The test Karlton made may be a bit over simplified on details.
Here is the detailed way in trying to manage thing under equal basis.
Table will be of 100% wood without any stretch of metals. Do not place
all receiver on the same picnic table but one at a time. This will
eliminate unintend antenna array by the adjacent antenna not under
test (yagi model), for equality purpose. Failing to do so will cast a
doubt to the equality to the contestants.
One test at a time, all Rx and its antenna will be held down securely
on wood table. Antenna root will be strangle hold by a first rubber
band and pin down on wood table. Do the same to the antenna tip with a
2nd rubber band but stretched before pin down onto the same table such
that the antenna is pull straight and is always right angle to the Tx.
Antenna tip is define as the last half inch at the open end. It is
prohibited to alter any Rx antenna length during the contest.
Double side tape a soda straw onto the servo arm and then double side
tape it onto the same table such that the straw is neutral in
vertical. The staraw will act as a flag in a constant gentle cycle in
+/-30 degree by the test operator with stick input.
With a helper to safely guide the test operator to step backward
facing the Rx under test.
Observation guide.
Watch the straw in cycling for any abnormality operation as we are
backing off. Any Rx in fail safe mode need to preset in a unique
static displacement position to help indicate a fail safe state from a
cycling state. Once fail safe is latched, walk back to the Rx until RC
link is reestablish, mark that position. Perform the same to PPM
system using a difference threshold at which servo freeze from
proportional displacement, or suffer displacement limiting. Again walk
back to the Rx until RC link is reestablish.All three test must be
recorded and reported in absolute distance value and not in ratio or
in difference.
I do not see a need for a common physical Rx antenna, although that is
scientifically correct. I do not think there should be a significant
difference.
Concerns about all three categories:
A relative more sensitive Rx equip with IPD will illude the audience
about good IPD's performace. Like wise, a less sensitive Rx equip with
convensional scheme can indirectly illude the audience that IPD is
better. Or less sensitive Rx equip with PCM also make the other
candidates look good. These are the concerns, where everything else
cannot be equal. Straightly speaking, it is not easy to draw any
conclusion beyond any reasonable doubt, for or against any post
detection scheme, PPM, IPD or PCM.
More concern:
A more sensitive Rx is good when no off channel signal present. It is
also very easy to produce high sensitive Rx than to produce both
high-sentitive and robusness in the same Rx. Robusness is what Jason
refers to RF link integrity or high immunity to interference.
Therefore Karlton's report is good for range contest and is lagging of
data for 2nd source interfering source kind of performance.
That leads to Two Tx ground range test. This reminds of what YK
introduced special ground range test that involve two or more Tx. More
comment on that upon request.
YK Chan
Seattle
----- Original Message -----
From: Karlton Spindle <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Wednesday, July 19, 2000 9:20 AM
Subject: Re: [RCSE] Re: PCM / IPD / PPM
> Don't take my word take my test! We were over 50 feet and still
receiving no
> glitch this morning with collapsed antennas.
>
> Smooth Sailing,
> Karlton Spindle
> http://www.MultiplexRC.com
> ----- Original Message -----
> From: <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Wednesday, July 19, 2000 7:48 AM
> Subject: [RCSE] Re: PCM / IPD / PPM
>
>
> > OK- so lets have the hard numbers-Was it a 10 foot difference, or
100 feet
> ,
> > or a 1/4 mile difference. You certainly don't expect us to take
your wo
r
> > it do you? ;-)
> > Vince D
> >
> > In a message dated 00-07-19 10:16:43 EDT, you write:
> > > Date: 00-07-19 10:16:43 EDT
> > > From: [EMAIL PROTECTED] (Karlton Spindle)
> >
> > > Simple test take a radio that goes PCM and PPM take three
receivers wad
> up
> > > the antennas on the receivers and place them on a wood table
off the
> ground
> > > all three in a row all on the same channel.
> > >
> > > Now do a range test ONE at a time PLEASE. SAME TX, SAME
Battery pack
> in TX
> > > same battery for the receiver. Now take the TX far enough away
where
> the
> > > PCM NO LONGER WORKS it goes in to fail safe, mark the distance.
Switch
> > > batteries and fire up the PPM receiver go to the same spot with
the TX
> > where
> > > the PCM stopped. Note the glitches of the PPM or move further
if the
> PPM
> > is
> > > not glitching. Mark the spot and do the same test with IPD.
> > >
> > > SIMPLE TEST we did it this morning IPD wins GLITCH down. But
do the
> test
> > > yourself and you WILL SEE!.
> > >
> > > Remember it was Multiplex that brought PCM to R/C so why would
they
> > replace
> > > it? Answer IPD is BETTER!
> > >
> > >
> > > Smooth Sailing,
> > > Karlton Spindle
> > > http://www.MultiplexRC.com
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> >
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