Data Sheet(pdf)

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
NTR2
UHF Narrow Band FM Transceiver
Issue 1, 30 July 2012
The NTR2 transceiver offers a low power,
reliable data link in a Radiometrix SIL
standard pin out and footprint. This
makes the NTR2 ideally suited to those
low power applications where existing
single frequency wideband UHF modules
have insufficient range.
Figure 1: NTR2-434.650-10
Features
Conforms to ETSI EN 300 220-3 (radio) and EN 301 489-3 (EMC)
Standard frequencies: 434.075MHz, 434.650MHz and 458.700MHz
Custom frequencies available in 433MHz (EU) and 458MHz (UK) band
Data rates up to 10kbps
Usable range over 500m
25kHz Channel spacing
Longer range compared to Wide Band FM modules
Available for licence-exempt operation in the 433MHz (EU) and 458MHz (UK) bands, the NTR2 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, NTR2 is ideal for use in battery-powered portable applications.
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
3 stage crystal controlled VCXO
Data bit rate: 10kbps max.
Transmit power: +10dBm (10mW)
Double conversion FM superhet
SAW band pass filter, image rejection: 50dB
RX sensitivity: -118dBm (for 12dB SINAD)
RX Adjacent Channel: -70dBm
Supply 2.9V - 15V @ 18mA (internal 2.8V voltage regulator)
Size: 57 x 24 x 8mm
Evaluation platforms: NBEK + NTR carrier
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 1
Functional description
The transmit section of the NTR2 consists of a frequency modulated Voltage Controlled Crystal Oscillator
(VCXO) feeding a frequency multiplier with two stage amplifier and RF filter. Final Power Amplifier stage is
factory pre-set to appropriate band power level. Operation can be controlled by the TXE line. The transmitter
achieves 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 RF output is filtered
to ensure compliance with the appropriate radio regulations and fed via a fast Tx/Rx changeover switch to
the 50Ω antenna pin.
The receive section is a double conversion NBFM superhet with IF at 21.4MHz and 455kHz fed by a Low
Noise Amplifier (LNA) on the RF front-end. Quadrature detector output is available as Audio Frequency
(AF) output and transmitted digital data is regenerated from AF using adaptive data slicer. A Received Signal
Strength Indicator (RSSI) output with some 60dB of range is provided.
User interface
57.7mm
8mm
24.1mm
30.48mm (1.2")
1
2
3
4
5
6
7
8
9
7 holes of 0.7mm dia pin spacing 2.54mm (0.1")
1 = RF in
2 = RF gnd
3 = RSSI
4 = 0V
5 = Vcc
6 = AF
7 = RXD
8 = TXE
9 = TXD
Figure 2: NTR2 pin-out and dimension
NTR2 pin
Name
Function
1
2
RF in/out
RF gnd
3
RSSI
4
5
6
7
0V
Vcc
AF
RXD
8
9
TXE
TXD
50Ω RF input from the antenna
RF Ground is internally connected to the module screen and pin 4 (0V).
These pins should be directly connected to the RF return path - e.g. coax
braid, main PCB ground plane etc.
Received Signal Strength Indicator with >60dB range.
DC level between 0.5V and 2V
Ground
2.9 – 15V DC power supply
500mVpk-pk audio. DC coupled, approx 0.8V bias
Logic data output from the internal data slicer. The data is squared version
of the Audio signal on pin 6 and is true data, i.e. as fed to the transmitter.
Output is "open-collector" format with internal 10kΩ pull-up to Vcc (pin 5).
Suitable for bi-phase codes
Low = TX enable (3V CMOS logic)
DC coupled input (3V CMOS logic). Rin = 100kΩ
Notes: 1. TXE has 47kΩ internal pullup to 2.8V
2. Compatible with NiM2, NRX2 and NTX2.
3. Pinout resembles an NRX2 receiver with 2 added pins ( N_TXE and TXD)
4. There is no complete unit enable pin: the user must switch the Vcc.
5. There are two versions of the interface pinning:
Batten & Allen 'edge leadframe' for vertical SIL mounting
Conventional 0.1" pitch square pin headers for minimum height horizontal mount.
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 2
Performance specifications
(Vcc = 3V / temperature = 20°C unless stated)
General
Operating temperature
Storage temperature
pin
min.
-10
-30
typ.
-
max.
