ated from af using adaptive data slicer. a received signal strength indicator (rssi) output with some 60db of range is provided. user interface 7 holes of 0.7mm dia pin spacing 2.54mm (0.1") 1 2 3 4 5 6 8 7 9 57.7mm 24.1mm 30.48mm (1.2") 8mm 1 = rf in 2 = rf gnd 3 = rssi 4 = 0v 5 = vcc 6 = af 7 = rxd 8 = 9 = txd txe figure 2: NTR2 pin-out and dimension NTR2 pin name function 1 rf in/out 50 rf input from the antenna 2 rf gnd rf ground is internally connected to the m odule screen and pin 4 (0v). these pins should be directly connected to the rf r eturn path - e.g. coax braid, main pcb ground plane etc. 3 rssi received signal strength indicator with >60d b range. dc level between 0.5v and 2v 4 0v ground 5 vcc 2.9 ? 15v dc power supply 6 af 500mv pk - pk audio. dc coupled, approx 0.8v bias 7 rxd logic data output from the internal data slic er. the data is squared version of the audio signal on pin 6 and is true data, i.e. as fed to the transmitter. output is "open-collector" format with internal 10k pull-up to vcc (pin 5). suitable for bi-phase codes 8 txe low = tx enable (3v cmos logic) 9 txd dc coupled input (3v cmos logic). r in = 100k notes : 1. txe has 47k internal pullup to 2.8v 2. compatible with nim2, nrx2 and ntx2. 3. pinout resembles an nrx2 receiver with 2 added p ins ( n_txe and txd) 4. there is no complete unit enable pin: the user m ust switch the vcc. 5. there are two versions of the interface pinning: batten & allen 'edge leadframe' for vertical sil m ounting conventional 0.1" pitch square pin headers for min imum height horizontal mount.
radiometrix ltd., NTR2 transceiver data sheet page 3 performance specifications (vcc = 3v / temperature = 20 c unless stated) general pin min. typ. max. units notes operating temperature -10 - +60 c storage temperature -30 +70 c dc supply supply voltage 5 2.9 3.0 15 v tx supply current 5 - 20 - ma rx supply current 5 - 15 - ma antenna pin impedance 1 - 50 - rf centre frequency NTR2-434.650-10 NTR2-434.075-10 NTR2-458.700-10 - - - 434.650 434.075 458.700 - - - mhz 1 channel spacing - 25 - khz number of channels - 1 - transmitter rf rf power output 1 9 10 11 dbm 2 spurious emissions 1 - - -40 dbm adjacent channel tx power - -37 - dbm frequency accuracy - - 2.5 khz 3 fm deviation (peak) 2.5 3.0 3.5 khz 4 baseband modulation type - fsk - f3d modulation bandwidth @ -3db 0 - 5 khz txd input level (logic low) 9 - 0 - v 5 txd input level (logic high) 9 - 3.0 - v 5 distortion - - 10 % 6 dynamic timing tx enable to full rf 8 - - 5 ms pin min. typ. max. units notes receiver rf/if rf sensitivity @ 12db sinad 1, 6 - -118 - dbm rf sensitivity @ 1ppm ber 1, 7 - -112 - dbm rssi threshold 1, 3 - -125 - dbm 7 rssi range 1, 3 - 60 - db 7 if bandwidth - tba - khz blocking 1 - 84 - db image rejection 1 - 55 - db adjacent channel 1 - 70 - db spurious response rejection 1 - 55 - db lo re-radiation 1 - - -60 dbm 8 baseband baseband bandwidth @ -3db 6 0 - 5 khz af level 6 - 500 - mv p - p 9 dc offset on af out 6 - 0.8 - v distortion on recovered af 6 - - 10 % dynamic timing power up with signal present power up to valid rssi 3, 5 - 3 - ms power up to valid af 5, 6 2 ms power up to stable data 5, 7 - - 10 ms signal applied with supply on signal to valid rssi 1, 3 - 2 - ms
radiometrix ltd., NTR2 transceiver data sheet page 4 pin min. typ. max. units notes signal to valid af 1, 6 1 ms signal to stable data 1, 7 - - 5 ms 10 time between data transitions 7 - - 0.1 ms notes: 1. available in 25khz channel steps on other custom frequencies in 433mhz/458mhz band 2. measured into 50 resistive load. 3. total over full supply and temperature range. 4. with 0v ? 3.0v modulation input. 5. to achieve specified fm deviation. 6. for 1v pk-pk signal biased at 1.4v 7. see applications information for further details . 8. exceeds en/emc requirements at all frequencies. 9. for received signal with 3khz fm deviation 10. for 50:50 mark to space ratio (i.e. squarewave) .
