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LMT2/LMR2
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The LMT2 transmitter LMR2 receiver offer
a low power, reliable data link in an industry standard pin
out and foot print. This makes the LMT2/LMR2 pair ideally
suited to those low power applications where existing wideband
modules have insufficient range, or where low cost multi-channel
operation is needed without compromising on RF specification
or regulatory requirement.
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Figure 1: LMT2-433-5 and LMR2-433-5 |
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-
Conforms to EN
300 220-3 and EN 301 489-3
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High performance
double superhet, PLL synthesizer with TCXO
- quasi-dc (peak sampling) data recovery circuit (for enhanced
performance on unbalanced datastreams)
- SAW front end filter
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Data rates up
to 5 kbps for standard module
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Usable range over
1km
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Fully screened.
Low profile
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Feature-rich interface
(RSSI, analogue and digital baseband)
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Re-programmable
via RS232 interface
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Low power requirements
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Handheld terminals
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EPOS equipment,
barcode scanners
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Data loggers
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Industrial telemetry
and telecommand
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In-building environmental
monitoring and control
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High-end security
and fire alarms
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DGPS systems
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Vehicle data up/download
- Heavy vehicle/machinery controls
Technical Summary
- Operating
frequency: 433.875-434.650MHz (EU band)
458.525
- 459.1MHz (UK band)
- Other custom
UHF bands
- 32 channels
- Transmit
power: +10dBm (10mW) / +20dBm (100mW)
- Supply
range: 3.1 - 15V (TX @ 10mW and RX), 4.1 - 15V (TX @ 100mW)
- Current
consumption: 34mA @ 10mW, 90mA @ 100mW (transmit) and 20mA
(receive)
- Data bit
rate: 5kbps max. (standard module)
- Receiver
sensitivity: -118dBm (for 12 dB SINAD)
- Serial
configuration by inverted RS232 at 3V CMOS level
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| Evaluation
Platform: Narrow
Band Evaluation Kit |
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Figure 2: LMT2 block diagram |
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Figure 3: LMT2 Footprint
(Top view)
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| Pin Description - LMT2 |
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Pin
|
Name
|
Function
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|
1a
|
Vcc |
3.1 - 15V power supply
(@ 10mW)
4.1 - 15V power supply (@ 100mW) |
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2a
|
0V |
Ground |
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3a
|
TXE |
Transmit Enable (active low) |
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4a
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TXD |
DC coupled input for 3V CMOS
logic. Rin=47kW |
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5a
|
No pin |
Not present in LMT2 |
| 1b |
P0/PGM
|
Parallel Channel select LSB
Serial frequency programming / configuration1 |
| 2b |
P1 |
Parallel Channel select |
| 3b |
P2 |
Parallel Channel select |
| 4b |
P3 |
Parallel Channel select MSB |
| 5b |
No pin |
Not present in LMT2 |
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NOTES:
1. Serial programming is by an inverted, CMOS logic level,
2400 baud RS232 datastream applied to the P0 pin.
2. Channel select inputs have pullups (50kW)
to 3v internal rail. Do not exceed 3V logic levels on this
port.
3. Channel select inputs are active low
4. TXE has a 100kW
pullup to Vcc
5. All pins are on an 0.1" grid
6. The pins 5a/b are not present, but are included in footprint
for compatibility with other units in this family
7. In the 'off' state a PIN switch open circuits the RF output
pin. There are no 'off' state spuri.
8. Unit will operate (with marginally reduced specifications
and lower (6-8mW) output power) from a 3.0V rail. This must
be well regulated and without noise or ripple, as in this
state the unit's internal regulator no longer operates, and
provides no supply rejection.
9. 100mW versions should not be run continuously from supply
voltages > 9v
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Figure 4: LMR2 block diagram
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Figure 5: LMR2 Footprint
(Top view)
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| Pin Description -
LMR2 |
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Pin
|
Name
|
Function
|
| 1a |
Vcc |
3.1 - 15V power supply |
| 2a |
0V |
Ground |
| 3a |
RXE |
Receiver Enable (active high) |
| 4a |
RXD |
Data out (open collector, no
pullup) |
| 5a |
AF out |
700mV p-p audio. DC coupled,
approx 0.8v bias. |
| 1b |
P0/PGM
|
Parallel Channel select LSBSerial
frequency programming / configuration1 |
| 2b |
P1 |
Parallel Channel select |
| 3b |
P2 |
Parallel Channel select |
| 4b |
P3 |
Parallel Channel select MSB |
| 5b |
RSSI |
DC level between
0.5v and 2.2v. 60dB dynamic range |
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NOTES:
1. Serial programming is by an inverted, cmos
logic level, 2400 baud RS232 datastream applied to the P0 pin.
