Radiometrix NiM2BR-434.65-10 Frequency programmable 25khz nbfm transceiver Datasheet

Hartcran House, 231 Kenton Lane, Harrow, Middlesex, HA3 8RP, England
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233, www.radiometrix.com
NiM2B
Issue 1, 4 November 2014
Frequency Programmable 25kHz NBFM Transceiver
The narrow band NiM2B transceiver offers
a low power, reliable data link in a
Radiometrix transceiver standard pin out
and footprint. This makes the NiM2B ideally
suited to those low power applications
where existing single frequency wideband
UHF modules have insufficient range.
Features
 Conforms to ETSI EN 300 220-2 (radio) and EN 301 489-3 (EMC)
 Standard frequency - 434.650MHz (programs to any frequency in
the 432 - 436MHz range)
 458MHz (UK) and 448MHz band units are also available.
 Data rates up to 10kbps
 Usable range over 500m
 12.5kHz / 20kHz / 25kHz Channel spacing (factory set)
 Feature-rich interface (true analogue and/or digital baseband)
Figure 1: NiM2B-434.650-10
Available for licence-exempt operation in the 433MHz EU band, the NiM2B modules combine effective
screening with internal filtering to minimise spurious radiation and susceptibility thereby ensuring EMC
compliance. They can be used in existing low data rate (<10kbps) applications where the operating range of
the system using wide band transceivers need to be extended. Because of their small size and low power
consumption, NiM2B is ideal for use in battery-powered portable applications.
NiM2B is also available as separate NiM2BT transmitter and NiM2BR receiver, which can be used as dualin-line equivalents of NTX2B transmitter and NRX2B receiver respectively.
Applications
EPOS equipment, barcode scanners
Data loggers
Industrial telemetry and telecommand
In-building environmental monitoring and control
High-end security and fire alarms
 DGPS systems
 Vehicle data up/download





