radiometrix ltd., hx1 high power transmitter data s heet page 1 features standard frequencies: 144.390, 144.800 and 169.4125 mhz other frequencies from 120mhz to 180mhz data rates up to 3kbps usable range over 10km fully screened low power requirements the hx1 is a narrow band radio transmitter module f or use in long range data transfer applications at ranges up to 10kilometres. hx1 transmitter circuit is the bim1t transmitter circuit in the tx1 pin-out with s lightly enlarged dimension to accommodate extra power ampli fier circuit to produce 300mw rf output and available for operation on 169.4-169.475mhz europea n licence exempt frequency band. applications asset tracking and tracing meter reading systems automatic position reporting system (aprs) technical summary transmit power: 300mw (24.7dbm) operating frequency: 144.390, 144.800 and 169.4125m hz channel spacing: 25khz supply: 5v (regulated) current consumption: 140ma nominal transmit data bit rate: 3kbps or 10kbps max. size: 43 x 15 x 5mm evaluation platforms : nbek + sil carrier the special hx1 transmitter modules offer a 300mw rf output vhf data link in radiometrix sil standard pin-out and footprint. this makes the hx1 ideally suited to those low power applications where existing narrow band and wideband transmitters provide insufficient range. together with the matching nrx1 or bim1r receiver a one-way radio data link can be achieved over a distance up to 10km+ with suitable choice of data rate and antennas. figure 1: hx1-144.390-3 vhf narrow band fm 300mw transmitter 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 2, 27 july 2012 hx1
radiometrix ltd., hx1 high power transmitter data s heet page 2 figure 2: hx1 block diagram
radiometrix ltd., hx1 high power transmitter data s heet page 3 functional description the hx1 transmitter consists of a frequency modulat ed voltage controlled crystal oscillator (vcxo) fee ding a frequency doubler with two stage amplifier and rf filter. final power amplifier stage is factory pre -set to appropriate band power level. operation can be cont rolled by the en (enable) line, the transmitter ach ieving full rf output typically within 5ms of this line be ing pulled high. the rf output is filtered to ensur e compliance with the appropriate radio regulations a nd fed to the 50 antenna pin. user interface 7 holes of 0.7 mm dia. pin spacing 2.54 mm 1 2 3 4 5 6 7 5mm 43mm 14.5mm 15.24 mm pin spacing: 2.54 mm 1 = rf gnd 2 = rf out 3 = rf gnd 4 = en 5 = vcc 6 = 0v 7 = txd hx1(300mw) figure 3: hx1 pin-out and dimension pin name function 1, 3 rfgnd rf ground 2 rf out 50 rf output to the antenna 4 en pull high to enable transmitter 5 vcc 5v regulated dc power supply 6 0v ground 7 txd dc coupled input for 5v cmos logic. r in = 100k note : pinout and footprint as tx1. (but pcb is longer)
radiometrix ltd., hx1 high power transmitter data s heet page 4 absolute maximum ratings exceeding the values given below may cause permanen t damage to the module. operating temperature -10 c to +60 c storage temperature -30 c to +70 c performance specifications: (vcc = 5v / temperature = 20 c unless stated) pin min. typ. max. units notes supply supply voltage 4 - 5 - v tx supply current 4 - 140ma - ma rf rf power output 2 +23.7 +24.7 +25.7 dbm 1 spurious emissions 2 - -40 - dbm adjacent channel tx power - -37 - dbm 2 frequency accuracy -2.5 0 +2.5 khz 3 fm deviation (peak) 2.5 3.0 3.5 khz 4 antenna pin impedance 2 - 50 - rf centre frequency - 169.4125 - mhz 5 channel spacing - 25 - khz number of channels - 1 - baseband modulation bandwidth @ -3db 0 - 5 khz 6 txd input level (logic low) 6 - 0 - v 7 txd input level (logic high) 6 - 5.0 - v 7 dynamic timing tx select to full rf - 5 - ms notes: 1. measured into 50 resistive load 2. for 1kbps manchester encoded; the data bit rate is limited to 3kbps nrz max. to meet adjacent chann el power specification. 3. total over full supply and temperature range 4. with 0v ? 5.0v modulation input 5. other vhf 120-180mhz by special order 6. 5v cmos compatible 7. to achieve specified fm deviation
radiometrix ltd., hx1 high power transmitter data s heet page 5 applications information 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 1.2kbps half-wave half-wave rural/open 10-15km 10kbps half-wave half-wave rural/open 3-4km 10kbps helical half-wave urban/obstructed 500m-1km 10kbps helical helical in-building 100-200m note : the figure for 1.2kbps assumes that the receiver bandwidth has been suitably reduced by utilising a n outboard sallen-key active audio filter and data sl icer or similar arrangement. 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 vhf 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.
