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參數(shù)資料
型號： XRT75R12DIB-L
廠商： Exar Corporation
文件頁數(shù)： 4/133頁
文件大?。?/td> 0K
描述： IC LIU E3/DS3/STS-1 12CH 420TBGA
標(biāo)準(zhǔn)包裝： 40
類型： 線路接口裝置（LIU）
驅(qū)動器/接收器數(shù)： 12/12
規(guī)程： DS3，E3，STS-1
電源電壓： 3.135 V ~ 3.465 V
安裝類型： 表面貼裝
封裝/外殼： 420-LBGA 裸露焊盤
供應(yīng)商設(shè)備封裝： 420-TBGA（35x35）
包裝： 托盤
XRT75R12D
97
REV. 1.0.3
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
The Ideal Case (e.g., with no frequency offsets)
The 44.736Mbps + 1 ppm Case
The 44.736MHz - 1ppm Case
Throughout each of these cases, we will discuss how the resulting "bit-stuffing" (that was done when mapping
the DS3 signal into SONET) affects the amount of intrinsic jitter and wander that will be present in the DS3
signal, once it is ultimately de-mapped from SONET.
8.2.2.1
The Ideal Case for Mapping DS3 data into an STS-1 Signal (e.g., with no Frequency
Offsets)
Let us assume that we are mapping a DS3 signal, which has a bit rate of exactly 44.736Mbps (with no
frequency offset) into SONET. Further, let us assume that the SONET circuitry within the PTE is clocked at
exactly 51.84MHz (also with no frequency offset), as depicted below.
Given the above-mentioned assumptions, we can state the following.
The DS3 data-stream has a bit-rate of exactly 44.736Mbps
The PTE will create 8000 STS-1 SPE's per second
In order to properly map a DS3 data-stream into an STS-1 data-stream, then each STS-1 SPE must carry
(44.736Mbps/8000 =) 5592 DS3 data bits.
Is there a Problem?
According to Figure 44, each STS-1 SPE only contains 5589 bits that are specifically designated for "DS3 data
bits". In this case, each STS-1 SPE appears to be three bits "short".
No there is a Simple Solution
No, earlier we mentioned that each STS-1 SPE consists of nine (9) "Stuff Opportunity" bits. Therefore, these
three additional bits (for DS3 data) are obtained by using three of these "Stuff Opportunity" bits.
As a
consequence, three (3) of these nine (9) "Stuff Opportunity" bits, within each STS-1 SPE, will carry DS3 data-
bits. The remaining six (6) "Stuff Opportunity" bits will typically function as "stuff" bits.
In summary, for the "Ideal Case"; where there is no frequency offset between the DS3 and the STS-1 bit-rates,
once this DS3 data-stream has been mapped into the STS-1 data-stream, then each and every STS-1 SPE will
have the following "Stuff Opportunity" bit utilization.
3 "Stuff Opportunity" bits will carry DS3 data bits.
6 "Stuff Opportunity" bits will function as "stuff" bits
FIGURE 45. A SIMPLE ILLUSTRATION OF A DS3 DATA-STREAM BEING MAPPED INTO AN STS-1 SPE, VIA A PTE
PTE
44.736MHz + 0ppm
DS3_Data_In
STS-1_Data_Out
51.84MHz + 0ppm
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
XRT75R12ES 功能描述:時鐘合成器/抖動清除器 12CH T3/E3/STS1LIUJA 3.3V W/REDUNDANCY RoHS:否 制造商:Skyworks Solutions, Inc. 輸出端數(shù)量: 輸出電平: 最大輸出頻率: 輸入電平: 最大輸入頻率:6.1 GHz 電源電壓-最大:3.3 V 電源電壓-最小:2.7 V 封裝 / 箱體:TSSOP-28 封裝:Reel
XRT75R12IB 功能描述:外圍驅(qū)動器與原件 - PCI 12CH E3/DS3/STS W/JITTER R3 TECH RoHS:否 制造商:PLX Technology 工作電源電壓: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:FCBGA-1156 封裝:Tray
XRT75R12IB-F 功能描述:外圍驅(qū)動器與原件 - PCI 12 Channel 3.3V-5V temp -45 to 85C RoHS:否 制造商:PLX Technology 工作電源電壓: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:FCBGA-1156 封裝:Tray
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XRT75VL00 制造商:EXAR 制造商全稱:EXAR 功能描述:E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
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