AM Power Savings AM Power Savings Using IBOC and MDCL Using IBOC - - PowerPoint PPT Presentation

AM Power Savings AM Power Savings

Using IBOC and MDCL Using IBOC and MDCL together g

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Presentation Overview

• Common types of MDCL

A lit d M d l ti C di (AMC) – Amplitude Modulation Companding (AMC) – Dynamic Amplitude Modulation (DAM)

• Implementation on NX (and older products)
• Implementation on NX (and older products)
• What are the implications?

Typical power reduction – Typical power reduction – Spectral mask concerns – Will your listeners notice? Will your listeners notice?

• Recommendations and conclusions

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Amplitude Modulation Companding (AMC)

• Reduces overall

gain on envelope signal at high mod

• Relatively inaudible

to the listener T d t i t i

• Tends to maintain

high SNR on received signal received signal Optional Title

Dynamic Amplitude Modulation (DAM)

• Reduces carrier
• nly at low mod –

sidebands are h d unchanged

• Boosts received

audio at low mod audio at low mod

• Can result in higher

savings if less savings if less processed audio is used Optional Title

NX MDCL Implementation

• MDCL techniques are implemented digitally in the

NX exciter

– Precise peak control – Allows adjustable compression and different curves

• The MDCL-modified signal from the NX exciter is

used to replace the carrier from the Exgine used to replace the carrier from the Exgine

– Any technique can be used without requiring Ibiquity software support software support – Added benefit of removing the reliance of the analog AM on the IBOC equipment

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What does adding HD do to the AM?

• Envelope

bandwidth is increased

• To an AM receiver,

looks like additional noise additional noise

• Effect is worse

with DAM with DAM Optional Title

Typical power reductions

MDCL Carrier Mod IBOC Total Savings AM 50 2 62 2 84 55 46 0% AM 50 2.62 2.84 55.46 0% AMC 32.81 1.72 2.84 36.39 34.4% B i 30 18 2 62 2 84 3 64 3 % Basic DAM 30.18 2.62 2.84 35.64 35.7% F ll 40 04 2 62 2 84 45 50 18 0% Full DAM 40.04 2.62 2.84 45.50 18.0%

• Savings of 20-30% can be realized

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Spectral mask compliance

• Decreasing the carrier is effectively the same

as elevating the carriers to the transmitter

• This effect is worse for DAM

– AMC decreases the gain on the envelope signal during peaks and troughs DAM decreases the carrier when at lower mod – DAM decreases the carrier when at lower mod depths, effectively increasing mod depth – The majority of spectral regrowth energy occurs due j y p g gy to distortion in the troughs

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Audio quality measurements: enhanced carriers on

• Standard AM is the

best, as expected, but AMC is close

• SNR is worst at high

and low mod depths DAM h i

• DAM emphasizes

peaks and troughs, resulting in more resulting in more audible artifacts Optional Title

Audio quality measurements: enhanced carriers off

• Boosts the received

SNR by 4-5 dB

• Makes up for the

lost SNR from MDCL R d dibl

• Reduces audible

impact of IBOC Optional Title

Conclusions

• AMC offers the most benefit when used with IBOC

If t i MDCL

• If turning on MDCL:

– Spectral compliance must be rechecked Audio quality should be reevaluated – Audio quality should be reevaluated – If possible, enhanced carriers should be disabled

• Significant power savings of 20 30% are possible
• Significant power savings of 20-30% are possible

NXSeries MW NXSeries MW

NX50 NX25

25kW – 2.0MW

NX200 NX300 NX400 NX100

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Thank You Thank You

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