Data Sheet

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
AiM1
Issue 1, 04 February 2015
Frequency Programmable 25kHz NBFM VHF Transceiver
The narrow band AiM1 transceiver offers a
low power, reliable data link in a
Radiometrix transceiver standard pin out
and footprint. The AiM1 is a frequency
programmable,
narrowband
design,
suitable for licensed and unlicensed VHF
allocations
and
2M
amateur
band
applications.
Features
Figure 1: AiM1-144.390-5
Conforms to EN 300 220-3 and EN 301 489-3 (10mW version only)
Standard frequency 144.390MHz
Other frequencies from 120MHz to 175MHz: see BiM1B
Data rates up to 5kbps for standard module
Usable range over 1km
Low power requirements
25kHz Channel spacing
Feature-rich interface (true analogue and/or digital baseband)
The AiM1 is a half duplex radio transceiver module for use in long range bi-directional data transfer
applications at ranges up to 1kilometres. AiM1 is available for operation on the amateur 144MHz band
allocation as standard. AiM1 is also available as separate AiM1T transmitter and AiM1R receiver, which can
be, used as dual-in-line equivalents of TX1 transmitter and RX1/NRX1 receiver respectively.
Applications
Amateur radio
APRS systems
Packet operation
FM simplex telephony
Repeater monitoring
Technical Summary
Fully integrated sigma-delta PLL synthesizer based design
High stability TCXO reference
Data bit rate: 5kbps max.
Transmit power: +13dBm (20mW)
Image rejection: >70dB
Receiver sensitivity: -120dBm (for 12dB SINAD)
RSSI output with >50dBm range
Supply: 3.3V - 15V @ 30mA transmit, 18mA receive
Dimensions: 33 x 23 x 9mm
Evaluation platforms: NBEK + BiM / SMX carrier
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 1
Figure 2: AiM1 schematics
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 2
Functional description
The transmit section of the AiM1 consists of a highly integrated sigma delta (fractional N) synthesizer based
single chip RF device, configured over an SPI serial bus by an on-board microcontroller. The primary
frequency reference for the transmitter is a 30MHz VC-TCXO. Modulation is applied directly to this reference
via an AF baseband filter (rather than using the chip's internal modulator) to permit a wider range of
baseband data rates and waveforms. Operation is controlled by the N_TXE line, the transmitter achieving full
RF output typically within 5ms of this line being pulled low. The RF output is filtered to ensure compliance
with the appropriate radio regulations and fed to the 50Ω antenna pin.
The receiver section of the AiM1 consists of a highly integrated sigma delta (fractional N) synthesizer based
Local Oscillator (LO), configured over an SPI serial bus by an on-board microcontroller. The primary
frequency reference for the LO is a 26MHz VC-TCXO. The remainder of the reciever is a conventional dula
conversion superhet, using a wide dynamic range mosfet mixer and crystal / ceramic filter elements for
optimum performance. The RF input is filtered using a multi-stage LC filter in the frontend to provide image
rejection and enhanced blocking performance. This reduces the user programmable frequency range to the
filter passband, but can easily be re-banded (in the factory) to other frequencies.
User interface
Side view
9mm
top view
RF GND 1
Antenna 2
RF GND 3
4
5
6
No pin
7
8
9
18
17
16
15
14
13
12
11
10
RF OUT (TX)*
RF IN (RX)*
30.48 mm
33 mm
0 Volt
Vcc
N_TXE
TXD
AF
RXD
RSSI
0 Volt
23 mm
recommended PCB hole size: 1.2 mm
module footprint size: 25 x 32 mm
pin pitch: 2.54 mm
pins 4, 5, 6, 7, 8 & 9 are not fitted
Figure 3: AiM1 pin-out and dimension
AiM1 Pin
1, 3, 10, 18
17
16
15
14
13
12
Name
0V
VCC
N_RXE / RX PGM
N_TXE / TX PGM
TXD
AF
RXD
Function
Ground
3.3 – 15V DC power supply
Pull low to enable Receiver / receive programming in put
Pull low to enable Transmitter / transmit programming in put
DC coupled input for 3V CMOS logic. Rin = 100kΩ
500mV pk-pk audio. DC coupled, approx 1.5V bias
Open collector output, with a 10kΩ pullup to Vcc. Suitable for Biphase
codes
DC level between 0.5V and 2V. 50dB dynamic range
11
RSSI
NOTES:
1. N_Rxe and N_Txe have (10K approx.) pullups to +Vin
2. Unit is programmable using the N_Rxe or N_Txe pins. Contact Radiometrix for details
Reprogramming requires a 0v to +Vin logic level non-inverted RS232 data-stream to pin 3 or 4
An RS232 port can be directly connected to the enable pin for programming
3. Avoid N_Rxe and N_Txe both low: undefined module operation (but damage will not result)
4. Pinout is as BiM1. On RF connector end only pins 1,2,3 are present (*except for AiM1 with separate RX
and TX ports which has 4 pins. See ordering info ( p10) for further details on this special built).
