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BiM-418-40

器件型号:BiM-418-40
文件大小:690.24KB,共0页
厂商名称:RADIOMETRIX [Radiometrix Ltd]
厂商官网:http://www.radiometrix.com
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BiM-418-40器件文档内容

                                 Radiometrix

                                 Hartcran House, Gibbs Couch, Watford, WD19 5EZ, England

Issue 3, 13 July 2001            Tel: +44 (0) 20 8428 1220, Fax: +44 (0) 20 8428 1221     BiM-UHF

Low Power UHF Data Transceiver Module

UK Version - BiM-418-40
Euro Version - BiM-433-40

The BiM-418-40 and BiM-433-40 are
miniature UHF radio modules
capable of half duplex data
transmission at speeds upto 40 Kbit/s
over distances of 30 metres "in-
building" and 120 metres open ground

                                                                                          BiM-UHF transceiver

Features

          Miniature PCB Mounting module
          Licence Exempt operation in UK on 418MHz, MPT 1340 (BiM-418-40)
          ETS 300-220 tested for European use on 433.92 MHz (BiM-433-40)
          SAW controlled FM transmission at -6dBm ERP.
          Double conversion Superhet receiver
          -107dBm receive sensitivity
          Single 4.5 to 5.5V supply < 15mA (tx or rx)
          Half duplex data at upto 40 kbit/s
          Reliable 30 metre in-building range
          Direct interface to 5V CMOS logic
          Fast 1ms power up enable for duty cycle power saving
          On board data slicer, supply switches and antenna change over.

The module integrates a low power UHF FM transmitter and matching superhet receiver together with
the data recovery and TX/RX change over circuits to provide a low cost solution to implementing a Bi-
directional short range radio data link. The high data rates (upto 40kbit/s) and fast TX/RX changeover
(<1ms) make the BiM transceiver ideal for high integrity one to one links / multi-node packet switch
networks. Rapid RX power up ( <1ms ) allows effective duty cycle power saving of the receiver for
battery powered applications

(e.g. 15A average @ 1ms ON : 1sec OFF).

Typical applications :-

Medium speed computer networks
Laptop > PC > printer links
High integrity wireless Fire / Security alarms
Building environment control / monitoring
Vehicle alarm systems
Remote meter reading
Authorisation / Access control

Radiometrix Ltd, BiM Data Sheet                                                           page 1
figure 1: block diagram

  figure 2: mechanical dimensions  page 2

Radiometrix Ltd, BiM Data Sheet
Pin Description

pin 1 & 3  RF GND                These pins should be connected to the ground plane against
                                 which the integral antenna radiates . Internally connected to
                                 pins 9,10,18 .

pin 2      Antenna               RF input / RF output for connection to an integral antenna. It
                                 has a nominal RF impedance of 50 and is capacitively
                                 isolated from the internal circuit.

pin 9, 10, 18 Vss                0V connection for the modulation and supply

pin 11     CD                    Carrier Detect - When the receiver is enabled, a low indicates a
                                 signal above the detection threshold is being received. The

                                 output is high impedance (50k) and should only be used to drive a
                                 CMOS logic input.

pin 12     RXD                   This digital output from the internal data slicer is a squared
                                 version of the signal on pin 13 (AF). This signal is used to
                                 drive external digital decoders, it is true data (i.e. as fed to the

                                 transmitters data input). The 10k output impedance is
                                 suitable for driving CMOS logic.
                                 Note: this output contain squared noise when no signal is
                                 being received.

pin 13     RX Audio              This is the FM demodulator output. It has a standing DC
                                 bias of approximately 1.5V and may be used to drive
                                 analogue data decoders such as modems or DTMF decoders.

