seattle_helo
Key Veteran
Location: Seattle, WA USA
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| You must not read the same stuff I do . . . there is a 900MHz system announced already, just awaiting FCC approval, and the RF hostility of the 2.4GHz band, and it's less than ideal suitability for RC is extremely well documented. 2.4 was chosen because of easy access to off the shelf parts, and not for any particular benefit of the band.
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No, it does not seem we are reading the same stuff. I have not seen any of these well documented findings. But I would certainly love to read them. I'm trying to learn as much about this stuff as I can. Where can I find some of this info?
I've been following as much info as I can from nearly every RC forum on the internet. I've been tracking the release of the 12X long before it was announced back in the rumored 16X days... I have closely followed all of the nonsense related to XPS. And, I've been following everything I can that has to do with FASST. I am making my choices first and foremost based on what I believe to be the best RF transmission scheme. And so like many of us, I'm attempting to learn as much as I can.
That said, 2.4Ghz is no more hostile to RC than many other portions of the spectrum. It makes no difference that we have dedicated channels on 72Mhz since the very people who use those frequencies are most likely to be physically near one another when we are flying and thus present the potential to shoot a fellow pilot down. It's a bit ironic, but that's really one of the greatest vulnerabilities of our ancient single frequency system. Not to mention, the whole LF band is easy to wipe out with a single screwed up lawn mower that could send out enormous amounts of spurious RF. It's true that 2.4Ghz wavelength signals have less range then LF for the same ERP. That's a great reason, btw, why we won't be seeing 5.8Ghz RC equipment anytime soon. The challenges of the 2.4Ghz wavelength have been addressed for RC by each of the manufactures doing what they think was best. Moving to 5.8Ghz would provide no additional benefit, and in fact, would entail a whole new set of challenges. It's true that many types of devices operate on 2.4Ghz, but keep in mind that the whole point of the shared 2.4Ghz band is that each device knows how to work in the presence of other devices via a number of ways. Spread spectrum, by its nature, is suited for this purpose. And unique ID's for each system are the cornerstone of how things know what to stay linked to. I think the huge number of Spektrum systems at IRCHA last summer are pretty compelling evidence that a very, very large number of SS systems, or at least Spektrum systems, can co exist in a small area and work perfectly. Maybe if we had a fun fly in Manhattan there would be enough other ambient 2.4Ghz traffic to cause problems, but out where most people actually fly it would never, ever be an issue.
There is nothing wrong with off the shelf parts as long as they work. It also keeps costs down for all of us. $1500 would be the cost of one receiver if the manufacturers had to create all of this stuff from scratch.
As for a 900Mhz system, that could be interesting. But 900Mhz has as much traffic on it as anything, if not more than 2.4Ghz. I'd much rather have a low power network transmitter on my band than public service hand-helds putting out 4 watts. 900Mhz has a lot of different types of radio traffic on it, and I don't see it as being any "safer" RF wise. I guess time will tell. It's going to be ten years or more until we really know what ended up working and what did not.
I guess this is getting too much off topic now so maybe it would be best to start a new discussion in the right place. But I'll end with this to bring things back on track: I agree with Raz and JKos 100%. $1500 for the 12X is a great price and, IMO, maybe even a bargain.
nick |
