radiometrix ltd mtx2 data sheet page 1 the mtx2 transmitter module adds a totally new sub- miniature form factor to the existing rang e of radiometrix ism band devices. using cutting edge in tegrated rf devices, it offers multi channel, low power narrowband operation in a previously unobtainable size. it is ideally suited to applications w here existing wideband modules have insufficient range and where traditional narrowband modules would physically be too big to fit in. features conforms to en 300 220-2 and en 301 489-3 high performance fractional n (sigma-delta) synthes izer with tcxo vibration resistant (negligible microphony) data rates up to 10 kbps for standard module usable range over 500m (with suitable aerials and m atching receiver) fully screened. very low profile feature-rich interface (analogue and digital baseba nd) re-programmable via rs232 interface low power requirements applications keyfobs and other hand held terminals small form factor data loggers industrial telemetry and telecommand in-building environmental monitoring and control covert, high-end security devices unobtrusive fire alarm sensors heavy vehicle/machinery controls technical summary operating frequency: 433.875-434.650mhz (eu band) 458.525 - 459.1m hz (uk band) other custom uhf bands 850-950mhz version (mtx3) also available 4 parallel channels (also fully controllable via s erial port) transmit power: +10dbm (10mw) supply range: 3.1 ? 15v (will operate down to 2.9v ) current consumption: 20ma @ 10mw data bit rate: 10kbps max. (standard module) serial configuration by inverted rs232 at 3v cmos l evel size: 23 x 12.5 x 7 mm evaluation platforms : nbek + matching carrier board figure 1: mtx2-434.650-10 uhf narrow band fm sub - miniature 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, 28 may 2014 mtx2
radiometrix ltd mtx2 data sheet page 2 figure 2: mtx2 block diagram
radiometrix ltd mtx2 data sheet page 3 figure 3: mtx2 footpint (top view) pin description ? mtx2 pin name function 1 rf rf output (to antenna) 2 gnd ground 3 vcc 2.9v ? 15v dc power supply (@ 10mw) 4 en/pgm transmit enable (active high) serial frequency programming / configuration 1 5 txd dc coupled input for 3v cmos logic. r in =47k 6 p1 parallel channel select 7 p0 parallel channel select lsb 8 gnd ground notes: 1. serial programming is by the application of a lo gic level inverted rs232 datastream at 9600 baud to the en/pgm pin. the unit must be fully enabled (5ms after the rising edge of the en signal) before a programming burst can be properly decoded. 2. channel select inputs have pull-ups (50k ) to 3v internal rail. do not exceed 3v logic level s on this port. do not drive pins high when unit is turned of f 3. channel select inputs are active low. if unused, allow them to remain unconnected 4. en has a 100k pulldown resistor 5. all pins are on a 2mm grid 6. in the 'off' state there are no transmit state s purii 7. the unit will operate (with marginally reduced s pecifications and lower (6-8mw) output power) from a 2.9 ? 3.0v rail. this must be well regulated and without noise or ripple, as in this state the unit' s internal regulator no longer operates, and provides no supply rejection. 8. switching time as controlled by the en pin is <5 ms, but when power is first applied to the unit the re is a 20ms long ?calibration? period before the tran smitter becomes active 9. 25mw version uses 3v3 internal rail (not 3v0), b ut is otherwise identical
radiometrix ltd mtx2 data sheet page 4 condensed specifications frequency 433mhz eu band, and 458mhz uk band other custom uhf bands frequency stability 1.5khz channel spacing 25khz, 20khz or 12.5khz (to order) number of channels 4 channels controlled by parallel port, or 256 sequ ential, or direct control of pll device via rs232 interface operating temperature -20 oc to +70 oc (storage -3 0 oc to +70 oc) spurious radiations compliant with etsi en 300 220- 3 and en 301 489-3 transmitter output power +10dbm (10mw) 1db +14dbm (25mw) version available peak deviation 3khz tx on switching time 5ms from en transition modulation type fsk (f3d) tx modulation bandwidth dc ? 5khz (3v cmos compatib le) adjacent channel tx power <-37dbm tx spurious <-45dbm (no rf output in standby) supply voltage 3.1v ? 15v (usable down to 2.9v) current 20ma @ 10mw (nominal) <3 a standby (en low or floating) inputs data (cmos/ttl compatible) size 23 x 12.5 x 7mm interface user 6 pin, 2mm pitch header rf 2pin 2mm pitch hea der recommended pcb hole size 1mm
radiometrix ltd mtx2 data sheet page 5 channel programming it is useful at this point to describe how an mtx2 defines it's operating frequency: at the heart of the device is a fractional n synthe sizer locked to a high stability vcxo. the minimum step size of this pll is (approximately) 12.4hz the data required by the pll consists of two coeffi cients: the integer and the fraction. output freque ncy relates to these values thus: output frequency (in mhz) = 6.5 x (integer + (fract ion / 2^19)) for correct operation, the component (fraction / 2^ 19) must have a value between 1 and 2 (in other wor ds, the "fraction" coefficient varies between 524288 an d 1048576) while the value of "integer" is limited by the operating frequency range of the device (422.5 to 5 25mhz) so will lie between 64 and 79 so how do you calculate it by hand ? take the