Anywave Technical Seminar July 2016 OFDM ISDB-T2

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COMMUNICATION TECHNOLOGIES CO. LTD

Anywave Technical Presentation July 2016 – Focus on OFDM and ISDBT

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ANYWAVE Agenda1. A Brief Overview Of ISDB-Tb Standards

2. Transmission System Basics

3. Transmitter Design

4. Advances In Solid State Technology

5. ISDB-T Transmitter Measurements

6. Safety And The Basics Of Transmitter Maintenance

7. OCR and Single Frequency Network (SFN)

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1. A Brief Overview Of ISDB-T

ANYWAVE

ANYWAVE Presentation

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HD ENCODER

SD ENCODER

1 SEG ENCODER

REMULTIPLEXER

EXTERNAL GPS

ISDBT TRANSMITTER

HD-SDI ~ 1.5GB/sSD-SDI ~ 270MB/s

300KB/s

3MB/s

15MB/s

~ 32.5MB/s RF ON CHANNEL

ANYWAVE ISDB-T Overview

SYSTEM CONFIGURATION

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MPEG-4 VIDEO CODEC

MPEG-4 AAC AUDIO CODEC

AUDIO PACKET

VIDEO

SOUND

VIDEO PACKET

• The Audio and Video signals are converted to SDI signal

• The SDI is coded and compressed in MPEG-4 becoming a transport Stream (TS).

• The TS packet has 188 Bytes made up of the HEADER and PAYLOAD.


SYSTEM CONFIGURATION

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SYNCBYTE

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TRANSPORTERROR

INDICATOR1

STARTINDICATOR

1

TRANSPORTPRIORITY

1

PID

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SCRAMBLINGCONTROL

2

ADAPTIONCONTROL

2

CONTINUITYCONTROL

4

ADAPTIONFIELD

PAYLOAD


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THE ACRONYMS YOU SHOULD KNOW…

PSI/SI tables are responsible for the transmission of system and service information.

The main SI tables are: PAT, PMT, NIT, TOT and SDT.

• PAT – Program Association Table – Lists the PMT's present in the (TS)

• PMT – Program Map Table – Lists all PID's present in each service

• NIT – Network Information Table – Contains network info (Ex.: Station name, Station Id, etc...)

• TOT – Time Offset Table – Contains information related to time

• SDT – Service Description Table – Describes the services present in the TS


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• Although the root concepts of QPSK and 4-QAM are different, the resulting modulated radio waves are exactly the same.

• QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol

• Represents four possible states, changing only the signal’s phase. Very robust against noise (information farther from each other), but with small transmission capacity.

• Ideal for 1-Seg modulation

• QPSK constellation diagram: each adjacent symbol only differs by one bit


QPSK

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• QAM is both an analog and a digital modulation scheme; and represents 16 possible states

• It conveys two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme.

• The two carrier waves are out of phase with each other by 90° and are thus called quadrature carriers

• The modulated waves are summed, and the resulting waveform is a combination of both phase-shift keying (PSK) and amplitude-shift keying (ASK)

• Ideal for SD modulation


16QAM

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• 64-QAM Modulation Represents 64 possible states both changing phase and amplitude.

• Low strength signal but capable of high transmission rates.

• Ideal for HD


64QAM

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• FEC is the main component to burst noise immunity

• Guarantees the error correction for transmitted signals in the reception stage by simply adding redundancy bits.

• FEC can be adjusted to 1/2, 2/3, 3/4, 5/6 or 7/8.

• These numbers represent how many of the duplicated bits will be used. The higher the redundancy the higher is the immunity to burst noise, but the lower the transmission rate.


FORWARD ERROR CORRECTION

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• Guard Interval is responsible for multipath immunity;

• In analog what used to generate “ghosts”

• The size of this sample can be 1/4, 1/8, 1/16 or 1/32 of the symbol’s time.

• 1/4 – Greater multipath immunity but with less transmission capacity. 25% of the symbol is repeated.

• 1/32 – Less multipath immunity but with greater transmission capacity. Only 3.125% of the he symbol is repeated.

• The sample size influences the multipath immunity and the effective data transmission rate.

The OFDM symbol has its end part replicated at the beginning.ANYWAVE ISDB-T Overview

GUARD INTERVAL

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MODE

• Defines the number of OFDM carriers that make up the 6 MHz channel.

• It has no influence on the transmission rate; only in multipath immunity (the longer the symbol the better) and in the Doppler effect in mobile reception (more space between carriers, or the smaller the symbol, the better).

• Mode 8k proved itself to be adequate for all types of transmission and is normally used in ISDB-TB transmissions.


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Multipath interference(frequency selective) Flat fading or impulse noise

After De-interleaving2-dimensional random errorSuitable for Viterbi and Reed Solomon error correction

Corrected Output (No errors)


INTERLEAVING

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HIERARCHICAL MODULATION

Hierarchical Modulation is obtained by changing the modulation and error correction parameters

Modulation type : QPSK, 16QAM, 64 QAM or DQPSK

Error Correction: Coding rate of convolutional code (1/2 – 7/8)


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HDTV

SDTV

MOBILE

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SUMMARY

ISDB-T Is a very robust transmission system due to:• Hierarchical modulation, • OFDM and• Variable Guard Interval• Time and frequency interleaving

Uses of MPEG4 encoding which decreases complexity and cost and offers SD, HDTV and ONE-SEG (mobile)

Capable of being received by mobile and fixed reception

THE GOOD NEWS.. With ISDB-T … You have the tools to get the job done… - Good coverage with plenty of options for HD, SD and mobile


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THANK YOU FOR YOUR ATTENTION

ANYWAVE

ANYWAVE COMMUNICATION TECHNOLOGIES CO. LTD

300 KNIGHTSBRIDGE PARKWAY,LINCOLNSHIRE, IL 60069-3655, USA

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ANYWAVE for all your transmission needs

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ANYWAVE



SEND US AN [email protected]

[email protected]

CALL US(+66) 83 618-9333

(+1) 847 415 2258 (Ext. 1)

VISIT OUR WEBSITEwww.anywavecom.com/en

For Product Inquiries, please don’t hesitate to contact us.

