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
ENT1/ENR1
12.5kHz Channel VHF TX / RX
Issue 1, 27 July 2012
The ENT1 and ENR1 form a miniature VHF radio
transmitter/receiver pair designed for PCB
mounting and suitable for extended range
wireless data links at speeds up to 3kbps.
Wireless link ranges of 10km+ are achievable
with suitable choice of data rate and antennas.
Figure 1: ENT1 & ENR1
Features
Conforms to EN 300 220-3 (Radio) and EN 301 489-3 (EMC)
Versions available on 169.44375MHz and 169.40625MHz
12.5 kHz channel spacing
Data rates up to 3kbps
Usable range over 10km
Fully screened
Low power requirements
Applications
Remote meter reading
Industrial telemetry and telecommand
In-building environmental monitoring and control
High-end security and fire alarms
Technical Summary
ENT1
Supply range: 5v
Current consumption: 70mA Max
Data bit rate: 3kbps max.
Transmit power: 20dBm (100mW) nominal
Size: 43 x 14.5 x 5mm
ENR1
Double conversion FM superhet
SAW front end filter gives >80dB image rejection
Operation from 2.7V to 16V @ 13mA typical
Data bit rate: 5kbps max.
-115dBm sensitivity @ 1ppm BER
Size: 48 x 17.5 x 7.2mm
Evaluation platforms: NBEK + SIL carrier
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 1
Figure 2: ENT1 block diagram
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 2
Functional description: ENT1 transmitter
The ENT1 transmitter consists of a frequency modulated Voltage Controlled Temperature Controlled Crystal
Oscillator (VCTCXO) feeding a frequency multiplier with two stage amplifier and RF filter. Final Power
Amplifier stage is factory pre-set to appropriate band power level. Operation can be controlled by the EN
(Enable) line, the transmitter achieving full RF output typically within 7ms of this line being pulled high. The
RF output is filtered to ensure compliance with the appropriate radio regulations and fed to the 50Ω antenna
pin.
User interface
43mm
14.5mm
5mm
ENT1
pin spacing:
2.54 mm
15.24 mm
1
2
3
4
5
6
1 = RF gnd
2 = RF out
3 = RF gnd
4 = En
5 = Vcc
6 = 0V
7 = TXD
7
7 holes of 0.7 mm dia.
pin spacing 2.54 mm
Figure 3: ENT1 pin-out and dimension
RF GND
(Pins 1 & 3)
RF ground, internally connected to the module screen and pin 6 (0V). These pins should be directly
connected to the RF return path - e.g. coax braid, main PCB ground plane etc.
RF out
(Pin 2)
50Ω RF output to antenna. Internally DC-isolated. See antenna section of applications notes for details of
suitable antennas / feeds.
En
(Pin 4)
Tx enable. 0.15V or open-circuit on this pin disables module (current <1mA), 1.7V enables module. Input
impedance 1M approx. EN pin should not be left floating. Observe slew rate requirements (see applications
note).
Vcc
(Pin 5)
5V DC +ve supply. Max ripple content 0.1Vp-p. Decoupling is not generally required.
0V
(Pin 6)
DC supply ground. Internally connected to pins 1, 3 and module screen.
TXD
(Pin 7)
DC coupled input for 5V CMOS logic. Rin = 100k
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 3
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 4
RF
BPF
LNA
SAW
FILTER
OSC
X2
ENR1 BLOCK DIAGRAM
LNA
MIXER
21.4MHz
BPF
XTAL
20.945MHz
osc
Mix
455K
FILTER
Regulator
VCC
EN
RSSI
AF
Figure 4: ENR1 block diagram
AF
LPF
DATA
VCC
Functional description: ENR1 receiver
The ENR1 module is a double conversion NBFM superhet receiver capable of handling data rates of up to
5kbps. It will operate from a supply of 2.7V to 16V and draws 13mA when receiving. A signal strength (RSSI)
output with greater than 45dB of range is provided. The SIL style ENR1 measures 48 x 17.5 x 7.2 mm
excluding the pin
User interface
7.2 mm
17.5 mm
48 mm
pin spacing: 2.54 mm
25.4 mm
1
2
3
4
5
6
7
8
9
1 = RF in
2 = RF gnd
3 = RF gnd
4 = En
5 = RSSI
6 = 0V
7 = Vcc
8 = AF out
9 = RXD
9 holes of 0.7 mm dia. pin spacing 2.54mm
Figure 5: ENR1 pin-out and dimension
RF IN
(pin 1)
50 input from the antenna, DC isolated.