2. Channel select inputs have pullups (50kW)
to 3v internal rail. Do not exceed 3v logic levels on this port.
3. Channel select inputs are active low
4. All pins are on an 0.1" grid
5. Data recovery circuit used for RXD is not a simple 'average and
compare' type. It is a peak sampling quasi-DC coupled design, allowing
a greater than usual flexibility in data format.
6. Unit will operate (with maginally reduced specifications) from
a 3.0v rail. This must be well regulated and without noise or ripple,
as in this state the unit's internal regulator no longer operates,
and provides no supply rejection.]
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Serial interface commands
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| LMT2/LMR2 frequency/channel
can be serially configured using HyperTerminal or any other terminal
program configured with following setup: |
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| 2400 baud RS232, 8 bit
data, no parity, 1 start bit, 1 or 2 stop bits. No flow control |
| Serial data is sent
to the unit on one of the parallel channel select pins (P0). It is
very important that the unit does not 'decode' switch bounce in ordinary
operation as a command string, or spurious re-writing of the EEPROM
will result. For this reason the user must send the 16 character string
ENABLESERIALMODE to fully enable the serial command mode before sending
any of the command strings listed below. Command mode is disabled
on power down, or on reception of a # character. To successfully program
the unit, it must be enabled (RXE high (rx) or TXE
low (tx)). |
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| GOCHAN aa |
Serial select of
channel aa (0 to 31) |
| LOAD aa nnnnn |
Set value of N register for
channel aa, where aa is Channels 0 to 31 |
| RVALUE rrrr |
Set value for R register |
| SETPAR |
Channel selected
by 4 bit parallel inputs (ch0 to ch15 only) |
| SETSER |
Channel selected by most recent
'GOCHAN' operation |
| SINGLE nnnnn |
Set value of N for
single channel operation.
N value NOT stored in EEPROM |
| <cr> |
Process entry |
| / |
Clear all buffers |
| # |
Disable command mode |
aa = a two digit channel number from 00 to 31
nnnnn = a synthesizer N register value, (up to 65535)
rrrr = the synthesizer R register value, (up to 16383)
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So R = 520 |
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Notes:
A pause of at least 50ms must be allowed between command strings
(EEPROM programming time).
SINGLE mode does not store the N value in EEPROM. Therefore the
unit is inoperative after a power down until either another valid
SINGLE command is received, or mode is changed by a GOCHAN, SETPAR
or SETSER command. SINGLE mode is intended for frequency agile applications.
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| LMT2,
LMR2 channels are spaced at 50kHz interval into two frequency groups.
50kHz spacing between sequential channels minimises adjacent channel
interference.
e.g. 433MHz band
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Serial
or Parallel channel select
|
Frequency (MHz)
|
Serial channel select
|
Frequency (MHz)
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16
|
433.875 |
|
0 (P3:P0 = HHHH)*
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433.900 |
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17
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433.925 |
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1
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433.950 |
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18
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433.975 |
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2
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434.000 |
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19
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434.025 |
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3
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434.050 |
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20
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434.075 |
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4
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434.100 |
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21
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434.125 |
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5
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434.150 |
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22
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434.175 |
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6
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434.200 |
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23
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434.225 |
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7
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434.250 |
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24
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434.275 |
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8
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434.300 |
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25
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434.325 |
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9
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434.350 |
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26
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434.375 |
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10
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434.400 |
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27
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434.425 |
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11
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434.450 |
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28
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434.475 |
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12
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434.500 |
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29
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434.525 |
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13
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434.550 |
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30