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Anywave BTSI Presentation July 2016

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ANYWAVE


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ANYWAVE Transmission System Basics

A Transmission System design has to consider the following:

• Transmitter Power Output (TPO)• Transmission Line Efficiency• Antenna Gain• Effective Radiating Power (ERP)• Total System Price

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Two design methods:

• Fixed TPO• Objective ERP

With Fixed TPO

1. Select TPO to meet objective ERP2. Select type of antenna3. Select transmission line length and size

With Objective ERP

1. Select ERP2. Select type of antenna3. Select transmission line length and size

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Select a transmitter Power Output:LPTV Range20, 100, 200, 400, 500W

MPTV Range1000, 1500, 2000, 2500W

HPTV 5kW to 20kW in 1kW steps

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Type in Transmitter Power Output: 100, 200, 400, 800 ... etc.

Type in Channel (14-70)

Select Meters or Feet

Select Antenna typeChose Pattern if slot, choose number of panels and bays if Panel type.

Select transmission line size, type and length and if there is an additional horizontal run

For cost of OperationSelect Hours per Day and Average Cost of Electricity

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ResultsERP = 3.595kW

Estimated Transmitter Consumption = 1.905KW

Estimated Cost of Operation

$1,390 / Year$116 / Month

Estimated Cost of Equipment Purchase

$37,900

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Type in ERP Objective (5W – 1MW)

Type in Channel (14-70)

Select Meters or Feet

Select Antenna typeChose Pattern if slot, choose number of panels and bays if Panel type.

Select transmission line size, type and length and if there is an additional horizontal run

For cost of OperationSelect Hours per Day and Average Cost of Electricity

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ResultsTPO = 1.1595kW

Estimated Transmitter Consumption = 3.408KW

Estimated Cost of Operation

$2,985 / Year$249 / Month

Estimated Cost of Equipment Purchase

$92,246

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1650 3" SLOT $60,000

1750 2 1/4" SLOT $57,000

Selecting the right combination of Antenna type, Line size and TPO can realize significant savings.. In this case over $15,000.

TPO LINE SIZE ANT. TYPE PRICE

1650 3" SLOT $60,000

800 3" Panel $50,000

2100 1 5/8" SLOT $54,000

650 4" Panel $52,000

800 3" Panel $50,000

OBJECTIVE TO DELIVER 7KW ERP

1000 1 5/8" Panel $45,000

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ANYWAVE



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[email protected]

CALL US(+66) 83 618-9333

(+1) 847 415 2258 (Ext. 1)



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Anywave BTS Presentation July 2016

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ANYWAVE


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Criteria of developing a new Transmitter

• Its all about the MONEY!

From a manufacturers point of view• Lower manufacturing costs by using more effective and efficient methods, technology designs

and materials.• Include new features, benefits and concepts in order to be better than the rest

From the customers point of view• Lower capital costs• Lower Operational costs ; Efficiency, Maintenance, Spares and Repairs

ANYWAVE Transmitter Design

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So how do we meet all these criterion?

• It’s all in the DESIGN

• If you make a transmitter reliable, you lower operating costs for the user and decrease support costs for the manufacturer.

• Reliability is about oversizing the materials, not cutting corners in materials and providing the appropriate protection for all scenarios


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Carved ALUMINUM HEAT SINK

• Single Piece of Aluminum

• All BLF888 devices and reject loads are directly mounted onto heat sink for maximum heat dissipation and minimum heat transfer resistance

• Power cables are routed under the main board and within the carved heat sink.

AMPLIFIER DESIGN

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Carved ALUMINUM HEAT SINK

• High density, heavy duty

• Light weight

• Special fin structure provides large equivalent surface area

• High density fin panels create air flow “turbulence” for very fast heat removal

• RESULT: VERY COOL OPERATING TEMPERATURE OF ENTIRE AMPLIFIER

AMPLIFIER DESIGN

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AMPLIFIER DESIGN

COOLING

• Brushless, speed control fans

• 267 CFM rating for each fan(operates at <100CFM)

• Fan speeds displayed on control unit and via Web browser remote control

• Temperature controlled for optimum efficiency and extended life

• Easily field replaceable with two screws and plug in connectors

• RESULT: Amplifiers operate very quietly and reliably

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AMPLIFIER DESIGN RF OUTPUT

• Heavy duty 7-16 DIN output connector

• Connector rated at 1kW capable handling power

(45% over-rating)

• No tools required to connect or disconnect

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Power Supply

• HOT PLUGGABLE – FROM FRONT OF TRANSMITTER

• No tools required to remove power supply

• Heavy power capacity 4000W AC/DC power supplies

• Total 4000W capacity for 500W ISDBT output

• Fire and smoke resistant wiring

AMPLIFIER DESIGN

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• Well shielded multiple compartment design

• All-digital bias and measurement adjustment

• Dedicated micro controller in each PA module for local monitoring

• Real time and continuous measurements on current, voltage, bias on each BLF888 device temperature, forward power and reflected power levels

AMPLIFIER DESIGN

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• Comprehensive Graphical user interface for remote access

• Complete control and ALL information available

REMOTE CONTROL AND MONITORING

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• Complete monitoring and control functions

• Large 5” touch screen• 30W output power level• System Status displayed

• Forward power• Reflected power• Rejection power levels• Optional dBm, Wattage or

percentage display• VSWR

Driver Status display• Input level• Exciter presence and selection• Forward power reflected power, current, voltage.• Real time log• Amplifier mode status displayed• Forward power, reflected power current, voltage, temperature bias voltage• Fans Speed• Remote accessibility: (1) RS232, (2) RS485, (1) RJ45, Web interface

(Available on transmitters above 400W).

