Spectrum 7 Vs Futaba Fasst 7c [Archive]

jascamera

09-17-2007, 02:53 AM

Which is a more reliable radio platform. I don't care about function, just the most reliable. I am using on a gasser AP heli. I am leaning toward Spectrum, for one been around for a few year with the 2.4 GH technology, and seen to be a proven system. The futaba just started making to technology and won't be available for at least a month and half.

But at the Futaba website, it did mention that it have twice the bit and 8x the resolution compare to the competitor (spectrum?? I guess).

Futaba Fasst 7c 2.4 gh

http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXSBX1&P=V

Or

Spectrum 7

crewchief

09-17-2007, 05:52 PM

FASST is a system that Futaba has been using for quite a few years in critical industrial applications. They now realize there is a market created by Spektrum and are trying to play catch-up in the hobby markets.

FASST is a classic spread-spectrum frequency-hopping approach, which was patented back in 1942 by Hedy Lamarr, the movie star, and composer George Antheil (U.S. Patent 2,292,387). The key to this technology is of course the synchronization protocols that are used to ensure the receiver is always sitting on the right frequency bin that is being transmitted. FASST supposedly monitors the 2.4GHz band first, and excludes channels that appear to be active from the list. Also the number of frequencies used increases the security, but Futaba's not about to open the kimono on their algorithms.

Spektrum on the other hand picks two unused channels out of the 2.4GHz band, which the receiver loads when it powers up. Spektrum also uses a GUID - Globally Unique IDentifier, model binding, and redundant receivers that allow antenna separation and orientation. So essentially the incoming commands are monitored by signal strength and validated by GUID. I've heard there's never been a verified case of jamming or interference with the DSM/DSM2 technology. The weakness of this approach is that they're betting the farm on two pre-selected frequencies. The odds that both frequencies will be jammed is a remote but finite possibility with increased congestion on the 2.4GHz band.

Supposedly all new 2.4GHz equipment is designed to monitor the band first to avoid transmitting on an active frequency. This "gentleman's agreement" is of course left up to the manufacturers, and who knows how effective it will be when more and more of the popular 2.4GHz devices come on the market. Already everything from WiFi to baby monitors are using the band. In the future the FASST system might be the more robust approach due to band overcrowding. They could potentially be jammed by fresh signals that pop up, but the majority of the commands will get through to the Rx, with the "last command received" hold filling in for the corrupted frames.

If you want a solid command link today, I'd trust the Spektrum. In the future if the 2.4GHz band degrades the Futaba might be a better choice, but the Spektrum is a proven technology that's available now.