RXM-315-LC-P [ETC]
LC SERIES RECEIVER MODULE DATA; LC系列接收器模块数据
| 型号： | RXM-315-LC-P |
| 厂家： | 
ETC |
| 描述： | LC SERIES RECEIVER MODULE DATA |
| 文件： | 总9页 (文件大小：381K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
RXM-315-LC-S
RXM-418-LC-S
RXM-433-LC-S
WIRELESS MADE SIMPLE ®
LC SERIES RECEIVER MODULE DATA GUIDE
Covers Ultra-Compact S-Style (True SMD Version)
DESCRIPTION
0.14 in.
The LC Series is ideally suited for volume use in
OEM applications such as remote control,
.630 in.
security, identification, and periodic data transfer.
Available in 2 styles of compact SMD packages,
.812 in.
the LC-S receiver utilizes a highly optimized SAW
architecture to achieve an unmatched blend of
performance, size, efficiency and cost. When
PHYSICAL DIMENSIONS
TOP VIEW
paired with a matching LC Series transmitter, a
highly reliable wireless link is formed, capable of
transferring serial data at distances in excess of
300 feet. No external RF components, except an
antenna, are required, making design integration
straightforward.
PINOUTS
FEATURES
■
■
■
■
Low Cost
■
■
■
■
■
Stable SAW-based Architecture
Outstanding Sensitivity
Supports Data Rates to 5,000bps
Direct Serial Interface
No External RF Components Required
Low Power Consumption
Compact True Surface-Mount
Package
No Production Tuning
ORDERING INFORMATION
APPLICATIONS INCLUDE
PART #
EVAL-***-LC
DESCRIPTION
Basic Evaluation Kit
■ Remote control / Keyless entry
■ Garage / Gate openers
■ Lighting control
MDEV-***-LC
RXM-315-LC-P
RXM-418-LC-P
RXM-433-LC-P
RXM-315-LC-S
RXM-418-LC-S
RXM-433-LC-S
Master Development Kit
Receiver 315MHZ (Pinned SMD)
Receiver 418MHZ (Pinned SMD)
Receiver 433MHZ (Pinned SMD)
Receiver 315MHZ (SMD)
Receiver 418MHZ (SMD)
Receiver 433MHZ (SMD)
■ Medical monitoring / Call systems
■ Remote industrial monitoring
■ Periodic data transfer
■ Home / Industrial automation
■ Fire / Security alarms
■ Wire Elimination
*** Insert Frequency
Not covered in this manual
LC Receivers are supplied in tube
packaging - 40 pcs. per tube.
■ Long-range RFID
Revised 12/20/01
PERFORMANCE DATA–RXM-***-LC
ABOUT THESE MEASUREMENTS
Parameters
RXM-418-LC-S
Designation
VCC
Min.
2.7
Typical
Max.
4.2
Units
VDC
VDC
mA
Notes
Operating Voltage
w/Dropping Resistor
Current Continuous
Current in Sleep
–
–
–
3
–
–
–
–
4
The performance parameters listed
below are based on module
5VDC
VCC
4.7
5.2
1
2
3
4
5
6
7
8
NC
ANT
GND
NC
16
15
14
13
12
11
10
9
operation at 25°C from a 3VDC.
Figure 1 at the right illustrates the
connections necessary for testing
and operation. It is recommended
that all ground pads be connected to
the groundplane. The pads marked
NC have no physical connection and
are designed only to add support.
200
NC
3VDC
External
ICC (VCC=3V)
ISLP (VCC=3V)
VOL
4.0
5.0
700
–
7.0
NC
Resistor
GND
VCC
PDN
NC
NC
–
930
0.2
µA
NC
NC
Data Out Voltage
Logic Low
0
VDC
VDC
VDC
NC
DATA
NC
Data Out Voltage
Logic High
VOH
VCC-0.3
2.7
–
VCC
Figure 1: Test/Basic Application Circuit
VOH
3.4
VCC
(Note 5)
Receive Frequency
Noise BW
FC
417.925
418
280
-95
–
418.075
–
MHz
kHz
–
–
1
_
2
ABSOLUTE MAXIMUM RATINGS
–
-92
100
5
Supply voltage VCC
-0.3
to
to
+4.2
+5.2
VDC
VDC
Sensitivity @10-5 BER
Baud Rate
-100
5,000
10
dBm
bps
-0.3
(SEE NOTES 3,4)
+70°C
Operating temperature
Storage temperature
Soldering temperature
RF input, pin 16
-30°C
-45°C
to
to
Settling Time
7
mSec
+85°C
+225°C for 10 sec.