Technical Summary









Fully integrated sigma-delta PLL synthesizer based design
High stability TCXO reference
Data bit rate: 10kbps max.
Transmit power: +10dBm (10mW)
SAW front-end band pass filter, image rejection: >60dB
Receiver sensitivity: -118dBm (for 12dB SINAD)
RSSI output with >50dBm range
Supply: 3.1V - 15V @ 20mA transmit, 18mA receive
Dimensions: 33 x 23 x 11mm (fully screened)
Evaluation platforms: NBEK + BiM / SMX carrier
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 1
Figure 2: NiM2B-434.650-10
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 2
Functional description
The transmit section of the NiM2B consists of a highly integrated sigma delta (fractional N) synthesizer
based single chip RF device, configured over an SPI serial bus by an on-board microcontroller. The primary
frequency reference for the transmitter is a 26MHz VC-TCXO. Modulation is applied directly to this reference
via an AF baseband filter (rather than using the chip's internal modulator) to permit a wider range of
baseband data rates and waveforms. Operation is controlled by the N_TXE line, the transmitter achieving full
RF output typically within 5ms of this line being pulled low. The RF output is filtered to ensure compliance
with the appropriate radio regulations and fed to the 50Ω antenna pin.
The receiver section of the NiM2B consists of a highly integrated sigma delta (fractional N) synthesizer
based Local Oscillator (LO), configured over an SPI serial bus by an on-board microcontroller. The primary
frequency reference for the LO is a 26MHz VC-TCXO. The RF input is filtered using SAW filters in the frontend to provide image rejection and enhanced blocking performance. These SAW filters reduce user
programmable frequency range to the filter passband, but a wide number of (factory set) sub-bands are
available, determined by SAW filter availability.
User interface
side view (through can)
side view (with can)
11 mm
top view (without can)
RF GND 1
Antenna 2
RF GND 3
4
5
6
No pin
7
8
9
18 0 Volt
17 Vcc
16
15 N_TXE
14 TXD
13 AF
12 RXD
11 RSSI
10 0 Volt
RF OUT (TX)*
RF IN (RX)*
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
pins 4, 5, 6, 7, 8 & 9 are not fitted
Figure 3: NiM2B pin-out and dimension
NiM2B Pin
1, 3, 10, 18
17
16
15
14
13
12
Name
0V
VCC
N_RXE / RX PGM
N_TXE / TX PGM
TXD
AF
RXD
Function
Ground
3.1 – 15V DC power supply
Pull low to enable Receiver / receive programming in put
Pull low to enable Transmitter / transmit programming in put
DC coupled input for 3V CMOS logic. Rin = 100k
500mV pk-pk audio. DC coupled, approx 1.5V bias
Open collector output, with a 10k pullup to Vcc. Suitable for Biphase
codes
DC level between 0.5V and 2V. 60dB dynamic range
11
RSSI
NOTES:
1. N_Rxe and N_Txe have (10K approx.) pullups to +Vin
2. Unit is programmable (in the same way as an NTX2B or NRX2B) using the N_Rxe or N_Txe pins
Reprogramming requires a 0v to +Vin logic level non-inverted RS232 data-stream to pin 3 or 4
An RS232 port can be directly connected to the enable pin for programming
3. Avoid N_Rxe and N_Txe both low: undefined module operation (but damage will not result)
4. A 25mW version is available (3.4-15v operation, 40mA TX)
5. Pinout is as NiM2. On RF connector end only pins 1,2,3 are present (*except for NiM2B with separate
RX and TX ports which has 4 pins. See ordering info ( p10) for further details on this special built).
6. Switching time as controlled by N_Txe or N_Rxe pins is <5mS, but when power is first applied to the
unit there is a 20mS long “calibration” period before the transmitter becomes active.
If the rail is switched (as opposed to the EN pin) then this should be considered as a 25mS device
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 3
Absolute maximum ratings
Exceeding the values given below may cause permanent damage to the module.
Operating temperature
Storage temperature
-20C to +70C
-30C to +85C
RF in (pin 1)
All other pins
50V @ <10MHz, +13dBm @ >10MHz
-0.3V to +15.0V
Performance specifications:
(Vcc = 3.1V / temperature = 20C unless stated)
General
DC supply
Supply voltage
TX Supply current (10mW)
RX Supply current
Antenna pin impedance
RF centre frequency
Channel spacing
Number of channels
Transmitter
RF
RF power output
Spurious emissions
Adjacent channel TX power
Frequency accuracy
FM deviation (peak)
Baseband
Modulation bandwidth @ -3dB
TXD input level (logic low)
TXD input level (logic high)
pin
min.
typ.
max.
units
17
17
17
3.1
20
18
15
V
mA
mA
2
2
2
50
434.650
25
1
+9
+10
2.5
-37
1.5 (2.5ppm)
3.0
0
14
14
+11
-40
3.5
5
5
Receiver
RF/IF
RF sensitivity @ 12dB SINAD
RF sensitivity @ 1ppm BER
RSSI range
Blocking
Image rejection
Adjacent channel rejection
Spurious response rejection
LO leakage, radiated
2, 13
2, 12
2, 11
2
2
2
2
Baseband
Baseband bandwidth @ -3dB
AF level
DC offset on AF out
Distortion on recovered AF
13
13
13
12
50
-118
-112
60
80
dBm
dBm
dBm
kHz
kHz
kHz
V
V
60
60
-60
5
500
1.5
5
2
3
4
5
6
6
ms
dBm
dBm
dB
dB
dB
dB
dB
dBm
60
NiM2B transceiver data sheet
1
1
0
3.0
Dynamic timing
TX select to full RF
Radiometrix Ltd.,
Ω
MHz
kHz
notes
kHz
mVP-P
V
%
7
3
4
8
Page 4
General
pin
Dynamic timing
RX enable with signal present
N_RXE active (low) to stable AF output
N_RXD active (low) to stable RXD
output
Signal applied with receiver enabled
Signal to valid AF
Signal to stable data
min.
typ.
max.
units
16, 13
16, 12
10
25
ms
2, 11
2, 12
10
25
ms
ms
notes
Notes:
1. Programs to any frequency in the 432 - 436MHz range (other frequencies by special order, subject
to SAW filter availability). 458MHz and 448MHz band units also available
2. Measured into 50 resistive loads.
3. Exceeds EN/EMC requirements at all frequencies.
4. 2.5ppm TCXO. Total over full supply and temperature range.
5. With 0V – 3.0V modulation input.
6. To achieve specified FM deviation.
7. See applications information for further details.
8. For received signal with 3kHz FM deviation.
Channel Programming
At the heart of the device is a fractional N synthesizer 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 coefficients: the integer (INTE) and the fraction (FRAC). Output
frequency relates to these values thus:
FRAC  2  VCTCXO

