RXM-315-LR_1 [ETC]

LR SERIES RECEIVER MODULE DATA; LR系列接收器模块数据


型号：	RXM-315-LR_1
厂家：	ETC
描述：	LR SERIES RECEIVER MODULE DATA LR系列接收器模块数据
文件：	总11页 (文件大小：468K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

RXM-315-LR

RXM-418-LR

RXM-433-LR

WIRELESS MADE SIMPLE ^®

LR SERIES RECEIVER MODULE DATA GUIDE

DESCRIPTION

The LR Receiver is ideal for the wireless transfer of

serial data, control, or command information in the

0.812"

favorable 260-470MHz band. The receiver’s

advanced synthesized architecture achieves an

outstanding typical sensitivity of -112dBm, which

provides a 5 to 10 times improvement in range over

previous solutions. When paired with a compatible

Linx transmitter, a reliable wireless link is formed

capable of transferring data at rates of up to

10,000bps at distances of up to 3,000 feet.

Applications operating over shorter distances or at

lower data rates will also benefit from increased link

reliability and superior noise immunity. Housed in a

RF MODULE

RXM-418-LR-S

LOT 10000

0.630"

0.125"

Figure 1: Package Dimensions

tiny reflow-compatible SMD package, the LR Receiver module is footprint-compatible

with the popular LC-S Receiver, allowing existing users an instant path to improved

range and lower cost. No external components are required (except an antenna),

allowing for easy integration, even for engineers without previous RF experience.

FEATURES

Long range

Low power consumption

Low cost

Wide supply range (2.7 to 5.2VDC)

Compact surface-mount package

Wide temperature range

RSSI and Power-down functions

No production tuning

PLL-synthesized architecture

Direct serial interface

Data rates to 10,000bps

Qualified data output

No external components needed

APPLICATIONS INCLUDE

Remote Control

Keyless Entry

ORDERING INFORMATION

PART #

DESCRIPTION

Garage / Gate Openers

Lighting Control

TXM-315-LR

TXM-418-LR

TXM-433-LR

RXM-315-LR

RXM-418-LR

RXM-433-LR

EVAL-***-LR

*** = Frequency

Transmitter 315MHz

Transmitter 418MHz

Transmitter 433MHz

Receiver 315MHz

Receiver 418MHz

Receiver 433MHz

Basic Evaluation Kit

Medical Monitoring / Call Systems

Remote Industrial Monitoring

Periodic Data Transfer

Home / Industrial Automation

Fire / Security Alarms

Remote Status / Position Sensing

Long-Range RFID

Receivers are supplied in tubes of 25 pcs.

Wire Elimination

Revised 1/25/08

ELECTRICAL SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

Parameter

Designation

Min.

Typical

Max.

Units

Notes

Supply Voltage V_CC

Supply Voltage V_CC, Using Resistor -0.3

-0.3

+3.6

+5.2

+3.6

VDC

dBm

°C

POWER SUPPLY

Operating Voltage

V_CC

2.7

3.0

3.6

VDC

–

Any Input or Output Pin

RF Input

Operating Temperature

Storage Temperature

Soldering Temperature

-0.3

With Dropping Resistor

Supply Current

4.3

4.0

5.0

5.2

7.0

VDC

1,5

–

I_CC

-40

-45

+70

+85

Power-Down Current

I_PDN

20.0

28.0

35.0

µA

°C

RECEIVER SECTION

Receive Frequency Range:

+225°C for 10 seconds

F_C

*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.

RXM-315-LR

RXM-418-LR

RXM-433-LR

Center Frequency Accuracy

LO Feedthrough

IF Frequency

–

-50

–

315

418

433.92

–

-80

10.7

–

+50

–

MHz

kHz

dBm

MHz

–

2,5

–

F_IF

PERFORMANCE DATA

These performance parameters

are based on module operation at

25°C from a 3.0VDC supply unless

Noise Bandwidth

N_3DB

–

280

–

kHz

bps

–

5VDC

Data Rate

Data Output:

Logic Low

100

10,000

ANT

GND

330Ω

otherwise

illustrates

necessary

noted.

the

for

Figure

connections

testing and

3VDC

External

Resistor

V_OL

V_OH

–

0.0

3.0

–

VDC

GND

VCC

PDN

RSSI

DATA

Logic High

Power-Down Input:

Logic Low

operation. It is recommended all

ground pins be connected to the

ground plane. The pins marked NC

have no electrical connection.

