[SI-LIST] Re: 答复: 答复: 答复: HDMI Frequency Failing RE Test by 7dB!!!!
- From: steve weir <weirsi@xxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 30 May 2012 00:39:20 -0700
All non-rigid cables leak, especially at tight bends.
Steve.
On 5/29/2012 11:53 PM, vinod ah wrote:
> Hi all,
>
> I Got additional 2.5dB margin which i was looking for, after
> re-routing the cables. The 2 HDMI cables were overlapping earlier, but
> when i separated them i got the additional margin. So is it possible
> to explain why it so happened? Why i am asking is, the cables used are
> shielded cables, so overlapping or non-overlapping should not have
> mattered right?
>
> Regards
> Vinod A H
>
> On Mon, May 28, 2012 at 6:20 PM, steve weir <weirsi@xxxxxxxxxx> wrote:
>> 1) Metallize the enclosure and bond the cable shield to that.
>> 2) Modify the differential pair trace routes and/or add CM magnetics /
>> structures to minimize even mode current.
>> 3) Make the image plane part of the PCB.
>> 4) Further improve the bond between the cable shield and the PCB.
>> 5) Optimize the ferrite used over the cable.
>> 6) Introduce PCB trace structures that load the signals with a notch at
>> 742MHz.
>>
>> Steve.
>> On 5/28/2012 2:43 AM, vinod ah wrote:
>>> HI All,
>>>
>>> I had been to EMC lab for testing and here are the results.
>>>
>>> 1) With image plane addition to the HDMI shield pins and shield pins
>>> grounded directly to ground at multiple points, there was 4 dB
>>> reduction in radiation level.
>>>
>>> 2) With Only shield pins grounded directly to ground at multiple
>>> points, there was 2dB reduction in radiation level.
>>>
>>> 3) With ferrite clamp on the HDMI cables, there was 2dB reduction in
>>> radiation level at 742MHz.
>>>
>>> 4) Reducing the voltage swing of HDMI signals gave another 0.5dB
>>> reduction in radiation level
>>>
>>> 5) By turning on On-Die series termination in the HDMI TX output
>>> drivers, we could get another 0.5dB reduction in radiation level.
>>>
>>> 6) During ambient readings i.e. Blu ray player connected to TV through
>>> HDMI cable, the 742MHz is passing by 8dB only. Previous lab visits,
>>> the EMC lab person had shown us Min envelope instead of Max envelope
>>> during peak scan, thus mis-leading us to think that the setup is not
>>> contributing to the radiation.
>>>
>>> So Although i am just passing the FCC limits, is there anything i can
>>> do to make it pass by some margin, so that in final certification i
>>> have some confidence of passing FCC ? Is the setup which itself is
>>> passing by 8dB is acceptable to use or should i try some other setup?
>>> Currently i am using Sony Blu ray player, LG TV and Copper shielded
>>> HDMI cable with ferrite clamp. Is there any better Blu ray players or
>>> TV is suggested for final certification?
>>>
>>> Regards
>>> Vinod A H
>>>
>>> On Fri, May 25, 2012 at 8:28 AM, Zhenwei Wang (zhenwwan)
>>> <zhenwwan@xxxxxxxxx> wrote:
>>>> One suggestion:
>>>>
>>>> The most possible way to confirm if the return current through shielding
>>>> line cause EMI issue (as mentioned by Vend +7db above FCC limitation) is
>>>> that:
>>>>
>>>> 1. Open the shielding line of each TMDS signal pair in ONE END,
>>>> prefer
>>>> in own board.
>>>>
>>>> 2. Keep HDMI_DDC ground for functional operation.
>>>>
>>>> 3. Measure the EMI in lab with same environment.
>>>>
>>>> If no return current through shielding line, the measurement will be as
>>>> same
>>>> as before.
>>>>
>>>> If some return current through HDMI_DDC ground, EMI will be much bigger
>>>> than
>>>> 7db above FCC limitation.
>>>>
>>>>
>>>>
>>>> BR
>>>>
>>>> Zhenwei(Jason) Wang
>>>>
>>>> Cisco Systems (Shanghai) Video Technology Co., Ltd.
