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Old 19-12-2013, 07:54   #76
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Re: LED Noise?

Looking at pictures of the optolamp it looks very much like there are a significant number of resistors on the LEDs.

I wonder if they have taken the approach of using a voltage regulator and resistors.
That provides an easier pass to low noise than a pwm current source - though with some efficiency loss.

Regardless of their approach it shows that it can be done and that the failure of the existing product is related to it's design not to the whole class of products.

I have a Lopo anchor and strobe and I cannot measure any radio interference from it.
The inverter is another matter!
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Old 24-12-2013, 06:13   #77
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Re: LED Noise?

I was going to change my anchor light out to LED while the mast was steped but my electrican advised aganist it stating just exactly this would happen if i did...I am going to keep it standard ....
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Old 24-12-2013, 10:55   #78
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Re: LED Noise?

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Originally Posted by Hank Kivett View Post
I was going to change my anchor light out to LED while the mast was steped but my electrican advised aganist it stating just exactly this would happen if i did...I am going to keep it standard ....
The Optolamp "Amazonia" tri/anchor/strobe has caused no interference to my VHF or SSB radios (I discussed my measurements a few posts previously). Apparently the Lopolight is also quiet. So not all LED lights will cause interference.

As for the Amazonia not being a switcher -- this may be true. The 150mA current is slightly higher than a switching LED replacement bulb I used to have in my previously-incandescent tricolor, and the Amazonia has a specified voltage range of 10.6 to 14.4V. A switcher would typically have a wider voltage range.
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Old 24-12-2013, 12:21   #79
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Re: LED Noise?

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Originally Posted by Paul Elliott View Post
The Optolamp "Amazonia" tri/anchor/strobe has caused no interference to my VHF or SSB radios (I discussed my measurements a few posts previously).
Paul, do you have a masthead AIS?

Before I rush out and get an opto and go to the (relatively significant) trouble of installing in on the masthead, I would like to know pretty much for sure when I turn it on, that AIS targets will not be disappearing. I have already installed/tried two led lights and am not eager to go to the work for a third failure.

Or are you 100% confident that your measurement excludes the possibility of any AIS target degredidation?

I would feel better if you measured one of the bad solutions and actually found something. That would show you are measuring the right thing.

The Lopos may or may not be "quiet" but their reliability sucks. No way in hell I am installing one of them at the masthead.
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Old 24-12-2013, 12:50   #80
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Re: LED Noise?

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Originally Posted by estarzinger View Post
Paul, do you have a masthead AIS?

Before I rush out and get an opto and go to the (relatively significant) trouble of installing in on the masthead, I would like to know pretty much for sure when I turn it on, that AIS targets will not be disappearing.

Or are you 100% confident that your measurement excludes the possibility of any AIS target degredidation?
100%? Of course not. To give you that I would want to use a calibrated antenna / preamp / etc, so I could compare the measurements to the receiver sensitivity. Even then, my personal analytic abilities break down when we have a potential EMI source only inches from the receiving antenna. I can do far-field calculations, but extremely near-field stuff is way over my head.

My testing was more of a "survey" than a measurement.

My VHF whip is at the masthead, within a foot of the tricolor. That's the antenna I connected to the spectrum analyzer. The analyzer noise floor is no doubt worse than the VHF radio, but I could see no LED emissions when I scanned the full VHF band (including the AIS channels). I only did one narrow-band measurement, right on top of Ch16, and again saw no noise. I've also done the unsquelched VHF noise check, and this tricolor has come up clean, at least on the handful of channels I checked.

My AIS antenna is on the upper spreader, so it isn't in a position for a good LED noise measurement.

If you like, I can re-run the test, but zoomed in on the AIS channels for better sensitivity.

The more I think about the Amazonia light, the more convinced I am that it uses a linear regulator. As "mub" mentioned, there seem to be quite a few resistors in the LED circuit. Also the current drain and voltage range suggest it's not a switcher.

If it's truly using a linear regulator, then I can comfortably say that there will be no AIS signal interference -- unless they did a crappy job on the regulator and it has parasitic oscillations. I've seen no evidence of this though.

Can you tell that I'm an engineer? After all that typing I still haven't given you a definite answer!
I would love to study it more closely, but it's on top of my mast...
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Old 24-12-2013, 13:07   #81
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Re: LED Noise?

