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Transmitter -TX2
Receiver -RX2
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| Evaluation Platform: Universal Evaluation kit or Narrow Band Evaluation Kit | |||
Functional description:
TX2 Transmitter
The TX2 transmitter module is a two stage, SAW controlled FM transmitter
operating between 2V and 6V and is available in 433.92MHz. The 433.92
MHz unit is type-approved to EN 300 220-3 for European use and will delivers
nominally +9 dBm from a 5V supply at 12mA Themodule measures 12 x 32 x
3.8 mm.
Figure1 : TX2 block diagram
Pin description
RF GND (pin 1)
RF ground pin, internally connected to the module screen and pin 4 (0
Volt).
This pin should be connected to the RF return path (e.g. coax braid, main
PCB ground plane etc.)
RF out (pin 2)
50W RF output to the antenna, it is DC isolated
internally. (See antenna section of TX2 applications note for suggested
antenna/feeds).
Figure 2: TX2 physical dimensions
Vcc (pin 3)
+ve supply pin. The module will generate RF when the Vcc supply is present.
Max ripple content 0.1Vp-p. A 100nF de-coupling ceramic capacitor
is suggested.
0 V (pin 4)0
Supply ground connection, connected to pin 1 and screen.
TXD (pin 5)
This DC coupled modulation input will accept either serial digital data
( 0 V to Vcc levels) or high level linear signals. Input impedance is
100 kW.
RX2 receiver
The RX2 module is a double conversion FM superhet receiver capable
of handling date rates of up to 160kbit/s.
The SIL style RX2 receiver measures 17.5 x 48 x 4.5 mm. It will operate
from a supply of 3.2V-6V and draws just 14mA when receiving. A fast-acting
carrier detect and a power-up enable time of less than 1ms. This allows
effective duty cycle power saving and a -107dBm sensitivity. This, combined
with a SAW front-end filter results in an excellent RF performance and
EMC conformance.
Figure 3: RX2 block diagram
Figure 4: RX2 physical dimensions
Pin description
RF in (pin1)
50W RF input from the antenna, it is DC isolate internally.
(See antenna section of RX2 applications note for suggested
antenna/feeds).
RF GND (pin2)
RF ground pin, internally connected to the module screen and pin 4 (0
Volt).
This pin should be connected to the RF return path (e.g. coax braid, main
PCB ground plane etc.)
CD (pin 3)
The Carrier Detect may be used to drive an external PNP transistor to
obtain a logic level carrier
detect signal, See test circuit. If not required it should be connected
to pin 5 (Vcc).
0V (pin 4)
Supply ground connection, connected to pin 1 and screen.
Vcc (pin 5)
+ve supply pin. +3.0 to +6.0V @ <17mA . The supply must be clean <2mVp-p
ripple. A 10µF de-coupling capacitor and 10W
series resistor is recommended if a clean supply is not available.
AF (pin 6)
This is a buffered and filtered analogue output from the FM demodulator.
It has a standing DC bias of 1.2V and 400mV P-P base band signal.
It is useful as a test point or to drive linear decoders. Load impedance
should be > 2kW and <100pF.
RXD(pin 7)
This digital output from the internal data slicer is a squared version
of the signal on pin 6 (AF). It may be used to drive external decoders.
The data is true data, i.e. as fed to the transmitter. Load impedance
should be > 1kW and <1nF.
Survival Maximums
| Operating temperature: | -10°C to +55°C |
| Storage temperature : | -40°C to + 100°C |
| TX2, all variants | |
| Vcc (pin 3) | -0.1V to +10.0V |
| Data input (pin 5) | -0.1V to +10.0V |
| RF out (pin 2) | ±50V @ < 10MHz , +20dBm @ > 10MHz |
| RX2, all variants | |
| Vcc (pin 5) | -0.1V to +10.0V |
| Data , CD & AF (pin 7,3,6) | -0.1V to + Vcc V |
| RF input (pin 1) | ±50V @ < 10MHz , +13dBm @ > 10MHz |
note: Operation of the TX2 above 6V may cause the module to exceed the licensed power level.
Electrical Performance: TX2 transmitter
note:
1. Measured into a 50W load.
2. For 160kbps versio
Electrical Performance: RX2 Receiver
Unless otherwise noted: Figures apply to 5V versions unless otherwise
noted Vcc = 5.0V, temperature 20°C unless noted.
Module test circuits
Fig.5: TX2 test circuit
Fig.6: RX2 test circuit | * | The PNP transistor enables a CMOS compatible Carrier Detect signal to be derived from pin 3. If no CD signal required pin 3 should be connected directly to pin 5 (Vcc). |
Module mounting considerations
The modules may be mounted horizontally or vertically on an area of ground
plane preferably close to the antenna to minimize feed length.
The receiver and it's antenna should be kept away from sources of interference
(micro's, SMPS etc.).
The modules may be potted if required in a viscous compound which can
not enter the screen can.
Warning: Do NOT wash the modules. They are not hermetically
sealed
Fig.7: Module mounting options
Antenna requirements
Three types of integral antenna are recommended and approved for use with
the module:
| A) Helical | Wire coil, connected directly to pin 2, open circuit at other end. This antenna is very efficient given it's small size (20mm x 4mm dia.). The helical is a high Q antenna, trim the wire length or expand the coil for optimum results. The helical de-tunes badly with proximity to other conductive objects. |
| B) Loop | 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. |
| C) Whip | This is a wire, rod ,PCB track or combination connected directly to pin 2 of the module. Optimum total length is 15.5cm (1/4 wave at @433MHz) 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 |
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.
Fig. 8: Antenna configurations
Variants and Ordering information
The TX2 transmitter and RX2 receiver are manufactured in several variants:
| Supply voltage | 5V ( 4 to 6V TX2 & RX2) 3V ( 3.2 to 4V for RX2, 2.2 to 4V for TX2) |
| RX Data Rate | Slower version, 7kHz baseband
BW, data rate up to 14kbit/s Faster version, 20kHz baseband BW, data rate up to 40kbit/s Very fast version, 91kHz baseband BW, data rate up to 160kbit/s |
| TX Data Rate |
Faster version, 20kHz baseband BW, data rate up to 40kbit/s |
The following are standard:
| TX2-433-40-5V | 433.92 MHz, 5V TX, +10dBm |
| TX2-433-160-5V | 433.92 MHz, 5V TX, +10dBm |
| RX2-433-14-5V | 433.92 MHz, 5V RX, 14kbps |
| RX2-433-40-5V | 433.92 MHz, 5V RX, 40kbps |
| RX2-433-160-5V | 433.92 MHz, 5V RX, 160kbps |
3V versions of the above are available and should
be ordered with a 3V suffix on the part number.
(E.g. RX2-433-14-3V is setup for 3.2 to 4 volt operation).
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:
Licensing
policy manual