>>>>
>>>>
>>>>
>>>> 发件人: Traa, Boris [mailto:boris.traa@xxxxxxxxxxx]
>>>> 发送时间: 2012年5月24日 18:22
>>>> 收件人: Zhenwei Wang (zhenwwan); Long Yang
>>>> 抄送: ah.vinod@xxxxxxxxx; SI-LIST
>>>> 主题: RE: [SI-LIST] 答复: 答复: HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>>
>>>>
>>>> Dear Zhenwei Wang,
>>>>
>>>>
>>>>
>>>> By calculations it can be concluded that intra-pair skew of a differential
>>>> pseudo random bit stream will only result in a low level wide band EMI
>>>> without spectral lines.
>>>>
>>>>
>>>>
>>>> In case of non equal rise and fall times this will lead to spectral lines
>>>> that are 6 dB lower for PRBS compared to clock.
>>>>
>>>>
>>>>
>>>> Kind regards
>>>>
>>>> Boris Traa
>>>>
>>>> System design engineer EMC
>>>>
>>>>
>>>>
>>>> It's the currents that make circuits work or fail.
>>>>
>>>>
>>>>
>>>> Philips Innovation Services/EMC center
>>>>
>>>> Room 2.020
>>>>
>>>> High Tech Campus 26
>>>>
>>>> 5656AE Eindhoven, The Netherlands
>>>>
>>>> Tel: ++ 31 40 27 43766
>>>>
>>>> Fax: ++ 31 40 27 42224
>>>>
>>>> E-mail: boris.traa@xxxxxxxxxxx
>>>>
>>>>
>>>>
>>>> From: Zhenwei Wang (zhenwwan) [mailto:zhenwwan@xxxxxxxxx]
>>>> Sent: Thursday 24 May 2012 11:49 AM
>>>> To: Long Yang
>>>> Cc: Traa, Boris; ah.vinod@xxxxxxxxx; SI-LIST
>>>> Subject: 答复: [SI-LIST] 答复: 答复: HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>>
>>>>
>>>> If the intra-pair skew is too much bigger, the cross-point of Data+ and
>>>> Data- will not stand on the virtual ground. Then DC return current will
>>>> flow
>>>> through a ground line. You know every line has inductance. So the noise can
>>>> be get with equation V=Lx(did/dot). The power of return current could be
>>>> radiate through long cable.
>>>>
>>>> Maybe the reason I said was not the dominant part. We needs
>>>> information to deny it.
>>>>
>>>>
>>>>
>>>> BR
>>>>
>>>> Zhenwei(Jason) Wang
>>>>
>>>> Cisco Systems (Shanghai) Video Technology Co., Ltd.
>>>>
>>>>
>>>>
>>>> 发件人: Long Yang [mailto:long.0.yang@xxxxxxxxx]
>>>> 发送时间: 2012年5月24日 17:38
>>>> 收件人: Zhenwei Wang (zhenwwan)
>>>> 抄送: Traa, Boris; ah.vinod@xxxxxxxxx; SI-LIST
>>>> 主题: Re: [SI-LIST] 答复: 答复: HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>>
>>>>
>>>> Skew should be related to stand-wave antenna resonance.
>>>>
>>>> On Thu, May 24, 2012 at 2:11 AM, Zhenwei Wang (zhenwwan)
>>>> <zhenwwan@xxxxxxxxx> wrote:
>>>>
>>>> Hi Boris,
>>>> Actually, I am just guessing. EMI issue has three key features:
>>>> Aggressor, Coupling trace and Receiver. Based Vine's description, the HDMI
>>>> cable acted as the coupling trace in his design. But when the same cable
>>>> connected Sony Blue ray disc and TV, the radiation disappear(Vend did not
>>>> say that directly). So I guessed that in one or two or three TMDS
>>>> differential pair, some shielding line worked as the antenna to radiate the
>>>> bit clock frequency.
