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Radiometrix
Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England
Issue 1, 06 March 2008
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233
LMT1/LMR1
VHF Narrow Band FM Low Cost multi channel radio modules
The LMT1 transmitter and LMR1
receiver modules offer a multi channel,
low power, and reliable VHF data link.
This makes the LMT1/LMR1 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.
Figure 1: LMT1 transmitter and LMR1 receiver
Features
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Conforms to EN 300 220-3 and EN 301 489-3
High performance double superhet. PLL synthesizer with TCXO
quasi-dc (peak sampling) data recovery circuit (for enhanced performance on unbalanced
datastreams)
Data rates up to 5 kbps for standard module
Usable range over 1km
Fully screened. Low profile
Feature-rich interface (RSSI, analogue and digital baseband)
Re-programmable via RS232 interface
Low power requirements
Applications
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Handheld terminals
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
Heavy vehicle/machinery controls
Technical Summary
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Operating frequency: 173.200 - 173.325MHz (UK band)
150.825 - 152.450MHz (Australian Band)
Other VHF frequencies available
4 UK allocation channels (32 maximum)
Transmit power: +10dBm (10mW) nominal @ 3.1V (Adjustable 1 - 25mW)
+20dBm (100mW) nominal @ 4.1V (Adjustable 25 - 100mW)
Supply range: 3.1 – 15V (@10mW) transmitter and receiver
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
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 1
Figure 2: LMT1 block diagram
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 2
Figure 3: LMT1 footpint (top view)
Pin description – LMT1
Pin
1a
Name
Vcc
2a
3a
4a
5a
0V
TXE
TXD
No pin
1b
P0/PGM
2b
3b
4b
5b
P1
P2
P3
No pin
Function
3.1 – 15V power supply (10mW)
4.1V – 15V power supply (100mW)
Ground
Transmit Enable (active low)
DC coupled input for 3V CMOS logic. Rin=47kΩ
Not present in LMT1
Parallel Channel select LSB
Serial frequency programming / configuration1
Parallel Channel select
Parallel Channel select
Parallel Channel select MSB
Not present in LMT1
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 (50kΩ) to 3v internal rail. Do not exceed 3V logic levels on
this port.
3. Channel select inputs are active low
4. TXE has a 100kΩ 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
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 3
Figure 4: LMR1 block diagram
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 4
Figure 5: LMR1 footpint (top view)
Pin description – LMR1
Pin
1a
2a
3a
4a
5a
Name
Vcc
0V
RXE
RXD
AF out
Function
3.1 – 15V power supply
Ground
Receiver Enable (active high)
Data out (open collector, no pullup)
700mV p-p audio. DC coupled, approx 0.8v bias.`
1b
P0/PGM
2b
3b
4b
5b
P1
P2
P3
RSSI
Parallel Channel select LSB
Serial frequency programming / configuration1
Parallel Channel select
Parallel Channel select
Parallel Channel select MSB
DC level between 0.5v and 2.2v. 60dB dynamic range
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 (50kΩ) 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 marginally 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.
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 5
Serial interface commands
2400 baud RS232. 8 bit data, no parity, 1 start bit, 1 or 2 stop bits.
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 rewriting of the e2prom will result. For this reason the user must send the 16 character string
ENABLESERIALMODE (followed by a carriage return) to activate 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)).
GOCHAN aa
LOAD aa nnnnn
SETPAR
SETSER
RVALUE rrrr
SINGLE nnnnn
Serially select channel aa, where aa is ch0 to ch31
Set value of N register for channel aa, where aa is Channels 0 to 31
Channel selected by 4 bit parallel inputs (ch0 to ch15 only)
Channel selected by most recent GOCHAN operation
Set value for R register
Set value of N for single channel operation.
N value NOT stored in EEPROM
Process entry
Clear all buffers
Disable command mode
<cr>
/
#
aa = a two digit channel number from 00 to 31
nnnnn = synthesizer N register value (up to 65535)
rrrr = synthesizer R register value (up to 16383)
For LMT1 Transmitter:
R=
N TX
f Xtal
=
10MHz
, So R=400
25kHz
f channelspacing
f RF
173.250MHz
=
=
= 6930
f Channelspacing
25kHz
For LMR1 Receiver:
R=
f Xtal
f channelspacing
N RX =
=
13MHz
, So R=520
25kHz
f RF − 21.4MHz 173.250MHz − 21.4
=
= 6074
f Channelspacing
25kHz
Notes: 1. A pause of at least 50ms must be allowed between command strings (EEPROM
programming time).
2. 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.
