Data Sheet(pdf)

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
SAR3
PRELIMINARY
Issue 1, 1 September 2009
Multi channel UHF FM Class 1 Social Alarm Receiver
The SAR3 is a miniature PCB mounting UHF
radio data receiver. It is a narrowband 25KHz
spacing receiver incorporating a received
signal strength indicator (RSSI) and 4 channel
capability. It allows the simple implementation
of data links at speeds up to 8kbps.
Figure 1: SAR3-869-8
Available for operation in European 868MHz band, the SAR3 combines full screening with internal filtering to
ensure EMC compliance by minimising spurious radiation and susceptibility. The module suits one-to-one
and multi-node wireless links in applications including automatic meter reading (AMR), car and building
security, Social alarms, EPOS and inventory tracking and remote industrial process monitoring.
Features
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Designed to comply with harmonised radio standard EN 300 220-3
Designed to comply with harmonised EMC standard EN 301 489-3
Class 1 performance (as per EN 300-220 V2.3.1)
Data rates up to 8kbps
4 pre programmed 869MHz band social alarm frequencies as standard
Versions available on any frequency from 868 to 869MHz
Fully screened
4 channel selectable
Technical Summary
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Double conversion FM superhet
SAW front end filter gives >65dB image rejection
Operation from 4V to 16V @ 46mA typical
Built-in regulator for improved stability and supply noise rejection
-115dBm sensitivity @ 1ppm BER
RSSI output with 65dB range
Radiometrix Ltd
SAR3 Data Sheet
page 1
6.1 mm
21.8 mm
47 mm
pin spacing: 2.54 mm
22.85 mm
1
2
3
4 5
6
7
8
10 holes of 0.7 mm dia. pin spacing 2.54mm
9
10
1 = RF in
2 = RF gnd
3 = Fsel 1
4 = Fsel 2
5 = EN
6 = RSSI
7 = Gnd
8 = VCC
9 = AF
10 = RXD
Fig. 2: Physical dimensions
Pin description
RF IN
pin 1
50 Ohm input from the antenna, DC isolated.
RF GND pin 2
RF ground pin, internally connected to the module screen and pin 7 (GND). This pin should be connected to
the RF return path (coax braid, main PCB ground plane etc.)
FSEL 1 pin 3 Internal 10K pullup
FSEL 2 pin 4 Internal 10K pullup
En
FSEL 1 FSEL 2
1
1
1
0
0
1
0
0
STANDARD FREQUENCIES
869.2125MHz (Fsel 1 and 2 open cct.)
869.2375 MHz
868.650 MHz
869.675 MHz
pin 5
Rx enable. <0.15V shuts down module (current <1uA). >1.7V enables the receiver. Impedance ~1Mohm.
RSSI
pin 6
Received signal strength indicator with 65dB range. See page 5 for typical characteristics.
0V
pin 7
DC supply ground. Internally connected to pin 2 and module screen.
Vcc
pin 8
DC supply. Max ripple content 0.1Vp-p.
AF out
pin 9
Buffered and filtered analogue output from the FM demodulator. Standing DC bias 1.0V approx. External
load should be >10kΩ // <100pF.
RXD
pin 10
Digital output from the internal data slicer. The data is a squared version of the signal on pin 9 (AF) and is
true data, i.e. as fed to the transmitter. Output is “open-collector” format with internal 47kΩ pull-up to Vcc
(pin 8).
Radiometrix Ltd
SAR3 Data Sheet
page 2
Absolute maximum ratings
Exceeding the values below may cause permanent damage to the module.
Operating temperature
-20°C to +55°C
Storage temperature
-40°C to +100°C
Vcc (pin 8)
-0.3V to +16V
RSSI, AF, RXD (pins 6, 9, 10) -0.1V to +3V
RF IN (pin 1)
±50V DC, +10dBm RF
Performance specifications
Figures apply to standard version @ Vcc=5.0V, temperature +20°C, unless stated.
General
Supply voltage
Supply current
pin
8
8
min.
4
-
typ.
5
46
max.
16
55
units
V
mA
notes
RF/IF
RF sensitivity for 12dB (S+N/N)
RF sensitivity for 1ppm BER
1, 2
1, 2
-118
-
-120
-115
-
dBm
dBm
1, 2
1, 2
1, 2
1
1
-54
-44
-20
65
15
65
-65
-10
100
-
dB
kHz
dB
dBm
dBm
dBm
dB
9
9
9
9
9
0
600
0.65
-
700
0.95
4
-
4.5
800
1.5
6
100
kHz
mV p-p
V
%
pF
Dynamic Timing
Rx power up with signal present
Power up to valid RSSI, tPU-RSSI
Power up to stable data, tPU-data
8
10
-
40
40
55
55
ms
ms
Signal applied with Rx on
RSSI response time (rise/fall)
Signal to stable data, tsig-data
1, 6
10
-
1
1
-
ms
ms
RSSI range
IF bandwidth
Image rejection (fRF-21.4MHz)
LO leakage, conducted
Adjacent channel rejection
Blocking
Blocking (relative)
Baseband
Baseband bandwidth @ -3dB
AF level
DC offset on AF output
Distortion on recovered AF
Load capacitance, AF & RXD
1
1, 2
Note: 1. For received signal with ±3kHz FM deviation 1kHz tone
2. Typical figures are for signal at centre frequency
Radiometrix Ltd
SAR3 Data Sheet
page 3
VCC
455K
F IL T E R
DATA
P L L /P IC
O S C IL L A T O R
F sel 1
F sel 2
XTAL
BPF
M IX E R
AF
M ix
VCTCXO
13M H z
RF
AF
LPF
2 1 .4 M H z
o sc
LNA
LNA
R SSI
SAW
F IL T E R
BPF
VCC
EN
2 0 .9 4 5 M H z
R e g u l a to r
Fig. 3: SAR3 block diagram
Power supply requirement
The SAR3 incorporates a built-in regulator which delivers a constant 4.0V to the module circuitry when the
external supply voltage is 4V 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 4V 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.
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 65dB. This allows assessment of link quality and available margin and is useful when
performing range tests.
The output on pin 6 of the module has a standing DC bias in the region of 0.8V with no signal, rising to
around 2.5V at maximum indication. The RSSI output source impedance is high (~100kΩ) and external
loading should therefore be kept to a minimum.
Typical RSSI characteristic is as shown below:
Typical RSSI characteristic is shown below (this is for indicative purposes only and is not a
guarantee of actual RSSI characteristics):
2600
2400
RSSI VOLTAGE
2200
2000
1800
1600
1400
1200
1000
800
600
400
-130
-120
-110
-100
-90
-80
-70
-60
-50
RF input level (dBm)
Fig. 4: Typical RSSI response
Radiometrix Ltd
SAR3 Data Sheet
page 4
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 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.
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.
Ordering Information:
SAR3-869-8 (869.2125MHz, 869.2375 MHz, 868.650 MHz and 869.675 MHz)
The SAR3 receiver is also available on other frequencies with in the 868 – 869MHz band. Please contact
sales department for further details.
Radiometrix Ltd
SAR3 Data Sheet
page 5
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
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