Comtech-ef-data MCED-100 User Manual download pdf (Page 21)

MCED-100 MetaCarrier Embedding Device Revision 1

Introduction MN-MCED100

1–3

TheentireCIDmessageisbrokeninto18packetscontaining12 2bits(formatting,FECanduser

information) for a total message length of 2,196 bits for the transmission of the MetaCarrier.

Each packet ofthe MetaCarrier message carries 32  bits of CIDinformation data.However, the

MAC address is sent at a higher rate (more often)

, so that upon reception of a frame that is

comprisedofthree(3)pa ckets,theMACaddressmaybeobtained .



ThedatarateofmessagesbeingcarriedintheMetaCarrierisshownbeforespreadingisapplied

and the associated time to send a complete CIDmessage (incl

uding the framing and FEC). The

time for a complete message is only valid once the MCDD‐100 has achieved lock to the

MetaCarrierwhichmaycausethestatedtimestobelonger:



Embedded MetaCarrier CID Data Rate Time for Complete Message

224 kcps 56 bps 41.0 seconds

112 kcps 28 bps 82.0 seconds



Therefore,thetimefortheMCED‐100toinsertacompleteCIDIDsequenceisasfollows.Note

that the time for unique ID may be shorter than shown, since upon achieving lock to the

MetaCarrier, the uniqueID is immediately made available, since MetaCarrier lock requires the

receptionofthreefullpa

cketstodeclarelock:



Embedded MetaCarrier CID Data Rate Time for Unique ID

224 kcps 56 bps 6.9 seconds

112 kcps 28 bps 13.8 seconds



TheMCED‐100providesfail‐safeembeddin g oftheMetaCarrierbypassivelycouplingtheCIDonto

the transmission such that the transmission path remains unbroken in the event the MCED‐100

fails,losespower,oristurnedoff.



Changes to the MCED‐100’s configuration are typically not required. However, when

characteristics of the transmission carrier (e.g

., frequency, symbol rate, modulation) are

changed,theMCED‐100mustbeforcedtore‐analyzetheuplinkcarrier.Thiscanbeperformed

inthreeways:



1. Disable, Reconfigure, Re‐enable Carrier Transmission – Turn the transmit carrier off,

reconfigurethecarrier,andthenturnthecarrierbackon.



Most satellite modems will automatically turn the carrier off while carrier

parameters such as frequency or symbol rate are being changed, and

then automatically turn the carrier back on. Some modems, however,

will execute these steps faster than the MCED-100 can detect the loss of

transmit carrier power and return to the carrier detect mode. To ensure

reacquisition of the new transmission carrier, force the carrier off for a

minimum of two seconds.



2. Perform a “soft” reboot of the MCED‐100 – Reboot the unit via the MCED‐100 HTTP

WebServerInterface‘UTILITY|REBOOT’or‘ADMIN|FIRMWARE’pages.



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Comtech-ef-data MCED-100 User Manual Page 21

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