5. Switching time as controlled by N_Txe or N_Rxe pins is <5mS, but when power is first applied to the
unit there is a 20mS long “calibration” period before the transmitter becomes active.
If the rail is switched (as opposed to the EN pin) then this should be considered as a 25mS device
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 3
Absolute maximum ratings
Exceeding the values given below may cause permanent damage to the module.
Operating temperature
Storage temperature
-20°C to +70°C
-30°C to +85°C
RF in (pin 1)
All other pins
±50V @ <10MHz, +13dBm @ >10MHz
-0.3V to +15.0V
Performance specifications:
(Vcc = 5V / temperature = 20°C unless stated)
General
DC supply
Supply voltage
TX Supply current (20mW)
RX Supply current
Antenna pin impedance
RF centre frequency
Channel spacing
Number of channels
Transmitter
RF
RF power output
Spurious emissions
Adjacent channel TX power
Frequency accuracy
FM deviation (peak)
Baseband
Modulation bandwidth @ -3dB
TXD input level (logic low)
TXD input level (logic high)
pin
min.
typ.
max.
units
17
17
17
3.3
30
18
15
V
mA
mA
2
2
2
50
144.390
25
1
+12
±2.5
+13
-50
-37
±1.5 (5ppm)
±3.0
0
14
14
Baseband
Baseband bandwidth @ -3dB
AF level
DC offset on AF out
Distortion on recovered AF
Radiometrix Ltd.,
2, 13
2, 12
2, 11
2
2
2
2
50
+14
dBm
dBm
dBm
kHz
kHz
4
5
3.5
kHz
V
V
DC coupled
6
6
5
ms
-70
dBm
dBm
dB
dB
dB
dB
dB
dBm
±3.5
-120
-112
50
84
70
63
13
13
13
12
AiM1 transceiver data sheet
70
5
500
1.5
5
1
1
0
3.0
Dynamic timing
TX select to full RF
Receiver
RF/IF
RF sensitivity @ 12dB SINAD
RF sensitivity @ 1ppm BER
RSSI range
Blocking
Image rejection
Adjacent channel rejection
Spurious response rejection
LO leakage, radiated
Ω
MHz
kHz
notes
kHz
mVP-P
V
%
2
3
7
3
4
8
Page 4
General
pin
Dynamic timing
RX enable with signal present
N_RXE active (low) to stable AF output
N_RXD active (low) to stable RXD
output
Signal applied with receiver enabled
Signal to valid AF
Signal to stable data
min.
typ.
max.
units
16, 13
16, 12
10
25
ms
2, 11
2, 12
10
25
ms
ms
notes
Notes:
1.
2.
3.
4.
5.
6.
7.
8.
Programs to any frequency with in the 120 - 175MHz range
Measured into 50Ω resistive loads.
Exceeds EN/EMC requirements at all frequencies.
5ppm TCXO. Total over full supply and temperature range.
With 0V – 3.0V modulation input.
To achieve specified FM deviation.
See applications information for further details.
For received signal with ±3kHz FM deviation.
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 5
Applications information
Power supply requirements
The AiM1 have built-in regulators which deliver a constant 3.3V to the transmitter and the receiver circuitry
when the external supply voltage exceeds 3.3V. This ensures constant performance up to the maximum
permitted 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). The unit will continue to function with a 3v supply, but power
output will fall".
