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參數(shù)資料
| 型號： | GS9001-CQM |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | EDH COPROCESSOR |
| 中文描述： | 硬腦膜外血腫協(xié)處理器 |
| 文件頁數(shù)： | 14/14頁 |
| 文件大?。?/td> | 211K |
| 代理商： | GS9001-CQM |
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521 - 38 - 02
DOCUMENT
IDENTIFICATION
PRODUCT PROPOSAL
This data has been compiled for market investigation purposes
only, and does not constitute an offer for sale.
ADVANCE INFORMATION NOTE
This product is in development phase and specifications are
subject to change without notice. Gennum reserves the right to
remove the product at any time. Listing the product does not
constitute an offer for sale.
PRELIMINARY DATA SHEET
The product is in a preproduction phase and specifications are
subject to change without notice.
DATA SHEET
The product is in production. Gennum reserves the right to make
changes at any time to improve reliability, function or design, in
order to provide the best product possible.
Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement.
Copyright June 1995 Gennum Corporation. All rights reserved. Printed in Canada.
References:
1. Singar Bala, Eric Fankhauser and Paul Moore,
An IC Implementation of SMPTE RP165: Error Detection and Handling,
SMPTE Journal, Volume 104, Number 7, July 1995, pp 459 - 464.
EDH
EDH
ANCILLARY
INSERT
e.g. VITC
VIDEO
SOURCE
MICROPROCESSOR
MODIFIED
VIDEO
DATA
Fig. 11
REVISION NOTES
Ordering information part number changed to GS9001-CQM
If the modifying equipment employs EDH on the output, a new
CRC will be calculated and inserted. If, however, the equipment
has no EDH capability, the original CRC would be passed
through. This would result in incorrect CRC comparison and
erroneous error flag generation by the next piece of equipment.
This problem can be mitigated if the downstream equipment
has the ability to override specific error flags. Unfortunately,
there is no way for the downstream equipment to determine if
errors were caused by data modification or transmission
errors. It is therefore important that the equipment which
modified the video data either implement EDH properly or
remove the full field EDH packets from the data stream.
Removing these packets will cause the
UES
flag to be
asserted but this is preferable to reporting false errors.
As shown in Figure 11, the preferred way to implement EDH in
equipment which modifies the data is to have an EDH
coprocessor at both the input and output. The input EDH
coprocessor validates the integrity of the input data. The
output EDH coprocessor, set to receive mode, will pass any
error flags that may have been generated upstream and
recalculate any CRCs that need to be changed due to data
modification. Flag masking is then enabled in this output EDH
coprocessor to avoid flagging an erroneous full field error due
to CRC mismatch in the modified data.
Partial EDH System Implementation
In real system implementations not all equipment will have
EDH capability. EDH is still useful in this environment. Figure
10 shows the same system implementation as Figure 9 except
the VTR and router do not have EDH capability.
With reference to Figure 10, the audio encoder will detect the
lack of imbedded EDH in the incoming video, create the EDH
Packet and assert the
UES
(Unknown Error Status) flag.The
system will now have EDH monitoring for all downstream
transmission and equipment errors.
The router, without EDH, will simply pass the EDH packet
unmodified to the DA which has EDH capability. Any errors
reported at the DA could have occurred:
1.
on the link between the audio encoder and the router,
2.
in the router, or
3.
on the link from the router to the DA.
Although this does not provide ideal coverage, the source of
errors can still be isolated to allow the required maintenance.
Data Modification and EDH
It is often necessary to modify the data stream after the initial
generation of the CRC words. This would occur in applications
such as vertical interval timecode (VITC) or audio insertion.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| GS9001-CQME3 | 制造商:Semtech Corporation 功能描述:EDH Co-Processer |
| GS9001-CTM | 制造商:Rochester Electronics LLC 功能描述: 制造商:Gennum Corporation 功能描述: |
| GS9001-CTME3 | 制造商:Semtech Corporation 功能描述:EDH Co-Processer |
| GS9001-QCM | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPTE |
| GS9002 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述: |
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