FM Radio Cache Idea

[+Mr. Wilson & a Mt. Goat]

Reading the other thread about radio got me thinking.

There is a park near where I live and I had this idea: A mystery cache where you stand at the posted coords, take out a portable fm radio and tune in to a channel which has the coords to the final playing over and over.

I would transmit the coords from my house nearby using an FM transmitter.

 

Any ideas on how I could do this?

[+ZeLonewolf]

There is a cache quite near me that does this exact thing (I haven't found it yet, but it's high on my list!) and it's well regarded. I think generally you'll want to have some kind of access to a permanent power source in a building in a public area. The CO reads the forums, so he can probably give you some pointers. You'll obviously need to get explicit permission for this one unless your house abuts a public park or some such similar situation. Good luck!

Edited January 27, 2011 by ZeLonewolf

[+Mr. Wilson & a Mt. Goat]

There is a cache quite near me that does this exact thing (I haven't found it yet, but it's high on my list!) and it's well regarded. I think generally you'll want to have some kind of access to a permanent power source in a building in a public area. The CO reads the forums, so he can probably give you some pointers. You'll obviously need to get explicit permission for this one unless your house abuts a public park or some such similar situation. Good luck!

 

Luckily I do have somewhat close access to the park. 500ft to one access point, and 700ft to another. The other option would be to have the posted coordinates right in front of my house, but I don't think many cachers would like that.

[+TerraViators]

There was a similar cache in the Dallas area that was broadcast over AM. It's archived, now.

[+Mr. Wilson & a Mt. Goat]

Do you need a license to broadcast less then a 1/4 mile?

[+mpilchfamily]

Thats a great idea. You can probably find simple plans for an FM transmitter online. Problem is there are allot of regulations on the FM band. Mainly limitation in broadcast frequency and strength. Not that you'll want a strong signal anyway. Or you could go AM which is a bit more open.

 

How do you plan on transmitting the cords? Will it be a verbal recording playing over and over or something more devious like Morse code?

[+Mr. Wilson & a Mt. Goat]

Thats a great idea. You can probably find simple plans for an FM transmitter online. Problem is there are allot of regulations on the FM band. Mainly limitation in broadcast frequency and strength. Not that you'll want a strong signal anyway. Or you could go AM which is a bit more open.

 

How do you plan on transmitting the cords? Will it be a verbal recording playing over and over or something more devious like Morse code?

 

I was thinking a verbal recording, but Morse code sounds pretty "devious" as you said. It would also be much harder for muggles(who accidentally stumble on the frequency) to figure out.

I'm thinking AM because I found a transmitter that's about the right distance to broadcast where I want, and it's a decent price.

The problem is, I not sure how I would set it up... Then again, there are probably plenty of How-To websites out there with the right info.

[+mpilchfamily]

Take the transmitter. Connect it to the proper power source and connect the right Antenna to it. Then plug in your MP3 player, or whatever is going to play the recording, into the input and your good to go. You may need to set the frequency your transmitting on. Just make sure its not transmitting on top of another broadcast.

 

If your a DIY kind of a person then this sitelooks like a good resource for building your own and setting it up.

[+lamoracke]

there are a couple in Washington state that do that...one is a puzzle, one is a multi. Still, they are cool ideas.

[+BBWolf+3Pigs]

There is a cache quite near me that does this exact thing (I haven't found it yet, but it's high on my list!) and it's well regarded. I think generally you'll want to have some kind of access to a permanent power source in a building in a public area. The CO reads the forums, so he can probably give you some pointers. You'll obviously need to get explicit permission for this one unless your house abuts a public park or some such similar situation. Good luck!

 

Cache 9 From Outer Space is the cache ZeLoneWolf is referring to.

 

I use an FM transmitter with line-in input and a cheap MP3 player. Both have been configured to get power via AC/DC converters.

 

Be sure to read FCC regulations on use of low power FM transmitters. And be sure to set the transmitter at a frequency away from commercial stations.

[+Mom-n-Andy]

www.part15.us is a good site to help you understand the FCC regulations for unlicensed radio transmissions. The issue is the transmitter power output, not specifically the distance, but I think you will have problems finding a legal FM transmitter that will transmit 700 feet.

