742MHz sounds suspiciously like a harmonic of the 74.25MHz max TMDS clock rate for a Category 1 cable per the HDMI 1.3a spec. I don't have the HDMI 2.0 spec (not an adopter), but would love to know more about the test configurations. A few thoughts/tests:
4K resolution at lowest color depth (no Deep Color) and lowest frame rate (i.e. lowest bit rate remaining at 4K resolution)? Video sources with and without HDCP support? HDMI test pattern generator (Quantum Data, Kramer, etc.)? Comparison of several cables with Category 2 grade? http://www.hdmi.org/learningcenter/Premium_HDMI_Cable_Participant_List.aspx -- specific mention of EMC testing as part of qualification; see Participants list of you haven't already confirmed your cables Do you have a tool/development environment to access Sil9777 registers for lower level debug? Will be interested to hear what others have to say on this. Regards, Adam On Sat, Oct 15, 2016 at 6:57 PM, Brent DeWitt <[email protected]> wrote: > I’ve been working with some Silicon Images (Lattice Semi) 9777 multiplexer > chips lately and would appreciate any insight list members might have. > When used at any resolution below 4k, there seems to be a 10 dB emission > “pedestal” that stands out of the baseline emission at several frequencies, > 742 MHz in particular. The pedestal is 666 usec long and repeats at > whatever frame rate is selected. At first, I thought it was correlated > with the SPI bus activity, since the timing was identical, but further > experiments show that not to be true. > > > > My question is, is this inherent to HDMI, or to the 9777? As is probably > obvious, I don’t have a whole lot of experience with HDMI video. > > > > Thanks all! > > > > Brent DeWitt, AB1LF > > Milford, MA > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=icon> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=link> > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to < > [email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