CONTROL AND MONITORING

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• Transport Stream Processing

• Modulation• Automatic Digital

Pre-correction• Digital to Analog

Conversion• Amplification –• -25 – 5dBmb

Pre-amplification +18dBPre-amplification 14dBSplitter -6dBFinal amplification +17dB Combiner +6dBOutput ~ 400W

DigitalExciter

RF Power Amplifier

DirectionalCoupler

TS1input

Band Pass filter10-20dB shoulder reductionInsertion Loss of 0.6dB

Band PassFilter

Feedback Samples for power metering

Directional Coupler Single Probe provides samples for pre-correction(non-linear and linear)

Functionality

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EXCITER FUNCTIONAL DESCRIPTION

Digital Inputs

Analog Inputs

Digital (IP) and analogremote management inputs

Reference inputs (GPS, 1PPS etc.)

SIGNAL FLOW

SYNCRONIZATION CONTROL FEEDBACK

DISPLAY and CONTROL FUNCTIONS

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Output is made up of Two microstrips L3 and Balun B1.

C1 – C9 used to match transistor Impedance to 50 ohm.

Inductor L5 and C17/C18 improve match at LF.

The length of the Balun B1 is 1/8 the central frequency of mid UHF frequency i.e. 550MHz.

Input is made up of Two microstrips L32 and Balun B2.

R1/R2 LF DampingC34/C35 RFDecoupling for the Balun

R3-R6 and C35/C37Provides damping function that helps improve stability

AMPLIFIER OPERATIONAL DESCRIPTION

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ANYWAVE Transmitter DesignTRANSISTORDESIGNUPDATE

NOW

NOW

SOON

FUTURE

Non-DohertyBroadband

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ANYWAVE




[email protected]

CALL US(+66) 83 618-9333

(+1) 847 415 2258 (Ext. 1)



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Anywave BTSI Presentation July 2016

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4. Advances in Solid State Technology

ANYWAVE


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A Brief History Of Solid State Transmitter Efficiencies

ANYWAVE Advances in Solid State Technology

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Introduction

• Generation 1 released in the late 80’s was inefficient and unreliable• Generation 2: Philips BLF861A and Motorola MRF372 (180 watt – 14dB Gain)

• Efficiency of 2nd Generation devices (digital operation) ~18%

• In 2008 came Generation 3 was introduced; the “50” volt LDMOS • This resulted in lower cost per watt and helped reduced the cost of much higher

power transmitters• Efficiency increased to ~ 25%• The BLF888A became the standard for all manufacturers• However, efficiency of these devices “stalled” at the 25% level

• Improvements could be made in other areas of the transmitter but most only saw very small improvements in efficiency


5757

To compete with vacuum tubes at high power namely the MSDC-IOT which had efficiencies in excess of 50%... A much higher efficiency was needed:

Two new “ideas” to make solid state efficiency compete with the IOT…

• Drain Modulation (or Envelope Tracking)

• Doherty Modulation

Efficiency


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PA

V dc

ATSC Modulator

ASI

RF

Operates by modulating the DRAIN of a FET amplifier with the input signal so that the Power Supply voltage follows the level of the input signal. The amplifier operates near the high-efficiency saturation.

Drain Modulation via Envelope Tracking (DM/ET)


Wasted Power

V dc

Resulting in a Drain Efficiency is about 25%

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ATSC Modulator PA

V dc

ASI

RF

DC - DC Converter

Wasted Power

V dc1mS




Resulting in a Drain Efficiency is about 30%

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ATSC Modulator PA

V dc

ASI

RF

Envelope Detector

SupplyModulator

De

lay

Wasted Power



Resulting in a Drain Efficiency is about 40-50%

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Drain Efficiency• Now ~ 38%• Future ~ 40-50%• Theoretical maximum ~ 80%

• Sophisticated circuitry including DAC, Filter, I/Q detector and quadrature mixer required.

• Circuitry has to be included very near and on every amplifier, hence complexity increases with number of amplifiers.

• Significantly higher component count decreases the mean time between failure (MTBF).

• Not chosen by most manufacturers due to complexity and additional costs


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Doherty Modulation

A1

A2

RF Input

Carrier Amplifier Class AB (saturates at high power input)

Peak Amplifier Class C (Turns on at high power input)

ANYWAVE Advances in Solid State TechnologyParalleling two amplifiers devices; first operating in Class AB which amplifies the average power level, and the second operates in Class C amplifying just the peaks of the waveform. Output of two devices are combined with a matched transformer.

6363

• DOHERTY configuration improves linearity at the high power input by complementing the saturation of the carrier amplifier with the turn on characteristics of the peak amplifier

Doherty Modulation

• Originally designed by William Doherty of Bell Labs in 1934

• In 2008 NXP semiconductors (founded by Philips, now called Ampelon) released a transistor “optimized” for Doherty amplifier applications. It has since been improved and commonly available… Example BLF888


6464

P out

P in

Saturation

Carrier Amplifier

Doherty Modulation

Peak Amplifier

The addition of the PEAK and CARRIER Amplifiers

“Turn on”


6565

• Amplifier efficiency

• Now ~ 40%• Future ~ 40-50%• Theoretical maximum ~ 50-60%

• Simple to implement with current circuitry available

• Due to two different devices feeding same load, impedance matching section is required and hence is frequency dependent limiting broadband operation.

• Band-limiting output combiner/matching section can be configured to provide easy “Broadband” operation; thru’ simple interchangeable parts. The “D” and “E” versions are becoming more broadband overcoming this issue.

