ORIGINAL: tyrick69
With a DSSS systems, if the receiver is shadowed behind an engine, battery, carbon fuselage, etc.. it can actually mistake a reflected signal as the actual signal which would appear as a glitch, unintended input, or delayed input. FHSS systems are not really susceptible to reflected signals because by the time the reflected signal reaches the receiver, the transmitter and receiver have already hopped to a new frequency, thus the reflected signal is ignored. With the Spektrum system, the main and satellite receiver are always talking to one another and use the strongest signal that's being received by either the main or satellite thus reducing the potential for reflected signals to cause glitching because any direct signal will have more strength than a reflected signal.
Sorry, but that's
wrong - on a number of different issues. The main one being that multipath (which is what its called) does not result in "glitches" although if its bad enough, it can result in a packet being lost. Frequency hopping systems experience multipath as well (its a function of the frequency), its just that if multipath is bad enough to block the transmission, then when the system moves to another frequency, it changes the signal path enough (usually) that the transmission will get through.
Since DSMX is now "frequency agile" does that eliminate the need for the satellite RXs? Again, its not a function of what transmission mechanism you use, its a function of how good your receiver is... The chipset used in the Spektrum RX's (at least according to the info. that is out there - I haven't taken a Spektrum RX apart) was designed for short-range communication is USB-type devices, not long range radio control.
Bob