3. For UK version (173.200 - 173.325MHz band) the following channel assignment is
supplied:
CH0: 173.250MHz
CH1: 173.275MHz
CH2: 173.300MHz
CH3: 173.325MHz
CH4 - CH7: 173.225MHz (only used for alarm applications)
CH8 - CH31: 173.325MHz
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 6
Condensed specifications
Frequency
Any frequency in the 173MHz and 151MHz bands
In UK band, only 173.250, 173.275, 173.300 and 173.325 MHz are
used as standard
Other custom variants from 130 - 180MHz on any 2MHz band
Frequency stability
Channel spacing
Number of channels
Operating temperature
Spurious radiations
Transmitter
Output power
Peak deviation
TX on switching time
Modulation type
TX modulation bandwidth
Adjacent channel TX power
TX spurious
Supply
Voltage
Current
Inputs
Size
Interface
User
RF
Recommended PCB hole size
Receiver
Sensitivity
S/N ratio
AF bandwidth (-3dB)
image
Othr spurious
Blocking
Adjacent channel
LO re-radiation
Supply
Voltage
Current
Outputs
Size
Interface
User
RF
Recommended PCB hole size
Radiometrix Ltd
±1.5kHz
25kHz (12.5kHz by special order)
16 channels controlled by parallel port
or 32 via serial RS232 interface
-20 ºC to +70 ºC (Storage -30 ºC to +70 ºC)
Compliant with ETSI EN 300 220-3 and EN 301 489-3
+10dBm (10mW) ±1dB nominal (factory adjustable 1 - 25mW) and
+20dBm (100mW) ±1dB nominal (factory adjustable 25 - 100mW)
±3kHz (±1.5kHz @ 12.5kHz channel spacing)
30ms from TXE transition
FSK (F3D)
DC – 5kHz (3V CMOS compatible)
<-37dBm
<-40dBm (no RF output in Standby)
3.1V – 15V (10 – 25mW)
4.1V – 15V (25 – 100mW);
34mA nominal transmit (@10mW)
90mA nominal transmit (@100mW)
<8µA standby (TXE high or floating)
data (CMOS/TTL compatible)
33 x 23 x 9mm
10 (8) pin 0.1" pitch dual row (5+5) header
2pin 0.1” pitch
1.2mm
-118dBm for 12dB SINAD
35dB (min), 40dB (typ) on AF output
4kHz
<-60db
<-70dbm
Better than 84dB
<-60dB
-70dBm
3.1V – 15V
20mA receive
<1µA standby (RXE low)
RSSI, audio, data (quasi DC data recovery circuit)
46 x 23 x 9 mm
10 pin 0.1" pitch dual row (5+5) header
2pin 0.1” pitch
1.2mm
LMT1/LMR1 Data Sheet
page 7
RX Received Signal Strength Indicator (RSSI)
The LMR1 has wide range RSSI that 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.
RSSI output (V)
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). ∆Vmin-max is typically 2V and is
largely independent of standing bias variations. Output impedance is 40kΩ. Pin 5b can drive a 100µA
meter directly, for simple monitoring.
2.6
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-140 -130 -120 -110 -100 -90
-80
-70
-60
-50
-40
RF level (dBm)
Figure 6: typical RSSI level with respect to received RF level at LMR1 antenna pin
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 410mm (1/4 wave @ 173MHz). 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.
Ultimate performance
Easy of design set-up
Size
Immunity proximity effects
Radiometrix Ltd
A
whip
***
***
*
*
LMT1/LMR1 Data Sheet
B
helical
**
**
***
**
C
loop
*
*
**
***
page 8
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.
410mm @ 173MHz
R
F
Whip antenna
R
F
Helical antenna
RF
Ctune
C match
wire, rod, PCB track
or a combination of these
length(mm) = 71250 / freq(MHz)
35-40 turns wire spring
length 120mm, dia 10mm
trim wire length or expand coil for
best results
track width = 1mm
2
min. area 500mm
capacitors may be variable or fixed
(values depend on loop dimensions)
RF GND
Loop antenna
Figure 7: Antenna types
Ordering Information:
Part No.
LMT1-173-5
LMR1-173-5
LMT1-151-5
LMR1-151-5
Transmitter
Receiver
Transmitter
Receiver
Frequency band
(MHz)
173.225 - 173.325
173.225 - 173.325
150.825 - 152.450
150.825 - 152.450
LMT1-173-5-12k5
LMR1-173-5-12k5
LMT1-151-5-12k5
LMR1-151-5-12k5
Transmitter
Receiver
Transmitter
Receiver
173.225 - 173.325
173.225 - 173.325
150.825 - 152.450
150.825 - 152.450
10
LMT1-173-10
LMR1-173-10
Transmitter
Receiver
173.225 - 173.325
173.225 - 173.325
10
25
25
10
10
LMT1-xxx-5
LMR1-xxx-5
Where xxx is any 2MHz band
from 130MHz to-180MHz
10/100
25
25
5
5
Radiometrix Ltd
Description
RF power
(mW)
10
100
100
LMT1/LMR1 Data Sheet
Channel spacing
(kHz)
25
25
25
25
Data rate
kbps
5
5
5
5
12.5
12.5
12.5
12.5
5
5
5
5
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/radiocomms/ifi/
Information Requests
Ofcom
Riverside House
2a Southwark Bridge Road
London SE1 9HA
Tel: +44 (0)845 456 3000 or 020 7981 3040
Fax: +44 (0)20 7783 4033
[email protected]
European Radiocommunications Office (ERO)
Peblingehus
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
[email protected]
www.ero.dk