V_IL

V_IH

–

0.4

–

VDC

dBm

–

Logic High

V_CC-0.4

-106

Receiver Sensitivity

RSSI / Analog:

-112

-118

Figure 2: Test / Basic Application Circuit

Dynamic Range

Analog Bandwidth

Gain

Voltage With No Carrier

ANTENNA PORT

RF Input Impedance

–

1.5

–

5,000

–

mV / dB

TYPICAL PERFORMANCE GRAPHS

–

PDN

RX DATA

R_IN

–

Supply

TIMING

Receiver Turn-On Time:

Via V_CC

–

3.0

7.0

10.0

mSec

5,6

RX Data

Via PDN

Max. Time Between Transitions

ENVIRONMENTAL

–

0.04

–

0.25

10.0

0.50

–

mSec

5,6

Operating Temperature Range

–

-40

–

+70

°C

Table 1: LR Series Receiver Specifications

Figure 4: Turn-On Time from PDN

Figure 3: Turn-On Time from V_CC

Notes

1. The LR can utilize a 4.3 to 5.2VDC supply provided a 330-ohm resistor is placed in series with VCC.

2. Into a 50-ohm load.

5.40

5.35

5.30

5.25

3. When operating from a 5V 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 requirement of the device to which data is being sent.

RFIN >-35dBm

NO RFIN

-5

4. For BER of 10 at 1,200bps.

5. Characterized, but not tested.

6. Time to valid data output.

With Dropping

Resistor

5.20

5.15

*CAUTION*

This product incorporates numerous static-sensitive components.

Always wear an ESD wrist strap and observe proper ESD handling

procedures when working with this device. Failure to observe this

precaution may result in module damage or failure.

5.10

2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2

Supply Voltage (VDC)

Figure 6: RSSI Response Time

Figure 5: Consumption vs. Supply

Page 3

Page 2

PIN ASSIGNMENTS

MODULE DESCRIPTION

The LR receiver is a low-cost, high-performance synthesized AM / OOK receiver,

capable of receiving serial data at up to 10,000bps. Its exceptional sensitivity

results in outstanding range performance. The LR’s compact surface-mount

package is friendly to automated or hand production. LR Series modules are

capable of meeting the regulatory requirements of many domestic and

international applications.

ANT 16

GND 15

NC 14

NC 13

NC 12

GND

VCC

PDN

RSSI

DATA

50Ω RF IN

(Antenna)

NC 10

Band Select

Filter

10.7MHz

IF Filter

Data Slicer

0˚

Data Out

LNA

Limiter

∑

90˚

RSSI/Analog

Figure 7: LR Series Receiver Pinout (Top View)

PIN DESCRIPTIONS

PLL

VCO

Pin # Name

Description

No Connection

Analog Ground

Supply Voltage

XTAL

Figure 8: LR Series Receiver Block Diagram

THEORY OF OPERATION

The LR receiver is designed to recover

data sent by an AM or Carrier-Present

Carrier-Absent (CPCA) transmitter, also

referred to as CW or On-Off Keying

(OOK). 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. The

GND

V_CC

Data

Carrier

Power Down. Pulling this line low will place the receiver

into a low-current state. The module will not be able to

receive a signal in this state.

PDN

Figure 9: CPCA (AM) Modulation

two most important are: 1) cost-effectiveness due to design simplicity and 2)

higher allowable output power and thus greater range in countries (such as the

U.S.) that average output power measurements over time. Please refer to Linx

Application Note AN-00130 for a further discussion of modulation techniques.

Received Signal Strength Indicator. This line will supply an

analog voltage that is proportional to the strength of the

received signal.

RSSI

The LR receiver utilizes an advanced single-conversion superheterodyne

architecture. Transmitted signals enter the module through a 50-ohm RF port

intended for single-ended connection to an external antenna. RF signals

entering the antenna are filtered and then amplified by an NMOS cascode Low

Noise Amplifier (LNA). The filtered, amplified signal is then down-converted to a

10.7MHz Intermediate Frequency (IF) by mixing it with a low-side Local

Oscillator (LO). The LO frequency is generated by a Voltage Controlled

Oscillator (VCO) locked by a Phase-Locked Loop (PLL) frequency synthesizer

that utilizes a precision crystal reference. The mixer stage incorporates a pair of

double-balanced mixers and a unique image rejection circuit. This circuit, along

with the high IF frequency and ceramic IF filters, reduces susceptibility to

interference. The IF frequency is further amplified, filtered, and demodulated to

recover the baseband signal originally transmitted. The baseband signal is

squared by a data slicer and output to the DATA pin. The architecture and quality

of the components utilized in the LR module enable it to outperform many far

more expensive receiver products.