Until some brand name products get an established reputation, it might be simplest to take any new LED masthead light, hook it up to a small "alarm" or "exit light" battery, or a roll of zip cord, and just hoist it up to the masthead to see if anything else gets upset, before even thinking about going aloft to install it.

Cheap kludge, but it should get fast answers.
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Old 24-12-2013, 13:12   #82
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Re: LED Noise?

I've been using the mast VHF ant to get Digial TV for some time & then replaced the anchor light with a nice bright LED. Killed off any TV RX 100%. So I deem the RFI to be a good level!!
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Old 24-12-2013, 13:33   #83
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Re: LED Noise?

Ok . . . Thanks to you both. I was wondering if I should get the opto given Paul's measurements . . . But I guess I will wait.

I don't know much about rf, but just have some skepticism about the noise analyzer measurements because two people on the thread have now done them and found zero noise. One of them testing a bulb very like one that I know for certain impacts the AIS. I would be more confident if we had tests that did identify the problems with some lights that we know actually do have problems and then found other lights with no problems.

The battery and hoist test is an idea . . . But one of the led MFG's told me they thought the fact the 12vt cable to the light was running 75' right along the AIS coax was a contributor to the problem (eg it was radiating the noise). So it is probably better to use test leads from the old fixture to power the new one, to replicate all potential problems.
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Old 24-12-2013, 17:46   #84
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Re: LED Noise?

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Originally Posted by estarzinger View Post
Ok . . . Thanks to you both. I was wondering if I should get the opto given Paul's measurements . . . But I guess I will wait.

I don't know much about rf, but just have some skepticism about the noise analyzer measurements because two people on the thread have now done them and found zero noise. One of them testing a bulb very like one that I know for certain impacts the AIS. I would be more confident if we had tests that did identify the problems with some lights that we know actually do have problems and then found other lights with no problems.

The battery and hoist test is an idea . . . But one of the led MFG's told me they thought the fact the 12vt cable to the light was running 75' right along the AIS coax was a contributor to the problem (eg it was radiating the noise). So it is probably better to use test leads from the old fixture to power the new one, to replicate all potential problems.
Yes - the tests by other boaters will have the problem that the yes/no result (for interference) was obtained using a particular type of (receiving) equipment. Different receivers will have all kinds of different (internal) intermediate frequencies of operation depending upon the design, and any of them might be an enabling point for interference. Any tests of specific LEDs using a particular receiving device, may not (necessarily) accurately test interference to any other (device). Complicated. So - the real win on this is to find a zero emitter that interferes with no devices, and for that the tests would have to be broad scope (spectrum analyzer, etc) - but including some fairly low frequencies that could interfere with intermediate receiver processing. It could be a matter of analyzer discrimination/resolution over a very wide range and complicated by the interpretation of all the odd junk that's in there. Just 2 cents ...
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Old 24-12-2013, 18:11   #85
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Re: LED Noise?

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Originally Posted by Sailor_Hutch View Post
Yes - the tests by other boaters will have the problem that the yes/no result (for interference) was obtained using a particular type of (receiving) equipment. Different receivers will have all kinds of different (internal) intermediate frequencies of operation depending upon the design, and any of them might be an enabling point for interference. Any tests of specific LEDs using a particular receiving device, may not (necessarily) accurately test interference to any other (device). Complicated. So - the real win on this is to find a zero emitter that interferes with no devices, and for that the tests would have to be broad scope (spectrum analyzer, etc) - but including some fairly low frequencies that could interfere with intermediate receiver processing. It could be a matter of analyzer discrimination/resolution over a very wide range and complicated by the interpretation of all the odd junk that's in there. Just 2 cents ...
You're right about this. Casual testing is just that, and if one person's VHF antenna is a few inches closer/farther/higher/lower, that person's "OK" is another's "Fail".

I used to do this kind of testing on electronics devices, for FCC Part 15 compliance (in this case the rules would be for Unintentional Radiators). We used tunable dipoles and broadband antennas for open-field testing (or sometimes shielded anechoic chamber testing) in the VHF and UHF range. Below 30 MHz we did line-conducted EMI measurements, probably more for convenience, although there are good technical reasons for it as well.

