We talk a
lot about our cables while we are planning our displays for the CEDIA
booth. Hours are spent grouping our cables together by category and the
different technology they provide. I ask questions about each of our
cables and when I started looking at my notes I saw these questions:
“What
is the truth regarding HDMI and is there in fact a difference from one cable to
another? Is there a reason to buy a better HDMI cable?”
In getting these answers, this blog
post was born and over the next six weeks we are going to discuss the six parts
of an HDMI cable and why customers should purchase a better (and preferably one
of Metra Home’s) cables.
As most dealers know Metra Home has
been a DPL member (www.dpllabs.com) since
its inception. In our association with
DPL we have learned that the vast majority of claims made about HDMI and HDMI cables
are confusing and misleading. Metra Home
has been fortunate to be associated with DPL and has over time received a
reputation for good working, reliable and affordable products due to this
association.
Here is a short synapses of what
they taught us about cables and the differences that they possess:
#1: Cable
Architecture and Timing, Intra-pair & Inter-pair Skew: -
HDMI is
all about timing, timing of the TMDS feeds, timing of the DDC feeds, timing of
the voltage trigger and timing of the Hot Plug return. Timing can be affected
by poor wiring architecture with-in and between the twisted pairs, also
depending on where and how the twist ratios are incorrect will determine
whether the issue is intra or inter pair skew related. In the graphic below you
will see the cause of each of these failures.
Intra-Pair
Skew refers to the length time difference between the two wires within a single
shielded pair and is displayed in the top graphic , it is not uncommon to see
the twist point offset from the crossover center line. This failing can cause
jitter in the Audio and Video. Inter-Pair Skew is caused by the length and
twist points variance between the shielded pairs and will typically manifest
itself by showing sparkles in solid color or white on the display depending on
which cable (or how many pairs have an issue).
What does this
have to do with cables?
Well, wire gauge
and consistency of the twist ratio determine both Inter-pair and Intra-Pair
Skew. Better quality product better data transfer. It is important to
purchase a quality HDMI cable to ensure good wiring architecture to avoid
timing failures. Metra Home tests all HDMI
cables to receive the DPL seal of approval and because of this we have
over time received a reputation for good working, reliable and affordable HDMI
cables.
Follow
our blog to get the next installment of this six part series.
