[LASS Soaring] Really guys only 40 will be flying!
GordySoar at aol.com
GordySoar at aol.com
Sat Dec 29 15:54:08 EST 2007
It IS weird that phones went up in frequency when radio control industrial
users when down in freq. From 2.4 to 900, then to 455mhz. Guided farm
tractors to UAV's. The one thing they all agreed on when I spoke to various
vendors was that 2.4 didn't work reliably.
The recent helicopter event proved a few things, one is that 2.4 works
pretty good when the RX and TX are really close to each other.
Gordy
In a message dated 12/29/2007 10:50:22 A.M. Eastern Standard Time,
ewilson1 at bellsouth.net writes:
Makes me wonder. I started out with 900Mhz phones in my house. Then I went
to 2.4Ghz and the signal was better but along came 5.8Ghz. The sound was much
improved and the range of the phone doubled or triple what I had with 2.4. I
also saw a new 8.? while shopping this Christmas. Can we look forward to
5.8Ghz down the road? How about a channel between the cell phone frequencies?
There are gaps in the band so different carriers can set them up for their own
use.
Ed
Brian Kopke wrote:
I think there is one point we are all overlooking here. Even though the
2.4GHz systems are limited to 40 "channels", this is 40 more 72MHz friendly
channels than we have now. And it is not very likely the FCC is going to expand
the RC band any time soon. Or ever.
Now to get the 2.4 stuff to work in a full carbon fuse??.....
Brian
On Dec 27, 2007 8:51 AM, Ryan Woebkenberg <_rdwoebke at hotmail.com _
(mailto:rdwoebke at hotmail.com) > wrote:
Hey Brian,
Do you ever make it out to the Ferdinand area much any more? If you ever
do, we should try to fly sometime.
Spektrum (currently the most popular 2.4 manufacturer) divides the 2.4 ghz
bandwith into 80 1 mhz "channels". The Spektrum setup always grabs 2 channels
and transmits on both, hence in theory there can be 40 Spektrum systems
working concurrently. If the 41st system were to turn on or if there were other
wireless devices (like wireless routers) using up bandwith, then the Spektrum
system just "does not work" and it sort of scans waiting for something to
become available.
I really doubt there will be many times 40 systems will be on at once. The
scenerio Gordy mentions of "Visalia practice day" certianly could be one of
them, but at a regular contest, you would probably have at least 80 pilots to
get into this situation, since normally guys time for each other and those
guys then are not likely to be using their radio.
Ryan
____________________________________
Date: Thu, 27 Dec 2007 07:55:08 -0500
From: _bkopke at gmail.com_ (mailto:bkopke at gmail.com)
To: _soaring at louisvillesoaring.org_ (mailto:soaring at louisvillesoaring.org)
Subject: Re: [LASS Soaring] Really guys only 40 will be flying!
Where did the magic number of 40 come from. Sorry if I overlooked it in a
previous post.
Brian
On Dec 26, 2007 10:39 AM, David Gruneisen <_ david.gruneisen at gmail.com_
(mailto:david.gruneisen at gmail.com) > wrote:
According to Spektrum (and JR) -
"In the unlikely event that all channels are occupied, the next transmitter
will scan the band indefinitely until open channels are available. The
transmitter will then acquire the channel(s) and begin transmitting. Only then will
the system connect."
So the 10,000 TX handsets can all be on at once - only 40 will find and
acquire 2 discrete freqs, perform the necessary handshaking and actually
transmit.
Let's take my office environment as an example of multiple brands of 2.4 ghz
existing in the same environment. There are approximately 60 devices from 4
different mfgers (IBM, Dell Nortel and Linksys a ll transmitting and
receiving on the SAME frequency, using only packet collision detection to keep the
individual receivers straight.
I think JR and Futaba might do well to publish the FCC's 2.4g standards and
their successful test completion documentation to help clear up these very
reasonable questions about using this old technology in this new way.
-David G
On Dec 26, 2007 9:48 AM, <_GordySoar at aol.com_ (mailto:GordySoar at aol.com) >
wrote:
Okay Ryan,
What keeps the other 60 to 100 guys with various brands of 2.4 in their cars
and pits from being on all at once? Impound?
gordy
In a message dated 12/26/2007 9:31:19 A.M. Eastern Standard Time,
_rdwoebke at hotmail.com_ (mailto:rdwoebke at hotmail.com) writes:
I don't know about the rest of you all but I have seen the # of concurrent
systems limitations in a lot of the litareture out there on the Spektrum and
the Extreme.
The way Spektrum works is if it can't grab the 2 channels to opparate the
receiver simply won't start "working". So, assuming we are all being good
about doing our "wiggle checks" and if we are doing a good job of checking our
"blinkies" as suggested by Don Richmond, should not be an issue there.
_http://www.spektrumrc.com/DSM/FAQ.aspx_
(http://www.spektrumrc.com/DSM/FAQ.aspx)
So far as our soaring goes, I think it is unlikely we will exceed the 40
"channels" at a soaring event. Take the Nats for example, there might be pilot
groups of 10, so perhaps there could be 10 guys turned on and waiting at the
winch staging area, 10 guys launching and 10 guys in the air soon landing,
but that still leaves 10 channels and perhaps a few guys "in the pits" might
have radios on fiddling with trims/etc, but worst case one of the 10 guys
that is turning on at the staging area just lets the "round master" know he
can't get a free channel.
Hope you all had a good Christmas. I got some servos to help complete Psyko
#2.
Ryan
____________________________________
From: _GordySoar at aol.com_ (mailto:GordySoar at aol.com)
Correct me if I am wrong but I believe the general modeler believed that
with 2.4 all concerns for freq control were over....Millions could all be on at
once...there was the story about the huge heli event with hundreds of
attendees most enjoying the freedom of 2.4....hmmmn.
Did you all believe that the amount of 2.4 TXs on at once was almost
unlimited?
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