lsjpeng

Anyone knows the definition? I know Futaba and Hitec are using negative shift, JR and Airtronics are using positive ****. Somebody told me that the negative shift is using a negative deviation, then what is the negative deviation?

FLYBOY

My Feedback: (11)

I always read those posts and laugh to myself. I ask myself "is it something I can fix when I am flying" and the answer is always "no".

One of those things I never understood why people worry about unless they are trying to mix a JR rec with a Futaba transmitter. Again, not something worth doing. I guess I fly all the same brand and don't mix so I don't have to deal with it.

Sorry, don't mean to ramble and not answer your question. I just keep asking myself "what difference does it make anyway", other than the fact that everyone keeps talking about it here because people keep trying to mix brands.

Someone will tell you shortly though.

lsjpeng

I fly RC more than 20 years.
I never mix up Futaba and JR because I use Futaba only.
Yes, it makes no difference.
Sometimes just curious and ask myself what's the heck that means?
You may not know what is the "P-factor" but you can fly very well.
You don't have to know why there is a 2mm gap in the gasket of YS 120/140 engine caburator, but you know how to run your YS engine.
Just in a "know how" basis...............

Rodney

Check out www.torreypinesgulls.org/Radios.htm for some pretty good info. Basically, positive shift means that the deviation from the basic frequency is an increase in frequency (approx. 5 KC) by a data pulse while negative is a frequency decrease from the basic frequency for a data pulse. This is an over simplification, if you want an exact one, there are many books on the subject dealing with modulation techniques.

lsjpeng

Thanks! That's very clear!

3DFanatic

My Feedback: (5)

A radio wave is a sine wave. However our equipment only uses one half of the wave. JR/Airt would use the positive portion of the wave while the Fut/Hitec uses the negative portion. (I.E. Top and bottom)

Rodney

3DFanatic, hey, this isn't April First, stop the spoofing; at least I hope you are spoofing. If not, best you open a text book or two.

pettit

My Feedback: (23)

I wonder if your "engineering club" is for mechanical engineers?

It certainly doesn't sound like a club for Electrical Engineers...

Old Rodney put into as simple a term as I have heard.

(and I don't know if Rodney is actually Old...)

nashtm

He must be old if he uses the term KC

3DFanatic

My Feedback: (5)

Oops. That's just what somebody told me once... []

FHHuber

FM = Frequency modulation. the + shift or - shift = the direction of modulation from the nominal frequency.

Rodney didn't really oversimplify... it really is just that simple.