X9303 and R921 affected by outside "interference"
12-16-2007, 03:10 AM
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X9303 and R921 affected by outside "interference"
Greetings Danny,
I wrote two years ago asking about an interference issue that scared me a bit. My R945 PCM system was NOT going into failsafe and was NOT responding to my inputs, then I would get the plane back after approximately three seconds. It was always in the same part of the sky at about 300 ft above ground level. We suspect a high powered directional "beam" that is swamping out the RX and making it act strange at the same time. A link to my previous question two years ago is here:
http://www.rcuniverse.com/forum/fb.asp?m=3622416
Well, this happened again, this time with the 2.4GHz X9303 and R921 combo. I landed immediately and checked the receiver with the data logger...NO HOLDS were recorded. Nine frame losses on the right remote receiver and five on the internal receiver. I couldn't believe it...not only did it not show any holds, but the plane did not respond for at least two seconds as I was holding the ailerons over to roll upright on the back side of a cuban eight.
Set up: 38% Colombo Anderson Extra 300
JR X9303
R921 with one external RX and data logger
DA-150
Smart-Fly Power Expander EQ10
Smart-Fly Turbo Regulator
Twin 5600mah Li-Ion batteries connected through Dean's connectors
DS8611A servos
Since the data logger didn't show any holds I thought maybe I was just "over reacting" since there are so many skeptics out there bashing 2.4 technology. So, I decided to trust my data logger and fly again. After all, the 2.4GHz system is impervious to the same interference that plagued the 72MHz band.
See the picture below for a graphic result of the following recap. While flying an immelman, having just leveled off at the top while powering back, and about to complete the roll, my aircraft ceased to roll and the throttle stayed at 1/4. It flew a nice level inverted pass at about 300 feet above ground level, with the throttle maintaining 1/4, NOT going to idle as my failsafe was set (during the binding process). After about five seconds the aircraft descended inverted, wings level as I held full down elevator and full right aileron so when I got control back I would know it and could recover. No recovery was afforded. Impact was more than a 1/4 mile away.
I completely forgot to bring the data logger with me to retrieve the aircraft. Big mistake there, no data to share as a result. There were no lights on to indicate the R921 was operating, maybe because the remote RX had been pulled out during impact.
Please shed any light on this if you can. Specifically:
1. How I am getting a hold on the throttle instead of the expected idle during a presumed "failsafe" condition?
2. Is RX swamping possible by flying through a line-of-sight transmission, such as a surveilance video?
3. Why did I not get a "HOLD" on the DATA LOGGER when this happened the first time? With no control I had lost all three RX links simultaneously for at least one whole second.
4. Is there something I could have done to get my link back after the plane went through the swamped area and was trying to reacquire the TX signal before the crash?
Thanks for you help in advance.
Thank you.
I wrote two years ago asking about an interference issue that scared me a bit. My R945 PCM system was NOT going into failsafe and was NOT responding to my inputs, then I would get the plane back after approximately three seconds. It was always in the same part of the sky at about 300 ft above ground level. We suspect a high powered directional "beam" that is swamping out the RX and making it act strange at the same time. A link to my previous question two years ago is here:
http://www.rcuniverse.com/forum/fb.asp?m=3622416
Well, this happened again, this time with the 2.4GHz X9303 and R921 combo. I landed immediately and checked the receiver with the data logger...NO HOLDS were recorded. Nine frame losses on the right remote receiver and five on the internal receiver. I couldn't believe it...not only did it not show any holds, but the plane did not respond for at least two seconds as I was holding the ailerons over to roll upright on the back side of a cuban eight.
Set up: 38% Colombo Anderson Extra 300
JR X9303
R921 with one external RX and data logger
DA-150
Smart-Fly Power Expander EQ10
Smart-Fly Turbo Regulator
Twin 5600mah Li-Ion batteries connected through Dean's connectors
DS8611A servos
Since the data logger didn't show any holds I thought maybe I was just "over reacting" since there are so many skeptics out there bashing 2.4 technology. So, I decided to trust my data logger and fly again. After all, the 2.4GHz system is impervious to the same interference that plagued the 72MHz band.
See the picture below for a graphic result of the following recap. While flying an immelman, having just leveled off at the top while powering back, and about to complete the roll, my aircraft ceased to roll and the throttle stayed at 1/4. It flew a nice level inverted pass at about 300 feet above ground level, with the throttle maintaining 1/4, NOT going to idle as my failsafe was set (during the binding process). After about five seconds the aircraft descended inverted, wings level as I held full down elevator and full right aileron so when I got control back I would know it and could recover. No recovery was afforded. Impact was more than a 1/4 mile away.
I completely forgot to bring the data logger with me to retrieve the aircraft. Big mistake there, no data to share as a result. There were no lights on to indicate the R921 was operating, maybe because the remote RX had been pulled out during impact.