radiometrix ltd., NTR2 transceiver data sheet page 5 applications information power supply requirements the NTR2 has built-in regulator which deliver a con stant 2.8v to the module circuitry when the externa l supply voltage is 2.9v or greater, with 40db or mor e of supply ripple rejection. this ensures constant performance up to the maximum permitted rail, and r emoves the need for external supply decoupling exce pt in cases where the supply rail is extremely poor (r ipple/noise content >100mv pk-pk ). tx modulation requirements the module is factory-set to produce the specified fm deviation with a txd input to pin 9 of 3v amplit ude, i.e. 0v ?low?, 3v ?high if the data input level is greater than 3v, a resis tor must be added in series with the txd input to l imit the modulating input voltage to a maximum of 3v on pin 9. txd input resistance is 100k to ground, giving typical required resistor values as follows: vcc series resistor 3v 3.3v 5v 9v - 10 k 68k 220k NTR2 received signal strength indicator (rssi) the NTR2 incorporates a wide range rssi which measu res the strength of an incoming signal over a range of 55db or more. this allows assessment of link qua lity and available margin and is useful when perfor ming range tests. the output on pin 3 of the module has a standing dc bias of <0.5v with no signal, rising to 2v at maxi mum indication. typical rssi characteristic is as shown below: figure 3: rssi response curve
radiometrix ltd., NTR2 transceiver data sheet page 6 expected range predicting the range obtainable in any given situat ion is notoriously difficult since there are many f actors involved. the main ones to consider are as follows: ? type and location of antennas in use ? type of terrain and degree of obstruction of the l ink path ? sources of interference affecting the receiver ? ?dead? spots caused by signal reflections from nea rby conductive objects ? data rate and degree of filtering employed the following are typical examples ? but range test s should always be performed before assuming that a particular range can be achieved in a given situati on: data rate tx antenna rx antenna environment range 10kbps ? wave ? wave urban/obstructed 300m 10kbps ? wave ? wave rural/open 500m 10kbps helical helical in-building 100m data formats and range extension the NTR2?s txd input is normally driven directly by logic levels but will also accept analogue drive ( e.g. 2- tone signalling). in this case it is recommended th at txd (pin 9) be dc-biased to 1.2v approx. with th e modulation ac-coupled and limited to a maximum of 2 v p-p to minimise distortion over the link. the varactor modulator in the NTR2 introduces some 2 nd harmonic distortion which may be reduced if necess ary by predistortion of the analogue waveform. although the modulation bandwidth of the NTR2 exten ds down to dc it is not advisable to use data containing a dc component. this is because frequenc y errors and drifts between the transmitter and receiver occur in normal operation, resulting in dc offset errors on the NTR2?s audio output. the nrt2 in standard form incorporates a low pass f ilter with a 5khz nominal bandwidth. this is suitab le for transmission of data at raw bit rates up to 10kbps.
radiometrix ltd., NTR2 transceiver data sheet page 7 antennas the choice and positioning of transmitter and recei ver 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 us er in choosing the most effective antenna type for any gi ven application. integral antennas these are relatively inefficient compared to the la rger externally-mounted types and hence tend to be effective only over limited ranges. they do however result in physically compact equipment and for thi s reason are often preferred for portable application s. particular care is required with this type of an tenna to achieve optimum results and the following should be taken into account: 1. nearby conducting objects such as a pcb or batte ry can cause detuning or screening of the antenna which severely reduces efficiency. ideally the ante nna should stick out from the top of the product an d be entirely in the clear, however this is often not desirable for practical/ergonomic reasons and a compromise may need to be reached. if an internal a ntenna must be used try to keep it away from other metal components and pay particular attention to th e ?hot? end (i.e. the far end) as this is generally the most susceptible to detuning. the space around the antenna is as important as the antenna itself. 2. microprocessors and microcontrollers tend to rad iate significant amounts of radio frequency hash wh ich can cause desensitisation of the receiver if its an tenna is in close proximity. the problem becomes worse as logic speeds increase, because fast logic edges generate harmonics across the uhf range which are then radiated effectively by the pcb trac king. in extreme cases system range may be reduced by a factor of 5 or more. to minimise any adverse e ffects situate antenna and module as far as possibl e from any such circuitry and keep pcb track lengths to the minimum possible. a ground plane can be highly effective in cutting radiated interference a nd its use is strongly recommended. a simple test for interference is to monitor the re ceiver rssi output voltage, which should be the sam e regardless of whether the microcontroller or other logic circuitry is running or in reset. the following types of integral antenna are in comm on use: quarter-wave whip. this consists simply of a piece of wire or rod con nected to the module at one end. at 434mhz the total length should be 164mm from module pin to antenna tip including any interconnecting w