Questions and Answers If you have general RC questions or answers discuss it here.

Pos/Neg Shift? Please Explain

Reply

Old 01-02-2003, 11:49 PM
  #1  
Steve Guinn
Senior Member
Thread Starter
 
Join Date: Aug 2002
Location: WV
Posts: 835
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Pos/Neg Shift? Please Explain

I've got the low/high band..PPM/PCM pretty much understood, but what the heck is this shift stuff.
Thanks,
Steve
Steve Guinn is offline  
Reply With Quote
Old 01-03-2003, 10:37 AM
  #2  
Steve Lewin
Senior Member
 
Join Date: Mar 2002
Location: Reading, UNITED KINGDOM
Posts: 904
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Pos/Neg Shift? Please Explain

From http://www.torreypinesgulls.org/Radios.htm (well worth reading)

In R/C "FM" there is only full modulation i.e., carrier shifted by 5 Khz or NO modulation (carrier only). R/C FM is identical to wireless data transmission "frequency shift keying" (FSK), at least the computer people don't pretend to be FM.

The Futaba, Hitec and Tower Hobbies camp are NEGATIVE shift (carrier - 5 Khz)= ON. The Airtronics/ JR camp are POSITIVE shift (carrier + 5 kHz)= ON. Carrier only is OFF for both. For example an Airtronics PPM frame, with all servos at Neutral, would start with 72.075 MHz (ON) for 1.5 m then 72.070 MHz (OFF) for 0.5 ms repeated for 2 - 9 servos and wraps up with 2 ms at 72.070 (OFF) synch.
"

HTH - Steve
Steve Lewin is offline  
Reply With Quote
Old 01-03-2003, 09:48 PM
  #3  
Steve Guinn
Senior Member
Thread Starter
 
Join Date: Aug 2002
Location: WV
Posts: 835
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Pos/Neg Shift? Please Explain

Thank you Steve. Explained very well.
Steve Guinn is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service