>>>> BTW, if have a HDMI SI report(especially intra-pair skew or
>>>> cross-point of TMDS), the guessing will be clear. I know the feeling when
>>>> EMC test failed, much more pressure. So good luck to Vend.
>>>>
>>>> BR
>>>> Zhenwei(Jason) Wang
>>>> Cisco Systems (Shanghai) Video Technology Co., Ltd.
>>>>
>>>>
>>>> -----邮件原件-----
>>>>
>>>> 发件人: Traa, Boris [mailto:boris.traa@xxxxxxxxxxx]
>>>> 发送时间: 2012年5月24日 16:34
>>>> 收件人: Zhenwei Wang (zhenwwan); ah.vinod@xxxxxxxxx; SI-LIST
>>>> 主题: RE: [SI-LIST] 答复: HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>>
>>>> Dear Zhenwei Wang,
>>>>
>>>> Assuming the data is pseudo random, do you think that inter and intra pair
>>>> skew will cause clock related spectral lines. I'm would think that EMI will
>>>> look like wide band noise. Only in case of different rise and fall times
>>>> for
>>>> intra pair signals spectral lines may appear.
>>>>
>>>> Kind regards
>>>> Boris Traa
>>>> System design engineer EMC
>>>>
>>>> It's the currents that make circuits work or fail.
>>>>
>>>> Philips Innovation Services/EMC center
>>>> Room 2.020
>>>> High Tech Campus 26
>>>> 5656AE Eindhoven, The Netherlands
>>>> Tel: ++ 31 40 27 43766
>>>> Fax: ++ 31 40 27 42224
>>>> E-mail: boris.traa@xxxxxxxxxxx
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
>>>> Behalf Of Zhenwei Wang (zhenwwan)
>>>> Sent: Thursday 24 May 2012 4:05 AM
>>>> To: ah.vinod@xxxxxxxxx; SI-LIST
>>>> Subject: [SI-LIST] 答复: HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>> Hi Vinod,
>>>> I went through the email about your issue. Yes, if the pixel clock
>>>> is
>>>> 74.25Mhz, the data rate is ten times of pixel clock, equal 742.5Mhz.
>>>> Conceptually, TMDS signal have a virtual AC ground. So there is no DC
>>>> current requirement through ground pin. My suggestion: you should check the
>>>> parameter "inter pair skew" of each differential data line.
>>>>
>>>> BR
>>>> Zhenwei(Jason) Wang
>>>> Cisco Systems (Shanghai) Video Technology Co., Ltd.
>>>>
>>>>
>>>> -----邮件原件-----
>>>> 发件人: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] 代表
>>>> vinod ah
>>>> 发送时间: 2012年5月23日 21:58
>>>> 收件人: SI-LIST
>>>> 主题: [SI-LIST] HDMI Frequency Failing RE Test by 7dB!!!!
>>>>
>>>> Hi All,
>>>>
>>>> I am designing a board with HDMI input and HDMI output. I am facing EMI
>>>> issue at 742.5MHz (failing FCC limits by 7dB) when running 1080p30 on both
>>>> Input and output HDMI i.e. BLu ray player connected to HDMI input connector
>>>> of my board is giving out data at 1080p30 and HDMI out of my board is
>>>> connected to TV which is also 1080p30 content. So i am unable to find out
>>>> how is 742.5MHz coming out as radiation as it is 10th Harmonic of pixel
>>>> clock 74.25MHz!!!!!!!. I am not facing any issues with other harmonics
>>>> except for this. So i am totally confused on how to go about debugging this
>>>> issue.
>>>>
>>>> Note: All the signals are routed on top layer without vias and all signals
>>>> have solid ground plane reference. The blu ray player and TV used, is
>>>> tested
>>>> for radiation and no significant levels seen.