Freq   INTE  19  
Outdiv
2


where
2  26MHz
 6.5MHz
8
NiM2B uses 26MHz VCTCXO and Output Divider (Outdiv) value for 425MHz - 525MHz band is 8.
For correct operation, the component (FRAC / 219) must have a value between 1 and 2
FRAC 

Freq   INTE  19   6.5
2


1
 Freq 
INTE  WholeNum 
1
 6.5 
FRAC
2
219
524,288  FRAC  1,048,576

 Freq  
FRAC   DecimalNum 
 1  524288
 6.5  

In interface terms, these coefficients are expressed as a 32-bit binary word (eight hexadecimal digits) where
the most significant byte comprises the integer value, and the remaining three bytes (24 bits) make up
"fraction"
TX Example:
434.650MHz
 66.8692307692
6.5MHz
INTE = 66-1 = 65 (0x41)
FRAC = (0.8692307692 +1)  524288 = 980015 (0x0EF42F)
FRAC2 = 0x0E
FRAC1 = 0xF4
FRAC0 = 0x2F


Freq =  65 
Radiometrix Ltd.,
980015 
  6.5  434.649998MHz  434.650 MHz  3.2 Hz
524288 
NiM2B transceiver data sheet
Page 5
However, the frequency programmed into the receiver section is the LOCAL OSCILLATOR (LO) frequency,
not the actual channel frequency.
For unit operating on a channel frequency of 446MHz or higher, the local oscillator is 21.4MHz below the
carrier (so subtract 21.4MHz). AF output will be inverted on higher receive frequency units.
LO  RF  IF  458.700 MHz  21.4 MHz  437.3MHz
for RF  446 MHz
For units operating on frequencies below 446MHz, the local oscillator is 21.4MHz above the channel.
LO  RF  IF  434.650 MHz  21.4 MHz  456.05MHz for RF  446 MHz
RX Example:
434.650 MHz  21.4 MHz
 70.1615384615
6.5MHz
INTE = 70-1 = 69 (0x45)
FRAC = (0.1615384615 +1)  524288 = 608980 (0x094AD4) 0x094AD4
FRAC2 = 0x09
FRAC1 = 0x4A
FRAC0 = 0xD4


