Receiver Choices/PCM fail safe

[Jerry Wilson]

I've heard it suggested that the right way to program a fail-safe/hold
position was to be sure a plane which was no longer under control was
brought to earth quickly so that the danger was minimized.  In other words
the fail safe is to protect other people and property, not the operator's
model aircraft.

Personally I have not done this and am reluctant to do so.  But they have a
point.

Would like to hear comments from the list.

TIA
Jerry Wilson
Houston, TX



-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Tony Stillman
Sent: Sunday, September 29, 2002 7:26 PM
To: discussion at nsrca.org
Subject: Re: Receiver Choices


The PCM receivers are what I like best, due to the fail-safe/hold feature.
However, I use less expensive PPM receivers in my "sport" planes.  Most
times, you will NEVER see the difference between the two.  The PCM will work
in high noise (make that interference) areas much better than PPM receivers.

You should have confidence with either!

Tony Stillman
Radio South
3702 N. Pace Blvd.
Pensacola, FL 32505
www.radiosouthrc.com

1-800-962-7802
----- Original Message -----
From: "RC Steve Sterling" <rcsteve at tcrcm.org>
To: <discussion at nsrca.org>
Sent: Friday, September 27, 2002 5:54 PM
Subject: RE: Receiver Choices


> You are right-- I was thinking of the 148DF (not the P)which is PPM.
>
> Now I really don't know what would differenciate them. Maybe Tony Stillman
> will check in.
>
>
> -----Original Message-----
> From: discussion-request at nsrca.org
> [mailto:discussion-request at nsrca.org]On Behalf Of Brian Young
> Sent: Friday, September 27, 2002 2:01 PM
> To: discussion at nsrca.org
> Subject: RE: Receiver Choices
>
>
> Thanks Steve, the 148DP is a PCM receiver also (listed
> as such on Futaba site). Part of the reason I am
> curious about the difference in cost between the
> three, I can see the difference for an added channel.
> But the large price difference for the 138DP has me
> quite curious. I mean why pay $30 more if the 138 does
> the same thing.
>
> --- RC Steve Sterling <rcsteve at tcrcm.org> wrote:
> > The 138DP is an 8 channel PCM receiver. PCM
> > transmits a digital data stream
> > like a modem and the receiver has a microprocessor
> > to decode it all.
> >
> > The 148DP is an 8 channel PPM receiver. An old
> > standby. PPM varies the width
> > of FM modulation pulses to communicate servo
> > position.
> >
> > The 149DP is a 9 channel PCM receiver.
> >
> > PPM receivers see interference or low signal as some
> > different pulse widths,
> > so they tend to cause the servos to jitter and jump
> > and be pretty
> > unpredictable when there is a problem.
> >
> > When PCM receivers get interference or low signal,
> > they either just stay
> > put, or go to a pre-programmed setting, like low
> > throttle, wings level.
> >
> > PCM receivers generally have cost quite a bit more
> > than the PPM receivers,
> > so the 138DP price is encouraging. There is much
> > debate, particularly on
> > this list, on which is better/more reliable. PPM
> > proponents say that they
> > see problems coming when the plane starts jumping
> > around, and with the
> > warning, may have time to get down and solve it. PCM
> > proponents say they
> > don't see as many problems in the first place, and
> > would rather have their
> > servos do predictable things when faced with
> > interference.
> >
> > I run PCM in my pattern planes, PPM (cheaper) in my
> > sport, funfly, float
> > planes, etc. No problem with either. Have seen
> > others with failures in both
> > types of receivers. Because equipment does fail, you
> > will get anecdotal
> > stories from both sides, but nobody has done a
> > scientific study to really
> > determine which is better, and under what condtions.
> >
> > -----Original Message-----
> > From: discussion-request at nsrca.org
> > [mailto:discussion-request at nsrca.org]On Behalf Of
> > Brian Young
> > Sent: Friday, September 27, 2002 11:24 AM
> > To: discussion at nsrca.org
> > Subject: Receiver Choices
> >
> >
> > Im looking to buy a couple new receivers, flying
> > Futaba so thats my area of preference. I have an
> > 8UAP
> > currently. I notice Futaba has available a new 8 CH
> > RX, 138DP for about $100, then they have 148DP for
> > about $130, and 149DP for $160.
> >
> > Each of these receivers have the required capacity
> > for
> > my plane. Can anyone enlighten me as to a method to
> > evaluate the price of the expensive one vs. the
> > cheap
> > one? Does the extra money bring more reliability,
> > etc?
> >
> > The 138 is a new model, so may have the use of
> > latest
> > technology, the other two have been around awhile so
> > maybe they are more of a proven design.
> >
> > And if anyone has any spares they want to sell I may
> > be interested.
> >
> > =====
> > Brian Young
> > Tulsa
> > b4598070 at yahoo.com
> > 918-745-6046h
> > 918-838-0900w
> >
> > __________________________________________________
> > Do you Yahoo!?
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> > http://sbc.yahoo.com
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>
>
> =====
> Brian Young
> Tulsa
> b4598070 at yahoo.com
> 918-745-6046h
> 918-838-0900w
>
> __________________________________________________
> Do you Yahoo!?
> New DSL Internet Access from SBC & Yahoo!
> http://sbc.yahoo.com
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