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mrfliboy

Lost Model Locator Ideas

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Thought I'd try something a little different and cheap. While browsing good old ebay I ran across luggage locator for pratically nothing:

http://cgi.ebay.com/Wireless-Remote-Lost-Luggage-Car-Key-Bag-Locator-Finder-/110578798052?pt=LH_DefaultDomain_0&hash=item19bf028de4

Upon receiving it, stock form yielded 100' range with a little directional control. Upon opening it up, I find it transmits on 315mhz, the tx comes with a 12v battery, but operates on a single cell lipo, the Rx has a 1.2v battery but also operates on a single cell lipo.

After opening everything up, soldering on lipo connectors, extending the coiled antennas, I was able to get over 250yds w/lipo and 350yds with 3s lipo in my neighborhood, thru some houses and windows. Now pointing antenna seems to help a little but not a whole lot.

I'm thinking there is some way to use this for plane locator when the general lost area is known. The questions being how?? Neither pull very little power when dormant. The Rx has a bright blue led and a buzzer (pulsing) that can be heard for maybe 100yds or so.

First idea is to have Rx in plane with buzzer and Led in a decent location on the plane. Plane gets lost, activate Tx and hope to hear or see plane led.

Second would be to have Tx in plane, with single lipo, plane gets lost and use some sort of signal indicator to find plane. Two way radio or something

Is it the tx thats sending a pulsing signal or the rx decodes the signal and pulses the led?

Thanks as always for any and all help. And i know of existing locators available. Just like to tinker.

Pic is my FPV easy star 70' up a big old oak. I knew the general location of the crash, but still took 2 hrs to find.

post-5645-079097700 1287846772_thumb.jpg

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mrfliboy

Mmmmmm …. that’s not a bad idea. I tried to chase this product up on the FCC website, and I couldn’t find the exact same product, but I did find a very similar product – bearing an almost identical brand name ("Luggage Locator" - but not including the "Pro" word) using identical type-face, and bearing an identical trade mark (a solid colored central dot surrounded by 3 concentric circles). The molded plastic packaging of the "Luggage Locator" on the FCC website is different – so what do we have(?) - a knock off, or an updated version of the same product in revised packaging?

My guess: the FCC listed product is little more than an updated version of the product you found on eBay. Anyhow, that’s all by and by. The reason why I chased this up on the FCC website was to read the approval report submitted to the FCC to get some insight on the tech detail about the product.

Why?

Well, I think your idea has potential, but, as you rightly note, the output power strangles practical/usable operational radius – it ain’t very practical for RC model use. However, if there is nothing sophisticated about the rf output the Tx sends to the Rx to “activate”, then extending operational range may require no more than, for example having to key the PTT button on a commercial 315Mhz radio transmitter, or, adding a low/medium power amp to the Tx ouput – both cheap, uncomplicated “upgrade” options which could turn the luggage locater into a real world usable product. Why I use the PTT/mike switch as an example is because, whatever has to be done, you want it to be simple, cheap and easily used or adapted to use. I think a large part to these exercises is that they should "practical".

Anyhow, back to the FCC report. The report provides the following detail (amongst other info):

1) The primary freq (as you have already noted) is 315 Mhz – for which average tested Tx power is 66.63dBuV (-40dBm), or 0.0001milliwatts – not much output power, hence that +/-250 - 350yards radius you are getting. Not very practical for a lost model. The Peak Tx power ain’t much better: 78.81dBuV (-28dBm), or 0.0016milliwatts! (should be noted that the above figures are given for a vertically polarized antenna through coax running at 2.15dB.).

2) there are loads of harmonics all the way through to around 3,5Ghz.

…… and there are a whole bunch of additional spec’s - all viewable in the main PDF report on:

https://fjallfoss.fcc.gov/eas/GetApplicationAttachment.html?id=937782

Photos and other related detail about the luggage locator can be accessed through the links from this FCC page:

https://fjallfoss.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=432988&fcc_id=%27V8TLL-000%27

The whole point behind looking at this page, as already said, was to establish whether or not this luggage locator was a viable platform to use in the way you have suggested.

In it’s “out-the-box” config, nope, not very practical, but I can’t see anything in the report that suggests that you’d need anything more sophisticated than a clean low/medium power rf amp to boost the Tx signal to whatever level you feel appropriate (within reason!).

RF Amplifiers (www.rfamplifiers.com) have probably the largest range of commercial-off-the-shelf rf amp products – you can source a decent low/medium power VHF/UHF amp from them for well under $100 (around 1watt – 2watts?). Now you have something with real usuable radius/coverage – could be used now to activate the receiver to switch on, say, a strobe-light(?): the model will stick out like a sore thumb - could save a good few hours of having to wonder around rural fields looking for a downed model at night (or day time).

Note - The note earlier regards the antenna is provided for good reason: a major influence on test figure accuracy comes down to antenna setup/type/choice/config etc etc .... and no less so when put to use on a DIY project- on both ther Rx & Tx side - antenna setup will have a big impact on how well this project actually works in real world conditions, especially as one has little control on how a "downed" model orientates its self in a crash.

Anyhow, mrfliboy - what's your take on what I have suggested here?

Edited by Helix1

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Why not use a common R/C lost model alarm that beeps when the R/C link is lost or has been idle for several minutes? There are several on the market to choose from and cost is quite low. Or, if you like to tinker, the rc-cam LOMA project can be built.

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Why not use a common R/C lost model alarm that beeps when the R/C link is lost or has been idle for several minutes? There are several on the market to choose from and cost is quite low. Or, if you like to tinker, the rc-cam LOMA project can be built.

None - I see no reason at all why the products you have suggested can not or should be used. I haven't looked in any detail at either of those products, so they could be better suited. Been designed for RC model plane use (specificaly?), chances are theres' a bunch of reasons which would make them preferable options. Fair comment. Secondly, and I can't speak for mrfliboy either, but from my perspective the comments shared were not in any way mean't to suggest or reccomend one product over another - only to share with the OP some ideas regards the product he had and was asking about

Edited by Helix1

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Helix1 and Mr Rc Cam, thanks for the replies.

Mr RcCam I have looked at your LOMA but do not have the programmer. Even though I have dabbled in AVR programming.

http://www.rcgroups.com/forums/showthread.php?t=645228

Commercial LOMA are only a few blocks from my residence. RAM Products is in a neighboring town and the owner is a member of our flying club.

My thoughts were to end up with something as simple as FMKits great RF Beacon.

Basically picking up a $5 ebay (for example having to key the PTT button on a commercial 315Mhz radio transmitter) quote from Helix1 radio/walkie talkie and locating the plane from the signal strength.

I'm not sure how long these luggage locators have even been around but thought they'd be a good project, or at least I'll be able to find the TV Remote now. LOL

After my success (following others leads) with my wireless FPV home simulator :

http://www.rcgroups.com/forums/showpost.php?p=15310636&postcount=1609

I needed another electronic tinkering project be it flop or useable. Thought maybe I was on to something.

Helix1 I'm still digesting all you wrote and will be looking into it more Thanks

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