                                 Output impedance is 10k. Signal level approx. 0.4V pk to
                                 pk. We recommend this signal always be available on a
                                 convenient test point for diagnostic purposes.
                                 Note: unlike the RXD output which is always true data, this
                                 output is true data on the BiM-418 and inverted on
                                 the BiM-433.

pin 14     TXD                   Should be driven directly by a CMOS logic device running on
                                 the same supply voltage as the module. Analogue drive may
                                 be used but must not drive this input above Vcc or below
                                 0V. This input should be held at <0.5V when the TX is
                                 not selected to prevent current leak (see block diagram).

Radiometrix Ltd, BiM Data Sheet                                                                        page 3
pin 15     TX select             Active low transmit / receive selects with 10k internal
pin 16     RX select             pull-ups. They may be driven by open collector or CMOS logic

All states are valid.

Pin 15 TX  Pin 16 RX             function
1          1                     power down (<1A)
1          0                     receiver enabled
0          1                     transmitter enabled
0          0                     self test loop back

Note - loop test is at reduced TX power.

pin 17     Vcc                   positive supply, supply voltages from 4.5V to 5.5V may be used. Reverse

                                 polarity will destroy the module. Supply is internally decoupled.

                                 Maximum ripple content 50mV pk to pk.

figure 3: test circuit BiM-UHF

Warning:   Don't be tempted to adjust the trimmer on the module, it controls
           the receive frequency and can only be correctly set-up with an
           accurate RF signal generator.

Radiometrix Ltd, BiM Data Sheet                                                                     page 4
Performance Data

ambient temperature: 20 C
supply voltage:   + 5.0 V, unless noted otherwise

Data applies to all frequency versions, except where noted

Parameter                                      Min   Typ.   Max         Units Notes

DC parameters

Operating supply range, Vcc                    4.5   -      5.5         V    -

Supply current, transmit (40kbps version) 8          12     15          mA   -

                 Transmit (-HP version)        15    17     21          mA   -

receive                                        10    12     16          mA   -

loop test                                      -     20     25          mA   -

stand-by                                       -     -      1           A   -

RF Parameters - Transmit                       -10   -6     -3          dBm  1
Radiated power (ERP) (-40kbps version)
                                               +3    +6     +10         dBm  1
                                (-HP version)
Transmit frequency (Frf) BiM-418-40            -     418.000 -          MHz  -
Transmit frequency (Frf) BiM-433-40
Initial frequency accuracy                     -     433.920 -          MHz  -
Overall frequency accuracy
Spurious radiation                             -75   0      +75         kHz  -
FM deviation (+/-)
Distortion                                     -95   0      +95         kHz  -
Modulation response @ -3dB
                                                     meets ETS 300-220

                                               15    20     30          kHz  2

                                               -     5      10          %    3

                                               DC    -      32          kHz  -

RF Parameters - Receive

Receive frequency (Frf) BiM-418-40             -     418.000 -          MHz  -

Receive frequency (Frf) BiM-433-40             -     433.920 -          MHz  -

Receiver sensitivity                           -100  -107   -           dBm  -
AF bandwidth @ -3dB
AF output level, pin 13, pk to pk              0.1   -      22          kHz  -
Local Oscillator leakage, pin 2
IF Bandwidth                                   -     400    -           mV   -
AFC lock range (5V signal)
                                               -     -57    -           dBm  -

                                               -     200    -           kHz  -

                                               -     200    -           kHz  -

Timing                                         -     -      1           ms   -
RX select low to valid CD
RX select low to valid RXD                     -     -      3           ms   -
Transmit to Receive delay
RF input (5V) to valid CD                     -     -      1           ms   -
RF input (5V) to stable AF
                                               -     -      0.5         ms   -

                                               -     -      0.5         ms   -

Radiometrix Ltd, BiM Data Sheet                                                 page 5
Parameter                                  Min      Typ.     Max           Unit Notes

Base Band transfer function
(through a pair of transceivers)

Linear drive (4Volt pk to pk, sine)        0.1      -        17            kHz   -
AF response @ -3dB
Analogue distortion                        -        5        10            %     -