0 dBm
Parameters
RXM-433-LC-S
Designation
VCC
Min.
2.7
Typical
Max.
4.2
Units
VDC
VDC
mA
Notes
Any input or output pin
-0.3
to
Vcc
Operating Voltage
w/Dropping Resistor
Current Continuous
Current in Sleep
–
–
–
3
–
–
–
–
4
*NOTE* Exceeding any of the limits of this section may lead to permanent
damage to the device. Furthermore, extended operation at these maximum
ratings may reduce the life of this device.
VCC
4.7
5.2
ICC (VCC=3V)
ISLP (VCC=3V)
VOL
4.0
5.0
700
–
7.0
Parameters
–
930
0.2
µA
RXM-315-LC-S
Designation
VCC
Min.
2.7
Typical
Max.
4.2
Units
VDC
VDC
mA
Notes
Data Out Voltage
Logic Low
Data Out Voltage
Logic High
0
VDC
VDC
VDC
Operating Voltage
w/Dropping Resistor
Current Continuous
Current in Sleep
–
–
–
3
–
–
–
–
4
VOH
VCC-0.3
2.7
–
VCC
VCC
4.7
5.2
VOH
3.4
VCC
(Note 5)
ICC (VCC=3V)
ISLP (VCC=3V)
VOL
4.0
5.0
700
–
7.0
Receive Frequency
Noise BW
FC
433.845 433.92
433.995
–
MHz
kHz
–
–
1
–
2
–
930
0.2
µA
Data Out Voltage
Logic Low
–
-92
100
5
280
-95
–
0
VDC
VDC
VDC
Sensitivity @10-5 BER
Baud Rate
-100
5,000
10
dBm
bps
Data Out Voltage
Logic High
VOH
VCC-0.3
2.7
–
VCC
VOH
3.4
VCC
(Note 5)
Settling Time
7
mSec
Receive Frequency
Noise BW
FC
314.925
315.0
280
-95
–
315.075
–
MHz
kHz
–
–
1
_
2
Notes:
1. For BER of 10-5 at 4800 baud. Sensitivity is affected by antenna SWR. See Figure 3.
2. Time to valid data output.
–
-92
100
5
Sensitivity @10-5 BER
Baud Rate
-100
5,000
10
dBm
bps
3. *CRITICAL* In order to operate the device over this range it is necessary for a 200 resistor to be placed
in-line with VCC.
4. When operating from a 5 volt source it is important to consider that the output will swing to well less than
5 volts as a result of the required dropping resistor. Please verify that the minimum voltage will meet the
high threshold requirment of the device to which data is being sent.
Settling Time
7
mSec
5. Maximum output voltage measured after in-line dropping resistor.
Page 2
Page 3
PHYSICAL PACKAGING
TYPICAL PERFORMANCE GRAPHS
The receiver is packaged as a hybrid SMD module with sixteen pads spaced
0.100" on center. The castellated SMD package allows for easy prototyping or
hand assembly while maintaining full compatibility with automated pick-and-
place equipment. Modules are supplied in tube packaging.
SENSITIVITY vs. VSWR
(VSWR)
Supply current
(mA)
16
12
8
10.0
6.0
5.0
4.0
3.0
2.5
2.0
1.5
1.0
4
0
2.7
3
3.5
4 (V)
0
0.18
0.5 0.9 1.25 1.94 2.53 3.10 4.80
SENSITIVITY DECREASE (dB)
16
15
14
13
12
11
10
9
ANT
GND
NC
NC
NC
1
2
3
4
5
6
7
8
Supply voltage
0.812"
NC
Figure 4: Consumption vs. Supply Voltage
Figure 3: Sensitivity vs. VSWR
NC
GND
VCC
PDN
NC
NC
0.630"
NC
0.14"
NC
LOT 2000
NC
DATA
Data Out
Bottom View
Data Out
Figure 2: LC-S Series Receiver Package Dimensions
Carrier
Carrier
PIN DESCRIPTIONS:
Pin 1, 2, 3, 7, 9, 10, 11, 12, 13, 14 - NO CONNECTION
Figure 5: RF in vs. Receiver Response Time
Figure 6: Typical Receiver Turn-Off Time
Attach to an isolated pad to provide support for the module. Do not make any electrical
connection.
