ECU putting out lots of RF noise
12-06-2003, 05:40 PM
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ECU putting out lots of RF noise
Kevin, I am getting alot of ECU RF that is putting my reciever into failsafe mode when I do my range check. This is with the turbine not running and and the switch in the ready mode I only get 60 FT. When I turn the switch off I get 200 + ft of range out of my futaba PCM reciever. Is my ECU going bad?
Dave
Dave
12-07-2003, 12:19 PM
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RE: ECU putting out lots of RF noise
Hi Dave,
It is highly unlikely that your ECU is "going bad", it sounds more to me like a system integration issue. If this ECU required filtering of some sort to keep it quiet enough for use I might wonder, but no such filtering is present. (It's never been required.) Speaking from the point of someone who knows this ECU on a component level and as someone who's done EMI testing in the professional world, there is no way I know of for this ECU to "go bad" and suddenly start generating lots of RF.
What transmitter, receiver and antenna are you using? What happens to your range if you turn on the Rx and ECU, but leave the throttle channel disconnected from the Rx? (This will help to determine if the problem is conducted or radiated in nature...) How close is your Rx and antenna to (any part of) the turbine system? Is there something that can be better isolated? Have you extended any of the cabling to achieve your installation? (I'm sure other questions will come up as we work to resolve this, but these are the first to come to mind...)
Also, while antenna down checks are a good thing to do, the only real measure of a system is to do a full blown extended antenna check.
EMI problems are always tough, but I have no doubt a solution will be found.
It is highly unlikely that your ECU is "going bad", it sounds more to me like a system integration issue. If this ECU required filtering of some sort to keep it quiet enough for use I might wonder, but no such filtering is present. (It's never been required.) Speaking from the point of someone who knows this ECU on a component level and as someone who's done EMI testing in the professional world, there is no way I know of for this ECU to "go bad" and suddenly start generating lots of RF.
What transmitter, receiver and antenna are you using? What happens to your range if you turn on the Rx and ECU, but leave the throttle channel disconnected from the Rx? (This will help to determine if the problem is conducted or radiated in nature...) How close is your Rx and antenna to (any part of) the turbine system? Is there something that can be better isolated? Have you extended any of the cabling to achieve your installation? (I'm sure other questions will come up as we work to resolve this, but these are the first to come to mind...)
Also, while antenna down checks are a good thing to do, the only real measure of a system is to do a full blown extended antenna check.
EMI problems are always tough, but I have no doubt a solution will be found.
12-07-2003, 01:28 PM
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RE: ECU putting out lots of RF noise
Kevin, I just did an antenna down check with out the IR plugged in and I got better range of over 200FT. So it seams to be the IR is emitting noise.
When I did the radio check it was with the antenna down and the receiver antenna out of the plane running along the side of the plane and the IR unplugged and I got better range with the IR plugged in my receiver goes into fail safe at 50FT. I have isolated the problem down to the IR, now we just need to find out why the IR is emitting noise...
Oh I have not added any extentions to the turbine/ ECU except for the throttle witch is 12"" also I am using the Futaba 9CAP system. You can see the mount I provided for the IR and it is in the center of the plane the ECU is about 2FT from my receiver the IR is about 2.5FT from my receiver.
Dave
When I did the radio check it was with the antenna down and the receiver antenna out of the plane running along the side of the plane and the IR unplugged and I got better range with the IR plugged in my receiver goes into fail safe at 50FT. I have isolated the problem down to the IR, now we just need to find out why the IR is emitting noise...
Oh I have not added any extentions to the turbine/ ECU except for the throttle witch is 12"" also I am using the Futaba 9CAP system. You can see the mount I provided for the IR and it is in the center of the plane the ECU is about 2FT from my receiver the IR is about 2.5FT from my receiver.
Dave
12-08-2003, 10:19 AM
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RE: ECU putting out lots of RF noise
Great find Dave.
Based on your photo (which makes things much better, thanks!) what happens if you route your antenna farther away from the IR Tx board? I'll have a careful look at one tonight and see if there's anything else I can think of to try with it. (As with the ECU, there's no EMI filtering on this board that I'm aware of.)
Based on your photo (which makes things much better, thanks!) what happens if you route your antenna farther away from the IR Tx board? I'll have a careful look at one tonight and see if there's anything else I can think of to try with it. (As with the ECU, there's no EMI filtering on this board that I'm aware of.)
12-08-2003, 10:50 AM
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RE: ECU putting out lots of RF noise
Kevin,
I was helping Dave with the range checks and we even routed the antenna forward of the the plane (outside) and still had very poor range. With the ECU off range was excellent, ECU power on and range was reduced at least 60%. Never seen this much noise generated by an ECU (or as Dave has found, IR). ???
