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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 10: APPLICATIONS GUIDE 173

Voice-over applications communicating with non-Telos codecs

Most Common:

G.722isthemostcommonlyavailablecodingmodeintheworld.UseG.722foryourTransmit&

Receivemodes.Note:SincethequalityofG.722isonlymoderate,youshouldonlyusethis

modewithclientswhodonothaveabetteroptionavailable.OneBchannel(1call)requiredfor

mono.

Mos

t Popular:

MPEGLayer‐2Mono128seemstobethedefactostandardusedinthevoiceIndustry.Setyour

TransmittoL2Mono128andyourReceivetoL2.TwoBchannels(2calls)required.

Use48kHzsamplerate

Radio remotes (Mono) using a single B channel (1 call)

Good:

Fieldunit:L3Dual/MonoTransmitandG.722Receive

Studiounit:G.722TransmitandL3Dual/MonoReceive(ZephyrXstream)orL3Mono(Zephyr)

Use32kHzsamplerateforbestfidelity,or48kHzsamplerateforreduceddelay

5

.

Better:

Fieldunit:AAC‐LDMono64TransmitandG.722Receive

Studiounit:G.722TransmitandAAC‐LDReceive

Thisoptionhaslowround‐tripdelaywithfidelitycomparabletoLayer‐3

5

.

Use32kHzsamplerateforbestfidelityor48kHzforreduceddelay.

Best:

FieldUnit:AACMono64TransmitandG.722Receive.

StudioUnit:G.722TransmitandAAC64Receive

ThisoptionhasbetterfidelitythantheAAC‐LD,butlongerdelay.

Use32kHzsamplerateforbestfidelityor48kH

zforreduceddelay

5

.

5

We know that this statement seems contradictory. The sample rate determines the "frame rate"

through the Xstream's DSP. Therefore, higher sample rates result in reduced delay.

However, the higher sample rate also increases the amount of raw data. This requires a higher

compression ratio to get the data to the target transmission rate. Therefore using the increased

sample rate may cause more audible artifacts, as compared to a lower rate.

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