>>>>
>>>> Regards
>>>> Vinod A H
>>>> ------------------------------------------------------------------
>>>> To unsubscribe from si-list:
>>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>>>
>>>> or to administer your membership from a web page, go to:
>>>> //www.freelists.org/webpage/si-list
>>>>
>>>> For help:
>>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>>>
>>>>
>>>> List forum is accessible at:
>>>> http://tech.groups.yahoo.com/group/si-list
>>>>
>>>> List archives are viewable at:
>>>> //www.freelists.org/archives/si-list
>>>>
>>>> Old (prior to June 6, 2001) list archives are viewable at:
>>>> http://www.qsl.net/wb6tpu
>>>>
>>>>
>>>> ------------------------------------------------------------------
>>>> To unsubscribe from si-list:
>>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>>>
>>>> or to administer your membership from a web page, go to:
>>>> //www.freelists.org/webpage/si-list
>>>>
>>>> For help:
>>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>>>
>>>>
>>>> List forum is accessible at:
>>>> http://tech.groups.yahoo.com/group/si-list
>>>>
>>>> List archives are viewable at:
>>>> //www.freelists.org/archives/si-list
>>>>
>>>> Old (prior to June 6, 2001) list archives are viewable at:
>>>> http://www.qsl.net/wb6tpu
>>>>
>>>>
>>>>
>>>> ________________________________
>>>> The information contained in this message may be confidential and legally
>>>> protected under applicable law. The message is intended solely for the
>>>> addressee(s). If you are not the intended recipient, you are hereby
>>>> notified
>>>> that any use, forwarding, dissemination, or reproduction of this message is
>>>> strictly prohibited and may be unlawful. If you are not the intended
>>>> recipient, please contact the sender by return e-mail and destroy all
>>>> copies
>>>> of the original message.
>>>> ------------------------------------------------------------------
>>>> To unsubscribe from si-list:
>>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>>>
>>>> or to administer your membership from a web page, go to:
>>>> //www.freelists.org/webpage/si-list
>>>>
>>>> For help:
>>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>>>
>>>>
>>>> List forum is accessible at:
>>>> http://tech.groups.yahoo.com/group/si-list
>>>>
>>>> List archives are viewable at:
>>>> //www.freelists.org/archives/si-list
>>>>
>>>> Old (prior to June 6, 2001) list archives are viewable at:
>>>> http://www.qsl.net/wb6tpu
>>>>
>>>>
>>> ------------------------------------------------------------------
>>> To unsubscribe from si-list:
>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>>
>>> or to administer your membership from a web page, go to:
>>> //www.freelists.org/webpage/si-list
>>>
>>> For help:
>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>>
>>>
>>> List forum is accessible at:
>>> http://tech.groups.yahoo.com/group/si-list
>>>
>>> List archives are viewable at:
>>> //www.freelists.org/archives/si-list
>>>
>>> Old (prior to June 6, 2001) list archives are viewable at:
>>> http://www.qsl.net/wb6tpu
>>>
>>>
>>>
>>
>> --
>> Steve Weir
>> IPBLOX, LLC
>> 150 N. Center St. #211
>> Reno, NV 89501
>> www.ipblox.com
>>
>> (775) 299-4236 Business
>> (866) 675-4630 Toll-free
>> (707) 780-1951 Fax
>>
>> All contents Copyright (c)2012 IPBLOX, LLC. All Rights Reserved.
>> This e-mail may contain confidential material.
>> If you are not the intended recipient, please destroy all records
>> and notify the sender.
>>
>> ------------------------------------------------------------------
>> To unsubscribe from si-list:
>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>
>> or to administer your membership from a web page, go to:
>> //www.freelists.org/webpage/si-list
>>
>> For help:
>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>
>>
>> List forum is accessible at:
>> http://tech.groups.yahoo.com/group/si-list
>>
>> List archives are viewable at:
>> //www.freelists.org/archives/si-list
>>
>> Old (prior to June 6, 2001) list archives are viewable at:
>> http://www.qsl.net/wb6tpu
>>
>>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List forum is accessible at:
> http://tech.groups.yahoo.com/group/si-list
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
>
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
--
Steve Weir
IPBLOX, LLC
150 N. Center St. #211
Reno, NV 89501
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
All contents Copyright (c)2012 IPBLOX, LLC. All Rights Reserved.
This e-mail may contain confidential material.
If you are not the intended recipient, please destroy all records
and notify the sender.
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