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 14 of 3V amplitude,
i.e. 0V “low”, 3V “high
If the data input level is greater than 3V, a resistor must be added in series with the TXD input to limit the
modulating input voltage to a maximum of around 3V on pin 14. TXD input resistance is 100kΩ to ground,
giving typical required resistor values as follows:
Vcc
≤3V
3.3V
5V
9V
Series resistor
10 kΩ
68kΩ
220kΩ
RX Received Signal Strength Indicator (RSSI)
The AiM1 wide range RSSI which measures the strength of an incoming signal over a range of 50dB or
more. This allows assessment of link quality and available margin and is useful when performing range tests.
The output on pin 11 of the module has a standing DC bias of up to 0.5V (approx.) with no signal, rising to
around 2.0V at maximum indication. DVmin-max is typically 1V and is largely independent of standing bias
variations. Output impedance is 56kΩ. Pin 11 can drive a 100µA meter directly, for simple monitoring.
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.
Typical RSSI characteristic is as shown below:
Figure 4: RSSI level with respect to received RF level at AiM1 antenna pin
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 6
Expected range
Predicting the range obtainable in any given situation is notoriously difficult since there are many factors
involved. The main ones to consider are as follows:
•
•
•
•
•
Type and location of antennas in use
Type of terrain and degree of obstruction of the link path
Sources of interference affecting the receiver
“Dead” spots caused by signal reflections from nearby conductive objects
Data rate and degree of filtering employed
The following are typical examples – but range tests should always be performed before assuming that a
particular range can be achieved in a given situation:
Data rate
5kbps
5kbps
5kbps
Tx antenna
half-wave
helical
helical
Rx antenna
half-wave
half-wave
helical
Environment
rural/open
urban/obstructed
in-building
Range
3-4km
500m-1km
100-200m
The AiM1 TXD input is often driven directly by logic signals, but will also accept analogue drive (e.g. suitably
conditioned voice). In this case the TXD pin can either be directly DC driven with a 3v pp waveform with a
1.5v centre point, or a 3v pp signal can be AC coupled (when the input circuits will self-bias to 1.5v). Do not
exceed 3v pp, or the baseband waveform will begin to clip. The VC-TCXO in the AiM1 is highly linear, and
tx distortion figures well under 5% should be seen. At the other end of the link the AiM1 RXD pin may be
used to drive an external decoder, or the audio can be taken from the AF out pin to further audio processing
and amplification circuits
Although the modulation bandwidth of the AiM1B extends down to DC 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 AiM1B audio output.
The AiM1B in standard form incorporates a low pass filter with a 3.5kHz nominal bandwidth. This is suitable
for transmission of data at raw bit rates up to 5kbps.
In applications such as long range fixed links where data speed is not of prime concern, a considerable
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.
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 7
Module mounting considerations
Good RF layout practice should be observed. If the connection between module and antenna is more than
about 20mm long use 50Ω 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.
Variants and ordering information
The AiM1T transmitters, AiM1R receivers and AiM1 transceivers are manufactured in the following variants
as standard:
At 144.390MHz: AiM1-144.390-5
AiM1T-144.390-5
AiM1R-144.390-5
Transceiver
Transmitter
Receiver
(These can be reprogrammed on any frequencies with in the 144 - 146MHz
band)
AiM1 with separate TX and RX RF ports: AiM1-144.390-5-TR
The AiM1 can be factory built with separate RX and TX ports.
This special built will have 4 pins on the RF connector instead of three (refer to figure 3)
Pin 1 RF GND
2 RF OUT (TX)
3 RF GND
4 RF IN (RX)
The RF IN (RX) port MUST be externally AC coupled, as it has a bias voltage on it
This is useful if an application requires using an external TX power amp, RX pre-amp, or separate antennas
TX and RX.
Radiometrix Ltd.,
AiM1 transceiver data sheet
Page 8
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/
Information Requests
Ofcom
Riverside House
2a Southwark Bridge Road
London SE1 9HA
Tel: +44 (0)300 123 3333 or 020 7981 3040
Fax: +44 (0)20 7981 3333
[email protected]
European Communications Office (ECO)
Peblingehus
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
[email protected]
www.ero.dk