Radiometrix BIM3B 869mhz wide band fm radio transceiver Datasheet

W
E
N
Radiometrix
Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England
24 April 2007
BiM3B
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233
869MHz Wide Band FM radio transceiver
The BiM3B radio transceiver module is an
enhanced high power replacement for the
European version BiM3B-869-64.
Two frequency variants are available in the
European unlicensed band, one with 5mW
RF power with no duty cycle restriction
other with 25mW RF power with 1% duty
cycle restriction.
Features
Fig. 1: BiM3B-869.85-64
Complies with European harmonised standards EN 300 220 and EN 301 489
869.85MHz 5mW 100% duty cycle or 868.30MHz 25mW 1% duty cycle
RF power output
+14dBm (25mW) on 868.30MHz
+7dBm (5mW) on 869.85MHz
Data rates up to 64kbps
Crystal controlled PLL FM circuitry for both Tx and Rx
SAW front end filter and full screening
Receiver Sensitivity:
-101dBm for 1ppm BER (64kbps)
-104dBm for 1ppm BER (10kbps)
Supply: 2.9V - 16V @ 35mA Tx (25mW), 17mA TX (5mW), 11mA Rx
Usable range up to 300 metres external, 75 metres in building
SAW front end filter and full screening
RSSI (standard) or carrier detect option
Analogue and digital baseband
Low profile with small footprint
33 x 23 x 5mm
Applications
PDAs, organisers and laptops
Handheld terminals
EPOS equipment, barcode scanners, belt clip printers
Data loggers
Audience response systems
In-building environmental monitoring and control
Security and fire alarms
Restaurant ordering systems
Vehicle data up/download
Radiometrix Ltd, BiM3B Data Sheet
page 1
Functional overview
The transmit section of the BiM3B consists of a frequency modulated crystal locked PLL feeding a
buffer amplifier and RF filter. A Tx select line controls operation. The transmitter achieves full RF
output typically within 1ms of this line being pulled low. Modulation is applied at the TXD input and
may be either a serial digital stream toggling between 0V and 3V (digital drive) or a high level analogue
waveform with the same peak limits (linear drive). Modulation shaping is performed internally by a 2nd
order lowpass filter, which minimises spectral spreading. The RF output is filtered to ensure compliance
with the appropriate regulations and fed via a Tx/Rx changeover switch to the antenna pin.
The receive section is a single conversion FM superhet with an IF of 10.7MHz. A SAW bandpass filter in
the receiver front-end provides image rejection and suppression of other unwanted out-of-band signals.
Like the transmitter, the receiver is controlled by its own active low RX select line. A post-detection
lowpass filter establishes the signal bandwidth and ensures clean operation of the subsequent adaptive
data slicer. The slicer is optimised for balanced data such as bi-phase code. The standard module
features a received signal strength (RSSI) output with 60dB of range. A version of BiM3B featuring a
fast acting Carrier Detect (CD) output on the same RSSI pin is also available. The CD output will
indicate the presence of any RF signals on the carrier frequency.
matching
& lpf
PA
VCO
÷ 64
φ
Loop
Filter
Antenna
÷ 32
Tx/Rx switch
VCO
φ
ref
osc
35kHz
LPF
ref
osc
TXD
Vcc
2.9 - 16V
Regulator
& Tx/Rx
logic
Tx select
Rx select
Loop
Filter
RSSI/CD
preamp
869MHz
BPF
IF Amp
Demod
Mixer
LPF
data
slicer
RXD
10.7MHz
AF
Pin description
Fig. 2: Block diagram
RF GND
pins 1 & 3
RF ground pins, internally connected to the module screen and to pins 5, 9, 10 & 18 (0V). These pins
should be connected directly to the RF return path (e.g. coax braid, main PCB ground plane etc).
Antenna
pin 2
50Ω RF connection to the antenna, DC-isolated. See pages 7 & 8 for details of suitable antennas and
feeds.
0V (GND)
pins 5, 9, 10 & 18
Supply ground connection and screen.
RSSI
pin 11
Received Signal Strength Indicator with 60dB range, operational when Rx is enabled. Output voltage
nominally 0.15 - 0.40Vdc (no signal), 1.40Vdc (maximum). See page.6 for typical characteristics.
