Actually, this was posted on the original 2.4Ghz thread, its just that
nobody responded to the post. I too would be interested in any feedback on
that point. I have no personal knowledge about the topic.
Here is a link to the post:
http://www.mail-archive.com/soaring@airage.com/msg105745.html
And below is a cut and paste of the text of the post:
I printed out the following post by Mike Lachowski. It specifically refers
to JR 2.4Ghz systems. I can't remember where it was originally posted,
maybe on RCSE, maybe on RCgroups:
------------------------------------------------------
posted by Mike Lachowski:
"And on the 40 channel topic, the original DX-6 transmitted
continuously on each of two channels in the band. The newer stuff only
transmits for very short periods of time. You can see it on a wireless LAN
sniffer if you know anyone who has one. So even if you have two pilots
using the same two frequencies, they will each only be using a small part
of the available bandwidth."
end quote
----- Original Message -----
From: "Ed Anderson" <[EMAIL PROTECTED]>
To: <Soaring@airage.com>
Sent: Friday, March 21, 2008 1:21 PM
Subject: [RCSE] Breaking the 40 Spektrum Radio Barrier
Sorry if this is a repeat, but I did not see it come through the first
time and
I thought it was important.
Breaking the 40 Spektrum Radio Barrier
Spektrum RC splits the 2.4 GHz band into 80 slices. When you turn on a
Spektrum
transmitter it takes two of these slices as its "channels" for talking to
the
receiver. It has long been expected that if you tried to turn on the 41st
Spektrum system, it would not be able to lock with the receiver. Some
people
have been concerned about this in terms of large contests. The earlier
report
about the International Heli competition where there were reported to be
over
400 2.4 GHz radios had no problems but no one could verify how many were
turned
on at any time. There was no no impound for 2.4 GHz systems.
Well, in this month's FlyRC they report on a test that was run. They
turned on
40 Spektrum DX7s operated them all at once, in close proximity. They all
seemed
to work fine. Then they turned on a JR 9303 2.4 GHz, the 41st transmitter
and
had no problems. Then they took it up to 44 DX7s plust the JR and still
no
problems
They flew test planes in predictable patterns to see if they saw any kinds
of
problems and there were none. I believe they did note a slight range check
reduction but still within spec. They also were logging flight
information on
the Spektrum reporter. No problems. Seems the 40 radio limit is not a
limit
after all. Cool!
I read elsewhere that the original DX6 transmits all the time, but the DX7
and
the rest of the DSM2 systems transmit on about a 10% duty cycle. I can't
say if
that is an on demand thing and I can't verify that this is true, but this
test
seems to suggest some kind of time sharing/channel sharing going on.
Ed Anderson
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