Digital Data Output. This line will output the demodulated

digital data.

DATA

No Connection

Analog Ground

50-ohm RF Input

GND

RF IN

Page 4

Page 5

POWER SUPPLY REQUIREMENTS

THE DATA OUTPUT

The module does not have an internal voltage regulator, therefore it requires a

clean, well-regulated power source. While it is preferable to power the unit from

a battery, it can also be operated from a power supply as long as noise is less

than 20mV. Power supply noise can significantly affect the receiver sensitivity,

therefore; providing clean power to the module should be a high priority during

The CMOS-compatible data output is normally used to drive a digital decoder IC

or a microprocessor that is performing the data decoding. In addition, the module

can be connected to an RS-232 level converter chip, like the MAX232, to a Linx

USB module for interfacing to a PC, or to a standard UART. Since a UART uses

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 receiver and the UART.

design.

Vcc TO

MODULE

A 10Ω resistor in series with the supply followed by a

The receiver’s output may appear to switch randomly in the absence of a

transmitter. This is a result of the receiver sensitivity being below the noise floor

of the board. This noise can be handled in software by implementing a noise-

tolerant protocol as described in Application Note AN-00160. If a software

solution is not appropriate, the squelch circuit in the figure below can be used

and the designer can make a compromise between noise level and range.

10µF tantalum capacitor from V_CCto ground will help

10Ω

Vcc IN

in cases where the quality of the supply power is poor.

Operation from 4.3V to 5.2V requires an external

330Ω series resistor to prevent V_CCfrom exceeding

3.6V. These values may need to be adjusted

10μF

Figure 10: Supply Filter

depending on the noise present on the supply line.

VCC

USING THE PDN PIN

DATA

500k

VCC

The Power Down (PDN) line can be used to power down the receiver without the

need for an external switch. This line has an internal pull-up, so when it is held

high or simply left floating, the module will be active.

VCC

200k

MAX4714

When the PDN line is pulled to ground, the receiver will enter into a low-current

(<40µA) power-down mode. During this time the receiver is off and cannot

perform any function. It may be useful to note that the startup time coming out of

RSSI

LMV393

0.1μ

Squelched Data

power-down will be slightly less than when applying V_CC

The PDN line allows easy control of the receiver state from external components,

like a microcontroller. By periodically activating the receiver, checking for data,

then powering down, the receiver’s average current consumption can be greatly

reduced, saving power in battery-operated applications.

Figure 11: LR Receiver and LS Decoder

RECEIVING DATA

Once an 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 LR modules do not incorporate internal

encoding / decoding, the user has tremendous flexibility in how data is handled.

Note: The voltage on the PDN line should not exceed V_CC. When used with a higher

voltage source, such as a 5V microcontroller, an open collector line should be used or a

diode placed in series with the control line. Either method will prevent damage to the

module by preventing 5V from being placed on the PDN line, while allowing the line to be

pulled low.

USING THE RSSI PIN

It is always important to separate what types of transmissions are technically

possible from those that are legally allowable in the country of intended

operation. Application Notes AN-00125 and AN-00140 should be reviewed along

with Part 15, Section 231 for further details on acceptable transmission content.

The receiver’s Received Signal Strength Indicator (RSSI) line serves a variety of

functions. This line has a dynamic range of 80dB (typical) and outputs a voltage

proportional to the incoming signal strength. It should be noted that the RSSI

levels and dynamic range will vary slightly from part to part. It is also important

to remember that RSSI output indicates the strength of any in-band RF energy

and not necessarily just that from the intended transmitter; therefore, it should be

used only to qualify the level and presence of a signal.

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 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

Linx, Microchip, and Holtek. These chips take care of all encoding 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 ICs 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 ICs.

The RSSI output can be utilized during testing or even as a product feature to

assess interference and channel quality by looking at the RSSI level with all

intended transmitters shut off. The RSSI output can also be used in direction-

finding applications, although there are many potential perils to consider in such

systems. Finally, it can be used to save system power by “waking up” external

circuitry when a transmission is received or crosses a certain threshold. The

RSSI output feature adds tremendous versatility for the creative designer.

Page 6

Page 7

PROTOCOL GUIDELINES

TYPICAL APPLICATIONS

While many RF solutions impose data formatting and balancing requirements,

Linx RF modules do not encode or packetize the signal content in any manner.

The received signal will be affected by such factors as noise, edge jitter, and

interference, but it is not purposefully manipulated or altered by the modules.