Please shed any light on this if you can. Specifically:
1. How I am getting a hold on the throttle instead of the expected idle during a presumed "failsafe" condition?
2. Is RX swamping possible by flying through a line-of-sight transmission, such as a surveilance video?
3. Why did I not get a "HOLD" on the DATA LOGGER when this happened the first time? With no control I had lost all three RX links simultaneously for at least one whole second.
4. Is there something I could have done to get my link back after the plane went through the swamped area and was trying to reacquire the TX signal before the crash?
Thanks for you help in advance.
Thank you.
12-16-2007, 05:31 AM
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RE: X9303 and R921 affected by outside "interference"
Sorry to see anything like this. There must be many of us that are interested in any answers to an incident like this.
12-17-2007, 09:51 AM
#3
RE: X9303 and R921 affected by outside "interference"
1. You could be having a battery or power issue or connector issue causing the problem.
2. No, only if the source is very close, even still it would be very unlikely.
3. That indicates that there is some other issue, see #1.
4. There wouldn't be anything that you could have done while the aircraft was in the air.
The remote wire becoming disconnected would not cause the lights on the main RX to drop out, that means that the receiver was not powered.
2. No, only if the source is very close, even still it would be very unlikely.
3. That indicates that there is some other issue, see #1.
4. There wouldn't be anything that you could have done while the aircraft was in the air.
The remote wire becoming disconnected would not cause the lights on the main RX to drop out, that means that the receiver was not powered.
12-17-2007, 04:57 PM
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RE: X9303 and R921 affected by outside "interference"
ORIGINAL: dsnyder
1. You could be having a battery or power issue or connector issue causing the problem.
2. No, only if the source is very close, even still it would be very unlikely.
3. That indicates that there is some other issue, see #1.
4. There wouldn't be anything that you could have done while the aircraft was in the air.
The remote wire becoming disconnected would not cause the lights on the main RX to drop out, that means that the receiver was not powered.
1. You could be having a battery or power issue or connector issue causing the problem.
2. No, only if the source is very close, even still it would be very unlikely.
3. That indicates that there is some other issue, see #1.
4. There wouldn't be anything that you could have done while the aircraft was in the air.
The remote wire becoming disconnected would not cause the lights on the main RX to drop out, that means that the receiver was not powered.
Please read the FULL message/question I asked.
To answer your points:
1. Did you see my set up list...I included those facts to make sure you knew IT COULD NOT HAVE BEEN A POWER ISSUE. Dual DEANS connectors from 5600mAH Li-Ion batts through the Smart-Fly Power Expander, worked flawlessly for ten flights and held those servos perfectly at neutral during the failsafe condition. All connections were still solidly plugged in, even after that horrific crash!
2. Well, it is REPEATABLE with PCM gas planes, and I'm not going to try it again with a 2.4MHz gas plane...it ONLY affects gasoline powered planes.
3. The fact that this loss of control happened in the SAME part of the sky that causes PCM 72MHz systems (several different planes owned by different people) to go into some psuedo failsafe is proof that this IS NOT A SET UP ISSUE that is plane specific.
4. It is nice to know I did all I could while the aircraft is in the air. For now we will limit gasoline aircraft flying at our field with a HUGE "fly at your own risk" disclaimer and identify that part of the sky as a "no fly zone" for gassers (this spot does not affect glow/electric powered planes).
12-18-2007, 09:28 AM
#5
RE: X9303 and R921 affected by outside "interference"
1. That does not guarantee that you did not have a battery issue, or some other connection issue inside the aircraft.
2. I'm not sure what you are getting at there. If you have onboard video transmitter on the aircraft, then placing it too close to the receiver 'could' swamp the receiver, but only if it is very close and if the unit is not an FCC approved device in which case it is illegal to use anyway. That wouldn't have anything to do with a gasoline engine.
3. Something that affects 72 MHz systems would not affect anything on 2.4 GHz. The difference between the 2 bands is much too far apart. In your case, you mentioned that you had an issue in an earlier flight, and when you landed you didn't have any holds on the flight log. That is a clear indication that there is some other issue than RF link in the aircraft.
4. I believe that to be the wrong way to approach the problems. Do range testing on the ground, if there is an issue in one area, range test the model on the ground in that area. Do this with and without the engine running. If there is any issue, it will show up in a range test. Try this with a few models.
2. I'm not sure what you are getting at there. If you have onboard video transmitter on the aircraft, then placing it too close to the receiver 'could' swamp the receiver, but only if it is very close and if the unit is not an FCC approved device in which case it is illegal to use anyway. That wouldn't have anything to do with a gasoline engine.
3. Something that affects 72 MHz systems would not affect anything on 2.4 GHz. The difference between the 2 bands is much too far apart. In your case, you mentioned that you had an issue in an earlier flight, and when you landed you didn't have any holds on the flight log. That is a clear indication that there is some other issue than RF link in the aircraft.
4. I believe that to be the wrong way to approach the problems. Do range testing on the ground, if there is an issue in one area, range test the model on the ground in that area. Do this with and without the engine running. If there is any issue, it will show up in a range test. Try this with a few models.