Pin 4, 15 - GROUND
Original
Original
Connect to quiet ground or groundplane. It is internally connected to pin 8.
Pin 5 - POSITIVE SUPPLY (VCC 2.7 - 4.2 VDC *4.7 - 5.2 w/ external dropping resistor)
Received
Received
The supply must be clean (<20mVpp), stable and free of high-frequency noise. A supply
filter is recommended unless the module is operated from its own regulated supply or
battery. Please note that operation from 4.7 to 5.2 volts requires the use of an external
200 resistor placed in series with V .
CC
Figure 8: Original vs. Received Data
4,800bps 80% Duty Cycle
Figure 7: Original vs. Received Data
4,800bps 20% Duty Cycle
Pin 6 - POWER DOWN
Pull this line low to put the receiver in sleep mode (700 µA). Leave floating or pull high to
enable the receiver.
Pin 8 - DATA OUT
P
DN Pin
Internally pulled to VCC. Open collector data output with internal pullup to VCC. Recovered data
is output on this pin. Output voltage during a high bit will average VCC- 0.3V.
Data Out
Pin 16 - RF IN
The receiver antenna connects to this input. It has nominal RF impedance of 50 and is
capacitively isolated from the internal circuitry.
Figure 9: Power-On Settling Time
(Time to Valid Data)
Page 5
Page 4
PRODUCTION GUIDELINES
AUTOMATED ASSEMBLY
The LC modules are packaged in a hybrid SMD package that supports hand- or
automated-assembly techniques. Since LC devices contain discrete
components internally, the assembly procedures are critical to ensuring the
reliable function of the LC product. The following procedures should be reviewed
with and practiced by all assembly personnel.
For high-volume assembly most users will want to auto-place the modules. The
receivers have been designed to maintain compatibility with reflow processing
techniques; however, due to the module's hybrid nature certain aspects of the
assembly process are far more critical than for other component types.
Following are brief discussions of the three primary areas where caution must be
observed.
PAD LAYOUT
The following pad layout diagrams are designed to facilitate both hand and
automated assembly.
Reflow Temperature Profile
The single most critical stage in the automated assembly process is the reflow
process. The reflow profile below should be closely followed since excessive
temperatures or transport times during reflow will irreparably damage the modules.
Assembly personnel will need to pay careful attention to the oven's profile to
ensure that it meets the requirements necessary to successfully reflow all
components while still meeting the limits mandated by the modules themselves.
LC-S RX Layout Rev. 1
TX Layout Pattern Rev. 2
LC-P RX Layout Pattern Rev. 3
(Not to Scale)
Compact SMD Version
Pinned SMD Version
(Not to Scale)
(Not to Scale)
0.100"
0.150
.100
0.065"
0.610"
0.310"
0.100"
.070
0.070"
0.775
0.070"
0.100"
300
250
200
150
100
50
Ideal Curve
Limit Curve
Forced Air Reflow Profile
Figure 10: Recommended Pad Layout
220oC
210oC
RECEIVER HAND ASSEMBLY
180oC
The LC-S Receiver’s primary mounting
surface is sixteen pads located on the
bottom of the module. Since these pads
are inaccessible during mounting,
castellations that run up the side of the
module have been provided to facilitate
solder wicking to the module's under-
side. If the recommended pad place-
ment has been followed, the pad on the
board will extend slightly past the edge
of the module. Touch both the PCB pad
and the module castellation with a fine
soldering tip. Tack one module corner
first, then work around the remaining
attachment points using care not to
exceed the times listed below.
Reflow Zone
125oC
Soldering Iron
Tip
20-40 Sec.
Soak Zone
2 Minutes Max.
Preheat Zone
2-2.3 Minutes
Cooling
Ramp-up
1-1.5 Minutes
0
0
30
60
90
120 150 180 210 240 270 300 330 360
Time (Seconds)
Solder
PCB Pads
Castellations
Figure 12: Required Reflow Profile
Shock During Reflow Transport
Revision 2 - 11/98
Figure 11: LC-S Soldering Technique
Since some internal module components may reflow along with the components
placed on the board being assembled, it is imperative that the module not be
subjected to shock or vibration during the time solder is liquidus.