CD
pin 11
Carrier Detect - When the receiver is enabled, a low indicates a signal above the detection threshold is
being received. The output is high impedance (50kΩ) and should only be used to drive a CMOS logic
input.
Radiometrix Ltd, BiM3B Data Sheet
page 2
RXD
pin 12
Digital output from internal data slicer. The output is a squared version of the signal on pin 13 (AF) and
may be used to drive a decoder directly. The data is true data, i.e. as fed to the transmitter. Output is
“open-collector” format with internal 10kΩ pullup to Vcc (pin 17).
AF
pin 13
Buffered & filtered analogue output from FM demodulator. Standing DC bias of 1V approx. Useful for
test purposes or for driving external decoders. External load should be >10kΩ // <100pF
TXD
pin 14
This DC-coupled transmitter modulation input will accept either serial digital data or high level linear
signals. Drive signal must be limited to 0V min, 3V max. See page 6 for suggested drive methods. Input
impedance >50kΩ.
TX select
pin 15
Active-low Transmit select. 47kΩ internal pull-up to Vcc.
RX select
pin 16
Active-low Receive select. 47kΩ internal pull-up to Vcc.
Pin 15 TX
Pin 16 RX
Function
1
1
1
0
Power down (<10µA)
Receiver enabled
0
1
Transmitter enabled
0
0
Self test loop-back*
* Loop-back allows the receiver to monitor the transmitted signal. Under these conditions the Tx
radiated signal level will be reduced to approximately -10dBm).
Vcc
pin 17
DC +ve supply pin. +2.9 to +16.0 volts @ <17mA (@ 5mW). The supply should be clean, <20mVP-P ripple.
side view (through can)
side view (with can)
5 mm
top view (without can)
RF GND 1
Antenna 2
RF GND 3
4
5
No pin
6
7
8
0V 9
18 0V
17 Vcc
16 RX SELECT
15 TX SELECT
14 TXD
13 AF
12 RXD
11 RSSI/CD
10 0V
30.48 mm
33 mm
23 mm
recommended PCB hole size: 1.2 mm
module footprint size: 25 x 32 mm
pin pitch: 2.54 mm (0.1")
pins 4, 5, 6, 7 & 8 are not fitted
Fig. 3: Physical dimensions
Radiometrix Ltd, BiM3B Data Sheet
page 3
Absolute maximum ratings
Exceeding the values below may cause permanent damage to the module.
Operating temperature
Storage temperature
-20°C to +70°C
-40°C to +100°C
Vcc (pin 17)
TX, RX select (pins 15, 16)
All other pins
Antenna (pin 2)
-0.3V to +16V
-9V to +16V
-0.3V to +Vcc
±50V DC, +10dBm RF
Performance specifications
Figures apply to standard version @ Vcc=3.0V, temperature +20°C, unless stated.
General
Supply voltage
Tx supply current
Tx supply current
Rx supply current
RF centre frequency
RF centre frequency
Antenna port impedance
TX & RX select: high (deselect)
low (select)
Internal select pull-ups
Balanced code bit rate
Balanced code bit rate
Transmitter section
RF power output @ 869.85MHz
RF power output @ 868.30MHz
TX harmonics/spurious emission
Initial centre frequency accuracy
FM deviation
Modulation bandwidth
Modulation distortion
TX spectral bandwidth @-40dBc
TXD input level: high
low
TX power up to full RF
Receiver section
RF sensitivity, 10dB S/N
RF sensitivity, 1ppm BER
RF sensitivity, 10dB S/N
RF sensitivity, 1ppm BER
RSSI output, no signal
RSSI output, max indication
RSSI range
IF bandwidth
Image rejection (fRF-21.4MHz)
IF rejection (10.7MHz)
Local osc. leakage, conducted
Baseband bandwidth @ -3dB
Baseband bandwidth @ -3dB
AF output signal level
Radiometrix Ltd, BiM3B Data Sheet
pin
17
17
17
17
2
15, 16
15, 16
15,16
12
12
min.
2.9
10
Vcc-0.5
0
-
typ.
3.0
14
32
11
869.85
868.30
50
47
-
max.