Doherty Modulation


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Consumption – ISDB-T

10kW UHF

74kW Of Wasted Power



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Doherty Class AB and Class C

Standard Dual Class AB

Average of 75.6 C

Operating Temperature

T1 = 62.9 CT2 = 54.6 C

T1 = 75.7 CT2 = 75.5 C

Drain Modulation via Envelope Tracking

T1 = 58.9 C

Average of 58.7 C

Average of 58.9 C

Reduces transistor operating

temperature by 23 C


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Conclusion

Doherty Modulation is

• Easier to implement

• Does not reduce the reliability of the standard Fixed Drain (FD) Transmitter

• Reduces operating temperature of amplifier

• (Potentially increasing the reliability)

• Provides a large efficiency improvement

• (Tens of thousands of savings compared to FD)

• Offers the lowest cost transmitter


6969


MPTV Range1kW, 1.5kW, 2kW, 3kW

Non-Doherty : 2, 20, 100, 200

Doherty: 400, 600W

All available in both Doherty and

Non Doherty

LPTV Range2, 20, 100, 200, 400, 600

The Choice is yours….

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[email protected]

CALL US(+66) 83 618-9333

(+1) 847 415 2258 (Ext. 1)



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5. ISDB-Tb Transmitter Measurements

ANYWAVE


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ANYWAVE ISDBT-Tb Transmitter Measurements

What are the KEY Measurements for an ISDB-Tb Transmitter?

• POWER

• Modulation Error Ratio (MER)

• Intermodulation Distortion (IMD)

And if possible….

• Harmonics (Out of band)

• Bit Error Rate (BER)

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INTRODUCTION

• Broadcasting transmitters are subject to particularly stringent standards with respect to broadcast signal quality

• Small faults can lead to service disruptions for many viewers

• A single instrument, such as the R&S® ETL TV analyzer* can perform all required ISDB-T transmitter measurements

* Instead of the ETL the ETC or ETH can be a lower cost option

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Two ways of making measurements

• OPTION 1: With External Test equipment

OR

• OPTION 2: With Anywave built in measurement system and Power calculation system using Historic data and component manufacturers results

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EXCITER/MODULATOR

ENCODER

TransportStream

• The R&S®ETL TS has a built TS generator. This feeds an ISDB-T-compliant MPEG-2 transport stream (TS) to the TS input on the ISDB-T transmitter.

• Or a compliant ISDB-T encoder can be used.

• Even without a Transport Stream source Output Power calibration and the measurements of MER, Shoulders can still be taken.

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ENCODER

EXCITER/MODULATOR

RF AMPLIFIER

RF BAND PASSFILTER

RF DUMMY LOAD

TEST EQUIPMENTR&S® ETL

R&S® NRP

PC

DIRECTIONALCOUPLER “A”

TransportStream

RF On Channel

DIRECTIONALCOUPLER “B”

RF On Channel

OPTION 1

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Orthogonal frequency division multiplex (OFDM) signals exhibit a very high crest factor because in extreme cases, all carriers could be overlaid or even eliminated at any given moment.

Where N = Number of carriers


It is important to know the crest factor so that the components that follow the transmitter – such as the mask filter, the antenna combiner, the coaxial cable and the antenna, can be sized adequately.

The crest factor (CF) defines the relationship between the highest occurring amplitude of the modulated carrier signal and the RMS voltage of a signal:

CF = 20 10

CF OFDM = 10 10 2

Crest Factor

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• The (CCDF) complementary cumulative distribution function includes the statistical probability that a signal peak will occur.

• For ISDB-T, a theoretical value of > 40 dB results for mode III .

• In practice, it is limited to about 13 dB in the transmitter.

Crest Factor

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0 2 4 6 8 10 12 14 16 18 20

10²

10

10ᴼ

10

1

-1

Instantaneous Power / Average Power Ratio

Pro

bab

ility

%

CF = ~ 13dB

4% at 10dB(4kW)

0.1% at 11.8dB7.6kW

Assume at TPO = 400WCrest Factor

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Modulator Characteristics I/Q Imbalance

ISDB-T modulators are essentially an IFFT signal processing block followed by an I/Q modulator. This I/Q modulator can be either digital or analog. Anywave’s modulator is Digital. If an ISDB-T modulator uses direct modulation, then the I/Q modulator it must be aligned cleanly to minimize the following influencing factors:

● Amplitude imbalance ● Quadrature error ● Carrier suppression

It is difficult to measure these items without a spectrum analyzer, as poor carrier suppression is recognizable as a notch directly at mid band and results in a contorted and compressed constellation diagram in mid-band. Amplitude imbalance and quadrature error negatively affect the MER.

The Anywave modulator automatically corrects for minimum I/Q imbalance

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Amplitude Frequency Response and Group Delay

• In analog television, amplitude frequency response and group delay were important parameters for a transmission path between the transmitter output and the receiver input.

• Because of the channel correction in the ISDB-T receiver, significantly larger tolerances can now be permitted without noticeable reductions in quality. The mask filter and antenna combiners cause linear distortions.

• These linear distortions can be compensated by a pre-corrector within the transmitter. As a result, however, the linear distortions appear reversed when measured at the transmitter output.

• Therefore, the preferred method is to measure amplitude frequency response and group delay after all filter stages.

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Out-of-Band Emissions

There are THREE distinct components:

● Shoulder attenuationDescribes the power of the noise components close to the edge of the channel

● Adjacent channel emissions Components within several MHz of the channel boundaries

● Harmonics Components at multiples of the transmit frequency

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Shoulder Attenuation and Adjacent Channel Emissions

• The mask filter is used to reduce these unwanted out-of-band emissions.

• Critical mask filters are used when an adjacent channel requires protection, making more stringent requirements for attenuation of out-of-band emissions necessary.