Digital drive                              -        -        40            kb/s  4
Data rate ( 50:50 )                                          2000
Time between transitions                   25       -        70            s    5
Average Mark:Space ratio                                     -
preamble duration (10101010)               30       50       -             %     6
data delay (TXD to RXD)
                                           3        -                      ms    -

                                           -        25                     s    -

Interface levels - inputs

TX & RX select,   V high                   Vcc-0.5           Vcc           V     -

                  V low                    0                 1             V     -

Source current @  V low = 0                0.5               1             mA    -

TXD               V high                   Vcc-0.5           Vcc           V     -
                  V low
                                           0                 0.5           V     -

Interface levels - outputs

RXD & CD          V high                            Vcc-0.6                V     -
                                                    0.2
(no load)         V low                                                    V     -

Notes: 1. module on 50mm square ground plane , 16cm whip antenna
          2. Standard modulation : 2kHz square wave, 0 to Vcc
          3. 1kHz, 4V pk to pk, Sinewave centred on +2.5V at pin 14 (TXD)
          4. Digital drive, 50:50 mark:space (over 4ms) data pattern.
          5. High or Low pulse.
          6. Averaged over any 4ms period

Absolute maximum ratings

Supply voltage Vcc, pin 17       -0.1 to      +6V
All input / output pins          -0.1 to      Vcc + 0.1V

Operating temperature            -20C to     +55C
                                 -40C to     +100C
Storage temperature

Radiometrix Ltd, BiM Data Sheet                                                     page 6
figure 4: signal to noise curve

figure 5: timing waveforms

Antenna requirements
Three types of integral antenna are recommended and approved for use with the BiM transceiver :

A) Helical:  Wire coil, connected directly to pin 2, open circuit at other end. This antenna is very
B) Loop,     efficient given it's small size (20mm x 4mm dia.). The helical is a high Q antenna, trim
C) Whip      the wire length or expand the coil for optimum results. The helical de-tunes badly with
             proximity to other conductive objects.

             A loop of PCB track tuned by a fixed or variable capacitor to ground at the 'hot' end and
             fed from pin 2 at a point 20% from the ground end. Loops have high immunity to
             proximity de-tuning.

             This is a wire, rod ,PCB track or combination connected directly to pin 2 of the module.
             Optimum total length is 17cm (1/4 wave @ 418MHz) Keep the open circuit (hot) end well
             away from metal components to prevent serious de-tuning. Whips are ground plane
             sensitive and will benefit from internal 1/4 wave earthed radial(s) if the product is small
             and plastic cased.

Radiometrix Ltd, BiM Data Sheet  page 7
figure 6: Antenna configurations

Antenna selection chart                A        B     C
                                       helical  loop  whip
Ultimate performance                  **       *     ***
Easy of design set-up                 **       *     ***
Size                                  ***      **    *
Immunity proximity effects            **       ***   *
Range open ground to similar antenna  80m      50m   120m

The antenna choice and position directly controls the system range. Keep it clear of other metal in the
system, particularly the 'hot' end. The best position 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 other metal components, particularly large ones
like transformers, batteries and PCB tracks/earth plane. The space around the antenna is as important
as the antenna itself.

Radiometrix Ltd, BiM Data Sheet                             page 8
Type Approval

The BiM-418-40 is type approved in the UK to MPT1340 for use in Telemetry, Telecommand and In-
Building alarm applications.

CONFORMANCE to MPT1340 REQUIRES THAT:

1. The transmitting antenna must be one of the 3 variants given in the data sheet. Antenna structures
    which yield ERP gain are not permitted.

2. The module must be directly and permanently connected to the transmitting antenna without the
    use of an external feeder. Increasing the RF power level by any means is not permitted.

3. The module must not be modified nor used outside it's specification limits.

4. The module may only be used to send digital or digitised data. Speech / music are not permitted.

5. The equipment in which the module is used must carry an inspection mark located on the outside of

the equipment and be clearly visible. The minimum dimensions of the inspection mark shall be 10 x

15 mm and the letter and figure height must be no less than 2mm. The wording shall read:                "

MPT 1340 W.T. LICENCE EXEMPT ".

