[NSRCA-discussion] RE: 2.4 Ghz radio

[Ed Alt]

The Spektrum system doesn't do frequency hopping though. When you turn it 
on, it scans for the two least active channels in the band, then locks to 
them.  Each of the two receiver circuits listens to one unique channel of 
the two selected.  So sure, if an interfering device comes on line after you 
start your flight, you could be in trouble.  That's not much different than 
the situation we have today on 72 Mhz, although we have an exclusive 
allocation for those 50 channels, we have to accept interference.

The scenario might that if there is heavy 2.4 Ghz usage in any one location, 
you would learn of this right away with a simple range check.  I guess you 
could have some really bad luck and experience problems if something high 
powered and nearby comes on line for the first time during your 15 minute 
flight, but with 80 channels to choose from, it would seem that other SS 
systems that a municipality might use would not take up all the bandwidth. 
Hopefully the way that other SS systems would work would be similar, i.e., 
avoid a channel already in use in favor of something else available.  I 
bought one of these systems today for Foamy work only, but I'm going to be 
reading up on how things should work in this space, just to be safe.

Ed

----- Original Message ----- 
From: "John Petterson" <rcpilotjohn at comcast.net>
To: "'Jay Marshall'" <lightfoot at sc.rr.com>; "'Troy A. Newman'" 
<troy_newman at msn.com>; <discussion at nsrca.org>
Sent: Friday, December 30, 2005 7:46 PM
Subject: [NSRCA-discussion] RE: 2.4 Ghz radio


> Folks,
>
> The only word of caution about these systems is that the 2.4GHz band is
> unlicensed, and unregulated. Anyone can put up transmitters on that band 
> in
> any legal power, (there are some limits, but they are much higher than the
> RC transmitters use) and most systems HAVE TO accept interference from 
> other
> users. Not only does your local 802.11 wireless network in your house use
> this band, but many municipalities are now rolling out networks using that
> band as well. Soon there will be too many users to guarantee glitch free 
> use
> of this band in many areas.
>
> Although the frequency hopping encoding helps to reduce the impact of
> interference, this is NOT a frequency band I would trust to anything 
> capable
> of causing more damage than a foamie. This technology (as long as it is in
> the 2.4 GHz band) is not going to be ready for .40 size planes let alone
> pattern planes. It is just too dangerous and possible for the plane to go
> out of control.
>
> Now if we can convert the already reserved for R/C bands to this 
> technology
> or get the FCC to allocate us some specific spectrum for low power RC use,
> then we could get excited about this. But please don't start using them on
> the bigger planes.
>
> I can find some more information about this if anyone is interested.
>
> John
>
> -----Original Message-----
> From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] 
> On
> Behalf Of Jay Marshall
> Sent: Thursday, November 17, 2005 12:45 PM
> To: 'Troy A. Newman'; discussion at nsrca.org
> Subject: RE: 2.4 Ghz radio
>
> Thanks. Very informative. New item on my Xmas list....
>
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