RF GND
(pin 2/3)
RF ground pin, internally connected to the module screen and pin 4 (0V). This pin should be
connected to the RF return path (coax braid, main PCB ground plane etc.)
En
(pin 4)
Rx enable. <0.15V shuts down module (current <1uA). >1.7V enables the receiver. Impedance
~1Mohm. Observe sle rate requirements (see apps notes).
RSSI
(pin 5)
Received signal strength indicator with 45dB range. See page 8 for typical characteristics.
0V
(pin 6)
DC supply ground. Internally connected to pin 2 and module screen.
Vcc
(pin 7)
DC supply. Max ripple content 0.1Vp-p.
AF out
(pin 8)
Buffered and filtered analogue output from the FM demodulator. Standing DC bias 0.75V approx.
External load should be >10kΩ // <100pF.
RXD
(pin 9)
Digital output from the internal data slicer. The data is a squared version of the signal on pin 8 (AF)
and is true data, i.e. as fed to the transmitter. Output is “open-collector” format with internal
10kΩpull-up to Vcc (pin 7).
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 5
Absolute maximum ratings
Exceeding the values given below may cause permanent damage to the module.
ENT1
Operating temperature
Storage temperature
RF out (pin 2)
All other pins
ENR1:
Operating temperature
Storage temperature
Vcc (pin 7)
RSSI, AF, RXD (pins 5,8,9)
RF IN (pin 1)
-40°C to +80°C
-40°C to +100°C
±50V @ <10MHz, +20dBm @ >10MHz
-0.3V to +5.5V
-20°C to +55°C
-40°C to +100°C
-0.1V to +16V
-0.1V to +3V
±50V DC, +10dBm RF
Performance specifications: ENT1
(Vcc = 5V / temperature = 20°C unless stated)
DC supply
Supply voltage
TX Supply current @ 100mW
Antenna pin impedance
RF centre frequency (100mW)
Channel spacing
Number of channels
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
5
5
2
4.5
5
65mA
50
169.406250
12.5
1
5.5
V
mA
MHz
kHz
+19
+20
+21
-1.5
±1.4
-40
0
±1.5
+1.5
±1.6
2
2
0
7
7
Dynamic timing
TX select to full RF
Notes:
1.
2.
3.
4.
5.
6.
0
5
7
2
notes
6
dBm
dBm
dBm
kHz
kHz
1
5
2
3
kHz
V
V
4
4
ms
Measured into 50Ω resistive load.
Total over full supply and temperature range.
With 0V – 5.0V modulation input.
To achieve specified FM deviation.
Meets EN300-220
Available on other frequencies from 120MHz to 180MHz (subject to MOQ and lead time)
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 6
Performance specifications: ENR1 receiver
(Vcc =5.0V / temperature = 20 C unless stated)
pin
min.
typ.
Max.
units
7
7
2.7
10
5.0
13
16
15
V
mA
1, 8
1, 9
1, 5
1
1
-118
70
-54
-120
-115
45
7.5
89
-65
<-70
>85
-
dBm
dBm
dB
kHz
dB
dBm
dB
dB
8
8
8
8
3,8
0
300
0.5
-
400
0.75
3
-
3
450
1.25
5
100
kHz
mVP-P
V
%
pF
Power up with signal present
Power up to valid RSSI
Power up to stable data
3,5
3,9
-
6.5
10
7.5
13
ms
ms
Signal applied with supply on
RSSI response time (rise/fall)
Signal to stable data
1,5
1,9
-
0.1
3.5
-
ms
ms
notes
DC supply
Supply voltage
Supply current
RF/ IF
RF sensitivity for 12dB (S+N/N)
RF sensitivity for 1ppm BER
RSSI range
IF bandwidth
Image rejection
LO leakage, conducted
Adjacent channel rejection
Blocking
Baseband
Baseband bandwidth @ -3dB
AF level
DC offset on AF out
Distortion on recovered AF
Load capacitance, AFout/RXD
1,2
1,2
1
1,2
DYNAMIC TIMING
Notes:
Radiometrix Ltd.,
1. For received signal with ±1.5kHz FM deviation.
2. Typical figures are for signal at centre frequency
ENT1/ ENR1 data sheet
Page 7
Applications information
Power supply requirements
The ENT1 transmitter requires a regulated 5V supply, but the ENR1 receiver incorporates a built-in regulator
which delivers a constant 2.8V to the module circuitry when the external supply voltage is 2.85V 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 2.85V 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 10µF lowESR tantalum or similar capacitor be added between the module supply pin (Vcc) and ground, together with
a 10Ω series feed resistor between the Vcc pin and the supply rail.