6. Products intended for UK commercial application must be notified to the Radiocommunications
    Agency (RA) on form RA 249 ( Cat I), obtainable from the RA's library service, Tel: +44 (0)171 211
    0502 / 0505

OEM Manufacturers incorporating the BiM-418-F transceiver as a component part of their product are
authorised by Radiometrix Ltd to quote our type-approval.

MPT 1340 is the type approval specification issued by the RA and may be obtained from the RA's library
service on +44 (0)171 211 0502 / 0505.

Radiometrix Ltd, BiM Data Sheet                                                           page 9
                    BiM-UHF Transceiver Applications Note

Sending and Receiving Digital data

The BiM contains no data coding or decoding functions. These must be provided by the external
controller, usually a single chip microprocessor, e.g. Arizona Microsystems PIC, Motorola MC68HC05 or
similar. Alternatively a dedicated protocol controller such as CML's FX909 or Echelon's Network chips
will work well.

The Radiometrix RPC-000-SO Radio Packet Controller IC provides all the processor intensive low-level
packet formatting and data recovery functions required in a high speed bi-directional data link/network.
The RPC-418-40 and RPC-433-40 provide a self-contained UHF radio port for a host micro controller.
The board combines a BiM transceiver and a RPC packet controller. (Data available on request.)

A pair of BiM transceiver's will transmit direct serial data applied to the TXD input and reproduce
direct serial data at the RXD output of receiving BiM. The BiM may also be used with linear data e.g.
from modem IC's (see test circuit for linear biasing of TXD input).

figure 7: typical microcontroller interface

Direct Digital, TXD > RXD at 5V CMOS Levels

The data path through a pair of BiM's is AC coupled. This places 3 basic constraints that any serial code

must satisfy for reliable transfer.

1. Pulse width time              The receiver base band bandwidth and the AC coupling determines that the

                                 time, T, between any 2 consecutive transitions in the serial code must

                                 satisfy: 25s < T < 2ms

2. RX settling time              The AFC and data slicer in the receiver require at least 3ms of '10101010'
                                 preamble to be transmitted before the data at the RXD output may be
                                 considered reliable. Increasing this time to 5ms will give increased
                                 immunity to RF interference.

3. Mark/Space ratio              The data slicer in the receiver is optimised for data waveforms with 50:50
                                 Mark:Space averaged over any 4ms period. The slicer will tolerate sustained
                                 asymmetry up to 30/70 (either way), however, this will result in up to
                                 increased in pulse width distortion and a decreased noise tolerance.

Any serial data waveform satisfying the above criteria will pass reliably through a pair of BiM's.

Radiometrix Ltd, BiM Data Sheet                           page 10
figure 8: fully buffered CMOS interface - digital drive

"RS232" Serial data

It is possible to transmit "RS232" serial data directly at 4.8 to 38.4kb/s baud between a pair of BiM
transceivers in half duplex . The data must be "packetised" with no gaps between bytes. i.e. : The data
must be preceded by >3ms of preamble (55h or AAh hex) to allow the data slicer in the BiM to settle,
followed by 1 or 2 FFh bytes to allow the receive UART to lock, followed by a unique start of message
byte, (01h), then the data bytes and finally terminated by a CRC or check sum. The receiver data slicer
provides the best bit error rate performance on codes with a 50:50 mark:space average over a 4ms
period, a string of FFh or 00h is a very asymmetric code and will give poor error rates where reception is
marginal. Only 50:50 codes may be used at data rates above 20kbit/s.

We recommend 3 methods of improving mark:space ratio of serial codes, all 3 coding methods are
suitable for transmission at 40kbit/s :-

      Method 1 - Bit coding

                                 Bit rate , Max 40kbit/s , Min 250bit/s
                                 Redundancy (per bit) 100% (Bi-phase), 200% (1/3 : 2/3)

                      Each bit to be sent is divided in half, the first half is the bit to be sent and the second
                      half, it's compliment. Thus each bit has a guaranteed transition in the centre and a
                      mark:space of 50:50 . This is Bi-phase or Manchester coding and gives good results,
                      however the 100% redundancy will give a true throughput of 20kbit/s.