Washability
Absolute Maximum Solder Times
The modules are wash resistant, but are not hermetically sealed. They may be
subject to a standard wash cycle; however, a twenty-four-hour drying time
should be allowed before applying electrical power to the modules. This will allow
any moisture that has migrated into the module to evaporate, thus eliminating the
potential for shorting during power-up or testing.
Hand-Solder Temp. TX +225°C for 10 Sec.
Hand-Solder Temp. RX +225°C for 10 Sec.
Recommended Solder Melting Point +180°C
Reflow Oven: +220° Max. (See adjoining diagram)
Page 6
Page 7
MODULE DESCRIPTION
POWER SUPPLY REQUIREMENTS
The receiver module requires a clean, well-regulated
power source. While it is preferable to power the unit from
a battery, the unit can also be operated from a power
supply as long as noise and ‘hash’ is less than 20 mV. A
10 resistor in series with the supply followed by a 10µF
tantalum capacitor from VCC to ground will help in cases
where the quality of supply power is poor. Please note that
operation from 4.7 to 5.2 volts requires the use of an
The RXM-LC-S is a low-cost, high-performance Surface Acoustic Wave (SAW)
based Carrier-Present Carrier-Absent (CPCA) receiver, capable of receiving
serial data at up to 5,000 bits/second. Its exceptional sensitivity provides
outstanding range at the maximum data rate. While oriented toward high-volume
automated production, the LC-S’s compact surface-mount package is also
friendly to prototype and hand production. When combined with a Linx LC series
transmitter, a highly reliable RF link capable of transferring digital data over line-
of-sight distances in excess of 300 feet (90m) is formed.
external 200 resistor placed in series with VCC
.
Figure 15: Supply Filter
THE DATA OUTPUT
50 Ω RF IN
(Ant.)
A CMOS-compatible data output is available on pin 8. This output is normally used to
drive directly a digital decoder IC or a microprocessor that is performing the data
decoding. The receiver’s output is internally qualified, meaning that it will only
transition when valid data is present. In instances where no carrier is present the
output will remain low. Since a UART utilizes high marking to indicate the absence of
data, a designer using a UART may wish to insert a logic inverter between the data
output of the RXM-LC-S and the UART.
Gilbert Cell
Mixer/Amp
10.7 Mhz
Bandpass Filter
Band Select
Filter
DATA
pre-
amplifier
10.7 Mhz
Limiting Amp Ceramic Filter
AM Detector
Data Slicer
SAW Local Oscillator
It is important to realize that the data output of the receiver may be subject to some
pulse stretching or shortening. This is caused by a combination of oscillator start-up
time on the transmitter and ring-down time in the receiver’s ceramic filter. It is
important to consider this effect when planning protocol. To learn more about protocol
considerations for the LC series we suggest you read Linx applications note #00232.
Figure 13: LC Series Receiver Block Diagram
THEORY OF OPERATION
The RXM-LC-S is designed to recover
data sent by a CPCA transmitter. This
type of AM modulation is often referred
to by other designations including CW
and OOK. As the CPCA designation
suggests, this type of modulation
represents a logic low ‘0’ by the
absence of a carrier and a logic high ‘1’
by the presence of a carrier. This
modulation method affords numerous
benefits. Two most important are: 1) Cost-effectiveness due to design simplicity
and 2) Higher output power and thus greater range in countries (such as the US)
which average output power measurements over time. Please refer to Linx
application note #00130 for a further discussion of modulation techniques
including CPCA.
RECEIVING DATA
Once a reliable RF link has been established, the challenge becomes how to
effectively transfer data across it. While a properly designed RF link provides
reliable data transfer under most conditions, there are still distinct differences from
a wired link that must be addressed. Since the RXM-LC-S modules do not
incorporate internal encoding/decoding, a user has tremendous flexibility in how data
is handled.
Daattaa
Caarrrriieerr
It is always important to separate what type of transmissions are technically
possible from those that are legally allowable in the country of intended operation.
You may wish to review application notes #00125 and #00140 along with Part 15
Sec. 231 for further details on acceptable transmission content.
