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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 9: The V.35/X.21 Interface Option 158

* Xstream does not support separate TX and RX clocks. RX Clock signal is sent out as TX

Clock.

# RTS and DTR are permanently asserted “true”.

t

DEEP TECH NOTE!

The standard uses electrically balanced transmission for both clock and data (but not for the

special auxiliary signals, which are identical to RS-232). The transmit voltage level is ± 5.5V,

but receivers must handle wider swings.

X.21,amoremodernstandard,isalsousedforconnectionstosynchronousdigitaldatapaths.

ThisstandardspecifiesthemuchmorereasonableDB‐15connector.Fortunately,itispossible

todesignaninterfacethatacceptsbothV.35andX.21signals.Thiswehavedonewiththe

ZephyrXstream,allowingconnectiontobothtypesju

stbychangingtheinterconnectcables.

TheX.21standardisfrequentlyseeninEuropeandotherareasoutsidetheUSA&Canada.The

followingSignalsareprovidedattheX.21endoftheTeloscable:

X.21 CONNECTOR PIN-OUT

Pin Description Direction (Xstream ◄► DCE)

2 TX Data ►

3 # RTS ►

4 RX Data ◄

5 CD (Carrier Detect) ◄

6 Clock ◄

8 Ground

9 /TX Data ►

10 # /RTS ►

11 /RX Data ◄

13 /Clock ◄

# RTS and DTR are permanently asserted “true”.

CSU’s and DSU’s

CSU.ChannelServiceUnit.DSU.DataServiceUnit.Thisiswhattheinterfacebetweenthe

Zephyranddigitalchannelisusuallycalled.Itconvertsthesignalsfromthetelephonelinetothe

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