                      A less efficient, variation of Bi-phase is 1/3 : 2/3 bit coding. Each bit to be sent is divided
                      into 3 parts, the first 1/3 is a low, mid 1/3 is the data bit and final 1/3 is high. This code
                      is easy to decode since each bit always starts with a negative transition. This code
                      should not be sent faster than 100s per bit (10kbit/s) since the mark/space can vary for
                      33 to 67%.

Radiometrix Ltd, BiM Data Sheet  page 11
Method 2 - Byte coding

                           Bitrate , Max 40kbit/s , Min 2kbit/s
                           Redundancy (per byte) 25% (synchronous), 50% (async)

                If only a subset of the ASCII code is required (e.g. 0-9 , A-Z and a few
                control codes) then translate (via. a look up table) the required
                ASCII codes into the 8 bit codes below. These codes all have a 50:50
                mark/space when sent serially.

                Of the 256 possible 8 bit codes, 70 contain 4 ones & 4 zeros. The 68 Hex codes below
                have a 50:50 mark:space and may either be sent/received from a standard serial port
                (UART) using 1 start, 1 stop and no parity or as bytes of a synchronous code. Use for this
                subset also allows simple byte error checking on reception as all received codes must
                contain exactly 4 one's and 4 zero's.

                   17 1B 1D 1E 27 2B 2D 2E 33 35 36 39 3A 3C 47 4B 4D
                   4E 53 55 56 59 5A 5C 63 65 66 69 6A 6C 71 72 74 78
                   87 8B 8D 8E 93 95 96 99 9A 9C A3 A5 A6 A9 AA AC B1
                   B2 B4 B8 C3 C5 C6 C9 CA CC D1 D2 D4 D8 E1 E2 E4 E8

                           (note 0Fh & F0h have been omitted to minimise consecutive 0 or 1's)

                Other subsets are also possible e.g. a 10bit code has 1024 differs, 252 of which have 5
                one's and 5 zero's i.e. a 50:50 M:S ratio.

Method 3 - FEC coding

                           Bit rate , Max 40kbit/s , Min 4.8kbit/s
                           Redundancy (per byte) 100%

                Each byte is sent twice; true then it's logical compliment. e.g. even bytes are true and
                odd bytes are inverted. this preserves a 50:50 balance.

                A refinement of this simple balancing method is to increase the stagger between the true
                and the inverted data streams and add parity to each byte. Thus the decoder may
                determine the integrity of each even byte received and on a parity failure select the
                subsequent inverted odd byte. The greater the stagger the higher the immunity to
                isolated burst errors.

Radiometrix Ltd, BiM Data Sheet  page 12
Linear operation

A pair of transceivers may also be viewed as a linear analogue channel with a pass baseband of 100Hz
to 17kHz with <10% distortion. The ultimate S/N ratio being >40dB (see quieting curves v RF input).
The test circuit shows the TXD input biased for linear operation and a simple digital filter to shape the
transmit data to a raise cosine wave shape. The 22k resistor linear- biases the TXD input. The drive
voltage should be between 3.5 and 5V pk to pk to achieve full modulation (greatest S/N at receiver)

figure 9: linear drive

Raised cosine shaping may be applied externally to any serial data stream and will yield better error
performance than unshaped data at high data rates (up to 40kbit/s) for data steams with 50:50
mark:space (4ms averaging period). Several excellent modem chips (FX 589 & FX 909) are available for
Consumer Microcircuits Ltd (CML Tel 44 1376 513833). These chips employ GMSK (shaped data and
matched receive filters) and enable operation up to 40kbit/s.

figure 10: raised cosine generator

Digitised analogue data

Linear operation of BiM transceivers will allow direct transfer of analogue data, however in many
applications the distortion and low frequency roll off are too high (e.g. bio-medical data such as ECG).
The use of delta modulation is an excellent solution for analogue data in the range 1Hz up to 4KHz with
less than 1% distortion. A number of propitiatory IC's
such as Motorola's MC3517/8 provide CVSD Delta mod/demod on a single chip.

