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TX2A/RX2A
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The TX2A and RX2A data link modules are
a miniature PCB mounting UHF radio transmitter and receiver
pair which enable the simple implementation of a data link at
up to 64 kbps at distances up to 75 metres in-building and 300
metres open ground.
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Figure 1: RX2A-433-64 and TX2A-433-64 |
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CE certified by independent Notified Body
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Verified to comply with harmonised radio
standard EN 300 220-3 and EMC standard EN 301 489-3 by accredited
Test Laboratory
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Data rates up to 64 kbps
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Usable range up to 300 m
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Versions available on 433.92MHz and 434.42MHz
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Fully screened
Available for operation at 433.92MHz or 434.42MHz in the UK
and Europe, both modules combine full screening with extensive
internal filtering to ensure EMC compliance by minimising spurious
radiations and susceptibilities. The TX2A and RX2A modules will
suit one-to-one and multi-node wireless links in applications
including car and building security, EPOS and inventory tracking,
remote industrial process monitoring and computer networking.
Because of their small size and low power requirements, both
modules are ideal for use in portable, battery-powered applications
such as hand-held terminals.
Technical Summary
Transmitter - TX2A
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Crystal-locked PLL, FM modulated at up to
64 Kbps
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Operation from 2.2V to 16V (Dependent on
version)+10dBm on 433.92MHz
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High efficiency, >30%, DC to RF
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Improved frequency and deviation accuracy
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2nd harmonic, > -60dBc
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Single conversion FM superhetSAW front end
filter gives >50dB image rejection
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Operation from 2.7V to 16V @ 12mA
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Built-in regulator for improved stability
and supply noise rejection
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-101dBm sensitivity @ 1ppm BER, 64kb/s version
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-108dBm sensitivity @ 1ppm BER, 10kb/s version
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RSSI output with 60dB range
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Extremely low LO leakage, <-100dBm
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| Evaluation
Platform: Universal
Evaluation kit or Narrow Band
Evaluation Kit |
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| Functional
description
The TX2A transmitter module is a crystal based PLL controlled
FM transmitter operating between 2.2V and 16V and is available
in 433.92MHz. The TX2A module is type approved to EN 300 220-3
for European use and delivers nominally +10dBm at 11mA. The
module measures 32 x 12 x 3.8 mm.
The RX2A module is a single conversion
FM superhet receiver capable of handling data rates of up to
64kbps. It will operate from a supply of 2.7V to 16V and draws
10mA when receiving. The RX2A features a fast power-up time
for effective duty cycle power saving and a signal strength
(RSSI) output with 60dB of range. Full screening and a SAW front-end
filter give good immunity to interference. The SIL style RX2A
measures 48 x 17.5 x 4.5 mm excluding the pins.
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| TX2A
transmitter |
Figure 2: TX2A block diagram |
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Figure 3: TX2A block diagram |
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| Pin Description -TX2A |
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Pin
|
Name
|
Function
|
| 1& 3 |
RF GND |
RF ground, internally
connected to the module screen and pin 6 (0V). These
pins should be directly connected to the RF return
path - e.g. coax braid, main PCB ground plane etc. |
| 2 |
RF IN |
50W
RF output to the antenna. Internally DC-isolated.
See antenna section of apps notes for details of
suitable antennas |
| 4 |
EN |
Tx enable. <0.15V
shuts down module (current <1mA).
>1.7V enables the transmitter. Impedance ~1MW.
Observe slew rate requirements (see apps notes) |
| 5 |
Vcc |
+2.2V to +16V DC
supply. Max ripple content 0.1VP-P.
Decoupling is not generally required |
| 6 |
0V |
DC supply ground.
Internally connected to pins 1 & 3 and module
screen |
| 7 |
TXD |
DC-coupled
modulation input. Accepts serial digital data at
0V to 2.5V levels.
See applications notes for suggested drive methods.
Input is high impedance (>100kW) |
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Notes:
1. The 3V and 5V
supply variant TX2As intended for direct replacement
to our SAW based TX2 modules and do not have internal
regulator. They also have identical pin out as of
TX2, hence lack pin 3 (GND) and pin 4 (Enable).