This gives the designer tremendous flexibility for protocol design and interface.

Figure 12 shows a circuit using the Linx LICAL-DEC-MS001 decoder. This chip

works with the LICAL-ENC-MS001 encoder to provide simple remote control

capabilities. The decoder will detect the transmission from the encoder, check for

errors, and if everything is correct, the encoder’s inputs will be replicated on the

decoder’s outputs. This makes sending key presses very easy.

SWITCHED OUTPUT

Despite this transparency and ease of use, it must be recognized that there are

distinct differences between a wired and a wireless environment. Issues such as

interference and contention must be understood and allowed for in the design

process. To learn more about protocol considerations, we suggest you read Linx

Application Note AN-00160.

RELAY

VCC

Errors from interference or changing signal conditions can cause corruption of

the data packet, so it is generally wise to structure the data being sent into small

packets. This allows errors to be managed without affecting large amounts of

data. A simple checksum or CRC could be used for basic error detection. Once

an error is detected, the protocol designer may wish to simply discard the corrupt

data or implement a more sophisticated scheme to correct it.

VCC

10k 2.2k

GND

VCC

PDN

RSSI

DATA

ANT

GND

SEL_BAUD0

SEL_BAUD1

GND

VCC

DATA_IN

LEARN

GND

LATCH

RX_CNTL

TX_ID

GND

220

MODE_IND

RXM-LR

100k

LICAL-DEC-MS001

GND

INTERFERENCE CONSIDERATIONS

GND

The RF spectrum is crowded and the potential for conflict with other unwanted

sources of RF is very real. While all RF products are at risk from interference, its

effects can be minimized by better understanding its characteristics.

Figure 12: LR Receiver and MS Decoder

Figure 13 shows a typical RS-232 circuit using the LR receiver and a Maxim

MAX232 chip. The LR will output a serial data stream and the MAX232 will

convert that to RS-232 compliant signals.

Interference may come from internal or external sources. The first step is to

eliminate interference from noise sources on the board. This means paying

careful attention to layout, grounding, filtering, and bypassing in order to

eliminate all radiated and conducted interference paths. For many products, this

is straightforward; however, products containing components such as switching

power supplies, motors, crystals, and other potential sources of noise must be

approached with care. Comparing your own design with a Linx evaluation board

can help to determine if and at what level design-specific interference is present.

VCC

4.7uF

DB-9

RXM-XXX-LR-S

MAX232

ANT

GND

4.7uF

C1+

V+

VCC

GND

C1-

C2+

VCC

4.7uF

V-

T2OUT

R2IN

RSSI

External interference can manifest itself in a variety of ways. Low-level

interference will produce noise and hashing on the output and reduce the link’s

overall range.

DATA

GND

4.7uF

GND

High-level interference is caused by nearby products sharing the same

frequency or from near-band high-power devices. It can even come from your

own products if more than one transmitter is active in the same area. It is

important to remember that only one transmitter at a time can occupy a

frequency, regardless of the coding of the transmitted signal. This type of

interference is less common than those mentioned previously, but in severe

cases it can prevent all useful function of the affected device.

Figure 13: LR Receiver and MAX232 IC

Figure 14 shows an example of combining the LR Series receiver with a Linx

SDM-USB-QS-S USB module. The LR will output a serial data stream and the

USB module will convert that to low-speed USB compliant signals.

USB-B

RXM-XXX-LR-S

SDM-USB-QS-S

USBDP

USBDM

GND

DAT+

DAT -

Although technically it is not interference, multipath is also a factor to be

understood. Multipath is a term used to refer to the signal cancellation effects

that occur when RF waves arrive at the receiver in different phase relationships.

This effect is a particularly significant factor in interior environments where

objects provide many different signal reflection paths. Multipath cancellation

results in lowered signal levels at the receiver and, thus, shorter useful distances

for the link.

ANT

GND

VCC

SUSP_IND

RX_IND

TX_IND

485_TX

GND GND

DTR

DATA

GND

Figure 14: LR Receiver and Linx USB Module

Page 8

Page 9

BOARD LAYOUT GUIDELINES

MICROSTRIP DETAILS

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 modules, integrating them is very straightforward. Despite

this ease of application, it is still necessary to maintain respect for the RF stage

and exercise appropriate care in layout and application in order to maximize

performance and ensure reliable operation. The antenna can also be influenced

by layout choices. Please review this data guide in its entirety prior to beginning

your design. By adhering to good layout principles and observing some basic

design rules, you will be on the path to RF success.