frequency, divide it by 6.5 take the whole number part remaining, subtract one from it, and that's "integer" take everything right of the decimal point, add one and multiply by 524288, and that's "fraction" example : 430mhz divide by 6.5 equals 66.15384615 so "integer" = 65 and fraction = (0.15384615 +1) x 524288 = 604948 and to confirm: 6.5 x (65+(604948/524288)) does ind eed equal 430mhz (plus 3.9hz) in interface terms, these coefficients are expresse d as a 32 bit binary word (eight hexadecimal digits ) where the most significant byte comprises the integer val ue, and the remaining three bytes (24 bits) make up "fraction" when programming the mtx2, keep in mind that the un it maintains (in ram) the current values of all programmable values (current frequency, band of ope ration, rf power and frequency offset adjustments and the sequential table values) and that toggling the en pin does not erase or corrupt them. these values are only loaded from eeprom at cold st art power-up (but not when the en pin is cycled) or when the unit is commanded to execute eeprom reads by certain serial functions (such as the "@prg_00000000" command) there are no (or very few) "write a value to eeprom " commands. it is usually necessary to load the rel evant current operating ram value(s) and then issue a sui table command to write the ram value to eeprom. the mtx2 eeprom stores a set of frequency coefficie nts for each parallel channel plus a fifth set for the sequential table start. it also stores power level, frequency offset, sequential table step size and s equential channel, and the band select constant programming a value or coefficient over the serial bus over-writes the previous value and implements t his change on the pll immediately, but does not change the eeprom contents until a relevant "program eepro m" command is issued in general, the most recent stimulus received by th e unit will decide the operating frequency and mode (although if sequential mode has been selected (ser ial channel not equal to zero) a change to the para llel port or a direct frequency program command will not initiate a frequency change).
radiometrix ltd mtx2 data sheet page 6 operation modes the mtx2 has three different modes of operation: 1. parallel . by default the mtx2 operates on one of the four channels selected by the parallel input pins. at power up, or when a change of parallel input is det ected, the current frequency coefficients are loade d from the eeprom stores corresponding to parallel channel s 0-3. the parallel input consists of an inverted 2 bit binary number applied to p0/p1 (often from a 2 pole switch) 2. sequential . if a (sequential) channel is programmed over the serial port, the unit sets it's operating frequency according to this channel number, the pro grammed table start frequency and the currently programmed table step size. if the channel is set t o zero, the unit returns to default parallel operat ion. if the (sequential) channel is programmed into eepr om, the unit will default to this channel at power up the table can be considered to be a 255 entry table , starting at channel 1, with the frequency increme nting by the programmed step size for each increment in c hannel number (it can be seen that, if a 256 entry table starting with channel zero is desired then programm ing all the parallel channels to the ch0 frequency, and the sequential table start value to ch1 will achiev e this) 3. direct . whenever a frequency coefficient is programmed in to the unit, the frequency will change immediately to this new value regardless of other m odes or operation. this is the simplest and most fl exible means of controlling the unit. if a unit is set in sequential table mode (ie: chan nel value isn't zero), then direct programming cann ot be used to over-ride the selected channel (executing a n @prg_iiffffff will just set up a set of frequency coefficients ready to be written to rom. it won't c hange the actual operating frequency) serial interface commands mtx2 serial interface consists of an inverted rs232 datastream (9600 baud, 1+8+1, no parity) applied t o the en pin (the idle state of the interface will turn t he transmitter on) every command string starts with the phrase "@prg_" the characters in a command string must not be sepa rated by more than 5ms (so typing individual characters on a terminal keyboard will not work), b ut a pause of at least 10ms is required between commands (more following a burn_rom command. in thi s case a much longer idle period, of 50ms at least, is needed for eeprom programming) frequency setting commands commands function @prg_iiffffff sets the current (temporary) fre quency iiffffff is an 8 digit hexadecimal number (4 bytes) : ii is the 1 byte "integer" coefficient ffffff is the 3 byte "fraction" coefficient frequency (in mhz) = 6.5 x integer + 6.5 x (fractio n/2^19) the component (fraction/2^19) must be in the range 1-2 @prg_burn_ch0 write current frequency into cha nnel 0 eeprom @prg_burn_ch1 write current frequency into cha nnel 1 eeprom @prg_burn_ch2 write current frequency into cha nnel 2 eeprom @prg_burn_ch3 write current frequency into cha nnel 3 eeprom (these functions do not program band/power/offset v alues)