Where the signal bandwidth extends down to DC , such as strain gauges, level sensing, load cells etc.
then V-F / F-V chips (such as Nat Semi LM331) provide a simple means of digitising.

Packet data                      page 13

Radiometrix Ltd, BiM Data Sheet
In general, data to be sent via a radio link is formed into a serial "packet" of the form :-

          Preamble - Control - Address - Data - CRC

Where: Preamble:  This is mandatory for the receiver in the BiM to stabilise. The BiM will
                  be stable after 3ms. Additional preamble time may be desired for
                  decoder bit sync., software carrier detection or receiver wake up.

Control:          The minimum requirement is a single bit or unique bit pattern to
                  indicate the start of message (frame sync.). Additionally, decoder
                  information is often placed here such as: packet count, byte count, flow
                  control bits (e.g. ACK, repeat count), repeater control, scrambler
                  information etc.

Address:          This information is used for identification purposes and would at least
                  contain a 16/24 bit source address, additionally - destination address,
                  site / system code , unit number and repeater address's may be placed
                  here.

Data:             User data , generally limited to 256 bytes of less (very long packets
                  should be avoided to minimise repeat overheads on CRC failure and
                  channel hogging).

CRC:              16/24 Bit CRC or Checksum of control-address-data fields used by the
                  decoder to verify the integrity of the packet.

The exact makeup of the packet depends upon the system requirements and may involve some complex
air-traffic density statistics to optimise through-put in large networked systems.

Networks

BiM's may be used in many different configurations from simple pair's to multi-node random access
networks. The BiM is a single frequency device thus in a multi node system the signalling protocol must
use Time Division Multiple Access. In a TDMA network only one transmitter may be on at a time,
"clash" occurs when two or more transmitters are on at the same time and will often cause data loss at
the receivers. TDMA networks may be configured in several ways - Synchronous (time slots), Polling
(master-slave) or Random access (async packet switching e.g. X25). Networked BiM's allow several
techniques for range / reliability enhancement:

Store and forward Repeaters: If the operating protocol of the network is designed to
                                           allow data path control then data may be routed "via"
                                           intermediate nodes. The inclusion of a repeating
                                           function in the network protocol either via dedicated
                                           repeater/router nodes or simply utilising existing
                                           nodes allows limitless network expansion.

Spacial Diversity:               In buildings multi-path signals create null spots in the
                                 coverage pattern as a result of signal cancellation. In
                                 master-slave networks it is cost effective to provide 2
                                 BiM's with separate antenna at the master station.
                                 The null spot patterns will be different for the two
                                 BiM's . This technique 'fills in' the null spots, i.e. a
                                 handshake failure on the first BiM due to a signal null
                                 is likely to succeed on the 2nd BiM.

Radiometrix Ltd, BiM Data Sheet                                                                   page 14
Receiver Battery Saving

In many applications the receiver need not be always waiting for a signal (i.e. drawing 15mA). Often it
is only required to turn the RX on after a transmission to receive handshake data , thereafter it may be
deselected (i.e. <1A leakage current).

In applications where a receiver needs to respond to a call, duty cycle power saving is very effective. For
example selecting the receiver 3 times a second for 1ms and sampling the CD output for the presence of
a signal will give an average current drain of < 50A. In this example a 700ms preamble "wake up"
would be used.

Interface logic

The logic control / data lines in and out of the BiM all have 10k series EMC isolation resistors internal
to the BiM (see BiM block diagram). We recommend that RXD and CD outputs be used only to drive
CMOS logic inputs and no more than 5 cm of PCB track. Care should also be taken in the routing of the
RXD , TXD , CD & AF tracking to minimise the cross talk between these high impedance lines. In some
applications it is desirable to mute the continuos noise output on the RXD line when no signal is
present, simple CMOS logic gating with the CD signal may be desirable.