radiometrix ltd., hx1 high power transmitter data s heet page 6 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 169mhz the total length should be 421mm 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 169mhz 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 5cm 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: features whip helical loop ultimate performance *** ** * ease of design set-up *** ** * size * *** ** immunity to proximity effects ** * *** helical antenna rf loop antenna rf gnd rf c tune c match capacitors may be variable or fixed (values depend on loop dimensions) track width = 1mm min. area 500mm 2 whip antenna 421mm @ 169mhz rf wire, rod, pcb track or a combination of these length(mm) = 71250 / freq(mhz) trim wire length or expand coil for best results 35-40 turns wire spring length 120mm, dia 10mm 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 type). these are compac t and simple to use as they come pre-tuned for a give n application, but are relatively inefficient and a re 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,
radiometrix ltd., hx1 high power transmitter data s heet page 7 from a simple bnc connector to wall brackets, throu gh-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 300mm or more (under these conditions performance approaches that of a half-wave dipole) but even relatively small m etal areas will produce a worthwhile improvement over th e whip alone. the ground plane should be electrical ly connected to the coax outer at the base of the whip . magnetic mounts are slightly different in that th ey rely on capacitance between the mount and the metal surf ace 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. fig.5: quarter wave antenna / ground plane configur ations half-wave. there are two main variants of this antenna, both of which are very effective and are recommended where long range and all-round coverage are required: 1. the half-wave dipole consists of two quarter-wav e whips mounted in line vertically and fed in the c entre with coaxial cable. the bottom whip takes the place of the ground plane described previously. a varian t is available using a helical instead of a whip for the lower element, giving similar performance with reduced overall length. this antenna is suitable fo r mounting on walls etc. but for best results shoul d be kept well clear of surrounding conductive objects a nd structures (ideally >1m separation). 2. the end-fed half wave is the same length as the dipole but consists of a single rod or whip fed at the bottom via a matching network. mounting options are similar to those for the quarter-wave whip. a ground plane is sometimes used but is not essential . the end-fed arrangement is often preferred over the centre-fed dipole because it is easier to mount in the clear and above surrounding obstructions. yagi. this antenna consists of two or more elements moun ted parallel to each other on a central boom. it is directional and exhibits gain but tends to be large and unwieldy ? for these reasons the yagi is the i deal choice for links over fixed paths where maximum ran ge is desired. 50 coax feed metal ground plane 50 coax feed 3 0 - 4 0 d e g . ( 3 -4, equally s p ace d ) 1/4-w a ve r ad ial e lemen t s 1/4-wave whip (421mm long @ 169mhz) 1/4-wave whip
radiometrix ltd., hx1 high power transmitter data s heet page 8 module mounting considerations the modules may be mounted vertically or bent horiz ontal to the motherboard. good rf layout practice should be observed. if the connection between module and antenna is more than about 20mm long use 50 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. variants and ordering information the hx1 transmitter is manufactured in the followin g variants as standard: hx1-144.390-10 us aprs hx1-144.800-10 eu aprs hx1-169.4125-3 eu meter reading, asset tracing and tracing other variants can be supplied to individual custom er requirements at frequencies from 120mhz to 180mh z subject to minimum order quantity and lead-time. matching receivers: nrx1-xxx.xxx-10 (sil footprint) bim1r-xxx.xxx-10 (dil footprint)
radiometrix ltd., hx1 high power transmitter data s heet page 9 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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