TX modulation requirements
The module is factory-set to produce the specified FM deviation with a TXD input to pin 14 of 5V amplitude,
i.e. 0V “low”, 5V “high
If the data input level is greater than 5V, a resistor must be added in series with the TXD input to limit the
modulating input voltage to a maximum of 5V on pin 7. TXD input resistance is 100kΩ to ground.
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 45dB. This allows assessment of link quality and available margin
and is useful when performing range tests.
The output on pin 5 of the module has a standing DC bias in the region of 0.6V with no signal,
rising to around 1.75V at maximum indication. The RSSI output source impedance is high
(~100k) and external loading should therefore be kept to a minimum.
Typical RSSI characteristic is as shown below:
1800
1600
RSSI Voltage
1400
1200
1000
800
600
400
200
0
-137 -130 -125 -120 -115 -110 -105 -100
-95
-90
-85
-80
-75
-70
-65
RF input level (dBm)
Figure 6: ENR1 RSSI response curve
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 8
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
1.2kbps
Tx antenna
half-wave
Rx antenna
half-wave
Environment
rural/open
Range
10-15km
The ENT1’s TXD input is normally driven directly by logic levels but will also accept analogue drive (e.g. 2tone signalling). In this case it is recommended that TXD (pin 14) be DC-biased to 2.5V approx. with the
modulation ac-coupled and limited to a maximum of 5Vp-p to minimise distortion over the link.
Although the modulation bandwidth of the ENT1 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 receiver’s audio output.
Antennas
The choice and positioning of transmitter and receiver antennas is of the utmost importance and is the single
most significant factor in determining system range. The following notes are intended to assist the user in
choosing the most effective antenna type for any given application.
Integral antennas
These are relatively inefficient compared to the larger externally-mounted types and hence tend to be
effective only over limited ranges. They do however result in physically compact equipment and for this
reason are often preferred for portable applications. Particular care is required with this type of antenna to
achieve optimum results and the following should be taken into account:
1. Nearby conducting objects such as a PCB or battery can cause detuning or screening of the antenna
which severely reduces efficiency. Ideally the antenna should stick out from the top of the product and
be entirely in the clear, however this is often not desirable for practical/ergonomic reasons and a
compromise may need to be reached. If an internal antenna must be used try to keep it away from other
metal components and pay particular attention to the “hot” end (i.e. the far end) as this is generally the
most susceptible to detuning. The space around the antenna is as important as the antenna itself.
2. Microprocessors and microcontrollers tend to radiate significant amounts of radio frequency hash which
can cause desensitisation of the receiver if its antenna is in close proximity. The problem becomes
worse as logic speeds increase, because fast logic edges generate harmonics across the VHF range
which are then radiated effectively by the PCB tracking. In extreme cases system range may be reduced
by a factor of 5 or more. To minimise any adverse effects situate antenna and module as far as possible
from any such circuitry and keep PCB track lengths to the minimum possible. A ground plane can be
highly effective in cutting radiated interference and its use is strongly recommended.
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 9
The following types of integral antenna are in common use:
Quarter-wave whip. This consists simply of a piece of wire or rod connected to the module at one end. At
169MHz the total length should be 421mm from module pin to antenna tip including any interconnecting wire
or tracking. Because of the length of this antenna it is almost always external to the product casing.
Helical. This is a more compact but slightly less effective antenna formed from a coil of wire. It is very
efficient for its size, but because of its high Q it suffers badly from detuning caused by proximity to nearby
conductive objects and needs to be carefully trimmed for best performance in a given situation. The size
shown is about the maximum commonly used at 169MHz and appropriate scaling of length, diameter and
number of turns can make individual designs much smaller.
