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Original thread:
Post 11 made on Tuesday November 29, 2005 at 11:15
Long Time Member
January 2003
very nice explanation. thanks for taking the time!

On September 11, 2005 at 17:19, shorthand said...
The delays are designed to make sure that every
device recieves every command that the Haromony

Note, times are measured in milliseconds (as mentioned),
so 1000 ms = 1 sec = 1 s.

Inter-key Delay:
The delay between any two successive commands.
If you tweak the repeats (discussed later), many
devices will work perfectly with a 0ms Inter-Key
delay. 100 ms (0.1 s) is the best starting point
for the vast majority of devices, though a very
few need something longer.

Power Delay:
Most devices have a period after they recieve
a power on command where they're busy starting
up and won't accept any other IR commands. This
tells the remote how long this period lasts so
that it can wait until its over before it sends
any more commands to that device.

Input Delay:
When you change inputs on many devices, the device
also becomes very busy acuqiring and syncing with
the new signal. As a result there is also a period
(generally shorter than the Power-on delay as
a Power-on necessarily includes a signal-acquisition
period) when the device won't accept any IR commands.
The Input Delay is the length of this period
so that the Harmony can wait until the device
is done changing inputs before it sends any additional

Inter-Device delay:
OK, so an IR signal goes out. There are 4 or
5 or more electric eyes in front of you ready
to recieve it. It reaches all of them, and each
device tries to decode the signal. The problem
is that if the device isn't familiar with the
signal coming in, it has a very hard time knowing
when that signal is over and the next one (wich
may be for it) has started. As a result, most
devices look for a period of "dead air" after
each signal to make sure that its over. The Inter-device
delay tells the Harmony how much dead air each
device needs before being ready to accept a command.
In multiple remote land, this is more than covered
by the time it takes you to pick up the next remote,
but its an important thing for the Harmony to
know. For most devices 100 or 200 ms is adequate.

The vast majority of IR standards repeat the signal
a few times to assure correct transmission. Most
standards call for the signal to be transmitted
3 times (original + 2 repeats). For most devices,
the Harmony defaults to transmit each command
4 times (original + 3 repeats). To change this,
go under troubleshooting for the device and select
"Not all commands recieved correctly" and then
either too many or not all commands.

How to set and tweak the input and power-on delays:

The most reliable way to do this is to use a stopwatch.
I usually remind people that there is a stopwatch
in most cell phones so you don't try to go digging
one out of a drawer somewhere. Press the power
or next input key on the original remote (for
the power - ovbiously we're talking about from
the power-off state) and then wait until the device
is up and running again. You can also try sending
additional commands until it starts recieving.
Stop the stopwatch. Add 1/2-1 second to your
time and then you have it. Just enter it in milliseconds.
(7.5 seconds = 7500 milliseconds). You can also
try the one-one-thousand-two-one-thousand technique
- but obviously its not as accurate.

Adjusting the inter-key delay: Start at 100 ms.
If the remote works and is fast enough for you,
you're done. If it doesn't work reliably, try
increasing the inter-key delay up to 200 ms and
then 1000. If the key isn't recieved reliably
at 1000 ms (1 second per key), go under troubleshooting
and play around with the number of repeats. (There
could be some stranger problems too.)

If the remote is sluggish at this inter-key delay,
drop it to 0 ms and tweak the repeats until it
feels right. Like I said, 2 repeats is usually
optimal for most devices.

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