2. The TXD input of 3V and 5V versions require serial
digital data at 0-Vcc levels. i.e. 0-3V and 0-5V
respectively |
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| RX2A receiver |
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Figure 4: RX2A block diagram |
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Figure 5: RX2A physical
dimensions
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| Pin Description
- RX2A |
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Pin
|
Name
|
Function
|
| 1 |
RF IN |
50W
input from the antenna. DC isolated |
| 2 |
RF GND |
RF ground
pin, internally connected to the module screen
and pin 4 (0V). This pin should be connected
to the RF return path (coax braid, main PCB
ground plane etc.) |
| 3 |
RSSI |
Received signal
strength indicator with 60dB range. See page
4 for typical characteristics |
| 4 |
0V |
DC supply
ground. Internally connected to pin 2 and
module screen |
| 5 |
Vcc |
+2.7V to +16.0V
DC supply. Max ripple content 0.1Vp-p. Decoupling
is not generally required |
| 6 |
AF out |
Buffered and
filtered analogue output from the FM demodulator.
Standing DC bias 1.1V approx. External load
should be >10kW
// <100pF |
| 7 |
RXD |
Digital output
from the internal data slicer. The data is
a squared version of the signal on pin 6 (AF)
and is true data, i.e. as fed to the transmitter.
Output is "open-collector" format
with internal 10kW
pull-up to Vcc (pin 5). |
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| Absolute
maximum ratings
Exceeding the values given below
may cause permanent damage to the module.
| Operating temperatutre |
- 20°C to +70°C |
| Storage temperatutre |
-40°C to +100°C |
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| TX2A all variants |
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| Vcc (pin 3 |
-0.3V to +16.0V |
| Data input (pin
5) |
± 7V |
| RF out (pin 2 |
±50V DC 10dBm
RF |
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| RX2A all variants |
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| Vcc(pin5) |
-0.1V to +16V |
| RSSI,
AF, RXD (pins 3,6,7) |
-0.1V
to + 3V |
| RF IN (pin 1) |
±50V DC,
+10dBm RF |
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Performance
specifications:TX2A
(Vcc = 5.0V / temperature = 20ºC
unless stated) |
|
pin |
min.
|
typ.
|
Max.
|
units
|
notes
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| DC
supply |
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| Supply
voltage |
3 |
2.2 |
3.0 |
4.0 |
V |
-3V
version |
| Supply
voltage |
3 |
4.0 |
5.0 |
6.0 |
V |
-5V
version |
| Supply
voltage |
3 |
3 |
- |
16 |
V |
STD |
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| Current
& RF Power |
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| TX2A
all variants |
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| supply
current |
3 |
9
|
11
|
13
|
mA
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| RF
power |
2
|
+8
|
+10
|
+12
|
dBm
|
1
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| RF |
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| 2nd
harmonic |
2
|
-
|
-70
|
-54
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dBc
|
1
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| Harmonics
@ >1GHz |
2
|
-
|
-60
|
-40
|
dBc
|
1
|
| Initial
frequency accuracy |
-
|
-20
|
+/-10
|
+20
|
kHz
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| overall
frequency accuracy |
-
|
-25 |
+/-10 |
+25 |
kHz |
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| Peak
FM deviation |
|
±20
|
±27 |
±35
|
kHz |
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| Baseband |
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| Modulation
bandwidth @ -3dB |
|
0 |
-
|
35 |
kHz |
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| Modulation
distortion (THD) |
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-
|
5
|
10 |
% |
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| Dynamic
timing |
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| Power-up
time (En --> full RF) |
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-
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1.0 |
1.5 |
ms |
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Notes:
1. Measured into a 50W
resistive load.
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Performance
specifications: RX2A
(Vcc = 5.0V / temperature = 20ºC unless stated) |
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|
pin
|
min.
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typ.
|
max.