+60
+70
units
°C
°C
5
5
5
1
2.9
-
3.0
20
15
50
434.650
434.075
458.700
15
-
V
mA
mA
-
25
1
-
kHz
9
±2.5
10
-37
±3.0
11
-40
±2.5
±3.5
dBm
dBm
dBm
kHz
kHz
0
-
FSK
0
3.0
-
5
10
kHz
V
V
%
8
-
-
5
ms
pin
min.
typ.
max.
units
1, 6
1, 7
1, 3
1, 3
1
1
1
1
1
-
-118
-112
-125
60
TBA
84
55
70
55
-
-60
dBm
dBm
dBm
dB
kHz
dB
dB
dB
dB
dBm
Baseband
Baseband bandwidth @ -3dB
AF level
DC offset on AF out
Distortion on recovered AF
6
6
6
6
0
-
500
0.8
-
5
10
kHz
mVP-P
V
%
Dynamic timing
Power up with signal present
Power up to valid RSSI
Power up to valid AF
Power up to stable data
3, 5
5, 6
5, 7
-
-
-
3
2
-
10
ms
ms
ms
Signal applied with supply on
Signal to valid RSSI
1, 3
-
2
-
ms
DC supply
Supply voltage
TX Supply current
RX Supply current
Antenna pin impedance
RF centre frequency
NTR2-434.650-10
NTR2-434.075-10
NTR2-458.700-10
Channel spacing
Number of channels
Transmitter
RF
RF power output
Spurious emissions
Adjacent channel TX power
Frequency accuracy
FM deviation (peak)
Baseband
Modulation type
Modulation bandwidth @ -3dB
TXD input level (logic low)
TXD input level (logic high)
Distortion
Dynamic timing
TX Enable to full RF
Receiver
RF/IF
RF sensitivity @ 12dB SINAD
RF sensitivity @ 1ppm BER
RSSI threshold
RSSI range
IF bandwidth
Blocking
Image rejection
Adjacent channel
Spurious response rejection
LO re-radiation
Radiometrix Ltd.,
1
1
9
9
NTR2 transceiver data sheet
MHz
notes
1
2
3
4
F3D
5
5
6
notes
7
7
8
9
Page 3
Signal to valid AF
Signal to stable data
Time between data transitions
Notes:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
pin
1, 6
1, 7
min.
max.
-
typ.
1
-
5
units
ms
ms
7
-
-
0.1
ms
notes
10
Available in 25kHz channel steps on other custom frequencies in 433MHz/458MHz band
Measured into 50Ω resistive load.
Total over full supply and temperature range.
With 0V – 3.0V modulation input.
To achieve specified FM deviation.
For 1Vpk-pk signal biased at 1.4V
See applications information for further details.
Exceeds EN/EMC requirements at all frequencies.
For received signal with ±3kHz FM deviation
For 50:50 mark to space ratio (i.e. squarewave).
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 4
Applications information
Power supply requirements
The NTR2 has built-in regulator which deliver a constant 2.8V to the module circuitry when the external
supply voltage is 2.9V or greater, with 40dB or more of supply ripple rejection. 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 >100mVpk-pk).
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 9 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 3V on pin 9. TXD input resistance is 100kΩ to ground, giving
typical required resistor values as follows:
Vcc
≤3V
3.3V
5V
9V
Series resistor
10 kΩ
68kΩ
220kΩ
NTR2 Received Signal Strength Indicator (RSSI)
The NTR2 incorporates a wide range RSSI which measures the strength of an incoming signal over a range
of 55dB or more. This allows assessment of link quality and available margin and is useful when performing
range tests.
The output on pin 3 of the module has a standing DC bias of <0.5V with no signal, rising to 2V at maximum
indication.
Typical RSSI characteristic is as shown below:
Figure 3: RSSI response curve
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 5
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
The following are typical examples – but range tests should always be performed before assuming that a
particular range can be achieved in a given situation:
Data rate
10kbps
10kbps
10kbps
Tx antenna
¼ wave
¼ wave
helical
Rx antenna
¼ wave
¼ wave
helical
Environment
urban/obstructed
Rural/open
in-building
Range
300m
500m
100m
Data formats and range extension
The NTR2’s TXD input is normally driven directly by logic levels but will also accept analogue drive (e.g. 2tone signalling). In this case it is recommended that TXD (pin 9) be DC-biased to 1.2V approx. with the
modulation ac-coupled and limited to a maximum of 2Vp-p to minimise distortion over the link. The varactor
nd
modulator in the NTR2 introduces some 2 harmonic distortion which may be reduced if necessary by
predistortion of the analogue waveform.