2
Loop. A loop of PCB track having an inside area as large as possible (minimum about 5cm ), tuned and
matched with 2 capacitors. Loops are relatively inefficient but have good immunity to proximity detuning, so
may be preferred in shorter range applications where high component packing density is necessary.
Integral antenna summary:
Ultimate performance
Ease of design set-up
Size
Immunity to proximity effects
whip
***
***
*
**
helical
**
**
***
*
loop
*
*
**
***
421mm @ 169MHz
RF
Whip antenna
RF
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: integral antenna configurations
External antennas
These have several advantages if portability is not an issue, and are essential for long range links. External
antennas can be optimised for individual circumstances and may be mounted in relatively good RF locations
away from sources of interference, being connected to the equipment by coax feeder.
Helical. Of similar dimensions and performance to the integral type mentioned above, commerciallyavailable helical antennas normally have the coil element protected by a plastic moulding or sleeve and
incorporate a coax connector at one end (usually a straight or right-angle BNC type). These are compact
and simple to use as they come pre-tuned for a given application, but are relatively inefficient and are best
suited to shorter ranges.
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 10
Quarter-wave whip. Again similar to the integral type, the element usually consists of a stainless steel rod
or a wire contained within a semi-flexible moulded plastic jacket. Various mounting options are available,
from a simple BNC connector to wall brackets, through-panel fixings and magnetic mounts for temporary
attachment to steel surfaces.
A significant improvement in performance is obtainable if the whip is used in conjunction with a metal ground
plane. For best results this should extend all round the base of the whip out to a radius of 300mm or more
(under these conditions performance approaches that of a half-wave dipole) but even relatively small metal
areas will produce a worthwhile improvement over the whip alone. The ground plane should be electrically
connected to the coax outer at the base of the whip. Magnetic mounts are slightly different in that they rely
on capacitance between the mount and the metal surface to achieve the same result.
Metal ground plane
1/4-wave whip
1/ (3-4
4w , eq
av u
e all
ra y
di s p
al
a
el ce
em d)
en
ts
1/4-wave
whip
(421mm long @ 169MHz)
A ground plane can also be simulated by using 3 or 4 quarter-wave radials equally spaced around the base
of the whip, connected at their inner ends to the outer of the coax feed. A better match to a 50Ω coax feed
can be achieved if the elements are angled downwards at approximately 30-40° to the horizontal.
50 Ω coax feed
30
-40
de
g.
50 Ω coax feed
Fig.8: Quarter wave antenna / ground plane configurations
Half-wave. There are two main variants of this antenna, both of which are very effective and are
recommended where long range and all-round coverage are required:
1. The half-wave dipole consists of two quarter-wave whips mounted in line vertically and fed in the centre
with coaxial cable. The bottom whip takes the place of the ground plane described previously. A variant
is available using a helical instead of a whip for the lower element, giving similar performance with
reduced overall length. This antenna is suitable for mounting on walls etc. but for best results should be
kept well clear of surrounding conductive objects and structures (ideally >1m separation).
2. The end-fed half wave is the same length as the dipole but consists of a single rod or whip fed at the
bottom via a matching network. Mounting options are similar to those for the quarter-wave whip. A
ground plane is sometimes used but is not essential. The end-fed arrangement is often preferred over
the centre-fed dipole because it is easier to mount in the clear and above surrounding obstructions.
Yagi. This antenna consists of two or more elements mounted parallel to each other on a central boom. It is
directional and exhibits gain but tends to be large and unwieldy – for these reasons the yagi is the ideal
choice for links over fixed paths where maximum range is desired.
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 11
Module mounting considerations
The modules may be mounted vertically or bent horizontal to the motherboard.
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.
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.
Variants and ordering information
The ENT1 and ENR1 are manufactured on the 169.44375MHz and 169.40625MHz European frequency
allocation as standard.
ENT1-169.40625-3
ENR1-169.40625-3
ENT1-169.44375-3
ENR1-169.44375-3
RF outputof ENT1 can also be factory set from +5dBm (3mW) to +20dBm (100mW) depending on minimum
order quantity.
Note: Other variants of ENT1 and ENR1 can be supplied to individual customer requirements at frequencies
from 120MHz to 180MHz and/or optimised for specific data speeds and formats. However these are subject
to minimum order quantity (MOQ) and long lead time. Please consult the Sales Department for further
information.
Radiometrix Ltd.,
ENT1/ ENR1 data sheet
Page 12
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