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units
|
notes
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| DC supply |
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| Voltage |
5
|
2.7
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5
|
16
|
V
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| Ciurrent |
5
|
9
|
10
|
18
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mA
|
1
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| RF/IF |
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| RF sensitivity for
10dB (S+N/N) |
1, 6
|
-
|
-115
|
-
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dBm
|
10kbps version
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| RF sensitivity for
10dB (S+N/N) |
1, 6
|
-
|
-108
|
-
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dBm
|
64kbps version
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| RF sensitivity for
1ppm BER |
1, 6
|
-
|
-108
|
-
|
dBm
|
10kbps version
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| RF sensitivity for
1ppm BER |
1, 6
|
-
|
-101
|
-
|
dBm
|
64kbps version
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| RSSI range |
1, 3
|
-
|
60
|
-
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dB
|
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| IF bandwidth |
-
|
-
|
180
|
-
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kHz
|
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| Image rejection |
1
|
50
|
54
|
-
|
dB
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| ½-IF spurious
rejection |
1
|
100
|
-
|
-
|
dB
|
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|
IF rejection (10.7MHz)
|
1
|
100
|
-
|
-
|
dB
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| LO leakage, conducted |
1
|
-
|
-125
|
-110
|
dBm
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| Baseband |
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| Baseband bandwidth
@ -3dB |
6
|
0
|
-
|
7.8
|
kHz
|
10kbps version
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| Baseband bandwidth
@ -3dB |
6
|
0
|
-
|
50
|
kHz
|
64kbps version
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| AF level |
6
|
350
|
450
|
550
|
mVp-p
|
2
|
| DC offset on AF
out |
6
|
0.45
|
1.1
|
1.75
|
V
|
3
|
| Distortion on recovered
AF |
6
|
-
|
1
|
10
|
%
|
3
|
| Ultimate (S+N)/N |
6
|
-
|
40
|
-
|
dB
|
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| Load capacitance,
AFout/RXD |
6, 7
|
-
|
-
|
100
|
pF
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| DYNAMIC TIMING |
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| Power up with signal
present |
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| Power up to valid
RSSI |
3, 5
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-
|
1
|
-
|
ms
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| Power up to stable
data |
5, 7
|
-
|
10
|
30
|
ms
|
3, 10kbps version
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| Power up to stable
data |
5, 7
|
-
|
5
|
10
|
ms
|
3, 64kbps version
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| Signal applied with
supply on |
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| RSSI response time
(rise/fall) |
1, 3
|
-
|
100
|
-
|
ms
|
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| Signal to stable
data |
1, 7
|
-
|
5
|
30
|
ms
|
3, 10kbps version
|
| Signal to stable
data |
1, 7
|
-
|
5
|
10
|
ms
|
3, 64kbps version
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| Time between data
transitions |
7
|
0.1
|
-
|
15
|
ms
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4, 10kbps version
|
| Time between data
transitions |
7
|
15.6
|
-
|
1500
|
ms
|
4, 64kbps version
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| Mark:space ratio |
7
|
20
|
50
|
80
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%
|
5
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| Notes: |
1. Current increases
at higher RF input levels (>-20dBm and above). |
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2. For received
signal with ±40kHz FM deviation |
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3. Typical figures
are for signal at centre frequency, max. figures
are for ±50kHz offset |
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4. For 50:50 mark
to space ratio (i.e. squarewave) |
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5. Average over
30ms (10kbps version) or 3ms (64kbps version) at
maximum data rate |
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| Power
supply requirements
The standard TX2A and the RX2A modules incorporate
a built-in regulator which delivers a constant 2.8V
to the module circuitry when the external supply voltage
is 2.85V or greater, with 40dB or more of supply ripple
rejection. This ensures constant performance up to the
maximum permitted supply 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).
Note, however, that for supply voltages lower than
2.85V the regulator is effectively inoperative and supply
ripple rejection is considerably reduced. Under these
conditions the ripple/noise on the supply rail should
be below 10mVp-p to avoid problems. If the quality of
the supply is in doubt, it is recommended that a 10mF
low-ESR tantalum or similar capacitor be added between
the module supply pin (Vcc) and ground, together with
a 10W series feed resistor
between the Vcc pin and the supply rail.
The Enable pin allows the module to be turned on or
off under logic control with a constant DC supply to
the Vcc pin. The module current in power-down mode is
less than 1mA.
NOTE: If this facility
is used, the logic control signal must have a slew rate
of 40mV/ms or more. Slew rates less than this value
may cause erratic operation of the on-board regulator
and therefore the module itself.
The TX2A incorporates a low voltage shutoff circuit
which prevents any possibility of erratic operation
by disabling the RF output if the supply voltage drops
below 2.2V (±5%). This feature is self-resetting,
i.e. restoring the supply to greater than 2.2V will
immediately restore full RF output from the module.