 

I have attempted something similar using the Canakit transmitter suggested by BBWolf and couldn't get it to work to my satisfaction. The two big problems I encountered were frequency drift and hum. To avoid frequency drift you need a phase-locked loop transmitter, and to avoid hum you need a transmitter with a really good power supply. My setup used the Canakit and a discarded iPod playing a message on loop. I built a capacitive filter circuit that reduced the hum quite a bit, but never got rid of it. And in several days of testing the frequency drifted onto licensed frequencies, which is not good. I know BBWolf has had very good luck with his Canakit, but I didn't, so YMMV. In any case you could certainly get one to prototype your cache and play with.

 

DO NOT waste your time and money on a "Talking House" transmitter. A caching friend used one and it requires almost daily maintenance to keep it running. I bought one too and had similar issues.

 

If the caching budget would cover it I would get the type of transmitter used with Christmas lights displays. One example would be the FM25B transmitter from ramseyelectronics.com. You do have to build this kit, but I think there are some electronics repair shops that sell assembled versions. I didn't do a thorough search for transmitters, but anything that the Christmas light aficionados have good luck with would work.

Edited January 27, 2011 by Mom-n-Andy

[+addisonbr]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobileblackbox.com/content/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

[+Team GPSaxophone]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobileblackbox.com/content/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

[+Ecylram]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobilebla...ent/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

 

This is a very interesting Multicache in Longmont, CO that takes this idea even further...GC2G604

[+addisonbr]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobileblackbox.com/content/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

I'm writing a puzzle with instructions that suggest a location and also "630 AM". I'm shooting to exploit the ambiguity between time of day and radio band. (It's not a puzzle that would be listed on this site, but after the event is over I would likely repurpose the equipment for a geocache rather than have it go to waste.)

[+Mom-n-Andy]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobileblackbox.com/content/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

 

I looked at both AM and FM and in my area the AM frequencies were clogged with radio preachers, conservative commentators and other obnoxious content. I could not find an open frequency. There is a great tool for finding an open FM frequency at http://www.radio-locator.com/cgi-bin/vacant You are still responsible for making sure your transmission doesn't step on any licensed transmissions so you need to listen at a frequency before transmitting on it.

Edited January 27, 2011 by Mom-n-Andy

[+Mom-n-Andy]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobileblackbox.com/content/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

I'm writing a puzzle with instructions that suggest a location and also "630 AM". I'm shooting to exploit the ambiguity between time of day and radio band. (It's not a puzzle that would be listed on this site, but after the event is over I would likely repurpose the equipment for a geocache rather than have it go to waste.)

 

I realized I did not answer your question. At a given power output AM signals can travel further than FM. AM transmission equipment is also cheaper. There are a few downsides of AM though, including the need for a much longer antenna.

[+GeoGeeBee]

I realized I did not answer your question. At a given power output AM signals can travel further than FM.

 

That's not true, at least not at FCC part 15 (no license required) power levels.

 

You might find my puzzle cache of interest: http://coord.info/GC28FRC

 

It uses an MP3 player connected to an FM Transmitter that I bought on eBay from a vendor in Hong Kong. Be careful, though... the transmitter I bought is barely legal in the US. If I connect a better antenna to it, it will broadcast at levels that make it illegal. They sell more powerful versions on eBay, too. All of them are illegal in the US, unless you have a broadcast license. But a lot of people use them for things like musical Christmas light displays with no problem.

[+Mom-n-Andy]

I realized I did not answer your question. At a given power output AM signals can travel further than FM.

 

That's not true, at least not at FCC part 15 (no license required) power levels.

 

You might find my puzzle cache of interest: http://coord.info/GC28FRC

 

It uses an MP3 player connected to an FM Transmitter that I bought on eBay from a vendor in Hong Kong. Be careful, though... the transmitter I bought is barely legal in the US. If I connect a better antenna to it, it will broadcast at levels that make it illegal. They sell more powerful versions on eBay, too. All of them are illegal in the US, unless you have a broadcast license. But a lot of people use them for things like musical Christmas light displays with no problem.