A transmission line is a medium whereby RF energy is transferred from one

place to another with minimal loss. This is a critical factor, especially in high-

frequency products like Linx RF modules, because the trace leading to the

module’s antenna can effectively contribute to the length of the antenna,

changing its resonant bandwidth. In order to minimize loss and detuning, some

form of transmission line between the antenna and the module should be used,

unless the antenna can be placed very close (<1/8in.) to the module. One

common form of transmission line is a coax cable, another is the microstrip. This

term refers to a PCB trace running over a ground plane that is designed to serve

as a transmission line between the module and the antenna. The width is based

on the desired characteristic impedance of the line, the thickness of the PCB,

and the dielectric constant of the board material. For standard 0.062in thick FR-

4 board material, the trace width would be 111 mils. The correct trace width can

be calculated for other widths and materials using the information below. Handy

software for calculating microstrip lines is also available on the Linx website,

www.linxtechnologies.com.

The adjacent figure shows the suggested

GROUND PLANE

PCB footprint for the module. The actual pad

ON LOWER LAYER

dimensions are shown in the Pad Layout

section of this manual. A ground plane (as

large as possible) should be placed on a

lower layer of your PC board opposite the

module. This ground plane can also be critical

to the performance of your antenna, which will

be discussed later. There should not be any

Trace

ground or traces under the module on the

same layer as the module, just bare PCB.

Figure 15: Suggested PCB Layout

Board

During prototyping, the module should be soldered to a properly laid-out circuit

board. The use of prototyping or “perf” boards will result in horrible performance

and is strongly discouraged.

Ground plane

No conductive items should be placed within 0.15in of the module’s top or sides.

Do not route PCB traces directly under the module. The underside of the module

has numerous signal-bearing traces and vias that could short or couple to traces

on the product’s circuit board.

The module’s ground lines should each have their own via to the ground plane

and be as short as possible.

AM / OOK receivers are particularly subject to noise. The module should, as

much as reasonably possible, be isolated from other components on your PCB,

especially high-frequency circuitry such as crystal oscillators, switching power

supplies, and high-speed bus lines. Make sure internal wiring is routed away

from the module and antenna, and is secured to prevent displacement.

The power supply filter should be placed close to the module’s V_CCline.

In some instances, a designer may wish to encapsulate or “pot” the product.

Many Linx customers have done this successfully; however, there are a wide

variety of potting compounds with varying dielectric properties. Since such

compounds can considerably impact RF performance, it is the responsibility of

the designer to carefully evaluate and qualify the impact and suitability of such

materials.

Figure 16: Microstrip Formulas

Effective Dielectric

Constant

Characteristic

Impedance

Dielectric Constant Width/Height (W/d)

The trace from the module to the antenna should be kept as short as possible.

A simple trace is suitable for runs up to 1/8-inch for antennas with wide

bandwidth characteristics. For longer runs or to avoid detuning narrow bandwidth

antennas, such as a helical, use a 50-ohm coax or 50-ohm microstrip

transmission line as described in the following section.

4.80

4.00

2.55

1.8

2.0

3.0

3.59

3.07

2.12

50.0

51.0

48.0

Page 10

Page 11

PAD LAYOUT

AUTOMATED ASSEMBLY

The following pad layout diagram is designed to facilitate both hand and

automated assembly.

For high-volume assembly, most users will want to auto-place the modules. The

modules have been designed to maintain compatibility with reflow processing

techniques; however, due to the their hybrid nature, certain aspects of the

assembly process are far more critical than for other component types.

0.065"

Following are brief discussions of the three primary areas where caution must be

observed.

Reflow Temperature Profile

0.610"

The single most critical stage in the automated assembly process is the reflow

stage. The reflow profile below should not be exceeded, 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 remaining within the limits mandated by the modules.

The figure below shows the recommended reflow oven profile for the modules.

0.070"

0.100"

Figure 17: Recommended PCB Layout

PRODUCTION GUIDELINES

300

Recommended RoHS Profile

Max RoHS Profile

Recommended Non-RoHS Profile

The modules are housed in a hybrid SMD package that supports hand or

automated assembly techniques. Since the modules contain discrete

components internally, the assembly procedures are critical to ensuring the

reliable function of the modules. The following procedures should be reviewed

with and practiced by all assembly personnel.

255°C

250

200

150

100

235°C

217°C

185°C

180°C

HAND ASSEMBLY

Pads located on the bottom of the

module are the primary mounting

surface. 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 underside. This allows for

very quick hand soldering for

Soldering Iron

125°C

Tip

Solder

PCB Pads

120

150

Time (Seconds)

180

210

240

270

300

330

360

Castellations

prototyping and small volume

Figure 19: Maximum Reflow Profile

Figure 18: Soldering Technique

production.