TX2A modulation requirements
The module will produce the specified FM deviation
with a TXD input to pin 7 of 2.5V amplitude, i.e. 0V
"low", 2.5V "high". Reducing the
amplitude of the data input from this value (usually
as a result of reducing the supply voltage) reduces
the transmitted FM deviation to typically ±25kHz
at the lower extreme of 2.2V. The receiver will cope
with this quite happily and no significant degradation
of link performance should be observed as a result.
Where standard 2-level digital data is employed with
a logic "low" level of 0V ±0.2V, the
logic "high" level applied to TXD may be any
value between +2.5V and +3V for correct operation. However,
if using multi-level or analogue signalling the maximum
positive excursion of the modulation applied to TXD
must not exceed +2.5V or waveform distortion will result.
If the input waveform exceeds this level a resistive
potential divider should be used at the TXD input to
reduce the waveform amplitude accordingly. This input
is high impedance (>100kW)
and can usually be ignored when calculating required
resistor values.
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Data formats and range extension
The TX2A data input 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 7) be DC-biased to 1.25V with the modulation
ac-coupled and limited to a maximum of 2.5Vp-p to minimise
distortion over the link. The varactor modulator in
the TX2A 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
RX2A AF output is used to drive an external decoder
directly.
Both the AF output on pin 8 and the
RXD output on pin 9 of the RX2A are "true"
sense, i.e. as originally fed to the transmitter.
Although the modulation bandwidth
of the TX2A extends down to DC, as does the AF output
of the RX2A, 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
RX2A audio output.
The RX2A incorporates a low pass
filter which works in conjunction with similar filtering
in the TX2A to obtain an overall system bandwidth of
32kHz. This is suitable for transmission of data at
raw bit rates up to 10kbps and 64kbps, depending on
the receiver version. To keep settling times within
reasonable limits for the data speed in use, the adaptive
data slicer in the RX2A is subject to a maximum time
limit between data transitions (see page 5). This limitation
must be taken into account when choosing a code format.
It is strongly recommended that a reasonably balanced
code containing no long 1s or 0s (such as Manchester
or similar) is employed.
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, because of the limitations of
the internal data slicer it is better to use the RX2A
audio output to drive an external filter and data slicer.
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| Received
Signal Strength Indicator (RSSI)
The module 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 3 of the module has a standing DC
bias of 0.15V-0.45V (0.25V typ.) with no signal, rising
to 0.9-1.3V (1.15V typ.) at maximum indication. The
RSSI output source impedance is high (~50kW)
and external loading should therefore be kept to a minimum.
To ensure a fast response the RSSI has limited internal
decoupling of 1nF to ground. This may result in a small
amount of ripple on the DC output at pin 3 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 3 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.
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Typical RSSI characteristic
is shown below (this is for indicative purposes only
and is not a guarantee of actual RSSI characteristics):
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Figure 6: Typical RSSI response curve
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| Module
mounting considerations
The module may be mounted vertically or bent horizontal to
the motherboard. 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 pin at the antenna
end of the module, and not to the OV pin which is intended as
a DC ground 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 50W
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.
The module may be potted if required in a viscous compound
which cannot enter the screen can.
Warning: DO NOT wash the module. It is not hermetically sealed.
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|
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| Figure
7: Module mounting options |
| Variants
and ordering information
The TX2A is manufactured in several variants
depending on their supply voltage and operating frequency:
Supply voltage:
| 3V version: |
TX2A-433-64-3V |
Direct replacement for the
TX2-433-40-3V |
| 5V version: |
TX2A-433-64-5V |
Direct replacement for the
TX2-433-40-5V |
| Standard: |
TX2A-433-64 |
Different frequency replacement
for TX3A |
The standard frequency is 433.92MHz, for other frequency variants,
please contact sales department.
The RX2A receiver is manufactured in several variants depending
on the :
| Data rate: |
|
|
| Slower version: |
7.8kHz baseband B/W |
data rate up to 10kbps (suffix
-10) |
| Faster version: |
50kHz baseband B/W |
data rate up to 64kbps (suffix
-64) |
Frequency: 433.92MHz (suffix -433)
434.42MHz (suffix -434)
The following variants are standard:
RX2A-433-10 (433.92MHz, 10kbps)
RX2A-433-64 (433.92MHz, 64kbps)
For other variants please contact our Sales Department
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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
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