• The high dynamic range of the signal after the mask filter makes it impossible to check adherence to the tolerance mask directly using a spectrum analyzer. This is why an adjustable notch filter is typically used to reduce the useful band power.

• The correct method is a complicated process using a tracking generator and additional notch filters to attenuate the fundamental frequency so as not to overload the analyzer.

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Harmonics

• In addition to adjacent channel emissions, multiples of the transmit frequency can also result in harmonics. A harmonic filter at the transmitter output is used to suppress these harmonics.

• The R&S®ETL TV analyzer can be used to measure out-of-band emissions in spectrum analyzer mode. Because the mask filter does not suppress these harmonics, but rather affects only the channel near range, the harmonics can be measured directly at transmitter output.

• The high dynamic range of the signal means that a suitable high pass filter must be used to attenuate the useful channel by at least 40 dB.

• Notch filters (which are coaxial cavity filters that can be manually adjusted to the channel being suppressed) are not suitable here because they do not attenuate in just the useful band, but rather are repeated at multiples of the useful band.

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Frequency Accuracy

• Single-frequency networks (SFN), in particular, place very stringent requirements on the frequency accuracy of an ISDB-T transmitter of less than 10-9.

• The carrier frequency offset can be measured using the R&S®ETL in TV/radio analyzer/receiver mode or a very accurate frequency counter.

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• Complex Modulation Error Ratio (Complex MER) is a complex form of the S/N measurement that is made by including Q (quadrature) channel information in the ideal and error signal power computations. MER is defined by the following formula:

∑

∑

Where

MER is the Modulation Error Ratio in dB

are the Ideal I-channel and Q-channel symbols.

∂ I j and ∂ Qj are the Errors between received and ideal I- channel and Q-channel symbols.

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Modulation Error Ratio

• A high MER value indicates good signal quality.

• In practice, the MER is 20 to 42 dB.

• A good ISDB-T transmitter has a MER in the range of approximately 35-38 dB.

• When receiving ISDB-T signals over a roof antenna with gain, a MER of 20 dB to 30 dB would be measurable at the antenna port.

• Values between 13 dB and 20 dB are expected for portable receivers with a indoor antenna.

• The MER is the single most important quality parameter for an ISDB-T transmitter.

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Constellation Diagram

• Good MER is indicated by small and concentrated dots

Bad MER, represented by scattered and distorted dots in the constellation.

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Bit Error Ratio

• ISDB-T provides an outer and inner error correction in the form of Reed-Solomon (RS) block coding and convolutional coding, which are assessed using a Viterbi decoder. Both methods are capable of recognizing and correcting bit errors in the data stream.

• All interference of an ISDB-T transmission path can be expressed as bit error ratios (BER).

• In the case of a functional ISDB-T transmitter, only the BER before Viterbi can differ from null. It will lie in the range of 10–9 or less.

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Phase Noise

• Can happen due to the local oscillator's instability

• In the OFDM modulation process, phase noise can cause a phase error in all of the sub-carriers at the same time.

• It causes the constellation dots to “twist” on their axis.

474 MHz 762 MHz 802 MHz

10 Hz 86.3 82.0 81.2

100 Hz 106.9 102.7 102.3

1 kHz 118.8 115.3 114.3

10 kHz 124.0 120.8 120.2

100 kHz 124.6 122.0 121.9

1 MHz 141.4 140.0 139.5

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Phase Noise

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Efficiency and Performance of Digital TV Transmitters

REF: Average Carrier Level

24dB

Un-corrected Class A-B Amplifier


IMD (Intermodulation Distortion) or Shoulders or Out of Band Mask

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42dB

Corrected Class A-B Amplifier



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17dB

Un-corrected DOHERTY Amplifier



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39dB

Corrected DOHERTY Amplifier



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Testing an Anywave Transmitter with NO TEST EQUIPMENT

FREQ617M

AGCOFF

GPSNOGPS

1PPSERR

CTRLLCA

ADPCOFF

• Frequency is measured in the exciter.

• With a GPS connected you can be assured of the accuracy.

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FWD100%

MER43.5

LIMD48

UIMD49

FREQ653M

Hz+00000

MODEMODE1

GI1/4

PROFF

A-B-C-13000

LAYA

RATE1/2

MAP16QAM

TI0

• Forward Power (+/- 3%)

• Modulation Error Ratio (+/- 1dB)

• Lower Intermodulation Distortion (+/- 1dB)

• Upper Intermodulation Distortion (+/- 1dB)

• On Channel Frequency

• Off Set Frequency

• Major status of modulation Modes: (GI, Layer, Rate, Modulation type and TI).

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VOL_98.72

VOL_1212.07

VOL_5049.37

PA_FWD443.67

Power Calibration (Using the PAC Screen)

• The Forward Power will be calibrated at the factory on the designated frequency.

• If frequency is changed this calibration will not be correct.

To Re-calibrate the Forward Power

• The sum of the currents multiplied by the 50V level divided by the frequency/efficiency factor = the output power (+/-5%)

CUR1_ 5011.2

CUR2_5011.7

CUR3_5012.1

CUR4_5011.8

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Filter PowerBand

CenterBand Edge Average Factor

100W 1.3 2.2 1.75 0.67

150W 1.0 2.0 1.50 0.71

250W 1.1 1.8 1.45 0.72

600W 1.2 1.6 1.4 0.72

1000W 0.8 1.4 1.10 0.78

1500W 0.6 1.1 0.85 0.82

1800W 0.6 1.1 0.85 0.82

2000W 0.6 1.1 0.85 0.82

3000W 0.6 1.1 0.85 0.82

7000W 0.6 1.1 0.85 0.82

Power Calibration

• Filters have a reasonably consistent attenuation over frequency

• The lower the power rating of the filter the higher the loss.