 

Thanks for the clarification. AM radio waves can travel great distances under some circumstances. I remember as a child being fascinated by AM radio broadcasts from Chicago and New York (we lived in Podunk, Tennessee.) But this does not make unlicensed transmission legal as you pointed out.

[+Chrysalides]

I realized I did not answer your question. At a given power output AM signals can travel further than FM. AM transmission equipment is also cheaper. There are a few downsides of AM though, including the need for a much longer antenna.

Do also consider that AM receivers are not included with most cell phones and MP3 players.

 

To reduce equipment needed, I thought of having a microcontroller transmitting morse code over radio. Found a circuit, but lots of DIY and customization needed to use this design. http://www.jbgizmo.com/page30.htm

[+GeoGeeBee]

I realized I did not answer your question. At a given power output AM signals can travel further than FM. AM transmission equipment is also cheaper. There are a few downsides of AM though, including the need for a much longer antenna.

Do also consider that AM receivers are not included with most cell phones and MP3 players.

 

To reduce equipment needed, I thought of having a microcontroller transmitting morse code over radio. Found a circuit, but lots of DIY and customization needed to use this design. http://www.jbgizmo.com/page30.htm

 

You're thinking too hard.

 

Download a free morse code training program. There are dozens of them. You want one that will let you type in a message, and it will play that message in morse code.

 

Record the sound and save it in an MP3 file. Load that MP3 file onto the cheapest old MP3 player you can find. Connect the output from that MP3 player to the input on your radio.

 

Much easier than building and customizing electronic circuits.

[+Chrysalides]

You're thinking too hard.

 

Download a free morse code training program. There are dozens of them. You want one that will let you type in a message, and it will play that message in morse code.

 

Record the sound and save it in an MP3 file. Load that MP3 file onto the cheapest old MP3 player you can find. Connect the output from that MP3 player to the input on your radio.

 

Much easier than building and customizing electronic circuits.

True, using off the shelf components is easier. But it seems so... inelegant.

 

Of course, I do have some electronics building experience, a PIC programmer, a little experience programming microcontrollers, and work as a software engineer, so I'm a little biased here But even then, I admit it is heck of a lot more work than the setup you have, and probably ends up being more expensive too.

 

Just curious, in what kind of environment is your setup kept, and how often do you need to maintain it?

[+BBWolf+3Pigs]

You're thinking too hard.

 

Download a free morse code training program. There are dozens of them. You want one that will let you type in a message, and it will play that message in morse code.

 

Record the sound and save it in an MP3 file. Load that MP3 file onto the cheapest old MP3 player you can find. Connect the output from that MP3 player to the input on your radio.

 

Much easier than building and customizing electronic circuits.

True, using off the shelf components is easier. But it seems so... inelegant.

 

Of course, I do have some electronics building experience, a PIC programmer, a little experience programming microcontrollers, and work as a software engineer, so I'm a little biased here But even then, I admit it is heck of a lot more work than the setup you have, and probably ends up being more expensive too.

 

Just curious, in what kind of environment is your setup kept, and how often do you need to maintain it?

 

I subscribe to the KISS principle.

 

The only issue I have had with my cache (which has been active for over 2.5 years) is that I have to occasionally get my friend to restart the MP3 player. Any sort of electrical noise and they lose power to the building. This of course shuts of the MP3 player (which I have wired to an AC/DC converter). I am thinking about buying an inexpensive UPS to solve that issue.

[+GeoGeeBee]

Just curious, in what kind of environment is your setup kept, and how often do you need to maintain it?

 

It sits on top of the file cabinet in the spare bedroom/home office. The only maintenance it's needed is to restart the MP3 player after a power failure. Every now and then I put my car radio on that frequency as I'm pulling in to the driveway, just to make sure it's still on.

[+Mom-n-Andy]

I seem to recall reading that you are not permitted to transmit Morse code continuously under part 15. I could be mistaken though, does anyone know for sure?

