[SPAM] Re: JR 10SX

[Ed Alt]

John:
I think that they used to call that Kraft with the syntesised RF module "dial-a-crash".  Actually, the technology for synthesising 50 channels is no big deal, PLL circuits have been used to do this for decades.  Back in the early 80's I did my senior year electronics project by taking an Ace Silver 7 receiver, disabled the local oscillator and injected the output of a PLL local oscillator of my own.  It was just a bench prototype for a grade, clunky to look at and with 7 seg LED readouts to display the channel it was on, but it worked.  I got alot of curious looks from the class when I hauled in a Kraft single stick, a Heathkit GD-19 and a Futaba FG series radio on different channels to demonstrate that it worked to the Prof.  Nowadays, this stuff can done in software with DSP technology.  I can see the wheels turning in your head already!  :)

Spread Spectrum would be one way to go, or maybe something using WiMax technology, whenever that shakes out.  Eric is right, our technology for the RF link is totally archaic.  Nice that we have good, reliable "narrow band" stuff now, but it could be much better.

Ed


----- Original Message ----- 
  From: John Pavlick 
  To: discussion at nsrca.org 
  Sent: Tuesday, March 22, 2005 1:10 AM
  Subject: RE: JR 10SX


  Yeah, I agree with Eric. As far as I'm concerned, the new Futaba radio (14MZ) is really nice looking, and of course I wouldn't mind having one BUT since I don't fly the really big stuff where 14 channels is a big help (multiple servos on each control surface), it wouldn't be much of an improvement over my 9ZAP. It seems like the RF section is always an after-thought. I remember when all the "new" frequencies were being discussed (pre 1991 times). One of the ideas behind getting all the new frequencies was to reduce the chance of someone being on your frequency. I always thought a better approach would have been to make everything with synthesized RF decks. Since the plan we adopted ended up making a lot of otherwise good equipment obsolete anyway, I don't see what the problem would have been. We wouldn't need as many channels that way either (more room for other stuff). If you can select your frequency, rather than just increase the odds of not being on someone else's frequency, then the real problem is solved. I seem to recall that Kraft had synthesized RF and "narrow band" FM equipment before anyone else. Almost every major radio manufacturer has some type of synthesized RF deck today.
   If you add the synthesized RF deck to a digital encoding "code hopping" transmitter and receiver you have a good solution to our newest problem. As long as the receiver isn't swamped by a very high output transmitter, this is safer than what we have now. A code hopping system uses a digital encoding scheme in addition to the base frequency. The "digital key" changes when the system powers up. You don't even know it's happening. Even if someone is transmitting on the same frequency, if the "keys" don't match the receiver won't respond. That's over simplifying a bit but that's the basic idea. There's more to the link than just the RF frequency, which as we all know is not always exclusive. Clothes pins with channel numbers are not exactly a foolproof method of securing your frequency. This kind of stuff is in $40.00 cordless phones and garage door openers - remember the old garage door openers that used to open for "no reason"? How do you think they fixed that? Why can't this technology be used in a $2000.00 radio? If we keep building bigger and bigger airplanes and controlling them with what is basically outdated technology, it's only a matter of time...
  John Pavlick
  http://www.idseng.com
    


   -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Grow Pattern
  Sent: Monday, March 21, 2005 11:48 PM
  To: discussion at nsrca.org
  Subject: Re: JR 10SX


    Bill, the update to the 10SX (actually a 10SXII) was the digital trim 10X.  

    Is the 10X what you meant to say?

    In general terms I don't intend to buy another radio, of any brand, until they fix the weakness of our RF link to the plane. We can all still be radio-shot-down far too easily.

    Regards,

    Eric.
      ----- Original Message ----- 
      From: William C. Harden 
      To: discussion at nsrca.org 
      Sent: Monday, March 21, 2005 9:42 PM
      Subject: JR 10SX


      Now that JR has come to market with their new 9303 radio, does JR intend to update their 10SX radio?  If so, when will the new radio be available???  Just curious.

       

       

      Bill 
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