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434.575 |
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14
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434.600 |
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31
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434.625 |
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15 (P3:P0=LLLL)*
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434.650 |
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NOTE: Parallel select pins: H=3V, L=
0V |
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Condensed specifications
| Frequency |
433MHz EU band,
and 458MHz UK bandAs supplied: EU version: 433.875 - 434.65MHz
(25kHz steps)
UK version 458.525 - 459.1MHz (25kHz steps)
and other custom UHF bands (depend on SAW filter) |
|
Frequency
stability
|
+/- 1.5kHz |
|
Channel
spacing
|
25kHz |
|
Number
of channels
|
16 channels controlled by parallel port or 32 via RS232
interface
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| Operating temperature |
-10 to +60 °C (Storage
-30 to +70 °C) |
| Spurious radiations |
Compliant with ETSI EN 300
220-3 and EN 301 489-3 |
| Intended approval |
ETSI EN 300 220-3 (radio)
and EN 301 489-3 (EMC) |
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| Transmitter |
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| Supply |
|
| Voltage |
3.1V - 15V (1-25mW)
4.1 - 15V (25 - 100mW) |
| Current |
34mA @ 10mW (nominal)
65mA @ 50mW (nominal)
90mA @ 100mW (nominal)
<5mA standby (TXE high or floating) |
| Output power |
+10dBm (10mW) ±1dB
(factory adjustable 1 - 25mW)
+20dBm (100mW) ±1dB (factory adjustable 25 - 100mW) |
| TX on switching
time |
50ms from power
up |
| Peak FM deviation |
+/-3kHz |
| Modulation type |
FSK (F3D) |
| TX modulation bandwidth |
DC - 5kHz (3V CMOS
compatible) |
| Adjacent channel TX power |
-37dBm |
| TX spurious |
<-45dBm (no RF output in
Standby) |
| Inputs |
data (CMOS/TTL compatible) |
| Size |
33x23x9mm |
| User |
10 (8) pin 0.1"
pitch dual row (5+5) header |
| RF |
2pin .1"
pitch |
| Recommended PCB
hole size |
1.2mm |
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| Receiver |
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| Sensitivity |
-118dBm for 12
dB SINAD |
| S/N ratio |
35dB (min), 40dB
(typ) on AF output |
| AF bandwidth (-3dB) |
4kHz |
| image |
< -60dB |
| other spurious |
<-70dBm |
| blocking |
better than -84dB |
| LO re-radiation |
-70dBm |
| adj. Channel |
better than -60dB (Tested
per. ETSI EN 301 489-3) |
| Supply |
|
| Voltage |
3.1V - 15V |
| Current |
20mA; <1mA
standby (RXE low) |
| outputs |
RSSI, audio, digital
data |
| Size |
46 x 23 x 9 mm |
| Interface |
|
| User |
10 pin 0.1"
pitch dual row (5+5) header |
| RF |
2pin 0.1"
pitch molex |
| Recommended PCB
hole size |
1.2mm |
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| Dynamic timing |
|
| RXE high/active
to RX AF stable |
25ms |
|
RXE high/active RX data stable
|
40ms |
| RX data recovery
settling time |
20ms |
| Power on to stable
(50:50 mark / space) RXD |
50ms
(TXE low/active to stable RX
data out) |
| Maximum time between data transitions |
250ms |
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RX Received Signal Strength Indicator (RSSI)
The LMR2 has 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 5b of the module has a standing DC bias of up
to 0.5V with no signal, rising to 2.5V at maximum indication (RF
input levels of -40dBm and above). DVmin-max
is typically 2V and is largely independent of standing bias variations.
Output impedance is 40kW. pin 5b can
drive a 100mA meter directly, for simple
monitoring.
Typical RSSI characteristic is as shown below:
Figure 6: RSSI level with respect to received RF level at LMR2
antenna pin
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| Antenna
requirements
Three types of integral antenna are recommended
and approved for use with the module:
A) Whip: This
is a wire, rod, PCB track or combination connected directly to RF
pin of the module. Optimum total length is 16cm (1/4 wave @ 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
B) Helical: Wire
coil, connected directly to RF pin, 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.
C) Loop:
A loop of PCB track tuned by a fixed or variable capacitor to ground
at the 'hot' end and fed from RF pin at a point 20% from the ground
end. Loops have high immunity to proximity de-tuning.
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A
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B
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C
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Whip
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Helical
|
Loop
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| Ultimate performance |
***
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**
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*
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| Easy of design set-up |
***
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**
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*
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| Size |
*
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***
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**
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| Immunity proximity effects |
*
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**
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***
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| Range open ground to similar
antenna |
500
|
200
|
100
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| 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. |
Figure 7: Antenna types
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| Ordering
Information |
| Part No. |
Description |
RF power (mW) |
Frequency
band (MHz) |
| LMT2-433-5 |
Transmitter |
10mW |
433.900- 434.650 |
| LMR2-433-5 |
Receiver |
- |
433.900 - 434.650 |
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| LMT2-458-5 |
Transmitter |
100mW |
458.525 - 459.1 |
| LMR2-458-5 |
Receiver |
- |
458.525 - 459.1 |
Note: Also available on the other UHF band frequencies subject to
SAW filter availability. e.g. 315, 419, 429, 448, 465MHz etc and with
different RF power outputs. |
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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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Figure 7: Antenna types