Freq =  65 
608980 
  6.5  456.0499992MHz  456.050 MHz  8.4 Hz
524288 
When programming the NiM2B, keep in mind that the unit maintains in SRAM the current values of all
programmable values (frequency, band of operation, RF power and frequency offset adjustments values)
and that toggling the PGM pin does NOT erase or corrupt them.
These values are only loaded from EEPROM at cold start power-up (but not when the relevant N_TXE or
N_RXE pins are cycled)
There is one "write all values to EEPROM" command. It is usually necessary to load the relevant current
operating RAM value(s) and THEN issue a suitable command to write the RAM value to EEPROM.
The NiM2B stores Frequency coefficients (for transmit and receive), frequency Offsets, band select and TX
RF Power level constants in internal EPROMs.
ALWAYS REMEMBER THAT THE TRANSMIT AND RECEIVE SECTIONS OF THE NiM2B ARE
INDEPENDANT, AND ARE PROGRAMMED ENTIRELY SEPARATELY.
No command sent to the transmitter will have any effect on the receiver, and vice-versa.
For the NiM2B RX section, power level should always be set to 3
Programming a value or coefficient over the serial bus over-writes the previous value and implements this
change on the PLL immediately, but does not change the EEPROM contents until a relevant "program
EEPROM" command is issued
In general, the most recent stimulus received by the unit will decide the operating frequency.
Whenever a frequency coefficient is programmed into the unit, the frequency will change immediately to this
new value regardless of other modes or operation. This is the simplest and most flexible means of controlling
the unit.
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 6
Serial interface commands
NiM2B is programmable (in the same way as an NTX2B or NRX2B) using the N_Rxe or N_Txe pins
Reprogramming requires a 0v to +Vin logic level non-inverted RS232 data-stream to pin 3 (RX PGM) or 4
(TX PGM)
An RS232 port can be directly connected to the enable pin for programming.
The serial data should be in the following format: 9600bps, 8 data bits, No Parity, 1 Stop
Every command string starts with the phrase "@PRG_" and terminated with Carriage Return <cr>.
The characters in a command string must not be separated by more than 5ms (so typing individual
characters on a terminal keyboard will NOT work), but a pause of at least 10ms is required between
commands (more following a BURN_ROM command. In this case a much longer idle period, of 50mS at
least, is needed for EEPROM programming)
User commands
Commands
@PRG_iif2f1f0<cr>
@PRG_BURN_ROM<cr>
@PRG_POWER 00<cr>
@PRG_POWER FF<cr>
@PRG_00000000<cr>
Function
sets the transmitter / receiver frequency
iif2f1f0 is an 8 digit hexadecimal number, coding 4 bytes:
ii is the "integer" value
f2 most significant FRAC2 byte in the 24 bit FRAC word
f1 bits 8 through 15 of the fraction word (FRAC1)
f0 least significant FRAC0 byte
e.g. @PRG_410EF42F<cr> to program 434.650MHz
(@PRG_45094AD4 <cr> for receiver)
write current setup into EEPROM
Turn the unit completely OFF (power down)
Turn the unit ON (power up)
TX /RX PGM pin can also be cycled
Re-sets itself to the values currently stored in EEPROM
(this usually only happens at power-up)
Factory alignment commands
Commands
@PRG_POWER pp <cr>
@PRG_TRIM+ aa <cr>
@PRG_TRIM- aa <cr>
@PRG_BAND# bb
@PRG_BURN_ROM<cr>
Radiometrix Ltd.,
Function
Sets the RF Power output
pp is a 2 digit hexadecimal number (in the range 00 to 3F)
00 - power OFF, FF – power ON
e.g. @PRG_POWER 32<cr>
set an "up" offset
aa is 00 (0Hz) to 7F (+1574.8Hz) at 12.4Hz per bit
@PRG_TRIM+1E<cr>
sets a "down" offset
aa is 00 (0Hz) to 7F (-1574.8Hz) at 12.4Hz per bit
band divider value (bb)
08
850-1050MHz
0A 425-520MHz
0B 280-350MHz
0D 140-175MHz
e.g. PRG_BAND# 0A<cr>
write current setup into EEPROM
NiM2B transceiver data sheet
Page 7
Applications information
Power supply requirements
The NiM2B have built-in regulators which deliver a constant 3.0V to the transmitter and the receiver circuitry
when the external supply voltage is 3.1V or greater. This ensures constant performance up to the maximum
permitted rail, and removes the need for external supply decoupling except in cases where the supply rail is
extremely poor (ripple/noise content >0.1Vp-p).
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 14 of 3V amplitude,
i.e. 0V “low”, 3V “high
If the data input level is greater than 3V, a resistor must be added in series with the TXD input to limit the
modulating input voltage to a maximum of around 3V on pin 14. TXD input resistance is 100k to ground,
giving typical required resistor values as follows:
Vcc
3V
3.3V
5V
9V
Series resistor
10 k
68k
220k
RX Received Signal Strength Indicator (RSSI)
The NiM2B wide range RSSI which measures the strength of an incoming signal over a range of 60dB or
