LED Noise?

[rgleason]

Sure there are other links but here is one for optolite http://www.bluemarinestore.com/optol...nia-mirim.html
Thankyou for the technical review. ..don't mess with emi.
Paul you mention separate Ais (vhf) antenna on spreaders...is this the preferred way to do it? Will mast interfere in a sector? What about using the switching box and masthead...too much interferance? Also was thinking of mounting ais antenna on top of radar dome 12' up on backstay gimbal mount? ... any worse than the spreader? Thanks for the help with my tricolor led questions and ais.

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[Paul Elliott]

rgleason, I don't think there is a single "preferred" way to mount the AIS antenna. Generally, higher is better, although with a stern-rail mount you will still probably get reasonable AIS reception out to the horizon. This is adequate for collision-avoidance, although with the shorter range and weaker signal, it might take a while before the ship's name and callsign show up (these are only transmitted every six minutes).

With the spreader I do get better range, and I think my Class-B transponder is more likely to get picked up at a distance as well. There may be some interference from the mast and shroud, and I haven't done a careful 360-degree survey. However, the shroud, and even the mast, are pretty small in comparison to the wavelengths used for AIS. This means that a non-resonant small-diameter obstruction (such as the mast) will not have a big effect on the antenna pattern. It might slightly de-tune the antenna (but the SWR measurements were OK), and the pattern might be a bit distorted, but there should be no big dead zones.

I would not want to put the AIS and VHF antennas right next to each other. They will affect each other's radiation patterns, tuning, and possibly overload the AIS and VHF receivers. No doubt in many cases this arrangement will work well enough, but I prefer to keep these antennas apart. The upper spreader seemed to be a good compromise for me.

An above-the-radome location should be good too, as should be a stern-arch mount. Elevation is good, but even the stern-rail location is workable.

[hellosailor]

"TDPS Systems (True Dual Power Supply), digitally controlled"
Sounds like Coca-Cola's Secret Ingredient and McBurger's Secret King Sauce to me.

But hey, I'm still confused about why I can't make toast with a hairdryer, anyway.

[rgleason]

Paul Thanks. Waltz stern mount 12' with gimbal for radar would also gimbal vhf (any advantage?). If on spreader should antenna be at midpoint of spreader?

[Paul Elliott]

Originally Posted by rgleason

Paul Thanks. Waltz stern mount 12' with gimbal for radar would also gimbal vhf (any advantage?). If on spreader should antenna be at midpoint of spreader?

I would think that a gimbal mount would be good, since it should keep the antenna level too (make sure that the added weight doesn't upset the balance). You probably aren't going to use a high-gain narrow-pattern antenna for AIS, so normal heeling shouldn't make too much difference, but staying level can't hurt.

My AIS antenna is on the upper spreader, and it is mounted close enough to the mast so the antenna doesn't touch the shroud. It's about 2/3 of the way out. Your dimensions are probably different. A lower spreader wouldn't be a bad antenna location either, but you want to make sure that the mainsail won't be pressing on the antenna if you've got the sail laying against the spreaders on a run.

We should probably not monopolize this LED Noise thread with our antenna talk!

Speaking of which, I think the Optolamp lights should truly be noise-free, and my rough measurements support this, but I can't give Evans that 100% guarantee until we see something more specific from Optolamp.

I wonder who else makes a non-switching LED navlight? So far we know of Bebi, the FrankenBebi (available soon), and probably Optolamp. Any others?

The aluminum-cased LopoLights are switchers, but reportedly low-EMI. I have a Lopo bi-color on the bow of VALIS, and I will do a little RF sniffing soon.

I would love to see EMI reports for other LED navlights. Frequencies of interference (and non-interference) and light location relative to the antenna would be good to know.

[rgleason]

In thinking about tricolor/anchor light, is there any reason it could not be like tacktick instruments, solar powered with replaceable batteries for a week's worth of power, with bt or wifi control? Then no wires required.

[Paul Elliott]

Originally Posted by rgleason

In thinking about tricolor/anchor light, is there any reason it could not be like tacktick instruments, solar powered with replaceable batteries for a week's worth of power, with bt or wifi control? Then no wires required.

This is an interesting idea, so I did some math. I don't think this will work:

A modern high-efficiency LED anchor or tricolor light draws about 0.1A @ 12V.
To power this for 12 hours would require three high-capacity Lithium-ion AA batteries.
To recharge these batteries during the day would require a (roughly) 6" x 6" solar panel.
To make it through a few overcast days you would want to use more batteries (or one larger battery), and probably an 8" x 8" solar panel.

I haven't added in the power for the radio-control, but this should be pretty minor.

So, I think the battery and solar panel size would make it impractical for a mast-mounted device. Certainly not worse in size/weight than a radar, but still...

[rgleason]

Thanks Paul for taking it to the next step
This is one for next generation of solar PV 20% eff and more powerful batteries. Meanwhile the wires are pretty small.

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