[NSRCA-discussion] RX choices

[Fred Huber]

PCM is FM too... (well. there were a few AM PCM radios...)

I don't really think there's any increase in range or  ability to avoid 
getting interference with PPM or PCM.... its more a matter of what the RX 
does when the radio signal gets "scrambled"

Both use the same FM radio carrier wave.  Same power output... So the same 
interference source could scramble either.

PPM will respond to the "percieved" command.
PCM, being digital encoded, would immediately detect a "bad frame" and can 
reject it, holding the last good frame. (hinding the interferance from 
you...)

A short blip of interference will be seen with the PPM as the aircraft 
jumps.
A short blip of interference will likely be hidden from the pilot and the 
judges with PCM.

PPM, by not hiding the short blips of interference will sometimes serve as a 
warning that you need to get the plane down.  PPM your first indication may 
be a full lockout.

Advantages and disadvantages both ways...


----- Original Message ----- 
From: "Wayne" <Whinkle1024 at msn.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, September 14, 2006 10:28 AM
Subject: Re: [NSRCA-discussion] RX choices


>I have a question guys.
>
> I see in lots of posts guys using FM (PPM) RX's.  Why is this?
>
> In today's market there are so many choices of good PCM RX's I can't
> understand why someone would actually choose to run FM. Back in the days
> when I started RC there was no PCM and we had the choice of AM or FM. I 
> was
> taught that my model was too important to me not to run the best link
> possible, at the time FM was it.
>
> When PCM came in the price was much higher and I can see a reason to not 
> use
> it. Today however both Futaba and JR have PCM RX's that are good for under
> $99, JR now even has one that PLL Synth. So why use FM?
>
> It is my understanding with today's PCM that noise rejection is so much
> better with PCM that it seems along with its F/S properties both model and
> people are better protected. I can see the reasoning among average modeler
> its price why else do MPI, FMA and so on make such a profit on off brand
> leads and servos that are in my opinion very sub par. I felt that in the
> pattern community with available models shrinking, and the cost of models
> hitting larger prices that guys would trust their baby to better 
> equipment.
> I mean a basic pattern model that is on the cheap is going to be $1000 to
> $1500 all up. The difference in a 127 Futaba RX and say a Futaba 138DP PCM
> or JR 790 PCM version is about $40
>
> What am I missing?
>
> Wayne
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.12.4/448 - Release Date: 9/14/2006
>
>