[+GeoGeeBee]

I seem to recall reading that you are not permitted to transmit Morse code continuously under part 15. I could be mistaken though, does anyone know for sure?

 

I don't think Part 15 says anything about content. There are prohibitions on continuous operation in certain frequency bands, but they do not apply in the FM broadcast band.

 

My puzzle cache has a female voice sending an encrypted message as five-digit groups, in Spanish. I thought that might be disturbing to someone who came across it by accident, so every 10 minutes it also has a message, in English, explaining that it is a puzzle that is part of a game played on geocaching.com. The message also gives my phone number and says that if the transmitter is causing interference of any kind, please give me a call.

 

That's probably not needed if operating within the Part 15 limits, but it sure can't hurt.

[+TAZ427]

Ok, I'm reviving this thread from the dead as after searching I can't seem to find the answer.

 

Does anyone know about what kind of distance one would expect from one of the cheap FM Transmitters intended for Smartphones/MP3 players for the car? I'm wanting to make a cache w/ an audio broadcast to decode, but I want to keep the FM transmitter in my house, we're talking 30' to the street.

 

I can build an FM transmitter if I want, but if I can go simply on this side w/ a USB charger plugged into it and (and into an old MP3 player I have) this would make for a quick easy implementation.

[+CanadianRockies]

Ok, I'm reviving this thread from the dead as after searching I can't seem to find the answer.

 

Does anyone know about what kind of distance one would expect from one of the cheap FM Transmitters intended for Smartphones/MP3 players for the car? I'm wanting to make a cache w/ an audio broadcast to decode, but I want to keep the FM transmitter in my house, we're talking 30' to the street.

 

I can build an FM transmitter if I want, but if I can go simply on this side w/ a USB charger plugged into it and (and into an old MP3 player I have) this would make for a quick easy implementation.

Here's one that transmits up to 150 feet, but it costs $125. This one costs $50 but only transmits 45 feet. I'm sure there are others out there as well.

[+CanadianRockies]

By the way, I once found a fun, two-stage puzzle cache that loop broadcasts a song over FM near someone's house. The song is interrupted every few seconds and a single digit is announced. By the end of the song, you have the final coordinates. Also at the end of the song is an Altoids commercial, so you also have a hint for the final container.

Edited January 23, 2014 by CanadianRockies

[Mr.Yuck]

Ok, I'm reviving this thread from the dead as after searching I can't seem to find the answer.

 

Does anyone know about what kind of distance one would expect from one of the cheap FM Transmitters intended for Smartphones/MP3 players for the car? I'm wanting to make a cache w/ an audio broadcast to decode, but I want to keep the FM transmitter in my house, we're talking 30' to the street.

 

I can build an FM transmitter if I want, but if I can go simply on this side w/ a USB charger plugged into it and (and into an old MP3 player I have) this would make for a quick easy implementation.

 

I guess you would have to name the particular "cheap" one you have or are looking at. I'm going to doubt it's even good for the 30 feet though. You said you'd build your own if need be? I found a 150 foot one from a kit for $29.95. Beats the heck out of the $125 Canadian Rockies quoted, even with a little project box thrown in.

[+BBWolf+3Pigs]

I use this one from Canakit. $22 assembled.

 

Has a line-in and is battery powered (although I converted mine to use a wall-wart AC/DC adapter - email me for details).

 

Range is about 100-200'.

[+TAZ427]

I've seen some higher end ones w/ 0.5W power for $50-60 (on sale)but was really trying to keep it below $20, I may just go with the Canakit (self assemble $17 and I'd toss an AC/DC adapter on there but no need for details.)

 

Looks like it has a trim pot on it to adjust the frequency, how sensitive is it, and do you know if it drifts with temp thus channel drifting?

[+Viajero Perdido]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

Nowadays, I suspect more people have portable hardware that can get WiFi than AM or FM. (EDIT: Well, unless you can drive a car close enough.) Anyway, just a thought...

Edited January 23, 2014 by Viajero Perdido

[+Manville Possum]

Ok, I'm reviving this thread from the dead as after searching I can't seem to find the answer.