Figure 14: CPCA (AM) Modulation
Another area of consideration is that of data structure or protocol. If unfamiliar with
the considerations for sending serial data in a wireless environment, you will want
to review Linx application note #00232 (Considerations for sending data with the LC
series). These issues should be clearly understood prior to commencing a
significant design effort.
The LC series utilizes an advanced single-conversion superhet design which
incorporates a SAW device, high IF frequency and multi-layer ceramic filters.
The SAW device has been in use for more than a decade but has only recently
begun to receive the widespread acclaim its outstanding capabilities deserve. A
SAW device provides a highly accurate frequency source with excellent
immunity to frequency shift due to age or temperature. The use of SAW devices
in both the LC transmitter and receiver modules allows the receiver’s pass
opening to be quite narrow, thus increasing sensitivity and reducing
susceptibility to near-band interference. The quality of components and overall
architecture utilized in the LC series is unusual in a low-cost product and is one
of the primary reasons the LC receivers are able to outperform even far more
expensive products.
If you want to transfer simple control or status signals such as button presses or
switch closures, and your product does not have a microprocessor on board your
product or you wish to avoid protocol development, consider using an encoder and
decoder IC set. These chips are available from a wide range of manufacturers
including: Microchip (Keeloq), Holtek (available directly from Linx), and Motorola.
These chips take care of all encoding, error checking, and decoding functions and
generally provide a number of data pins to which switches can be directly
connected. In addition, address bits are usually provided for security and to allow
the addressing of multiple receivers independently. These IC’s are an excellent way
to bring basic Remote Control/Status products quickly and inexpensively to market.
Additionally, it is a simple task to interface with inexpensive microprocessors such
as the Microchip PIC or one of many IR, remote control, DTMF, and modem IC’s.
Page 8
Page 9
Basic Remote Control Receiver Circuit
4. Observe appropriate layout practice between the module and its antenna. A
simple trace may suffice for runs of less than 0.25" but longer distances should
be covered using 50 coax or a 50 microstrip transmission line. This is
because the trace leading to the module can effectively contribute to the length
of the antenna, thus lowering its resonant bandwidth. In order to minimize loss
and detuning, a microstrip transmission line is commonly utilized. The term
microstrip refers to a PCB trace running over a groundplane, the width of
which has been calculated to serve as a 50 transmission line between the
module and antenna. This effectively removes the trace as a source of
detuning.The correct trace width can be easily calculated using the information
below.
Figure 16 shows an
example of a basic remote
control receiver utilizing a
decoder chip from Holtek.
When a key is pressed at
the transmitter, a corres-
ponding pin at the receiver
goes high. A schematic for
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
ANT
GND
NC
NC
NC
GND
VCC
PDN
NC
NC
NC
NC
NC
DATA
NC
the
transmitter/encoder
circuit may be found in
the LC transmitter guide.
These circuits can be
easily modified and clearly
demonstrate the ease of
using the Linx LC modules
for remote control appli-
cations.
HT658
Figure 16: Basic Remote Control Receiver
BOARD LAYOUT CONSIDERATIONS
If you are at all familiar with RF devices you may be
concerned about specialized board layout
requirements. Fortunately, because of the care
taken by Linx in designing the LC Series,
integrating an LC-S receiver is very straightforward.
This ease of application is a result of the advanced
multi-layer isolated construction of the module. By
adhering to good layout principles and observing a
GROUNDPLANE
ON LOWER LAYER
Figure 17: Microstrip Formulas (Er = Dielectric constant of pc board material)
few basic design rules you can enjoy
straightforward path to RF success.
a
1. No conductive items should be placed within 0.15
in. of the module’s top or sides.
Effective
Dielectric Characteristic
Constant
3.59
Always incorporate
adequate groundplane
Dielectric Width/Height
2. A groundplane should be placed under the
module as shown. In most cases, it will be placed
Constant
(W/d)
1.8
2
Impedance
4.8
50.0
51.0
on the bottom layer. The amount of overall plane area is also critical for the
correct function of many antenna styles and is covered in the next section.
4
3.07
2.55
3
2.12
48.0
3. Keep receiver module away from interference sources. Any frequency of
sufficient amplitude to enter the receiver’s front end will reduce system range,
cause bit errors, and may even prevent reception entirely. There are many
possible sources of internally generated interference. High speed logic is one of
the worst in this respect, as fast logic edges have harmonics which extend into
the UHF band and the PCB tracks radiate these harmonics most efficiently.