Todd
I was helping Dave with the range checks and we even routed the antenna forward of the the plane (outside) and still had very poor range. With the ECU off range was excellent, ECU power on and range was reduced at least 60%. Never seen this much noise generated by an ECU (or as Dave has found, IR). ???
Todd
12-08-2003, 11:49 AM
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IR Tx putting out lots of RF noise
I figured you'd be there as well Todd,
Given the photo, it looked like the Rx antenna was run right over top of the Tx board so I wasn't sure it maybe there was some near field effect you were seeing or if there was a legit radiation issue of some sort.
I'll sit down tonight and see if I can duplicate the range loss with another system. What channel is the radio on?
Given the photo, it looked like the Rx antenna was run right over top of the Tx board so I wasn't sure it maybe there was some near field effect you were seeing or if there was a legit radiation issue of some sort.
I'll sit down tonight and see if I can duplicate the range loss with another system. What channel is the radio on?
12-08-2003, 03:37 PM
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RE: IR Tx putting out lots of RF noise
Kevin, worst case scenario I can always send it back to you and you can problem solve it on your in with my IR terminal. It’s good this is a part I can take off and still fly. 
I am going to put my antenna back in and do another range test with the ECU on, and with out IR plugged in and verify my antenna has enough clearance from ECU. May end up trying a Revolution antenna so that my antenna does not run near the ECU at all.
Dave
I am going to put my antenna back in and do another range test with the ECU on, and with out IR plugged in and verify my antenna has enough clearance from ECU. May end up trying a Revolution antenna so that my antenna does not run near the ECU at all.Dave
12-08-2003, 04:24 PM
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RE: IR Tx putting out lots of RF noise
ok I have just completed two test one with the antenna rerouted with out the IR Tx pluged in and I get 200+ FT. of range then I pluged the IR Tx back in for another test and I get just over 50 FT., it is definately the IR Tx...
Dave
Dave
12-09-2003, 04:56 PM
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RE: IR Tx putting out lots of RF noise
That all depends on what you consider to be luck...
I set up an outside test this morning with a turbine, my DP309 Rx and a single servo on a wooden bench about 3 feet off the ground. I tested with ECU off, ECU on (no IR Tx) and ECU on with IR Tx. (When the Ir Tx was employed, I ran the Rx wire across the top of the Ir Tx board to maximize any RF coupling.)
Without the Ir Tx, I noted about 300ft range with one antenna link extended. (It may have been better, 300 feet was about the limit I could reliably see motion on my indicator flag.) No loss in range was noted with the ECU turned on without the IR Tx. Like you, I also noted a significant drop in range when I tested using channel 18. (Couldn't remember when I got to the field what number you were.) I estimate the useable limit was about 100 feet in my case. When I switched frequencies (28 and 48) I noted a significant increase in range. Do you have any other frequencies that you can try? Being a Futaba in the low band, you should be able to get as high channel thirty-something without the need to retune.
If time and weather permit, I'll try re-running the test tomorrow with the IR Tx board in a Faraday cage to see if it cuts the interferance. (Keep the evil in the box for any of you EMI guys!)
One step at a time...
I set up an outside test this morning with a turbine, my DP309 Rx and a single servo on a wooden bench about 3 feet off the ground. I tested with ECU off, ECU on (no IR Tx) and ECU on with IR Tx. (When the Ir Tx was employed, I ran the Rx wire across the top of the Ir Tx board to maximize any RF coupling.)
Without the Ir Tx, I noted about 300ft range with one antenna link extended. (It may have been better, 300 feet was about the limit I could reliably see motion on my indicator flag.) No loss in range was noted with the ECU turned on without the IR Tx. Like you, I also noted a significant drop in range when I tested using channel 18. (Couldn't remember when I got to the field what number you were.) I estimate the useable limit was about 100 feet in my case. When I switched frequencies (28 and 48) I noted a significant increase in range. Do you have any other frequencies that you can try? Being a Futaba in the low band, you should be able to get as high channel thirty-something without the need to retune.
If time and weather permit, I'll try re-running the test tomorrow with the IR Tx board in a Faraday cage to see if it cuts the interferance. (Keep the evil in the box for any of you EMI guys!)
One step at a time...
12-09-2003, 07:24 PM
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RE: IR Tx putting out lots of RF noise
Not with out changing the Tx module and reciever crystal in which I do not have. So what you’re saying is that you are getting interference out of the IR Tx on low band channels... So this is a hardware bug that exists in the IR Tx?
12-09-2003, 11:10 PM
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RE: IR Tx putting out lots of RF noise
Bug? If that's what you choose to call any and all undesired aspects of a system... What I am saying is that I'm seeing reduced signal quality on channel 18 as compared to channels 28 and 48 when performing a "one antenna link extended" test.