 

Does anyone know about what kind of distance one would expect from one of the cheap FM Transmitters intended for Smartphones/MP3 players for the car? I'm wanting to make a cache w/ an audio broadcast to decode, but I want to keep the FM transmitter in my house, we're talking 30' to the street.

 

I can build an FM transmitter if I want, but if I can go simply on this side w/ a USB charger plugged into it and (and into an old MP3 player I have) this would make for a quick easy implementation.

 

I guess you would have to name the particular "cheap" one you have or are looking at. I'm going to doubt it's even good for the 30 feet though. You said you'd build your own if need be? I found a 150 foot one from a kit for $29.95. Beats the heck out of the $125 Canadian Rockies quoted, even with a little project box thrown in.

MP3 is even a cache type on one of the alternative geocaching sites is it not?

[+BBWolf+3Pigs]

I've seen some higher end ones w/ 0.5W power for $50-60 (on sale)but was really trying to keep it below $20, I may just go with the Canakit (self assemble $17 and I'd toss an AC/DC adapter on there but no need for details.)

 

Looks like it has a trim pot on it to adjust the frequency, how sensitive is it, and do you know if it drifts with temp thus channel drifting?

 

You are correct. I had to tweak it (barely) once in the few years I have had it running. It is in a parks building that is not climate controlled - so cold in the winter and hot in the summer. There's a little bit of rubber band in the pot to keep things from wiggling around.

[+TAZ427]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

Nowadays, I suspect more people have portable hardware that can get WiFi than AM or FM. (EDIT: Well, unless you can drive a car close enough.) Anyway, just a thought...

 

That's an interesting idea. I've got an old AP that's not in use (had it setup as a gateway to network a remote printer which has since been replaced by a WiFi capable printer.) I could set it up so that you should be able to see it at the street in front of the house. If not, I'll grab my old WRT54G which I know you could see out at the street. And most people can use a WiFi Analyser App on their smartphones to pick up the SSID. I could do a couple of caches requiring them to go by the house.

 

Maybe one day I'll even setup it up w/ a server and make people solve a puzzle on it or something like that.

 

I've seen some higher end ones w/ 0.5W power for $50-60 (on sale)but was really trying to keep it below $20, I may just go with the Canakit (self assemble $17 and I'd toss an AC/DC adapter on there but no need for details.)

 

Looks like it has a trim pot on it to adjust the frequency, how sensitive is it, and do you know if it drifts with temp thus channel drifting?

 

You are correct. I had to tweak it (barely) once in the few years I have had it running. It is in a parks building that is not climate controlled - so cold in the winter and hot in the summer. There's a little bit of rubber band in the pot to keep things from wiggling around.

 

Thanks, this will be indoor, but I use a programmable thermostat so when I'm not there it could be between 60-90deg.

[+J Grouchy]

4...8...15...16...23...42...

[+T.D.M.22]

With the WiFi idea, I could put the co-ords, or a hint to the cache location in the WiFi name. I know how to do that-but how? Could I take a wireless router and plug it in? Would that still broadcast the signal(and therefore name) without being connected to the internet?

 

 

4...8...15...16...23...42...

 

Makes you wonder if any of those are co-ords to a geocache.

[+NYPaddleCacher]

With the WiFi idea, I could put the co-ords, or a hint to the cache location in the WiFi name. I know how to do that-but how? Could I take a wireless router and plug it in? Would that still broadcast the signal(and therefore name) without being connected to the internet?

 

 

Yes, a router will broadcast it's SSID without an internet connection. I've got a couple of old wifi routers that I've replaced (and need to replace the one I have now) but the problem with them is that they would stop broadcasting the SSID or some other problem on the wifi side of the router.

 

 

4...8...15...16...23...42...

 

Makes you wonder if any of those are co-ords to a geocache.

 

Here is the closest cache (in Quebec, Canada) to N 48 15.1 W 62 34.2

GC1373V

 

 

 

[+wmpastor]

In looking into something along these lines over the past few months, I've found a number of reasonable options for consumer-grade FM transmitters (like this one http://www.mobilebla...ent/view/40/75/ )- but very little for AM. Does anyone know if there is a good / similar solution for an AM transmitter?