16
17
Vcc
0.5
64
10
units
V
mA
mA
mA
MHz
MHz
Ω
V
V
kΩ
kbps
kbps
pin
2
2
2
2
14
14
2
pin
2, 13
2, 12
2, 13
2, 12
11
11
2, 11
2
2
2
13
13
13
notes
min.
-10
±20
0
2.8
0
-
typ.
+7
+14
-55
0
±27
5
1
max.
-40
+10
±35
35
10
250
3.0
0.2
1.5
units
dBm
dBm
dBm
kHz
kHz
kHz
%
kHz
V
V
ms
notes
100% duty cycle
1% duty cycle
min.
0.15
40
100
0
0
200
typ.
-106
-100
-113
-107
0.25
1.15
60
180
50
-117
300
max.
0.4
1.40
-110
50
7.8
400
units
dBm
dBm
dBm
dBm
V
V
dB
kHz
dB
dB
dBm
kHz
kHz
mV p-p
notes
-64 version
-64 version
-10 version
-10 version
Note 1
5mW version
25mW version
Tx or Rx
To Vcc (pin 17)
-64 version
-10 version
Peak
@ -3db
Note 2
worst case
Note 3
Note 3
Note 4
-50dBm RF input
-64 version
-10 version
Note 5
page 4
Receiver section
DC offset on AF output
Distortion on recovered AF
Ultimate (S+N)/N
Load capacitance, AF & RXD
pin
13
13
13
12, 13
min.
0.3
-
typ.
1.0
1
40
-
max.
1.75
10
100
units
V
%
dB
pF
Dynamic Timing
Rx power up with signal present
Power up to valid RSSI, tPU-RSSI
Power up to valid CD, tPU-CD
Power up to stable data, tPU-data
Power up to stable data, tPU-data
11
11
12
12
-
1
1.5
5
10
10
30
ms
ms
ms
ms
-64 version
-10 version
Signal applied with Rx on
RSSI response time (rise/fall)
Signal to stable data, tsig-data
Signal to stable data, tsig-data
11
12
12
-
100
5
5
10
30
µs
ms
ms
-64 version
-10 version
Time between data transitions
Time between data transitions
Averaged code mark:space
14
14
14
15.6
0.1
20
50
1500
15
80
µs
ms
%
-64 version
-10 version
Note 8
Note:
notes
Note 6
Note 7
-50dBm RF input
1. Increases at high RF input level (>-20dBm)
2. See page 6 for further details
3. For specified FM deviation
4. Tx select low > full RF output
5. ±30kHz FM deviation
6. Min/max at ±50kHz offset
7. Max at ±50kHz offset
8. Average, at max. data rate
Application Information
Modulation formats and range extension
The module will produce the specified FM deviation with a 2-level digital input to TXD which toggles
between 0V and 3V. Reducing the amplitude of the data input from this value (usually as a result of
reducing the supply voltage) reduces the transmitted FM deviation, typically to ±20-22kHz minimum at
2.7V. The receiver will cope with this quite happily and no significant degradation of link performance
should be observed.
TXD is normally driven directly by logic levels but will also accept analogue drive, e.g. 2-tone signalling.
In this case it is recommended that TXD (pin 14) should be DC-biased to 1.5V with the modulation ACcoupled and limited to a maximum of 3V peak-to-peak. The instantaneous modulation voltage must not
swing below 0V or above 3V at any time if waveform distortion and excessive FM deviation is to be
avoided – use a resistive potential divider and/or level shifter to accomplish this if necessary. The
varactor modulator in the transmitter introduces some 2nd harmonic distortion which may be reduced if
necessary by predistortion of the analogue waveform.
At the other end of the link the AF output (pin 13) can be used to drive an external decoder directly.
Although the module baseband response extends down to DC, data formats containing a DC component
are unsuitable and should not be used. This is because frequency errors and drifts between the
transmitter and receiver occur in normal operation resulting in DC offset errors on the AF output.
The time constant of the adaptive data slicer in the BiM3B is set at a reasonable compromise to allow
the use of low code speeds where necessary whilst keeping settling times acceptably fast for batteryeconomised operation. RXD output on pin 12 is “true” sense, i.e. as originally fed to the transmitter.
