[LASS Soaring] Really guys only 40 will be flying!

Sun Dec 30 13:19:16 EST 2007

I think that the 2+GHz range is well suited to cordless phones, wireless
networks and other short range "indoor" applications.  It allows for
excellent data transfer rates and the short antenna is a good "fit".  But,
the 2.4GHz band is very close to the spectrum used by microwave ovens.  This
frequency is easily blocked by water which is why microwave ovens work so
well.  Hence the range problems in "outdoor" applications.  As far as phones
sounding better at the higher freq. this is probably just a matter of data
transfer being better at higher carrier frequencies.  Better range at higher
frequency may be a matter of output power and less blockage of the signal by
water.  Also, the 2.4 range is very power limited by FCC reg's where the
5.8+ range may not be, not sure.  I have a 5.8GHz phone and I can't tell
much difference from 2.4 or 900 or whatever.

I just read an article about part of the 700MHz band (or UHF to those of us
who remember TV's having knobs!) going up for auction.  One potential use
for this band is nationwide wireless internet.  According to the article, it
took 32,000 cell phone towers to get the coverage we now enjoy.  It is
estimated that it will take half that number for the same coverage at
700MHz.  The reason?  Cell phones operate around 1.5GHz and have about half
of the range as a result.  Hmmm.

I'm not ready to give up on 72MHz just yet.....

Brian

On Dec 29, 2007 3:54 PM, <GordySoar at aol.com> wrote:

>  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 > 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 2.4ghz 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
> > To: 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>
> > 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 2.4ghz 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> 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 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
> >
> > 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
> >
> > 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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