Just curious, why would you want to use AM?

 

This is a very interesting Multicache in Longmont, CO that takes this idea even further...GC2G604

Fascinating! The cache has 10 finds and 9 favorites.

[+Viajero Perdido]

they would stop broadcasting the SSID or some other problem

Funny you should mention, that's what happened (failed to happen?) when I visited the one WiFi cache I'd encountered.

 

I believe the SSID was something like "N12.345 W67.890", something obvious to a cacher. No need to connect, and almost certainly no internet access even if you did.

 

Although a tinkerer with time on their hands could create something "interesting" for them to connect to... A puzzle on a private intranet, say.

[7rxc]

Since this is an international forum...

 

I'll add a caution. While such things are subject to US FCC rules for sure, IN THE USA, the rest of the world has their own rules. Low power transmitters are legal in Canada under Industry Canada rules. As for the rest of the world, make sure you follow your own radio regulations. Some countries are quite strict. And they change.

 

Using one of those 'player device' to FM wireless connections might do the job. A friend has one he uses to redirect from his vehicle sat radio receiver to a portable stereo receiver indoors or wherever.

 

Don't ask me the Canadian rules, but they are probably close to the Part 15 FCC rules with mods.

 

Doug 7rxc

[+BBWolf+3Pigs]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

Nowadays, I suspect more people have portable hardware that can get WiFi than AM or FM. (EDIT: Well, unless you can drive a car close enough.) Anyway, just a thought...

 

That's an interesting idea. I've got an old AP that's not in use (had it setup as a gateway to network a remote printer which has since been replaced by a WiFi capable printer.) I could set it up so that you should be able to see it at the street in front of the house. If not, I'll grab my old WRT54G which I know you could see out at the street. And most people can use a WiFi Analyser App on their smartphones to pick up the SSID. I could do a couple of caches requiring them to go by the house.

 

Maybe one day I'll even setup it up w/ a server and make people solve a puzzle on it or something like that.

 

I've seen some higher end ones w/ 0.5W power for $50-60 (on sale)but was really trying to keep it below $20, I may just go with the Canakit (self assemble $17 and I'd toss an AC/DC adapter on there but no need for details.)

 

Looks like it has a trim pot on it to adjust the frequency, how sensitive is it, and do you know if it drifts with temp thus channel drifting?

 

You are correct. I had to tweak it (barely) once in the few years I have had it running. It is in a parks building that is not climate controlled - so cold in the winter and hot in the summer. There's a little bit of rubber band in the pot to keep things from wiggling around.

 

Thanks, this will be indoor, but I use a programmable thermostat so when I'm not there it could be between 60-90deg.

 

I am sure the building mine is in gets colder than that!

[+J Grouchy]

With the WiFi idea, I could put the co-ords, or a hint to the cache location in the WiFi name. I know how to do that-but how? Could I take a wireless router and plug it in? Would that still broadcast the signal(and therefore name) without being connected to the internet?

 

 

Yes, a router will broadcast it's SSID without an internet connection. I've got a couple of old wifi routers that I've replaced (and need to replace the one I have now) but the problem with them is that they would stop broadcasting the SSID or some other problem on the wifi side of the router.

 

 

4...8...15...16...23...42...

 

Makes you wonder if any of those are co-ords to a geocache.

 

Here is the closest cache (in Quebec, Canada) to N 48 15.1 W 62 34.2

GC1373V

 

Nah...I think it's supposed to be on an island somewhere, but it's pretty tough to find and even more difficult to leave.

[+secondgunman]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

Nowadays, I suspect more people have portable hardware that can get WiFi than AM or FM. (EDIT: Well, unless you can drive a car close enough.) Anyway, just a thought...

 

I used to have a cache exactly like that. GC35PVY was a WRT54G router in my office with the SSID set to broadcast the coordinates to the final. The building I was in also housed the university's Greek offices, hence the reference to spray-tanned sorority girls. Unfortunately, I was moved to a different office on campus and my new office is too close to an existing cache to keep it alive.

