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The Leader in Industrial Data Communication Solutions

Training:RF Path – Will it work?

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RF Design: Will this work?

ANTENNA

SRM6000

(425) 882-2206

12VDC

NC

4

DI

3

DO

2

CD

1

9 N

C

8 C

TS

7 R

TS

6 N

C

GD

5

DATA-LINC GROUP

P C I O

LightningArrestor

OmniAntenna

GroundWiring

LMR400Coax

LMR240Coax

SRMSeries

ANTENNA

SRM6000

(425) 882-2206

12VDC

NC

4

DI

3

DO

2

CD

1

9 N

C

8 C

TS

7 R

TS

6 N

C

GD

5

DATA-LINC GROUP

P C I O

LightningArrestor

OmniAntenna

GroundWiring

LMR400Coax

LMR240Coax

SRMSeries

RF Path12 miles

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RF Design: SRM Radios

900MHz constants RF Path Loss with LOS:

First mile: -96dB Each doubling of range: -6dB

Transmitter Power: 1watt or 30dB Receiver Sensitivity: -108dB @ BER 1E-6

2.4GHz constants RF Path loss with LOS:

First mile: -106dB Each doubling of range: -6dB

Transmitter Power: 500milliwatts or 27dB Receiver Sensitivity: -108dB @ BER 1E-6

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RF Design: Throughput

Fact - Distance decreases throughput To maximize radio throughput and reliability:

Maximize RF quality (shorter coax, higher gain antennas) If practical, don’t use store-and-forward repeaters. Use

back-to-back repeaters? Use point-to-point architecture

To minimize system throughput requirements: Avoid cross-network data movement Only retrieve data once (Client/Server HMI model) Avoid HMIs as slaves Exchange data in large groups rather than several smaller

groups (minimize protocol overhead) Minimize data needed and increase update period

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RF Design: Antennas (1)

Use radio manufacturer approved antennas Common types:

Directional (yagi, parabolic) Omni-directional (di-pole)

Gain is specified in dBd or dBi and achieved by directing (focusing) RF emission

Emission patterns must be considered such that other sites are within focused area

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RF Design: Antennas (2)

Antenna coaxTo Lightning Arrestor

Mounting

Hose clamps

N Type male connector

Ground

Antenna coaxTo Lightning Arrestor RF Signal Direction

N Type male connector

Ground

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RF Design: Coax (1)

Data-Linc offers two piece coax assembles: Good price/quality ratio Flexibility at radio mount position Lightning protection ready Bulkhead pass-through ready

Data-Linc only sells coax with end connectors that are inert gas welded, vapor sealed, and tested

Do not cut to length! Coil excess

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RF Design: Coax (2)

Data-Linc uses Times Microwave Coax Website: www.timesmicrowave.com Losses:

COAX 900MHz 2.4GHzLMR240 7.6dB/100foot 12.9dB/100footLMR400 3.9dB/100foot 6.8dB/100foot

Failure Modes Improper end connections Moisture penetration Crimped, collapsed

Weather Seal

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RF Design: Other RF Losses

SMA and N-Type Connectors Loss: .5dB each junction

Lightning Arrestors Always recommended for outdoor applications Install near equipment to be protected Loss: .1dB typical

N Type maleconnector N Type female

connectorN Type male

connector

SRM SeriesALL MODELS

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RF Design: EIRP

Effective Isotropic Radiated Power (EIRP) Set by government regulation This is maximum measured RF emission from an

antenna In most countries not to exceed 4 watts Discussion: 1 watt can be increased to 4 watts by

doubling the power twice (1w x 2 x 2 = 4w). A doubling of power equals 3dB, thus, doubling twice is 6dB. This means a 6dB gain antenna can be directly connected to a 900MHz radio to emit the maximum legal EIRP.

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RF Design: Fade Margin

This is the amount of RF signal strength exceeding the minimum needed for a specified receive sensitivity.

Desired fade margin minimums: 20dB for SRM serial radios 30dB for SRM Ethernet radios

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SRM Series900Mhz

SRM Series900Mhz

50 feetLMR400

50 feetLMR400

RF Path Theory Example 1

What is the fade margin – Will it work?

3dBOmni

3dBOmni

25 miles (40.2km)

30dBTransmit

-108 dBReceive

sensitivity