by Roger » Thu Sep 02, 2010 3:29 am
Correct me if I am wrong, but DSSS systems select a number of frequencies to work on and then continuously "hop" between those frequencies at a high rate in a fixed sequence, ie when using 3 frequencies, 1-2-3-1-2-3-1-2-3 etc. With FHSS the system "jumps" all over the band, essentially a more complex version of DSSS just with a lot more complex algorithm controling the next channel used in the sequence (right?) Where as most DSSS systems use 2 or 3 channels, FHSS systems might use 20 to 30 and jump around "randomly" (ok, using the complex algorithim, since nothing is actually random for this to work!) in those 20 to 30 channels continuously in the same way as the DSSS system does. SO does the advantage of FHSS just mean that it uses a wider selection of the frequency band..., why not just make DSSS systems that use 10 or more channels instead of 2 or 3, for more robust reception (or is that just FHSS as I have already described?)
Specktrum's Model match system is easy enough to replicate in other systems, when the transmitter sends out its signals there is an encoded "bleep" in there that indicates the start of the sequence, that bleep has the model memory number encoded and must match what is stored in the receiver memory or it won't work. Bruce has already suggested that Telemetry systems could reverse the same idea so that the receiver tells the transmitter what model memory to load. I wonder if we will start to see some systems arriving with very basic telemetry built in such as rx or lipo battery voltage and the ability to do just as Bruce has described in loading up the correct model - really it is the bare minium of useful information that we would need - and it wouldn't be overly hard to incorporate into current technologies, since the model memory bit need only be sent during the initial binding handshake as the systems turn on and begin to communicate.
Even more useful telemetry data might indicate the current draw on the battery including built in warnings if over drawing current etc, temperature alarms for motor and speed controller etc (I dunno about you guys, but Lipos resemble small flying bombs just itching to detonate..! and I'm kind of attached to my models!)