[+GopherGreg]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

 

This one was pretty cool. The posted coords bring you to the front of the cacher's house. The description says you need a handheld device, with internet capability. You need to get into the geocacher's WIFI, but I know cachers in my area who read these so I won't say what next.

 

There's probably some logs that give it away though. (GC3YVG4)

 

Your idea with radios, and such sounds interesting though. I'd like to find a cache like that.

 

Greg

[+NYPaddleCacher]

Or, you could set up a WiFi access point - not connected to anything - with an interesting SSID being broadcast. I know of a cache done that way.

 

Nowadays, I suspect more people have portable hardware that can get WiFi than AM or FM. (EDIT: Well, unless you can drive a car close enough.) Anyway, just a thought...

 

I used to have a cache exactly like that. GC35PVY was a WRT54G router in my office with the SSID set to broadcast the coordinates to the final. The building I was in also housed the university's Greek offices, hence the reference to spray-tanned sorority girls. Unfortunately, I was moved to a different office on campus and my new office is too close to an existing cache to keep it alive.

 

My office is on the second floor overlooking a small courtyard. I've thought about creating a multi with a stage that had coordinates in the middle of the courtyard. I could write down the coordinates for the next stage and put them in my window. It would be a good spot to do a wifi router cache because if you were standing in that courtyard you'd see multiple wifi ssids broadcasting.

 

I was staying in a apartment in a 15 story building in Manhattan a couple of weeks ago and when I connected to the wifi there were probably 20 different wifi points that showed up. Doing a wifi router multi in a spot like that could be pretty interesting as you'd have to pick out the right router.

[+Viajero Perdido]

In a crowded area full of WiFi access points, you'd want to be really careful about choosing a channel that doesn't conflict with the neighbors. If you're using it just for geo-purposes you might never even notice the collision, but the neighbors sure would.

 

I live near some highrise apartments, and the airwaves are packed; often I have to change channels on my own network because somebody new came along. In this kind of setting I wouldn't even attempt adding a new signal to the noise for this one single purpose - unless I simply renamed my own access point. Strong password of course.

[+JohnnyVegas]

Do you need a license to broadcast less then a 1/4 mile?

that depends on the frequency. You can not interfere with a broadcast station (there are low powered FM stations but they are licensed by the FCC) and you can not use the public service portion of the radio spectrum or the business portion. I have heard of cachers that have used and FRS radio but I am not sure how they set this up. FRS radio are cheap. The oter option is to use a Ham radio beacon transmitter but you would need to get a ham radio license which requires a very simple teat. Hams have been doing fox hunts, this is a low powered transmitter that send out a signal but the people looking for the cache with need a radio that can receive the signal.

[Mr.Yuck]

Do you need a license to broadcast less then a 1/4 mile?

that depends on the frequency. You can not interfere with a broadcast station (there are low powered FM stations but they are licensed by the FCC) and you can not use the public service portion of the radio spectrum or the business portion. I have heard of cachers that have used and FRS radio but I am not sure how they set this up. FRS radio are cheap. The oter option is to use a Ham radio beacon transmitter but you would need to get a ham radio license which requires a very simple teat. Hams have been doing fox hunts, this is a low powered transmitter that send out a signal but the people looking for the cache with need a radio that can receive the signal.

 

Now I was a novice only ham in like 1977, but don't hams still have to know ohms law and basic electronics for the test? I'm sure most people out there wouldn't consider that a "very simple" test.

 

Oh, by the way:

 

Ok, I'm reviving this thread from the dead as after searching I can't seem to find the answer.

 

Does anyone know about what kind of distance one would expect from one of the cheap FM Transmitters intended for Smartphones/MP3 players for the car? I'm wanting to make a cache w/ an audio broadcast to decode, but I want to keep the FM transmitter in my house, we're talking 30' to the street.

 

I didn't really know what the thread bumper was talking about the other day, but I was killing some time at Pep Boys today getting a tire repaired, and I saw one of these "cheap FM Transmitters intended for Smartphones/MP3 players for the car". There were no specs on the box, but I'd doubt you'll get even 15 feet out of those. I am however, going to buy one, I just didn't do it today.