• Losses vary from 1.75dB to 0.6dB • Multiply amplifier output power by

FACTOR to obtain real TPO.

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0.2

0.22

0.24

0.26

0.28

0.3

0.32

0.34

0.36

Efficiency Factor



200W (Two transistor) OFDM (DVB-T2 and ISDB-Tb)Example: Frequency 593MHz. Power Required 200W after the filter. Power factor at 593MHz = 0.28Filter loss is 0.72dB for a 250W filter. There are two transistors in aVOL_50 (50V PSU) = 49.87 CUR1_50 and CUR2_2 should read (ON AVERAGE)

200 / 0.28 / 49.87 / 0.72 / 2 = 9.95 AMPS i.e. 9.95 Amps* = 200W after filter output +/- 5%* Average of each transistor.

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0.2

0.22

0.24

0.26

0.28

0.3

0.32

0.34

0.36

Efficiency Factor



400W (Four transistor) OFDM (DVB-T2 and ISDB-Tb)Example: Frequency 533MHz. Power Required 400W after the filter.VOL_50 (50V PSU) = 49.97 CUR1_50, CUR2_2, CUR3_50 and CUR4_50 should read (ON AVERAGE)

400 / 0.33 / 49.97 / .72 / 4 = 9.95 AMPS i.e. 8.42 Amps* = 400W after filter output +/- 5%* Average of each transistor.

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0.2

0.22

0.24

0.26

0.28

0.3

0.32

0.34

0.36

Efficiency Factor



1500W (Six transistor, three amplifiers) OFDM (DVB-T2 and ISDB-Tb)Example: Frequency 497MHz. Power Required 1200W after the filter.VOL_50 (50V PSU) = 49.97 CUR1-6_50, should read (ON AVERAGE)

1200 / 0.35 / 49.97 / .82 / 6 / 3 = 4.65 AMPS i.e. 4.65 Amps* = 1200W after filter output +/- 5%* Average of each transistor.

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Anywave will provide customer with a Frequency versus Power versus Transmitter software

Enter Frequency of operation,

Model number of transmitter

Power required

And the software will automatically tell you the currents of each transistor to reach that power.

The transmitter then can be calibrated very accurately at any frequency

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Summary

• With Test Equipment make the following measurements regularly (one every six months)• POWER• Modulation Error Ratio (MER)• Bit Error Rate (BER) • Intermodulation Distortion (IMD)• Harmonics (Out of band emissions)

• Without Test Equipment• Transistor currents• MER• IMD

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112

7. Safety and Maintenance

ANYWAVE


113

Safety• SAFETY FIRST. When appropriate wear goggles, take off your rings and watches, tuck in your shirt.• When working on “hot” equipment .. Keep you hand in your pocket• Don’t work when you are tired.• Don’t drive to the site too quickly• Try to work in teams

Inspection• Visual inspections can resolve most issues. Visual inspection should be

done with Power OFF. Useful tools .. Power flash light and mirror.

Reliability• Most RF systems are reliable.. It is usually the low voltage stuff that fails

first.• Most problems occur due to control circuits.. Know how the control system

works before there is a problem

ANYWAVE Safety and Maintenance

114

Environmental Conditions• A HOT and DIRTY transmitter is an unhappy transmitter!• Unhappy transmitters FAIL.• Try to keep the transmitter site as clean as possible. Clean the

transmitter floor, clean table tops regularly, and clean any air filters.• Make sure the room is air conditioned. Make sure the room

temperature does exceed 30 degrees C (85 F).

• Make sure there is plenty of air flow around the transmitter.

• A nice feature is to include a stand alone duct for the transmitter about 30 cms above the top of the transmitter. And let the hot air simply exhaust, a small exhaust fan can be included if the duct is longer than 3 meters.


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FWD100%

MER38.5

LIMD43.5

UIMD44.0

Forward Power0 – 100%

Upper Intermodulation Distortion (UIMD): 20 – 60dB

Modulation Error Ratio(MER) 25 – 50dB

Lower Intermodulation Distortion (LIMD): 20 – 60dB

POWER 100% = 0dB

Meter readings


116

Grounding• The tower and incoming transmission line should be bonded

to the building lightning protective ground

• The Transmitter and electrical panel should be bonded to the building lightning protective ground


Grounding RodsBelow Ground

Tower

Transmission Line

Transmitter Electrical Panel

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• CHANGING CHANNEL


• If your amplifier is Non-Doherty

• The process is simply

• Change the exciter frequency• Re-tune or replace the filter on the correct

channel…

• Re-calibrate the forward power.. Done!

• However, with a Doherty Hi-Efficiency amplifier… it is not so easy

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• Hi-Efficiency Doherty Power Amplifiers based on the BLF 888B device provide high efficiencies (50% efficiency) but with narrow band operation

• The Anywave Doherty PA design has multiple sub-bands across UHF, and so re-tuning a Doherty PA involves replacing the three PA circuit boards (shown) with a circuit board that covers the desired channel frequency.


119

• First remove the boards from the amplifier.

• To remove the board you must

• Access the power transistor board• Remove top amplifier panel• Remove inner shield cover

• Remove all the screws from the printed circuit board (about 40)


120

• De-solder the power supply wires (2)


• De-solder the transistors and combiners

(to be re-used)

121

• Replace the board with a new board of the correct sub-band


122


• Once the circuit boards are replaced, the power transistors and combiners are re-soldered into place

• All screws replaced

• Power supply wires re-soldered

• Apply AC power to amplifier

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• After the amplifier is now complete and ready to operate, the only thing left to do is re-bias the transistors to the correct level.

• This is accomplished by adjusting the potentiometers to the correct idle current (~0.5A). The idle current is monitored on the web interface via the RJ45 connector on the rear of the amplifier. There are two potentiometers per transistor (four total) for the board.