Radiometrix Ltd, BiM3B Data Sheet
page 5
In applications such as longer range fixed links where data speed is not of primary importance, a
significant increase in range can be obtained by using the slowest possible data rate together with
filtering to reduce the receiver bandwidth to the minimum necessary. In these circumstances the AF
output can be used to drive an external filter and data slicer. The AF output waveform on pin 13 is in
the same sense as that originally fed to the transmitter, i.e. no inversion takes place.
Received Signal Strength Indicator (RSSI)
The BiM3B receiver 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 11 of the module has a standing DC bias in the region of 0.25V with no signal, rising
to around 1.15V at maximum indication (RF input levels of -50dBm and above). For any given RF input
level, absolute RSSI voltage is likely to vary somewhat between individual units - please refer to
specifications table on p4.
The RSSI output source impedance is high (~50kΩ) and external loading should therefore be kept to a
minimum.
Typical RSSI characteristic is shown below (this is for indicative purposes only and is not a guarantee of
actual RSSI characteristics):
Fig.4: Typical RSSI response curve
To ensure a reasonably fast response the RSSI has limited internal decoupling of 1nF to ground. This
may result in a small amount of audio ripple on the DC output at pin 11 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 11 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.
Radiometrix Ltd, BiM3B Data Sheet
page 6
Expected range
Predicting the range obtainable in any given situation is notoriously difficult since there are many
factors involved. The main ones to consider are as follows:
Type and location of antennas in use (see below)
Type of terrain and degree of obstruction of the link path
Sources of interference affecting the receiver
“Dead” spots caused by signal reflections from nearby conductive objects
Data rate and degree of filtering employed (see page 5)
Assuming the maximum 64kb/s data rate and ¼-wave whip antennas on both transmitter (@ 5mW) and
receiver, the following ranges may be used as a rough guide only:
Cluttered/obstructed environment, e.g. inside a building
Open, relatively unobstructed environment
:
:
50-75m
200-300m
It must be stressed, however, that range could be much greater or much less than these figures. Range
tests should always be performed before assuming that a particular range can be achieved in any given
application.
Antenna considerations and options
The choice and positioning of transmitter and receiver 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 user in choosing the most effective arrangement for a given application.
Nearby conducting objects such as a PCB or battery can cause detuning or screening of the antenna
which severely reduces efficiency. Ideally the antenna should stick out from the top of the product and
be entirely in the clear, however this is often not desirable for practical or ergonomic reasons and a
compromise may need to be reached. If an internal antenna must be used, try to keep it away from
other metal components and pay particular attention to the “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.
Microprocessors and microcontrollers tend to radiate significant amounts of radio frequency hash,
which can cause desensitisation of the receiver if its antenna is in close proximity. 868MHz band is
generally less prone to this effect than lower frequencies, but problems can still arise. Things become
worse as logic speeds increase, because fast logic edges are capable of generating harmonics across the
UHF range which are then radiated effectively by the PCB tracking. In extreme cases system range can
be reduced by a factor of 3 or more. To minimise any adverse effects, situate the antenna and module as
far as possible from any such circuitry and keep PCB track lengths to the minimum possible. A ground
plane can be highly effective in cutting radiated interference and its use is strongly recommended.
A simple test for interference is to monitor the receiver RSSI output voltage, which should be the same
regardless of whether the microcontroller or other logic circuitry is running or in reset.
Two types of antenna are recommended for use with the BiM3B:
Whip (¼-wave). This consists simply of a piece of wire or rod connected to the module at one end. The
lengths given below are from module pin to antenna tip including any interconnecting wire or tracking
(but not including any 50Ω coax or microstrip connection). This antenna is simple, cheap, easy to set up
and performs well. It is especially effective when used with a ground plane, which in practice is often
provided by the main PCB or by a metal case.
Base-loaded whip. In applications where space is at a premium a shortened whip may be used, tuned
by means of a coil inserted at the base. This coil may be air-wound for maximum efficiency, or a small
SMT inductor can be used. The value must be empirically chosen to tune the particular length of whip
for best results “in situ”, making this antenna more difficult to set up. Radiated power will generally be
slightly less than that obtained from a ¼-wave whip.
