Receiver Choices

[RC Steve Sterling]

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
>
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=====
Brian Young
Tulsa
b4598070 at yahoo.com
918-745-6046h
918-838-0900w

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