124

Summary

The key to success is

• Provide protected power• Thoroughly ground all equipment• Regularly check tightness of all connectors• Avoid using tools on RF connections less than 7/8” EIA flanges• Keep accurate records (initial snap shot of operation, then monthly)• Measure the SNR, IMD, Forward Power and Reflected power regularly (monthly)• Monitor PA device currents and temp – be sure do not reach max (monthly)• Keep the transmitter properly cooled• Keep the transmitter and the transmitter building clean• Don’t try to fix a working transmitter!

• SAFETY FIRST.. No one ever died because they could not watch your TV station !


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129

7. OCDR and SFN’s

ANYWAVE


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What is an OCR and a Translator

130

OCR: Process the input signal by eliminating the “echo”, boost it and re-send it at the same frequency as the received frequency

Translator: Usually perform demodulation and decode to the received signal, and can be re-send at any frequency desired

ANYWAVE OCDR and SFN

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• OCR uses the same frequency for re-transmitting (fin=fout)

• When the processing delay of OCR is much smaller than the guard interval, the re-transmitted signal and the original signal can form a SFN

• OCR is one of the most popular way to set up SFN

• Disadvantage of OCR• The transmitted power is limited by the “echo”• The quality of transmitted signal is easily deteriorated and can be a interference to other

tower

• Advantage of OCR• Doesn’t require additional transmit network• Easier installation and lower cost• Doesn’t require GPS as reference signal13

1

Interference Cancelling can overcome the disadvantage of OCR!


OCR and Single Frequency Network (SFN)

132

Echo Interference in OCR

Conclusion: The system gain of OCR is severely limited by the system isolation. Therefore how to increase the isolation is the key to OCR application!

G: System Gain

E: System Isolation

H: System transfer function


133

Interference Cancellation System (ICS)


Z is the phase relationship between the input and the output

134

Echo Types

1: Direct coupling between receiving antenna and transmitting antenna

2: Reflection of far-away mountain3: Reflection of nearby building4: Reflection of moving object


135

Echo Cancellation


136

Echo Cancellation in SFN


137

Concepts in Echo Cancellation

Signal Length: Length of received signal channel impulse response


Echo Delay: The delay between echo and received signal

Echo Window: Length of echo channel impulse response

Process Delay: The delay of echo cancellation process

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OCR System Gain Example (w/o ICS)


Assume:

Received signal level:-50dBm

Antenna isolation:80dB

Conclusion:

Max system gain: Antenna isolation- 10dB = 70dB

Max transmitted power: Received signal power + max system gain= -50 + 70 = 20dBm

139


Assume:

Received signal level:-50dBm

Antenna isolation:80dB

Conclusion:

Max system gain: Antenna isolation- 10dB +30dB= 100dB

Max transmitted power: Received signal power + max system gain= -50 + 100 = 50dBm

OCR System Gain Example (with ICS)

140

Key Spec in ICS

Echo-to-Signal-Ratio

But most of all…

MER!!!!


141

Echo-to-Signal-Ratio


142

Reasons of MER Deterioration

• The MER of received signal

• The linear and non-linear distortion of the transmitted system

• Echo Ratio


143

Anywave Gap Filler with ICS

EOCR8000

PA100W

PA20W

PA200/400W


144

Anywave OCR Features (1)

• Auto Shutdown/Turn ON Function：• When the main transmitted tower shuts down for maintenance, our OCR will shut down

automatically; when the main tower resumes transmitting signal, our OCR will turn on automatically. No manual intervention is required.

• Signal Quality Auto Detection:• When the received signal quality, echo level or re-transmitted signal quality has

changed, our OCR will adjust its transmitted signal level automatically. If transmitted signal cannot meet broadcasting requirement after the adjustment, the OCR will shut down its output automatically. No manual intervention is required.


• Patented AECTM (Adaptive Echo Cancellation) technology continuously, automatically, and adaptively eliminates dynamically varying echoes from the received signal, providing easy installation, reducing engineering cost, and producing stable operation as well as excellent performance

145

Anywave Features continued


Echo Cancellation Mode• Echo Cancellation:30 dB (typical value)• Echo Time Range:≤ 4 μs• MER Loss• 0 dB Echo: MER Loss ≤ 3 dB or MER ≥ 26 dB (depends on main signal SNR)

• 10 dB Echo: MER Loss ≤ 5 dB or • MER ≥ 26 dB (depends on main signal SNR)

• Echo Time Range:≤ 4 μs• Processing Delay:≤ 10 μs (including ICS and DPD）

146

Anywave Features continued

• Supports current digital and mobile TV standards including DTMB, CMMB, DVB-T/H, DVB-T2, ISDB-T, ATSC, and ATSC-MH

• Patented AECTM (Adaptive Echo Cancellation) technology eliminates dynamically varying echoes

• Powerful ADPCTM (Adaptive Digital Pre-Correction) provides superior digital correction of all linear and non-linear

• Accurate ESSI (Echo Signal Strength Indicator) and RSSI (Received Signal Strength Indicator) functions provide direct field signal condition assessment and easy installation

• Digital ALC (Automatic Level Control) function supports wide RF input range and eliminates the LNA module

• Powerful anti-interference of adjacent channel


147

Application 1

Directional Reception and Omni Transmit in city

Transmitted Power Level:100WReceived Signal:-50dBmReceived MER= 25.2dBRe-Transmitted Signal MER=23.5dBEcho Ratio= 9dB


148

Application 2

OCR in outlying mountain area

Transmitted Power Level:20WReceived Signal:-70dBmReceived MER= 28dBRe-Transmitted Signal MER=25dBEcho Ratio= 15dB


149

Wideband Broadcasting System (WBS)