radiometrix ltd mtx2 data sheet page 7 sequential table operations commands function @prg_0001zzzz program zzzz as the sequential table step size @prg_burn_chc sets the current frequency coef ficients as the sequential table start frequency and programs this, and the step size, int o eeprom @prg_000000 cc set cc as sequential channel nu mber @prg_0000ff cc set cc as above and program it into eeprom @prg_0000aa nn set a maximum channel limit (n n) for the table setting channel to zero disables sequential table o peration serial port on/off commands commands function @prg_power 00 will turn the unit completely off (this command does not also zero the power setting variable) @prg_power ff unit is turned back on (or by cycling the en pin) if the unit is in "software off" it will still deco de valid commands (although an invalid string will be interpreted as an en pin cycle, and the unit will turn on). the parallel port will also be read, although not a cted upon until the unit is re-activated @prg_00000000 will cause the unit to re-set it self to the values currently stored in eeprom (just like what happens at power-up). this also zer os the stored serial channel and does a parallel channel read note : the characters in a command string must not be se parated by more than 5ms, but a pause of at least 10ms is required between commands (more follo wing a burn_rom command a much longer idle period, of 50ms at least, is needed) the complete list of the mtx2 commands commands function @prg_iiffffff sets the current operating frequency (in ram) (ii is never zero, ffffff is in the range 080000 - 0fffff) @prg_0001zzzz will program zzzz as the sequen tial table step size @prg_00000000 eeprom values to ram (cold star t-up) and channel = 0 @prg_000000cc will set cc as sequential chann el number (in ram) @prg_0000ffcc will set cc as above and progra m it into eeprom @prg_0000aann will set (nn) as maximum channe l limit for the table and program it into eeprom @prg_burn_ch0 write current frequency into cha nnel 0 eeprom @prg_burn_ch1 write current frequency into cha nnel 1 eeprom @prg_burn_ch2 write current frequency into cha nnel 2 eeprom @prg_burn_ch3 write current frequency into cha nnel 3 eeprom @prg_burn_chf write band, power and offset int o eeprom @prg_burn_chc set table start to current freq uency and write both this and the current step size values to eeprom @prg_power pp sets power variable @prg_trim+ aa set a positive frequency trim of fset @prg_trim- aa set a negative frequency trim of fset @prg_band# bb set band divider code (bb is o8, 0a,0b or 0d) @prg_power 00 turn unit off @prg_power ff turn unit back on
radiometrix ltd mtx2 data sheet page 8 antenna requirements three types of integral antenna are recommended and approved for use with the module: a) whip this is a wire, rod ,pcb track or combination conn ected directly to rf pin of the module. optimum total length is 16.4cm (1/4 wave @ 433mhz). keep the open circuit (hot) end well away from metal components to prevent serious de-tu ning. whips are ground plane sensitive and will benefit from internal 1/4 wave e arthed radial(s) if the product is small and plastic cased b) helical wire coil, connected directly to rf pin, open circu it at other end. this antenna is very efficient given it?s small size (20mm x 4mm dia.). the helical is a high q antenna, trim the wire length or expand the coil for optimum results. the helical de-tunes badly with proximity to other conductive objects. c) loop a loop of pcb track tuned by a fixed or variable c apacitor to ground at the 'hot' end and fed from rf pin at a point 20% from the ground end. loo ps have high immunity to proximity de- tuning. feature a b c whip helical loop ultimate performance *** ** * easy of design set-up *** ** * size * *** ** immunity proximity effects * ** *** range open ground to similar antenna 500m 200 100 the antenna choice and position directly controls t he system range. keep it clear of other metal in th e system, particularly the 'hot' end. the best positi on by far, is sticking out the top of the product. this is often not desirable for practical/ergonomic reasons thus a compromise may need to be reached. if an internal antenna must be used, try to keep it away from othe r metal components, particularly large ones like transformers, batteries and pcb tracks/earth plane. the space around the antenna is as important as th e antenna itself. 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 7: antenna types
radiometrix ltd mtx2 data sheet page 9 ordering information standard frequency setup for 4 channel mtx radios u ses these default channels: part no. frequency MTX2-433-10 ch0: 434.650, ch1: 434.075, ch2: 434.50 0, ch3: 434.275mhz mtx2-458-10 ch0: 458.700, ch1: 458.525, ch2: 458.6 00, ch3: 458.750mhz mtx3-869-10-sal ch0: 869.2125, ch1-3: 869.2375mhz (for social alarm use) alternatively, the mtx2 can be supplied as a single frequency module with factory set channel (like th e ntx2b or similar unit). in this case all channels a re supplied programmed to the same frequency. part no. frequency mtx2-434.650-10 ch0 - 3: 434.650mhz mtx2-434.075-10 ch0 - 3: 434.075mhz mtx2-458.700-10 ch0 - 3: 458.700mhz note : also available on the other uhf band frequencies, including 869 or 915mhz (mtx3).
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/radiocomms/ifi/ 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
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