Although the modulation bandwidth of the NTR2 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 NTR2’s audio output.
The NRT2 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.
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 6
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.
Integral antennas
These are relatively inefficient compared to the larger externally-mounted types and hence tend to be
effective only over limited ranges. They do however result in physically compact equipment and for this
reason are often preferred for portable applications. Particular care is required with this type of antenna to
achieve optimum results and the following should be taken into account:
1. 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/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.
2. 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. The problem becomes
worse as logic speeds increase, because fast logic edges generate harmonics across the UHF range
which are then radiated effectively by the PCB tracking. In extreme cases system range may be reduced
by a factor of 5 or more. To minimise any adverse effects situate 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.
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 is about the maximum commonly used at 434MHz and appropriate scaling of length, diameter and
number of turns can make individual designs much smaller.
2
Loop. A loop of PCB track having an inside area as large as possible (minimum about 4cm ), tuned and
matched with 2 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
*
*
**
***
NTR2 transceiver data sheet
Page 7
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
C4
C1
4 to 10 cm inside area
RF
B. Loop antenna
16.4cm
C. Whip antenna
wire, rod, PCB-track or a combination
of these three
RF
433 MHz = 16.4 cm total from RF pin.
Figure 4: integral antenna configurations
External antennas
These have several advantages if portability is not an issue, and are essential for long range links. External
antennas can be optimised for individual circumstances and may be mounted in relatively good RF locations
away from sources of interference, being connected to the equipment by coax feeder.
Helical. Of similar dimensions and performance to the integral type mentioned above, commerciallyavailable helical antennas normally have the coil element protected by a plastic moulding or sleeve and
incorporate a coax connector at one end (usually a straight or right-angle BNC/SMA type). These are
compact and simple to use as they come pre-tuned for a given application, but are relatively inefficient and
are best suited to shorter ranges.
Quarter-wave whip. Again similar to the integral type, the element usually consists of a stainless steel rod
or a wire contained within a semi-flexible moulded plastic jacket. Various mounting options are available,
from a simple BNC/SMA connector to wall brackets, through-panel fixings and magnetic mounts for
temporary attachment to steel surfaces.
A significant improvement in performance is obtainable if the whip is used in conjunction with a metal ground
plane. For best results this should extend all round the base of the whip out to a radius of the length of the
whip used (under these conditions performance approaches that of a half-wave dipole) but even relatively
small metal areas will produce a worthwhile improvement over the whip alone. The ground plane should be
electrically connected to the coax outer at the base of the whip. Magnetic mounts are slightly different in that
they rely on capacitance between the mount and the metal surface to achieve the same result.
A ground plane can also be simulated by using 3 or 4 quarter-wave radials equally spaced around the base
of the whip, connected at their inner ends to the outer of the coax feed. A better match to a 50Ω coax feed
can be achieved if the elements are angled downwards at approximately 30-40° to the horizontal.
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 8
Module mounting considerations
The modules may be mounted vertically or bent horizontal to the motherboard. Note that the components
mounted on the underside of the NTR2 is relatively fragile – avoid direct mechanical contact between these
and other parts of the equipment if possible, particularly in situations where extreme mechanical stresses
could routinely occur (as a result of equipment being dropped onto the floor, etc).
Good RF layout practice should be observed. 50Ω microstrip line or coax or a combination of both should be
used to connect RF pin of the module to RF connector or antenna. It is desirable (but not essential) to fill all
unused PCB area around the module with ground plane.
Variants and ordering information
The NTR2 transceivers are manufactured in the following variants as standard:
At 434.650MHz: NTR2-434.650-10
At 434.075MHz: NTR2-434.075-10
At 458.700MHz: NTR2-458.700-10
Other frequency variants can be supplied to individual customer requirements in the 433MHz
(European) and 458MHz (UK) licence exempt bands
Radiometrix Ltd.,
NTR2 transceiver data sheet
Page 9
Radiometrix Ltd
Hartcran House
231 Kenton Lane
Harrow, Middlesex
HA3 8RP
ENGLAND
Tel: +44 (0) 20 8909 9595
Fax: +44 (0) 20 8909 2233
[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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