If the recommended pad guidelines have been followed, the pads will protrude

slightly past the edge of the module. Use a fine soldering tip to heat the board

pad and the castellation, then introduce solder to the pad at the module’s edge.

The solder will wick underneath the module, providing reliable attachment. Tack

one module corner first and then work around the device, taking care not to

exceed the times listed below.

Shock During Reflow Transport

Since some internal module components may reflow along with the components

placed on the board being assembled, it is imperative that the modules not be

subjected to shock or vibration during the time solder is liquid. Should a shock

be applied, some internal components could be lifted from their pads, causing

the module to not function properly.

Washability

Absolute Maximum Solder Times

The modules are wash resistant, but are not hermetically sealed. Linx

recommends wash-free manufacturing; however, the modules can be subjected

to a wash cycle provided that a drying time is allowed prior to applying electrical

power to the modules. The drying time should be sufficient to allow any moisture

that may have migrated into the module to evaporate, thus eliminating the

potential for shorting damage during power-up or testing. If the wash contains

contaminants, the performance may be adversely affected, even after drying.

Hand-Solder Temp. TX +225°C for 10 Seconds

Hand-Solder Temp. RX +225°C for 10 Seconds

Recommended Solder Melting Point +180°C

Reflow Oven: +220°C Max. (See adjoining diagram)

Page 12

Page 13

ANTENNA CONSIDERATIONS

GENERAL ANTENNA RULES

The choice of antennas is a critical

The following general rules should help in maximizing antenna performance.

and

consideration.

often

overlooked

The

design

range,

1. Proximity to objects such as a user’s hand, 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.

performance, and legality of an RF link

are critically dependent upon the

antenna. While adequate antenna

performance can often be obtained by

trial and error methods, antenna

design and matching is a complex

2. Optimum performance will be obtained

from a 1/4- or 1/2-wave straight whip

mounted at a right angle to the ground

plane. In many cases, this isn’t desirable

OPTIMUM

for practical or ergonomic reasons, thus,

NOT RECOMMENDED

task.

professionally designed

Figure 20: Linx Antennas

USEABLE

an alternative antenna style such as a

helical, loop, or patch may be utilized

antenna, such as those from Linx, will

help ensure maximum performance and FCC compliance.

Figure 22: Ground Plane Orientation

and the corresponding sacrifice in performance accepted.

Linx transmitter modules typically have an output power that is slightly higher

than the legal limits. This allows the designer to use an inefficient antenna, such

as a loop trace or helical, to meet size, cost, or cosmetic requirements and still

achieve full legal output power for maximum range. If an efficient antenna is

used, then some attenuation of the output power will likely be needed. This can

easily be accomplished by using the LADJ line or a T-pad attenuator. For more

details on T-pad attenuator design, please see Application Note AN-00150.

3. If an internal antenna is to be used, keep it away from other metal components,

particularly large items like transformers, batteries, PCB tracks, and ground

planes. In many cases, the space around the antenna is as important as the

antenna itself. Objects in close proximity to the antenna can cause direct

detuning, while those farther away will alter the antenna’s symmetry.

4. In many antenna designs, particularly 1/4-wave

VERTICAL λ/4 GROUNDED

ANTENNA (MARCONI)

whips, the ground plane acts as a counterpoise,

forming, in essence, a 1/2-wave dipole. For this

reason, adequate ground plane area is essential.

A receiver antenna should be optimized for the frequency or band in which the

receiver operates and to minimize the reception of 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 attenuation

or a reduction in antenna efficiency, the receiver’s antenna should be optimized

as much as is practical.

DIPOLE

ELEMENT

λ/4

The ground plane 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 ground plane as

GROUND

PLANE

VIRTUAL λ/4

DIPOLE

λ/4

It is usually best to utilize a basic quarter-wave whip until your prototype product

is operating satisfactorily. Other antennas can then be evaluated based on the

cost, size, and cosmetic requirements of the product. You may wish to review

Application Note AN-00500 “Antennas: Design, Application, Performance”

Figure 23: Dipole Antenna

possible in proximity to the base of the antenna. In cases where the antenna is

remotely located or the antenna is not in close proximity to a circuit board,

ground plane, or grounded metal case, a metal plate may be used to maximize

the antenna’s performance.