EMI issues are certainly not new to the world of turbines, and they can be solved. Patience, shielding and (if necessary) frequency selection have always been the solution.
EMI issues are certainly not new to the world of turbines, and they can be solved. Patience, shielding and (if necessary) frequency selection have always been the solution.
12-10-2003, 06:37 AM
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RE: IR Tx putting out lots of RF noise
The degrading of signal is caused by the IR Tx. In development, all aspects of testing should be done before being released, and this is sure an over sight and untested issue here. When I developed software I never release it until I have tested my software in every aspect of its environments. This just show that this has never been tested, and now a newly founded problem! This issue should be highly notated in the Turbine manual then. Now I am going to take the IR Tx out of my plane until you guys come up with a solution. I have plenty of patience since its not stopping me from flying, and I have full faith you guys will come up with a solution with out having to change my band.
You might want to make all your customers aware of the current problem, because this does have the potential problem of putting a jet in the ground or in the stands with the IR Tx installed in a jet with a low band. I hope the faraday cage works.
You might want to make all your customers aware of the current problem, because this does have the potential problem of putting a jet in the ground or in the stands with the IR Tx installed in a jet with a low band. I hope the faraday cage works.
12-10-2003, 09:11 AM
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RE: IR Tx putting out lots of RF noise
Kevin, I did not realize I had a Futaba 8UA laying around, so I took the module that is on CH40 and in stalled it in my 9CAP and put the crystal CH40 in another PCM receiver. I laid the receiver right next to the IR Tx and the antenna right over there IR Tx and used a JR 4721 servo with a flag on it. Did a range check with Tx antenna turbine ECU turned on and the IR Tx plugged in, I got 200+ range so it is for sure emitting EMI at the low band range, as for me staying with CH40 I am not sure if my radio is optimally tuned to that frequency. So to be safe, and everyone around me while I fly I will just keep it out until there is a resolution to this problem.
12-10-2003, 03:22 PM
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RE: IR Tx putting out lots of RF noise
David,
The radio will not need to be tuned since you are switching modules, not crystals. The receiver on the other hand has a range of channels they can use without retuning. Low band channels 11 to 35; High band channels 36 to 60, you cannot use a high band receiver with a low band crystal without a re-tune.
Todd
The radio will not need to be tuned since you are switching modules, not crystals. The receiver on the other hand has a range of channels they can use without retuning. Low band channels 11 to 35; High band channels 36 to 60, you cannot use a high band receiver with a low band crystal without a re-tune.
Todd
12-10-2003, 10:36 PM
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RE: IR Tx putting out lots of RF noise
Hi Dave,
While the fact that the issue at hand was not detected before release of the IRDT is unfortunate, as I said before EMI issues are not new to the turbine world and ultimately it's how we deal with it from here forward that is important. To bring up qualification here is really a mute point as Great Northern Models is not involved with product development or qualification for SimJet Denmark. SimJet puts all new products, including the IRDT, through their own qualification process and then releases them to the world market.
In a case such as this where an issue is found with fielded product, we prefer to take the lead in trying to resolve any issuess for the sake of expediency and for the maximum benefit of our customers. At this point, most of our IRDT customers have already been contacted and notified of the situation. (You're the only one being affected that we are aware of.) SimJet Denmark is also "in-the-loop" with the situation.
As Todd correctly pointed out, Ch 40 is part of Futaba's "High Band", so the Rx you mentionned using must also have been tuned for the high band if you're to use it safely. (And get accurate results from any further testing.) If you can do this, however, you're in the clear as the modules for the 8U and 9C are identical, and we've had many folks use the IR Tx without incident on higher channel numbers in the low band and high band alike.
I did get some time in today with an EMI sniffer, but don't as of yet have anything useable to present. I'll post further information in this thread as it becomes available.
While the fact that the issue at hand was not detected before release of the IRDT is unfortunate, as I said before EMI issues are not new to the turbine world and ultimately it's how we deal with it from here forward that is important. To bring up qualification here is really a mute point as Great Northern Models is not involved with product development or qualification for SimJet Denmark. SimJet puts all new products, including the IRDT, through their own qualification process and then releases them to the world market.
In a case such as this where an issue is found with fielded product, we prefer to take the lead in trying to resolve any issuess for the sake of expediency and for the maximum benefit of our customers. At this point, most of our IRDT customers have already been contacted and notified of the situation. (You're the only one being affected that we are aware of.) SimJet Denmark is also "in-the-loop" with the situation.
