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
LMT1/LMR1
The LMT1 transmitter and LMR1 receiver
modules offer a 12.5kHz / 25kHz channel
spacing 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.
Issue 2, 30 July 2012
VHF Narrow Band FM Low Cost multi channel radio modules
Figure 1: LMT1 transmitter and LMR1 receiver
Features
Conforms to EN 300 220-2 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 UART interface
Low power requirements
Applications
Handheld terminals
Industrial telemetry and telecommand
In-building environmental monitoring and control
High-end security and fire alarms
Heavy vehicle/machinery controls
Technical Summary
Operating frequency:
144-146MHz Amateur Radio
150.825-152.450MHz Australian LIPD Band
151.820-154.600MHz US Multi-Use Radio Service (MURS) band
156.525MHz Global Maritime Distress and Safety System
173.200 - 173.325MHz UK Telemetry, Telecommand, Fixed Alarm band
173.20375-173.39625MHz US FCC Part 90.238 Telemetry
Other custom variants from 130 - 180MHz on any 2MHz band
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)
Evaluation platforms:
NBEK + LM Series carrier
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 1
Radiometrix Ltd
LMT1/LMR1 Data Sheet
Figure 2: LMT1 block diagram
page 2
Figure 3: LMT1 footprint (top view)
Pin description –
LMT1
Pin
1a
2a
3a
4a
5a
1b
2b
3b
4b
5b
Name
Vcc
0V
TXE
TXD
No pin
P0/PGM
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. R
in
=47kΩ
See note 10 below for phase modulation (–PM) version
Not present in LMT1
Parallel Channel select LSB
1
Serial frequency programming / configuration
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 UART data stream applied to
the P0 pin.
2. Channel select inputs have pull-ups (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 pull-up 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 spurii.
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
10.
Phase Modulation (-PM) version LMT1:
2.6V peak-to-peak level 2100Hz sinewave tone via an
external 680pF series capacitor will produce FM deviation of 4.2kHz.
GND
RF
680pF
TXD
2.6V
pk-pk
2100Hz
LMT
The external 680pF series capacitor on LMT1 TXD input provides a defined 6dB per octave pre
emphasis response, to mimic the behavior of a Phase Modulated transmitter.
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 3
Radiometrix Ltd
LMT1/LMR1 Data Sheet
Figure 4: LMR1 block diagram
page 4
Figure 5: LMR1 footprint (top view)
Pin description –
LMR1
Pin
1a
2a
3a
4a
5a
1b
2b
3b
4b
5b
Name
Vcc
0V
RXE
RXD
AF out
P0/PGM
P1
P2
P3
RSSI
Function
3.1 – 15V power supply
Ground
Receiver Enable (active high)
Data out (open collector, no pull-up)
700mV p-p audio. DC coupled, approx 0.8v bias.
Parallel Channel select LSB
1
Serial frequency programming / configuration
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 UART data stream applied to the
P0 pin.
2. Channel select inputs have pull-ups (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
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