For OCRs


150

Wideband Broadcasting System (WBS)


A WBS system allows multiple Modulators, Translators and OCDR’s to use the same Power Amplifier

Uses ANYWAVE’s Patented WB PRECORRECTION SYSTEM

151

Advantage of WBS

• Does not require high-power combiner, therefore reduce the complexity and cost of the transmitter

• Easier to change transmitted frequency

• Particularly suitable for low-cost coverage application of multiple channels from the same location


152

Disadvantage of WBS

Severe distortion without an efficient pre-correction


153

Wideband Pre-Correction Technology


With the appropriate Wideband non-linearity correction system Intermodulation distortion can be removed

Result:

Significantly higher output power per amplifier

Improved Non-linearity = better coverage

Example from 5 Inputs / 100W amplifier- without WBCS = 1W- with WBCS = 10W(10dB improvement)

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SINGLE FREQUENCY NETORKS (SFN)


155

SFN


Advantages: - Better use of the frequency spectrum allowing growth for TV channels. - Uniform distribution of radiated power - Distribution increases system availability and reliability. - The presence of multiple transmission points gives the receiver an

- Additive Gain - addition of multiple signals-- and a Statistic Gain - more uniform coverage.

To implement SFN, i.e. synchronize the signals, Key parameters shall be observed: 1. Same transmission Frequency 2. At the same time 3. Same signal (BTS), bit by bit – No rearrangement of the MPEG Stream

156

SFN


The main parameters that influence a SFN, besides transmitter power are:

• Guard Interval (GI)

• Delay adjustment

157

SFN


• The GI defines the overlapping area in which an SFN is possible.

• If a receiver falls outside the area protected by the GI and continues to receive signal from more than one transmitter, it won’t be able to open the signal due to inter-symbol interference (ISI).

• i.e. it sees the second signal not as additive but subtractive

• The bigger the Guard Interval the less interference but the lower the bit rate (reduced quality and or reduced number of programs)

1/4

1/8

1/16

1/32

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126

63

26

76

38

17

8

G/I uS km

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SFN


Two transmitters in SFN

If there is no overlap on coverage then there is no interference issues.

TX A TX B

159

SFN


TX A

• The red area corresponds to the area that can’t be larger than the area in which the delay falls inside the GI.

TX B

• A delay adjustment between transmitters allows the signal to be transmitted at the same time (or with a delay that falls within the GI), allowing the receiver to capture this signal, making a SFN possible.

• Transmitters must be fed with same Broadcast Transport Stream at EXACTLY the same time

160

SFN


• The delay calculations are made at the generating station

• Calculations have to consider the necessary time for the BTS to arrive at the repeater station

• Once all stations are synchronized the SFN is established.

• This delay calculation can be made manually or automatically.

161

SFN


Example• TX A is 6km from TX B and 12km from TX C. • TX A is generator station• Using the propagation speeds it can be

determined that signal takes 20μs to get to B and 40μs to C

TX B

TX C

12km

TX A6km• Result : • Delay on TX A BTS = 40μs• Delay on TX B = 20μs • Delay on TX C = 0μs

• Additional fine adjustment may also be required for :

• Antenna phasing and directivity• Specific interference variation with each location

162

SFN

Example of GI adjustmentTX A + TX B gives interference designated by the yellow area

TX A TX B


If there is a populated area outside of the GI adjustment area (red circle)

There are two solutions:1. Increase the Guard Interval, but this will reduced the transmission rate (quality and possibly quantity of programs)

163

SFN

• Or adjust the delay to TX B to move the protected area

• Increasing the delay on TX B we make the region where these signals arrive together be closer to the transmitter B This allows the populated area to become protected by the GI.

• There was an intentional delay alteration to move a good reception area from a non-populated area to a more populated one


TX A TX B

164

SFN


To further reduce the interference area

• Lower power on the furthest transmitter

• Use of more robust modulation parameters – however, this again will decrease bandwidth and options of programming i.e. only SD instead of HD or UHF.

• Combined use of SFN/MFN, selecting a different channel for one of the stations

• Use of On Channel Digital repeaters in geographically advantageous locations

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SFN


• Main SFN components

• An SFN is composed of various equipment's that have specific functions such as BTS generation (encoders), distribution networks (fiber or microwave), delay inserters, modulators (exciters) and synchronization systems.

• None of these additional items are required with OCDR

IMPORTANT: Distribution equipment cannot alter content or packet order in the BTS!

• Equipment used for BTS distribution must be transparent, meaning that the order of the multiplex frame packets is not modified. Equipment used include IP radios, Digital microwave equipment, optic fiber, and satellite links for BTS distribution.

166

SFN


Network Types: SFN networks can be of two kinds depending on their operation mode: - Dynamic Network

-It is the easiest to implement and the most used configuration, because the delays are calculated automatically with base on the information in the NSI field of the IIP. For this the delay inserters must receive the same 1PPS reference. Maintenace in this type of network is simplified by the automatic calculations for delay, making replacements a simple task with no need to reconfiguration.

Static Network

• In this operation mode the delay calculations are not done by the system and the absolut delay info has to be informed to the Network Adapter (TIME_OFFSET) being necessary only a 10MHz reference for synchronization.

• It is more complex due to the fact that all delays in the distribution channel have to be known in order to configure SFN correctly.

167

SFN


Dynamic - Pros: Automatic Path Delay calculation - Cons: In case of 1PPS reference failure, transmitter “mutes” not to interfere with whole network.

Static - Pros: No necessity of 1PPS - Cons: Necessary to know all delays in the network. If a piece of equipment is substituted, a new calculation is needed. This info can be obtained from equipment manuals or by measurements.

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[email protected]

CALL US(+66) 83 618-9333

(+1) 847 415 2258 (Ext. 1)

