JR R921 2.4 Receiver Mounting

[Harleyflyer]

I am getting ready to mount my R921 2.4 receiver and have a question. I was thinking about mounting it in the center...near the bottom of where the canopy attaches......just a little behind the wingtube in my 35%er. My ignition and regulator are near the cowling some distance away but my 2600 Fromeco ignition battery is mounted just behind the wing tube so my main receiver would be a few inches above it.....does anyone think this would be a problem? Also, I am going to be using two satellite receivers and the second satellite will be as far back and low as I can get it....about 2 foot.

Thanks in advance.

[aviti]

Here's what I'd do. Mount it temporarily in different locations and perform range checks using the data logger. I found I got much better data when I moved my RX up away from the batteries and regulators.

[Harleyflyer]

Tony,

That sounds like a good plan....I will give that a try.

Thanks,
Keith

[Harleyflyer]

Okay, I did some testing with the Flight Log. I see the fades on the two antennas for the main receiver and the two for the primary satellite receiver. However, I do not see anything on the Flight Log screen that gives any information on the second satellite receiver I added. Does anyone know if I am doing something wrong or is the Flight Log just not set up to gather the data on the second satellite receiver?

Thanks,
Keith

[RobertV]

	Quote: Originally Posted by Harleyflyer
	Okay, I did some testing with the Flight Log. I see the fades on the two antennas for the main receiver and the two for the primary satellite receiver. However, I do not see anything on the Flight Log screen that gives any information on the second satellite receiver I added. Does anyone know if I am doing something wrong or is the Flight Log just not set up to gather the data on the second satellite receiver? Thanks, Keith

First, you need to make sure you bind after all RX's are hooked up. Are there any lights on your second satellite when you have the radio on? If not, re-bind and that should take care of it.

Also, if you look on the back of the card that the Flight Log came with, you'll see the following description of the info that it provides:

A - antenna fades on internal RX "A" (in the 921)
B - antenna fades on the internal RX "B"
L - antenna fades on the "left" remote RX (plugged into the left side of the 921)
R - antenna fades on the "right remote RX (plugged into the right side of the 921)
F - frame losses (simultaneous fades on all attached RX's)
H - holds (45 contiguous frame losses. This takes about 1 sec.)

I hope this helps!

[Zeeb]

	Quote: Originally Posted by RobertV
	H - holds (45 contiguous frame losses. This takes about 1 sec.) I hope this helps!

If I read the manual correctly, a hold which does require the 45 contiguous frame losses, produces a 1 second hold on the rx not that it takes 1 second to get the frame losses????

I'm not sure what the data transmission speed is, but I suspect that if you've got a problem, you could amass 45 frame losses in substantially less than 1 second.

[1bwana1]

The manual states that it takes about 1 second to reach 45 continious frame losses, and thereby a hold.

[Zeeb]

I stand corrected; page G-23 of the X9303 manual....

However that does bring up the question of how long the rx is in hold if the 45 contiguous frame losses occur?

Just curious if anyone's seen that information anywhere?

[1bwana1]

There is no set time for how long the hold will last. It will last until the RX begins getting a good signal from the TX. This is different that loss of control from a power brown out, which will last less that 1 second if you have the quick connect upgrade, or could go many seconds if you don't.

[Zeeb]

Yeah I knew it was a signal loss vs. power loss deal.

Interestingly enough I just got back all of my rx's from having the firmware update done. Like the videos PaleRider posted, the R921's seem to regain servo function faster than before they were sent in. It seemed like before, the lights would come on almost instantly, but servo function was just a bit behind the lights coming on. Now, servo function is regained either before or at the same time the lights come on. The other oddity is that the AR7000's now seem to actually re-link faster than the R921's with the AR6XXX series taking about the same time as the R921's.

Now of course this is all anecdotal as I don't have any rx's except my AR9100 which were not sent in, and I can't test the AR9100 until I get the A123 battery packs made up for it. According to Danny over on RCU, all of the AR9100's have the fast re-connect, but not all of them have the blinking lights to indicate a power brown out has occured.

Got to get those packs done up...

[Zeeb]

	Quote: Originally Posted by 1bwana1
	There is no set time for how long the hold will last. It will last until the RX begins getting a good signal from the TX. This is different that loss of control from a power brown out, which will last less that 1 second if you have the quick connect upgrade, or could go many seconds if you don't.

Hey Steve,

I know we're drifing off the thread topic, but since I've got your attention and you've done more testing with this 2.4 stuff than I have, I'll mention what I forgot to ask...