Microprocessors with external busses are generally incompatible with sensitive
radio receivers. Single-chip microprocessors do not generally pose a problem.
Switching power supplies, oscillators, even relays can also be significant
sources of potential interference. Here again, the single best weapon against
such problems is attention to placement and layout. Filter the supply with a high-
frequency bypass capacitor as described above. Place adequate groundplane
under all potential sources of noise.
RECEIVER ANTENNA CONSIDERATIONS
The choice of antennas is one of the most critical and often overlooked design
considerations. The range, performance, and legality of an RF link is critically
dependent upon the type of antenna employed. Proper design and matching of
an antenna is a complex task requiring sophisticated test equipment and a
strong background in principles of RF propagation. While adequate antenna
performance can often be obtained by trial and error methods, you may also
want to consider utilizing a professionally designed antenna such as those
offered by Linx. Our low-cost antenna line is designed to ensure maximum
performance and compliance with Part 15 attachment requirements.
Page 10
Page 11
ANTENNA CONSIDERATIONS (CONT.)
COMMON ANTENNA STYLES
There are literally hundreds of antenna styles that can be successfully employed with the
KH Series. Following is a brief discussion of the three styles most commonly utilized in
compact RF designs. Additional antenna information can be found in Linx application notes
#00100, #00126, #00140 and #00500. Linx also offers a broad line of antennas and
connectors that offer outstanding performance and cost-effectiveness.
A receiver antenna should give its optimum performance at the frequency or in
the band for which the receiver was designed, and capture as little as possible
of other off-frequency signals. The efficiency of the receiver’s antenna is critical
to maximizing range-performance. Unlike the transmitter antenna, where legal
operation may mandate a reduction in antenna efficiency or attenuation, the
receiver’s antenna should be optimized as much as is practical.
It is usually best to utilize a basic quarter-wave whip for your initial concept
evaluation. Once the prototype product is operating satisfactorily, a production
antenna should be selected to meet the cost, size and cosmetic requirements of
the product. To gain a better understanding of the considerations involved in the
design and selection of antennas, please review application note #00500
“Antennas: Design, Application, Performance".
Whip Style
A
whip-style monopole antenna provides outstanding overall
performance and stability. A low-cost whip can be easily fabricated from
wire or rod, but most product designers opt for the improved
performance and cosmetic appeal of a professionally made model. To
meet this need, Linx offers a wide variety of straight and reduced-height
whip-style antennas in permanent and connectorized mounting styles.
The following notes should help in optimizing antenna performance:
1. Proximity to objects such as a user’s hand or body, or metal objects will cause
an antenna to detune. For this reason the antenna shaft and tip should be
positioned as far away from such objects as possible.
The wavelength of the operational frequency determines an antenna's
overall length. Since a full wavelength is often quite long, a partial 1/4-
wave antenna is normally employed. Its size and natural radiation
resistance make it well matched to Linx modules. The proper length for
a 1/4-wave antenna can be easily found using the formula below. It is
also possible to reduce the overall height of the antenna by using a
helical winding. This decreases the antenna's bandwidth but is an
excellent way to minimize the antenna's physical size for compact
applications.
2. Optimum performance will be obtained from a 1/4- or 1/2-wave straight whip
mounted at a right angle to the groundplane. In many cases this isn’t desirable
for practical or ergonomic reasons; thus, an alternative antenna style such as
a helical, loop, patch, or base-loaded whip may be utilized.
1/4-wave wire lengths
for KH frequencies:
Where:
234
315Mhz
418Mhz
433Mhz
=
=
=
8.9"
6.7"
6.5"
3. If an internal antenna is to be used, keep it away from other metal
components, particularly large items like transformers, batteries, and PCB
tracks and groundplanes. In many cases, the space around the antenna is as
important as the antenna itself.
L = length in feet of quarter-wave length
L =
F
F = operating frequency in megahertz
MHz
4. In many antenna designs, particularly 1/4-wave whips, the groundplane acts
as a counterpoise, forming, in essence, a 1/2-wave dipole. For this reason
adequate groundplane area is essential. The groundplane can be a metal
case or ground-fill areas on a circuit board. Ideally, it should have a surface
area the overall length of the 1/4-wave radiating element. This is often not
practical due to size and configuration constraints. In these instances a
designer must make the best use of the area available to create as much
groundplane in proximity to the base of the antenna as possible. When the
antenna is remotely located or the antenna is not in close proximity to a circuit
board plane or grounded metal case, a small metal plate may be fabricated to
maximize antenna performance.