ANTENNA SHARING

In cases where a transmitter and receiver

module are combined to form a transceiver,

0.1μF

it is often advantageous to share a single

Module

Transmitter

^0.1μF

Antenna

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, or 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 ground plane under potential sources of noise

to shunt noise to ground and prevent it from coupling to the RF stage. Shield

noisy board areas whenever practical.

antenna. To accomplish this, an antenna

switch must be used to provide isolation

between the modules so that the full

^0.1μF

GND

^0.1μF

GND

Receiver

Module

transmitter output power is not put on the

^0.1μF

sensitive front end of the receiver. There

Select

are a wide variety of antenna switches that

are cost-effective and easy to use. Among

Figure 21: Typical Antenna Switch

the most popular are switches from Macom and NEC. Look for an antenna

switch that has high isolation and low loss at the desired frequency of operation.

Generally, the Tx or Rx status of a switch will be controlled by a product’s

microprocessor, but the user may also make the selection manually. In some

cases, where the characteristics of the Tx and Rx antennas need to be different

or antenna switch losses are unacceptable, it may be more appropriate to utilize

two discrete antennas.

6. In some applications, it is advantageous to

place the module and antenna away from the

CASE

main equipment. This can avoid interference

problems and allows the antenna to be

oriented for optimum performance. Always use

GROUND PLANE

NUT

(MAY BE NEEDED)

50Ω coax, like RG-174, for the remote feed.

Figure 24: Remote Ground Plane

Page 15

Page 14

COMMON ANTENNA STYLES

ONLINE RESOURCES

There are literally hundreds of antenna styles and variations that can be

employed with Linx RF modules. Following is a brief discussion of the styles

most commonly utilized. Additional antenna information can be found in Linx

Application Notes AN-00100, AN-00140, and AN-00500. Linx antennas and

connectors offer outstanding performance at a low price.

www.linxtechnologies.com

• Latest News

A whip-style antenna provides outstanding overall performance

Whip Style

and stability. A low-cost whip is can be easily fabricated from a

wire or rod, but most designers opt for the consistent

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.

• Data Guides

• Application Notes

• Knowledgebase

• Software Updates

The wavelength of the operational frequency determines an

antenna’s overall length. Since a full wavelength is often quite

If you have questions regarding any Linx product and have Internet access,

make www.linxtechnologies.com your first stop. Our website is organized in an

intuitive format to immediately give you the answers you need. Day or night, the

Linx website gives you instant access to the latest information regarding the

products and services of Linx. It’s all here: manual and software updates,

application notes, a comprehensive knowledgebase, FCC information, and much

more. Be sure to visit often!

long, a partial 1/2- or 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 straight 1/4-wave can be

easily determined using the adjacent formula. It is also possible

to reduce the overall height of the antenna by using a helical

winding. This reduces the antenna’s bandwidth, but is a great

way to minimize the antenna’s physical size for compact

applications. This also means that the physical appearance is

not always an indicator of the antenna’s frequency.

234

L =

MHz

Where:

= length in feet of

quarter-wave length

F = operating frequency

in megahertz

Specialty Styles

Linx offers a wide variety of specialized antenna styles.

Many of these styles utilize helical elements to reduce the

overall antenna size while maintaining reasonable

performance. A helical antenna’s bandwidth is often quite

narrow and the antenna can detune in proximity to other

objects, so care must be exercised in layout and placement.

www.antennafactor.com

The Antenna Factor division of Linx offers

a diverse array of antenna styles, many of

which are optimized for use with our RF

modules. From innovative embeddable

antennas to low-cost whips, domes to

Yagis, and even GPS, Antenna Factor

likely has an antenna for you, or can

design one to meet your requirements.

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. The element can be made self-resonant or externally

resonated with discrete components, but its actual layout is

usually product specific. Despite the cost advantages, loop-style

antennas are generally inefficient and useful only for short-range

applications. They are also very sensitive to changes in layout and

PCB dielectric, which can cause consistency issues during

production. In addition, printed styles 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, which can cause instability in the RF stage.

Loop Style

www.connectorcity.com

Through its Connector City division, Linx offers a wide

selection of high-quality RF connectors, including FCC-

compliant types such as RP-SMAs that are an ideal

match for our modules and antennas. Connector City

focuses on high-volume OEM requirements, which

allows standard and custom RF connectors to be offered

at a remarkably low cost.

Linx offers low-cost planar and chip antennas that mount directly

to a product’s PCB. These tiny antennas do not require testing and

provide excellent performance in light of their small size. They

offer a preferable alternative to the often-problematic “printed”

antenna.

