Hi Joel,
All valid points. Accurate and viable testing is in itself a science. My
full-time work has us using anechoic chambers that are "quiet" to
120+dB.
Amazingly, there is still a measurable noise floor present.
"Joel A. Foner" wrote:
>
> An interesting approach. There are a few other factors that I would
> like to add in.
>
> Transmitter signal strength and effective radiation pattern. Are we
> sure that the radiation pattern of all transmitters are identical?
> (If there are lobes in the radiation pattern of a transmitter, then
> the orientation of each transmitter/antenna system becomes important
> at the boundaries of control.)
>
> If, for some reason (low batteries?, other?) one transmitter has lower
> power output than another, the range will differ for reasons having
> nothing to do with the receiver. (Would radiated power differ based on
> transmitter case design - some with metal parts, others all plastic,
> routing of antenna couplers within the case, ergonomic effects of hand
> placement and inductive coupling to transmitter antenna?)
>
> If one transmitter is used with multiple receivers, is it equally
> optimized for all transmission modes?
>
> Given an earlier description of how IPD works, it seems that a truly
> even-handed test might monitor all channels, rather than just one. I
> remember an earlier post that suggested that IPD could disable a
> single channel if it's signal was corrupted without the "full lockout"
> of PCM. If this is the case, at the boundaries of control the IPD
> receiver may lockout a channel other than the one with the servo
> "flag" if we monitor only one channel.
>
> Regards,
>
> Joel
>
> > -----Original Message-----
> > From: YK Chan [mailto:[EMAIL PROTECTED]]
> > Sent: Thursday, July 20, 2000 3:17 AM
> > To: Karlton Spindle; [EMAIL PROTECTED]; [EMAIL PROTECTED]
> > Subject: Re: [RCSE] Re: PCM / IPD / PPM
> >
> >
> > 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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