Helical Style
A helical antenna is precisely formed from wire or rod. A helical antenna
is a good choice for low-cost products requiring average range-
performance and internal concealment. A helical can detune badly in
proximity to other objects and its bandwidth is quite narrow so care must
be exercised in layout and placement.
Loop Style
A loop- or trace-style antenna is normally printed directly on a product's
PCB. This makes it the most cost-effective of antenna styles. There are
a variety of shapes and layout styles that can be utilized. The element
can be made self-resonant or externally resonated with discrete
components. Despite its cost advantages, PCB antenna styles are
generally inefficient and useful only for short-range applications. Loop-
style antennas are also very sensitive to changes in layout or substrate
dielectric, which can introduce consistency issues into the production
process. In addition, printed styles initially are difficult to engineer,
requiring the use of expensive equipment, including a network analyzer.
An improperly designed loop will have a high SWR at the desired
frequency that can introduce substantial instability in the RF stages.
5. Remove the antenna as far as possible from potential interference sources.
Any frequency of sufficient amplitude to enter the receiver’s front end will
reduce system range and can even prevent reception entirely. Switching
power supplies, oscillators, even relays can also be significant sources of
potential interference. The single best weapon against such problems is
attention to placement and layout. Filter the module’s power supply with a
high-frequency bypass capacitor. Place adequate groundplane under
potential sources of noise. Shield noisy board areas whenever practical.
Linx offers a low-cost planar antenna called the “SPLATCH,” which is an
excellent alternative to the sometimes problematic PCB trace style. This
tiny antenna mounts directly to a product's PCB and requires no testing
or tuning. Its design is stable even in compact applications and it
provides excellent performance in light of its compact size.
6. In some applications it is advantageous to place the receiver and its antenna
away from the main equipment. This avoids interference problems and allows
the antenna to be oriented for optimum RF performance. Always use 50
coax, such as RG-174, for the remote feed.
Page 12
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SURVIVING AN RF IMPLEMENTATION
LEGAL CONSIDERATIONS
DECIDE TO UTILIZE RF
Adding an RF stage brings an exciting new dimension
to any product. It also means that additional effort and
commitment will be needed to bring the product
successfully to market. By utilizing premade RF
modules, such as the KH series, the design and
approval process will be greatly simplified. It is still
important, however, to have an objective view of the
RESEARCH RF OPTIONS
NOTE: KH Series Modules are designed as component devices which require
external components to function. The modules are intended to allow for full Part
15 compliance; however, they are not approved by the FCC or any other agency
worldwide. The purchaser understands that approvals may be required prior to
the sale or operation of the device, and agrees to utilize the component in keeping
with all laws governing its operation in the country of operation.
ORDER EVALUATION KIT(S)
TEST MODULE(S) WITH
BASIC HOOKUP
CHOOSE LINX MODULE
steps necessary to ensure
a successful RF
INTERFACE TO CHOSEN
CIRCUIT AND DEBUG
integration. Since the capabilities of each customer
vary widely it is difficult to recommend one particular
design path, but most projects follow steps similar to
those shown at the right.
When working with RF, a clear distinction must be made between what is technically
possible and what is legally acceptable in the country where operation is intended.
Many manufacturers have avoided incorporating RF into their products as a result of
uncertainty and even fear of the approval and certification process. Here at Linx our
desire is not only to expedite the design process, but also to assist you in achieving
a clear idea of what is involved in obtaining the necessary approvals to market your
completed product legally.
CONSULT LINX REGARDING
ANTENNA OPTIONS AND DESIGN
LAY OUT BOARD
SEND PRODUCTION-READY
PROTOTYPE TO LINX
In reviewing this sample design path you may notice
that Linx offers a variety of services, such as antenna
design, and FCC prequalification, that are unusual for
a high-volume component manufacturer. These
services, along with an exceptional level of technical
support, are offered because we recognize that RF is
a complex science requiring the highest caliber of
products and support. “Wireless Made Simple” is
more than just a motto, it’s our commitment. By
choosing Linx as your RF partner and taking
advantage of the resources we offer, you will not only
survive implementing RF, you may even find the
process enjoyable.
