[NSRCA-discussion] 2.4Ghz

Thu Jun 26 12:27:21 AKDT 2008

Allan,

in a range test situation you are going to be getting the worst possible
readings on the flight data log. You could be holding the range test
button and be on the fringes of loosing range yet the system is still
working. The Flight data device will tell you exactly that. Which it
did.

Here is what I do with the data log device. I will use a second person
to hold the model. I then will walk to a spot where the data starts to
show lager numbers of fades. Its doing its job telling you the signal is
getting weak.

I then will find the spot a little closer that has the best "low" fades.
This is where the signal starts to get "fuzzy" and the range is still
solid but further out it starts to increase the fades. With the model on
the ground, and you on the ground "level with it" the range test button
depressed you are giving the system its worst possible scenario. Of
course the flt log will show this.

I then will make a note of this location where the range starts to fade.

Simply walking until it stops working like we did with 72mhz stuff is
going to show a ton of fades....Remember this thing is taking readings
50-60 a sec. So to get 200-300-500 fades putting the range test process
in place you are are only talking about 10 secs. tops with weak signal.
So think about what is going on...this is a tool and along with it comes
some analysis of what is really happening and what the numbers mean. Its
not a device that is a green light for go and red light for NO.

So find the spot where you are not getting large numbers of fades..this
is your range check distance. 

Now start up the engine and go to this same spot....you could have
similar numbers of fades...remember that a given antenna may be blocked
partially depending on model orientation to you and the TX. So I will
walk around the model at this given distance and have my buddy looking
at the flt data log. 

This tells me how its performing. Is this type of device for everybody
Nope its not but its a powerful tool if you think about what the tool is
telling you. The real test is in the air, because the data logger is
going to rack up bigger numbers while under the range test
scenario....but fly it and you will see what is happening.  Also in
looking at those number 100fades is about 2-3 secs worth of weak
signal....this is a really small amount of time, and it doesn't mean the
system is in hold...it just means a given antenna is getting weak signal
for that amount of time. Compared to the number of seconds in a
flight...that's low, and beside a fade doesn't mean its not getting
signal just that its weak signal...and the signal from other antennas
are stronger and the system is using those. 

If you have a weak signal for all antennas at the same time you could
get a frame loss. It takes 45 frame losses in a row to make the system
go into hold and this all happens in less than a second. So to really
look at these numbers they have to be really really high to have a
problem..

For normal use in a pattern model I'm getting about 100-150 fades on the
main A-B antennas and low numbers on the remotes. My remotes are behind
the wing down the tail of a wood model. I have the remotes with antennas
mounted in different axis and planes to get the best diversity possible.
I often have single digit fades on the two remotes. Its common to get a
few Frame losses but its also common to have zero. I have seen numbers
as high as 20-30 on the frame losses...never seen any holds from a
flying situation.

Turning your RX on before the TX can affect your numbers and of course
turning the TX off before the taking readings on the RX will also add to
your numbers.

Obviously the instructions for this little device are not as clear as
they could be but if you think about it and what the data is telling
you...its well worth having it. Just think about the numbers mean and
how quickly the tick marks can build up in a range test situation.

Troy Newman
Team JR

________________________________

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
AWorrest at aol.com
Sent: Thursday, June 26, 2008 11:51 AM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] 2.4Ghz

I've got mixed opinions about the flight log. I flew my pattern ship all
last year using a DX7 and the AR7000 with no problems. Later I bought
the flight log and tested it on the AR7000. While it showed correctly
there were two receivers in operation, some of the other readings were
strange. It turned out my AR7000 wasn't upgraded to support the flight
log. Still the flight log acted as if it did.

Recently I bought a R921 on e-Bay. I range tested it with the flight
log. The readings were terrible. I sent the R921 back to Horizon. They
could find nothing wrong. When it returned I tested it again. Still bad
readings. Talked to Horizon again. Was told to try it in a plane. Before
doing that, one more time I range tested it on top of a paper box. Did
the exact same thing with two receivers that I had successfully test
flow in an airplane. This last test, the "bad" receiver had better
numbers than the two "good" ones!

I'm now wondering if these receivers retain some information after being
turned off and this leads to erratic flight log readings. BTW, someone
on one of the discussion lists says when there is a frame lost it is not
counted as an antenna fade. I don't know if this is true but it does
make the math work. Yes, I've had on occasion more frame losses than
antenna fades.

Allan

In a message dated 6/25/2008 9:20:15 AM Central Daylight Time,
jlkonn at hotmail.com writes:

	I am curious what other folk's experience has been with
JR/Spektrum 2.4Ghz.
	I have experienced a frame loss when one satelite Rx showed -0-
fades.  It's my understanding 
	this shouldn't happen.  I have another 9ch Rx from the "Great
Receiver Giveaway" I'm going to 
	try but was wondering what others are finding is average for
fades and frame losses per flight?
	Thanks!
	JLK

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