There is a dc path of 20 k from the TXD input to the internal switched TX supply.(see block diagram),
it is desirable to hold TXD low whilst TX select is high (i.e. when not transmitting data).

The CD output is designed to be fast acting (< 1 ms), and can under conditions of weak signal or
interference exhibit fast spurious pulses. It can be beneficial to drive a Schmitt trigger CMOS gate with
this output and to include an additional R-C time constant between the CD output and the Schmitt
input gate. The R should be 100 k or greater and the additional time constant delay must be allowed
for in the control software (i.e. preamble times etc.).

Signal Propagation

Three predominant effects are observed in the propagation of short range VHF / UHF signals in and
around obstacles :-

1. Signal reflection:  This gives rise to multiple paths between the transmitter
                       and the receiver. Since these paths will be of different lengths, the
                       arriving signals will have differing phases and strengths leading
                       to signal cancellation at specific points in space. i.e. null points are
                       observed. These nulls are physically small i.e. moving either the
                       transmitter or receiver a few centimetres will be enough to take
                       the signal out of the null. They are more frequent in situations of
                       weak signal and where lots of large metal items are present, they
                       are totally absent in open ground situations.

2. Signal shadowing:   This occurs behind large sheets of metal e.g. trucks, foil backed
                       plasterboard , steel reinforced floors etc. In such areas, signals are
                       received predominantly by reflection from other objects. The
                       shadow areas are of similar dimensions to the shielding object and
                       show as areas of weaker average signal level with
                       an increased occurrence of nulls due to multi path (see 1. above).

3. Signal absorption: Principally observed when signals pass through thick damp stone
                                walls, the effects are similar to 2. above but there is less reflected
                                signal.

Radiometrix Ltd, BiM Data Sheet                                                                         page 15
PCB Layout and design notes:

Leave 1mm all round module (i.e. PCB footprint area of 25x35mm)
PCB holes - 1.2mm or socket strips
Keep AF track away from RXD & TXD - to avoid cross talk.
Put a test point on the AF pin for simple radio checking with a scope.
Ground plane all unused PCB area around and under module.
Position module and antenna as far from high speed logic and SMPS as possible
Microprocessors with external data/address busses ALWAYS cause interference.
Provide LED status lights on TX, RX & CD (direct or by plug on test PCB)
For complex networks - provide software test routines for :-continuous RX, continuous TX, loop test,

    Simple master / slave "ping-pong".
The BiM-can (fig. 11) is available and may be used for shielding to achieve an optimal radio

    performance

figure 11: BiM-can layout

figure 12: hole pattern BiM-UHF + BiM-can

                All Radiometrix's products are designed and manufactured in England.

Radiometrix Ltd, BiM Data Sheet                                                       page 16
                  Radiometrix Ltd

                           Hartcran House
                             Gibbs Couch
                                Watford
                              WD19 5EZ
                              ENGLAND

                      Tel: +44 (0)20 8428 1220
                     Fax: +44 (0)20 8428 1221
                      info@radiometrix.co.uk
                      www.radiometrix.co.uk

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 Radiocommunications Agency (RA) web site:

         http://www.radio.gov.uk/topics/conformity/conform-index.htm

The Library and Information Service       European Radiocommunications Office (ERO)
The Radiocommunications Agency            Midtermolen 1
Wyndham House                             DK 2100 Copenhagen
189 Marsh Wall                            Denmark
London                                    Tel. +45 35250300
United Kingdom                            Fax +45 35250330
E14 9SX                                   ero@ero.dk
Tel: +44 (0)20 7211 0502/0505             www.ero.dk
Fax: +44 (0)20 7211 0507
library@ra.gsi.gov.uk
For further information on radio matters
contact the Agency's 24 Hour Telephone
Enquiry Point: +44 (0)20 7211 0211
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