Page 16

Page 17

LEGAL CONSIDERATIONS

ACHIEVING A SUCCESSFUL RF IMPLEMENTATION

Adding an RF stage brings an exciting new

DECIDE TO UTILIZE RF

NOTE: Linx RF modules are designed as component devices that 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 use in the country of operation.

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 LR Series, the

design and approval process is greatly simplified. It

is still important, however, to have an objective view

of the steps necessary to ensure a successful RF

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.

RESEARCH RF OPTIONS

ORDER EVALUATION KIT(S)

TEST MODULE(S) WITH

BASIC HOOKUP

CHOOSE LINX MODULE

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 legally market your

completed product.

INTERFACE TO CHOSEN

CIRCUIT AND DEBUG

CONSULT LINX REGARDING

ANTENNA OPTIONS AND DESIGN

LAY OUT BOARD

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

SEND PRODUCTION-READY

PROTOTYPE TO LINX

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 (FCC). The regulations are contained in Title

47 of the Code of Federal Regulations (CFR). 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 bookstore. Excerpts of applicable sections are

included with Linx evaluation kits or may be obtained from the Linx Technologies website,

www.linxtechnologies.com. In brief, these rules require that any device that 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 that 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 that is to be clearly placed on each product manufactured.

SEND TO PART 15

TEST FACILITY

RECEIVE FCC ID #

COMMENCE SELLING PRODUCT

Typical Steps For

Implementing RF

will not only survive implementing RF, you may even find the process enjoyable.

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. These

applications notes are available online at www.linxtechnologies.com or by

contacting the Linx literature department.

Questions regarding interpretations of the Part 2 and Part 15 rules or measurement

procedures used to test intentional radiators, such as Linx RF modules, for compliance

with the technical standards of Part 15, should be addressed to:

Federal Communications Commission

Equipment Authorization Division

Customer Service Branch, MS 1300F2

7435 Oakland Mills Road

NOTE

AN-00100

APPLICATION NOTE TITLE

RF 101: Information for the RF Challenged

Columbia, MD 21046

Phone: (301) 725-1585 Fax: (301) 344-2050 E-Mail: labinfo@fcc.gov

AN-00125

AN-00130

AN-00140

AN-00150

AN-00160

AN-00232

AN-00500

Considerations For Operation Within The 260-470MHz 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

International approvals are slightly more complex, although Linx 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.

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.

Considerations For Sending Data Over a Wireless Link

General Considerations For Sending Data With The LC Series

Antennas: Design, Application, Performance

Page 18

Page 19

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 to our products without notice. The information contained in this

Overview 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. "Typical" parameters can

and do vary over lots and application. Linx Technologies makes no guarantee, warranty, or representation

regarding the suitability of any product for use in any specific application. It is the customer's responsibility

to verify the suitability of the part for the intended application. NO LINX PRODUCT IS INTENDED FOR USE

IN ANY APPLICATION WHERE THE SAFETY OF LIFE OR PROPERTY IS AT RISK.

Linx Technologies DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

PARTICULAR PURPOSE. IN NO EVENT SHALL LINX TECHNOLOGIES BE LIABLE FOR ANY OF

CUSTOMER'S INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY FROM ANY DEFECTIVE

OR NON-CONFORMING PRODUCTS OR FOR ANY OTHER BREACH OF CONTRACT BY LINX

TECHNOLOGIES. The limitations on Linx Technologies' liability are applicable to any and all claims or

theories of recovery asserted by Customer, including, without limitation, breach of contract, breach of

warranty, strict liability, or negligence. Customer assumes all liability (including, without limitation, liability

for injury to person or property, economic loss, or business interruption) for all claims, including claims

from third parties, arising from the use of the Products. The Customer will indemnify, defend, protect, and

hold harmless Linx Technologies and its officers, employees, subsidiaries, affiliates, distributors, and

representatives from and against all claims, damages, actions, suits, proceedings, demands, assessments,

adjustments, costs, and expenses incurred by Linx Technologies as a result of or arising from any Products

sold by Linx Technologies to Customer. 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. Devices described in this publication may contain

proprietary, patented, or copyrighted techniques, components, or materials. Under no circumstances shall

any user be conveyed any license or right to the use or ownership of such items.

Linx, “Wireless Made Simple”, CipherLinx, and the stylized

CL logo are the trademarks of Linx Technologies, Inc.

Printed in U.S.A.

RXM-315-LR_1 [ETC]

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RXM-418-LC-S

RXM-418-LR

RXM-433-LC

RXM-433-LC-P

RXM-433-LC-S

RXM-433-LR

RXM-4B

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