Radiometrix Ltd, BiM3B Data Sheet
page 7
L
RF
wire, rod, PCB track
or a combination of these
L (mm) = 71250 / freq(MHz)
RF
shortened wire, rod, PCB track etc.
with loading coil.
SMT inductor may be used if reqd.
1/4-wave whip
Base-loaded whip
Fig. 5: Antenna configurations
Other types of antennas are feasible but tend to have drawbacks at these frequencies. Helical and tuned
loop antennas are both very compact but tricky to set up, and can be impractical at 868MHz because of
their very small size. Microstrip patch antennas are relatively large in area, directional, and have gain.
Note: Where the specified antennas are mounted on the PCB and/or in close proximity to metalwork
(module casing, components, PCB tracking etc), the antenna radiation pattern may be seriously affected.
Radiated power may be significantly increased in some directions (sometimes by as much as 10dB) and
correspondingly reduced in others. This may adversely affect system performance where good all-round
coverage is desired.
Care should also be taken to ensure that this effect does not increase the radiated power in any direction
beyond that allowed by type approval regulations. Where this occurs the antenna may need to be
relocated. In extreme cases a resistive attenuator of appropriate value may be required between the
module and antenna.
Radiometrix Ltd, BiM3B Data Sheet
page 8
Type Approval requirements: Europe
The modules comply with the requirements of the R&TTE Directive (including standards EN 300 220-3
and EN 301 489-3) when used in accordance with the information contained herein. The following
provisos apply:
1) The modules must not be modified or used outside their specification limits.
2) The modules may only be used to transfer digital or digitised data. Analogue speech and/or
music are not permitted.
3) The equipment in which the BiM3B is used must carry all necessary external labelling to meet
the requirements of the R&TTE directive.
4) The BiM3B has not been tested with antennas having gains greater than that of a quarter-wave
whip. The use of such antennas may require further R&TTE approval.
Module mounting considerations
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 pins at the antenna end of the module, and not to
the OV pins which are intended as DC grounds 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.
Variants and ordering information
BiM3B modules are manufactured in the following variants as standard:
For European applications in the 868 - 870MHz band:
Part number
BiM3B-869-64
BiM3B-869-10
RF power (typ.)
7dBm
7dBm
Frequency
869.85MHz
869.85MHz
Data rate
64kbps
10kbps
BiM3B-868-64
BiM3B-868-10
14dBm
14dBm
868.30MHz
868.30MHz
64kbps
10kbps
For carrier detect (CD) output variant add CD suffix to the above part numbers. e.g. BiM3B-869-64-CD
Non-standard versions can be supplied to individual customer requirements, optimised for specific data
speeds/formats. Minimum order quantities apply. Please consult the Sales department for further
information.
Radiometrix Ltd, BiM3B Data Sheet
page 9
10
100
500
868.0
[mW]
600kHz
25mW
<1% or LBT
Duty Cycle
868.60
100kHz
868.70
10mW
<1%
25kHz or
WB
No Spacing
Channel Spacing
Applications
Alarm
500kHz
<1%
25kHz
869.25
250kHz
500mW
869.65
869.70
50kHz
25mW
<10% or LBT <10%
869.30 869.40
50kHz 50kHz 100kHz
869.20
No Spacing
25kHz
25kHz
or Wide Band
300kHz
5mW
870.0
up to 100%
Non-specific
SRD
Alarm
Non-specific SRD
10mW 10mW 10mW
<0.1%
<0.1% or LBT
25mW
25kHz
Social Alarm
Alarm
No Spacing
Non-specific SRD
CEPT/ERC Rec 70-03, 868 MHz Band Plan
Non-specific SRD
RF POWER [ERP]
Radiometrix Ltd, BiM3B Data Sheet
page 10
[MHz]
Radiometrix Ltd
Hartcran House
231 Kenton Lane
Harrow, Middlesex
HA3 8RP
ENGLAND
Tel: +44 (0) 20 8909 9595
Fax: +44 (0) 20 8909 2233
[email protected]
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/
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
[email protected]
European Radiocommunications Office (ERO)
Peblingehus
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
[email protected]
www.ero.dk
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