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參數(shù)資料
| 型號： | XRT75R12DIB-L |
| 廠商： | Exar Corporation |
| 文件頁數(shù)： | 5/133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 |
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XRT75R12D
98
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
REV. 1.0.3
In this case, this DS3 signal (which has now been mapped into STS-1) will be transported across the SONET
network. As this STS-1 signal arrives at the "Destination PTE", this PTE will extract (or de-map) this DS3 data-
stream from each incoming STS-1 SPE. Now since each and every STS-1 SPE contains exactly 5592 DS3
data bits; then the bit rate of this DS3 signal will be exactly 44.736Mbps (such as it was when it was mapped
into SONET, at the "Source" PTE).
As a consequence, no "Mapping/De-Mapping" Jitter or Wander is induced in the "Ideal Case".
8.2.2.2
The 44.736Mbps + 1ppm Case
The "above example" was a very ideal case. In reality, there are going to be frequency offsets in both the DS3
and STS-1 signals. For instance Bellcore GR-499-CORE mandates that a DS3 signal have a bit rate of
44.736Mbps ± 20ppm. Hence, the bit-rate of a "Bellcore" compliant DS3 signal can vary from the exact correct
frequency for DS3 by as much of 20ppm in either direction. Similarly, many SONET applications mandate that
SONET equipment use at least a "Stratum 3" level clock as its timing source. This requirement mandates that
an STS-1 signal must have a bit rate that is in the range of 51.84 ± 4.6ppm. To make matters worse, there are
also provisions for SONET equipment to use (what is referred to as) a "SONET Minimum Clock" (SMC) as its
timing source. In this case, an STS-1 signal can have a bit-rate in the range of 51.84Mbps ± 20ppm.
In order to convey the impact that frequency offsets (in either the DS3 or STS-1 signal) will impose on the bit-
stuffing behavior, and the resulting bit-rate, intrinsic jitter and wander within the DS3 signal that is being
transported across the SONET network; let us assume that a DS3 signal, with a bit-rate of 44.736Mbps +
1ppm is being mapped into an STS-1 signal with a bit-rate of 51.84Mbps + 0ppm. In this case, the following
things will occur.
In general, most of the STS-1 SPE's will each transport 5592 DS3 data bits.
However, within a "one-second" period, a DS3 signal that has a bit-rate of 44.736Mbps + 1 ppm will deliver
approximately 44.7 additional bits (over and above that of a DS3 signal with a bit-rate of 44.736Mbps + 0
ppm). This means that this particular signal will need to "negative-stuff" or map in an additional DS3 data bit
every (1/44.736 =) 22.35ms. In other words, this additional DS3 data bit will need to be mapped into about
one in every (22.35ms 8000 =) 178.8 STS-1 SPEs in order to avoid dropping any DS3 data-bits.
What does this mean at the "Source" PTE?
All of this means that as the "Source" PTE maps this DS3 signal, with a data rate of 44.736Mbps + 1ppm into
an STS-1 signal, most of the resulting "outbound" STS-1 SPEs will transport 5592 DS3 data bits (e.g., 3 Stuff
Opportunity bits will be carrying DS3 data bits, the remaining 6 Stuff Opportunity bits are "stuff" bits, as in the
"Ideal" case). However, in approximately one out of 178.8 "outbound" STS-1 SPEs, there will be a need to
insert an additional DS3 data bit within this STS-1 SPE. Whenever this occurs, then (for these particular STS-
1 SPEs) the SPE will be carrying 5593 DS3 data bits (e.g., 4 Stuff Opportunity bits will be carrying DS3 data
bits, the remaining 5 Stuff Opportunity bits are "stuff" bits).
Figure 46 presents an illustration of the STS-1 SPE traffic that will be generated by the "Source" PTE, during
this condition.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| XRT75R12IB-L | IC LIU E3/DS3/STS-1 12CH 420TBGA |
| XRT75VL00DIV | IC LIU E3/DS3/STS-1 1CH 52TQFP |
| XRT75VL00IV-F | IC LIU E3/DS3/STS-1 1CH 52TQFP |
| XRT79L71IB-F | IC LIU/FRAMER DS3/E3 1CH 208BGA |
| XRT81L27IV-F | IC LIU EI 7CH 3.3V 128TQFP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| XRT75R12ES | 功能描述:時(shí)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 |
| XRT75R12IB-L | 功能描述:LIN 收發(fā)器 Attenuator RoHS:否 制造商:NXP Semiconductors 工作電源電壓: 電源電流: 最大工作溫度: 封裝 / 箱體:SO-8 |
| 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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