As Todd correctly pointed out, Ch 40 is part of Futaba's "High Band", so the Rx you mentionned using must also have been tuned for the high band if you're to use it safely. (And get accurate results from any further testing.) If you can do this, however, you're in the clear as the modules for the 8U and 9C are identical, and we've had many folks use the IR Tx without incident on higher channel numbers in the low band and high band alike.
I did get some time in today with an EMI sniffer, but don't as of yet have anything useable to present. I'll post further information in this thread as it becomes available.
12-11-2003, 12:35 AM
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RE: IR Tx putting out lots of RF noise
Kevin, The second receiver I used was originally on ch32 and I changed it to 40 to do this test. So it would not be optimally tuned and would need to be sent in to be tuned to ch40. My only problem is that my 9C that is 17 is hosting 6 other receivers that are 17 and would be expensive to send them all in to change to ch40 and be retuned. I would hope we can find a solution to the IRDT.
What is a good material that I could use to choke EMI’s? A faraday cage seams to be a good answer to this problem. What kind of screen is a good choke to be used? I wanted to make an enclosure for the IRDT anyway.
What is a good material that I could use to choke EMI’s? A faraday cage seams to be a good answer to this problem. What kind of screen is a good choke to be used? I wanted to make an enclosure for the IRDT anyway.
12-11-2003, 09:11 AM
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RE: IR Tx putting out lots of RF noise
Dave,
I'm not suggesting that you switch all your Rx's to a new frequency. I agree that would be expensive. (And hopefully unnecessary.)
The measurements I've taken so far indicate that the emissions are primarily electric in nature. This is good as electric emissions are (relatively) easily shileded by a metal enclosure. For the purposes of testing, this can be as simple as properly connected tin foil. This is one of the many things I intend to try...
I'm not suggesting that you switch all your Rx's to a new frequency. I agree that would be expensive. (And hopefully unnecessary.)
The measurements I've taken so far indicate that the emissions are primarily electric in nature. This is good as electric emissions are (relatively) easily shileded by a metal enclosure. For the purposes of testing, this can be as simple as properly connected tin foil. This is one of the many things I intend to try...
12-11-2003, 09:28 AM
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RE: IR Tx putting out lots of RF noise
Kevin,
I got your message regarding this situation.Thank you.I had already decided not to install the IR Tx in my jet for other reasons.I will be happy for now using the cable link for my data terminal.Also,I am on channel 46,so I should be good if I change my mind.Thanks again though for promptly notifying me of the situation.Stay well!!
Erik[8D]
I got your message regarding this situation.Thank you.I had already decided not to install the IR Tx in my jet for other reasons.I will be happy for now using the cable link for my data terminal.Also,I am on channel 46,so I should be good if I change my mind.Thanks again though for promptly notifying me of the situation.Stay well!!
Erik[8D]
12-11-2003, 11:08 AM
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RE: IR Tx putting out lots of RF noise
Kevin, I am working on a Carbon Fiber box now to see it this will reduce emissions... I will let you know my progress... and if this does not work I will line it with graphite which is supposed to absorb emissions.
Dave
Dave
12-11-2003, 11:45 AM
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RE: IR Tx putting out lots of RF noise
Ok, I have done a test with with a through together box, and I got 120Ft just using a carbonfiber mesh laid in with Z resin and plywood sides. I bet if I do a complete cage with Carbon and graphite this will work.
Dave
Dave
12-11-2003, 08:45 PM
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RE: IR Tx putting out lots of RF noise
Kevin, Tomarrow I will do another test with the new encloser that I made, and I will let you know what my results are. Why does it seam like I get the attention of problems lately [sm=crying.gif] ?
Dave
Dave
12-12-2003, 08:19 AM
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Problem solved on my part
Kevin, after much research in EMI suppression, my last enclosure gives me 200 ft of range and I did not recharge the batteries on the transmitter or receiver since I last ran the jet at the field.
IMO Simjet should do some more testing on the ground for near by emissions at lower radio bands. Just because higher bands are not affected there might be the potential of in air failure to other near aircraft at lower bands. I don't know how strong the emission is due to not having an oscilloscope to measure the signal. But I highly recommend if you due install this on a higher band add an enclosure that absorbs EMI's before installing this in any aircraft. My rudimentary testing is not scientific, so those who read this don't use my methods, wait until Simjet comes up with there resolution that they stand behind.
Dave
IMO Simjet should do some more testing on the ground for near by emissions at lower radio bands. Just because higher bands are not affected there might be the potential of in air failure to other near aircraft at lower bands. I don't know how strong the emission is due to not having an oscilloscope to measure the signal. But I highly recommend if you due install this on a higher band add an enclosure that absorbs EMI's before installing this in any aircraft. My rudimentary testing is not scientific, so those who read this don't use my methods, wait until Simjet comes up with there resolution that they stand behind.
Dave