more. This allows assessment of link quality and available margin and is useful when performing range tests.
The output on pin 11 of the module has a standing DC bias of up to 0.5V (approx.) with no signal, rising to
around 2.0V at maximum indication. DVmin-max is typically 1V and is largely independent of standing bias
variations. Output impedance is 56k. Pin 11 can drive a 100A meter directly, for simple monitoring.
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.
Typical RSSI characteristic is as shown below:
Figure 4: RSSI level with respect to received RF level at NiM2B antenna pin
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 8
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
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
Data formats and range extension
The NiM2B TXD input is normally driven directly by logic signals, but will also accept analogue drive (e.g. 2tone signalling). In this case the TXD pin can either be directly DC driven with a 3v pp waveform with a 1.5v
centre point, or a 3v pp signal can be AC coupled (when the input circuits will self-bias to 1.5v). Do not
exceed 3v pp, or the baseband waveform will begin to clip.
The VC-TCXO in the NiM2B is highly linear, and tx distortion figures well under 5% should be seen. At the
other end of the link the NiM2B AF output (or the RXD pin) may be used to drive an external decoder or
other signal processing circuitry.
Although the modulation bandwidth of the NiM2B extends down to DC it is not advisable to use data
containing a DC component. This is because frequency errors and drifts between the transmitter and
receiver occur in normal operation, resulting in DC offset errors on the NiM2B audio output.
The NiM2B in standard form incorporates a low pass filter with a 5kHz nominal bandwidth. This is suitable
for transmission of data at raw bit rates up to 10kbps.
Antennas
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 antenna type for any given application.
The following types of integral antenna are in common use:
Quarter-wave whip. This consists simply of a piece of wire or rod connected to the module at one end. At
434MHz the total length should be 164mm from module pin to antenna tip including any interconnecting wire
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 it suffers badly from detuning caused by proximity to nearby
conductive objects and needs to be carefully trimmed for best performance in a given situation. The size
shown in figure 5 below is about the maximum commonly used at 433MHz and appropriate scaling of length,
diameter and number of turns can make individual designs much smaller.
Loop. A loop of PCB track having an inside area as large as possible (minimum about 4cm2), tuned and
matched with 2 or 4 capacitors. Loops are relatively inefficient but have good immunity to proximity detuning,
so may be preferred in shorter range applications where high component packing density is necessary.
Integral antenna summary:
Feature
Ultimate performance
Ease of design set-up
Size
Immunity to proximity effects
Radiometrix Ltd.,
whip
***
***
*
**
helical
**
**
***
*
loop
*
*
**
***
NiM2B transceiver data sheet
Page 9
0.5 mm enameled copper wire
close wound on 3.2 mm diameter former
RF
433 MHz = 24 turns
A. Helical antenna
Feed point 15% to 25% of total loop length
RF-GND
track width = 1mm
2
C2
C3
C1
4 to 10 cm inside area
RF
C4
B. Loop antenna
16.4cm
wire, rod, PCB-track or a combination
of these three
RF
C. Whip antenna
433 MHz = 16.4 cm total from RF pin.
Figure 5: integral antenna configurations
Module mounting considerations
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 NiM2BT transmitters, NiM2BR receivers and NiM2B transceivers are manufactured in the following
variants as standard:
At 434.650MHz: NiM2B-434.65-10
Transceiver
NiM2BT-434.65-10
Transmitter
NiM2BR-434.65-10
Receiver
(These can be programmed on any frequency in the 432 - 436MHz range)
458MHz and 448MHz band units are also available
Other frequencies are by special order, subject to SAW filter availability
NiM2B with separate TX and RX RF ports: NiM2B-434.65-10-TR
The NiM2B can be factory built with separate RX and TX ports.
This special built will have 4 pins on the RF connector instead of three (refer to figure 3)
Pin 1 RF GND
2 RF OUT (TX)
3 RF GND
4 RF IN (RX)
The RF IN (RX) port MUST be externally AC coupled, as it has a bias voltage on it
This is useful if an application requires using an external TX power amp, RX pre-amp, or separate antennas
TX and RX.
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 10
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/
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
[email protected]
European Communications Office (ECO)
Peblingehus
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
[email protected]
www.ero.dk
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