None of these tests and requirements are sufficient to guarantee non-interference when the receiving antenna is only a few inches from the EMI-generating device.

A good linear regulator should guarantee zero EMI. It is possible to design a switcher that won't interfere, but we need a much stiffer set of emissions requirements to guarantee this.
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Old 24-12-2013, 18:38   #86
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Re: LED Noise?

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Originally Posted by estarzinger View Post
Ok . . . Thanks to you both. I was wondering if I should get the opto given Paul's measurements . . . But I guess I will wait.

I don't know much about rf, but just have some skepticism about the noise analyzer measurements because two people on the thread have now done them and found zero noise. One of them testing a bulb very like one that I know for certain impacts the AIS. I would be more confident if we had tests that did identify the problems with some lights that we know actually do have problems and then found other lights with no problems.

The battery and hoist test is an idea . . . But one of the led MFG's told me they thought the fact the 12vt cable to the light was running 75' right along the AIS coax was a contributor to the problem (eg it was radiating the noise). So it is probably better to use test leads from the old fixture to power the new one, to replicate all potential problems.
Evans, who besides myself has done these noise analyzer measurements? (this thread or elsewhere?) I just scanned this thread from the beginning and didn't see anyone using test equipment, or describing a careful listening test.

I wish these lights weren't so expensive, or I would buy a sampling of them and do some real tests. Does anyone have one they would like to lend me for a couple of weeks?

As for 12V power cable running alongside the antenna coax cable, we might want to look into the coax shielding specs. Some coax has a very sparse shield, and is quite susceptible to this kind of noise pickup. Other coax has (for example) two shield braids plus a foil shield. Its more expensive and heavier, but pretty good when it comes to shield leakage.

The good thing about power cable emissions is that these are pretty effectively cured with ferrites.
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Old 24-12-2013, 19:01   #87
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Re: LED Noise?

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Evans, who besides myself has done these noise analyzer measurements? (this thread or elsewhere?)
somewhere on the led anchor light thread?
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Old 24-12-2013, 20:54   #88
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Re: LED Noise?

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somewhere on the led anchor light thread?
I searched that, and while there were some mentions of testing and "no noise detected", I can't tell how these test were done. Not to discount these tests (well I guess I am doing just that), unless we have more details I wouldn't use these to reach any conclusions about the validity of a properly-conducted test.

I have PM'd Neptune's Gear (Optolamp rep) with some technical questions to pass along. Perhaps we will get some useful answers.
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Old 26-12-2013, 21:11   #89
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Re: LED Noise?

OK guys, I aked Optolamp the question. Their response is (please accept that English is not their native language);

The OPTOLAMP signaling generates "0" RF Noise. It has a TDPS Systems (True Dual Power Supply), digitally controlled (depending on the function performed). This system has proved stable and robust under all conditions without any interference to boat systems. For this reason OPTOLAMP does not change the system. Are made continuously updates on the circuit components.
This TDPS system ensures reliable signaling: If a problem occurs there will always be light at the masthead.

Therefore I will guarantee the optolamp will NOT cause any issues with VHF or AIS. If you buy one from us, and there is an issue, we will replace it free of charge, or issue a refund... Is that enough confidence for you??

Matt
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Old 26-12-2013, 23:07   #90
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Re: LED Noise?

Thanks Matt,

As you have probably seen, I have PM'd you with a request for clarification (from Optolamp). Their answer is good, and yours is great, but there are to my mind unanswered questions. I think I know more or less what they are doing in general terms (and general terms are all I need to know, I'm not looking to reverse-engineer their product). But the phrase "TDPS Systems (True Dual Power Supply), digitally controlled" really doesn't tell me much.

Anyway, I really appreciate you doing this for us. As I mentioned in my PM, having a guaranteed zero-interference LED navlight should be a big selling point for Optolamp. They just need to give us enough information so we can trust their claims.

Oh, if it matters, here's a disclosure: I am helping the FrankenBebi project with their electronics design. But we all know that this project is not going to compete in any significant way with Optolamp and other Navlight manufacturers. FrankenBebi (and the original Bebi) have a "zero interference" design. I think interference is an important consideration for any navlight product.
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