Since I had been thinking there was a 1 second "hold" if the 45 frame losses occured, I thought that the rx would then go into failsafe/smartsafe (depending on the rx and your settings) after that 1 second hold of all servos at last commanded position.

If it's going to "hold" until it gets a good signal from the tx, isn't it going to go into failsafe as soon as it loses the 45 frames?

Thanks!

[1bwana1]

Zeeb,
That is an interesting question, after reviewing all the documentation I have, I don't have a solid answer. Here is what we know.

The documentation states that it only takes "less than 4ms" to recover from a full signal loss (Frame drop, Hold, or Failsafe), once signal is regained.

A Fade is loss of signal to a single RX in the system. The plane would continue to operate normally because other RXs in the system are getting good data packets.

A Frame drop means that all RXs in the system failed to receive a valid data packet. This means that all controls (including throttle) remain in their last position. You have actually been in a "hold condition" for how ever many continuous frames have been dropped (# dropped frames X 20ms). However a single frame drop is so short (20ms) that it causes no problems.

A Hold represent 45 continuous dropped Frames. During that time, all controls (including throttle) have been "holding" the position called for in the last valid data packet. Since it takes 1 second (45 X 20ms) to trigger the "Hold" for the flight log data, you have really been is a sort of fail safe for 1 second before the flight log would show it.

Here is where it gets fuzzy for me. Since a recordable "Hold" takes 1 second to be recorded, you have really been in a default 'failsafe" for that period of time. The documentation does not say how long you can remain in this "hold" condition before one of the two types of official "Fail-Safes" kicks in.

In the case of "SmartSafe" which is the default, all controls hold their last position, except throttle, which goes to a preset "low position". So except for throttle, it is the same as what happens during a 20ms dropped frame, or 1 second hold.

In the case of "Preset Fail-Safe", all controls will move to a user programed position, usually low throttle and neutral on all other controls.

If no one knows how long we can be in the "Hold" condition before we go into "Fail-Safe", I guess we could do a simple test to determine that.

Program a Preset Fail-Safe that would be obvious to see when the controls move there.

Turn on the system and move the controls to some position far from the presets.

Turn off the TX and measure the time it takes for the controls to move to their preset position.

The amount of time in "Official Hold" would be:

(Time in "Official Hold") = (Time to Failsafe) - (1 second (45 continuous frame drops))

I'm not sure how useful this information would be, because I'm not flying any setup that ever shows a single Hold. Still interesting though...

[Zeeb]

Thanks for your thoughts.

I'm kind of chasing this as a friend recently had what he called an "I lost it" moment with his 40% Dietrich while doing a rolling circle.

I'd kind of been the primary information source for him on the switch to the Spektrum system, but he elected to go with the DX7 and I couldn't talk him into the R921. So when that happened he got understandably freaked out. Unfortunately, he couldn't really remember exactly what happened so I was unable to give him any more advice than what would happen if it were a signal loss vs. a power brown out. Considering his onboard power system, I can't really see it being a power brown out, so I was looking at signal loss.

I think I've convinced him to get his AR7000 upgraded and install a 921 so we can use a data logger to see if there's a problem. From my experience, I'm wondering about his rx location which is right between two big Li-Po's and he's only using the included 6 inch extension so the satellite rx is right in the same area. I suggested relocating the main rx and getting a longer extension for the satellite, but his confidence in the system is gone right now. In the meantime, he's gone back to his 9C as he's got contests lined up...

I'm a bit in the dark since as you noted, I've never had a hold show up on my data logger either.

[Harleyflyer]

Thanks for the information. I see what you are saying RobertV....I obviously overlooked the instructions. For some reason, I was thinking that the "L" and "R" related to the left and right antennas of first satellite receiver.....as opposed to the L being for the antenna fades on the entire left satellite receiver and the R being for the fades on the entire right, and second, satellite receiver. That makes much more sense now!

Thanks again,
Keith

[mikaelmiki]

i have a question

i have tried everything with moving the reciever and remote reciever and the best signal i get from the flight logger is

single digits for the antenna fades

But i have between 20 and 30 frame losses in advanced 1 minuted testing

and 0 holds


But when i first tried with the reciever in a different orientations i got fades between 50 and 118
and worst of all i had 157 frame losses

would this be enought to fly pattern

I fly a Krill spark with hacker inrunner

Please note that testing has been with not battery



my remote recievers are one about 6 inches behing the canopy and the other is right by the exit holes for the air

Please help

Mikael Fedon
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Fedon Aircraft
www.FedonAircraft.net
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