ire or tracking. because of the length of this antenna it is almost always external to the product casing. helical. this is a more compact but slightly less effective antenna formed from a coil of wire. it is very efficient for its size, but because of its high q i t suffers badly from detuning caused by proximity t o nearby conductive objects and needs to be carefully trimme d for best performance in a given situation. the si ze shown is about the maximum commonly used at 434mhz and appropriate scaling of length, diameter and number of turns can make individual designs much sm aller. loop. a loop of pcb track having an inside area as large as possible (minimum about 4cm 2 ), tuned and matched with 2 capacitors. loops are relatively ine fficient but have good immunity to proximity detuni ng, so may be preferred in shorter range applications wher e high component packing density is necessary. integral antenna summary: feature whip helical loop ultimate performance *** ** * ease of design set-up *** ** * size * *** ** immunity to proximity effects ** * ***
radiometrix ltd., NTR2 transceiver data sheet page 8 a. helical antenna b. loop antenna rf c1 c2 c4 c3 rf-gnd c. whip antenna 16.4cm rf 0.5 mm enameled copper wire close wound on 3.2 mm diameter former 433 mhz = 24 turns feed point 15% to 25% of total loop length track width = 1mm 4 to 10 cm inside area wire, rod, pcb-track or a combination of these three 433 mhz = 16.4 cm total from rf pin. 2 rf figure 4: 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 circumstan ces and may be mounted in relatively good rf locati ons away from sources of interference, being connected to the equipment by coax feeder. helical. of similar dimensions and performance to the integ ral type mentioned above, commercially- available helical antennas normally have the coil e lement protected by a plastic moulding or sleeve an d incorporate a coax connector at one end (usually a straight or right-angle bnc/sma type). these are compact and simple to use as they come pre-tuned fo r a given application, but are relatively inefficie nt and are best suited to shorter ranges. quarter-wave whip. again similar to the integral type, the element us ually consists of a stainless steel rod or a wire contained within a semi-flexible moulded plastic jacket. various mounting options are availa ble, from a simple bnc/sma connector to wall brackets, t hrough-panel fixings and magnetic mounts for temporary attachment to steel surfaces. a significant improvement in performance is obtaina ble if the whip is used in conjunction with a metal ground plane. for best results this should extend all roun d the base of the whip out to a radius of the lengt h of the whip used (under these conditions performance appro aches that of a half-wave dipole) but even relative ly small metal areas will produce a worthwhile improve ment over the whip alone. the ground plane should b e electrically connected to the coax outer at the bas e of the whip. magnetic mounts are slightly differe nt in that they rely on capacitance between the mount and the metal surface to achieve the same result. a ground plane can also be simulated by using 3 or 4 quarter-wave radials equally spaced around the ba se of the whip, connected at their inner ends to the o uter of the coax feed. a better match to a 50 coax feed can be achieved if the elements are angled downward s at approximately 30-40 to the horizontal.
radiometrix ltd., NTR2 transceiver data sheet page 9 module mounting considerations the modules may be mounted vertically or bent horiz ontal to the motherboard. note that the components mounted on the underside of the NTR2 is relatively fragile ? avoid direct mechanical contact between t hese and other parts of the equipment if possible, parti cularly in situations where extreme mechanical stre sses could routinely occur (as a result of equipment bei ng dropped onto the floor, etc). good rf layout practice should be observed. 50 microstrip line or coax or a combination of both s hould be used to connect rf pin of the module to rf connecto r or antenna. it is desirable (but not essential) t o fill all unused pcb area around the module with ground plane . variants and ordering information the NTR2 transceivers are manufactured in the follo wing variants as standard: at 434.650mhz : NTR2-434.650-10 at 434.075mhz : NTR2-434.075-10 at 458.700mhz : NTR2-458.700-10 other frequency variants can be supplied to individ ual customer requirements in the 433mhz (european) and 458mhz (uk) licence exempt bands
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 co pyrighted 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 bel ieved 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 lt d does not assume any liability arising from the application or use of any product or circuit descri bed herein, nor for any infringements of patents or other rights of third parties which may result from the u se of its products. this data sheet neither states nor implies warranty of any kind, including fitness for any particular application. these radio devices ma y 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 particula r equipment. further details are available on the office of comm unications (ofcom) web site: http://www.ofcom.org.uk/ information requests ofcom riverside house 2a southwark bridge road london se1 9ha tel: +44 (0)300 123 3333 or 020 7981 3040 fax: +44 (0)20 7981 3333 information.requests@ofcom.org.uk european communications office (eco) peblingehus nansensgade 19 dk 1366 copenhagen tel. +45 33896300 fax +45 33896330 ero@ero.dk www.ero.dk
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