FOR EMC PRESCREENING
OPTIMIZE USING RF SUMMARY
GENERATED BY LINX
In the United States the approval process is actually quite straightforward. The
regulations governing RF devices and the enforcement of them are the responsibility
of the Federal Communications Commission. The regulations are contained in the
Code of Federal Regulations (CFR), Title 47. Title 47 is made up of numerous
volumes; however, all regulations applicable to this module are contained in volume
0-19. It is strongly recommended that a copy be obtained from the Government
Printing Office in Washington, or from your local government book store. Excerpts of
applicable sections are included with Linx evaluation kits or may be obtained from the
Linx Technologies web site (www.linxtechnologies.com). In brief, these rules require
that any device which intentionally radiates RF energy be approved, that is, tested,
for compliance and issued a unique identification number. This is a relatively painless
process. Linx offers full EMC pre-compliance testing in our HP/Emco-equipped test
center. Final compliance testing is then performed by one of the many independent
testing laboratories across the country. Many labs can also provide other
certifications the product may require at the same time, such as UL, CLASS A/B, etc.
Once your completed product has passed, you will be issued an ID number which is
then clearly placed on each product manufactured.
SEND TO PART 15
TEST FACILITY
RECEIVE FCC ID #
COMMENCE SELLING PRODUCT
TYPICAL STEPS FOR
IMPLEMENTING RF
HELPFUL APPLICATION NOTES FROM LINX
It is not the intention of this manual to address in depth many of the issues that
should be considered to ensure that the modules function correctly and deliver
the maximum possible performance. As you proceed with your design you may
wish to obtain one or more of the following application notes, which address in
depth key areas of RF design and application of Linx products.
Questions regarding interpretations of the Part 2 and Part 15 rules or measurement
procedures used to test intentional radiators, such as the KH modules, for compliance
with the Part 15 technical standards, should be addressed to:
Federal Communications Commission
Equipment Authorization Division
Customer Service Branch, MS 1300F2
7435 Oakland Mills Road
Columbia, MD 21046
Tel: (301) 725-1585 / Fax: (301) 344-2050 E-Mail: labinfo@fcc.gov
NOTE #
LINX APPLICATION NOTE TITLE
00100
RF 101: Information for the RF challenged
International approvals are slightly more complex, although many modules are
designed to allow all international standards to be met. If you are considering the
export of your product abroad, you should contact Linx Technologies to determine the
specific suitability of the module to your application.
00125
00130
00140
00150
00500
Considerations for operation in the 260 Mhz to 470 Mhz band
Modulation techniques for low-cost RF data links
The FCC Road: Part 15 from concept to approval
Use and design of T-Attenuation Pads
All Linx modules are designed with the approval process in mind and thus much of
the frustration that is typically experienced with a discrete design is eliminated.
Approval is still dependent on many factors such as the choice of antennas, correct
use of the frequency selected, and physical packaging. While some extra cost and
design effort are required to address these issues, the additional usefulness and
profitability added to a product by RF makes the effort more than worthwhile.
Antennas: Design, Application, Performance
Page 14
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WIRELESS MADE SIMPLE ®
U.S. CORPORATE HEADQUARTERS
LINX TECHNOLOGIES, INC.
159 ORT LANE
MERLIN, OR 97532
PHONE: (541) 471-6256
FAX: (541) 471-6251
www.linxtechnologies.com
Disclaimer
Linx Technologies is continually striving to improve the quality and function of its products. For
this reason, we reserve the right to make changes without notice. The information contained in
this Data Guide is believed to be accurate as of the time of publication. Specifications are based
on representative lot samples. Values may vary from lot to lot and are not guaranteed. Linx
Technologies makes no guarantee, warranty, or representation regarding the suitability or
legality of any product for use in a specific application. None of these devices is intended for use
in applications of a critical nature where the safety of life or property is at risk. The user assumes
full liability for the use of product in such applications. Under no conditions will Linx Technologies
be responsible for losses arising from the use or failure of the device in any application, other
than the repair, replacement, or refund limited to the original product purchase price.
© 2006 by Linx Technologies, Inc. The stylized Linx logo,
Linx, “Wireless Made Simple”, CipherLinx and the stylized
CL logo are the trademarks of Linx Technologies, Inc.
Printed in U.S.A.
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