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Mystery Cache

Captain Crunch

A cache by LinuxOnTheBrain Send Message to Owner Message this owner
Hidden : 7/2/2008
4 out of 5
1.5 out of 5

Size: Size: regular (regular)

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Geocache Description:

Captain Crunch Geocache

[   by LinuxOnTheBrain   ]

!! Notice - Please Read First !!
!! This is an electronic geocache with an audio-triggered lock!!
!! An audio tone of a specific frequency is required to open !!

!! Do not attempt the cache at the coordinates listed. They are encoded below !!

    This is an electronic geocache with an audio-triggered lock inspired by John Draper, a.k.a. 'Captain Crunch'. In the early 1970's John and his phone phreaker friends discovered that a toy whistle being included in boxes of Cap'n Crunch® cereal played a tone which could be used to control the (now retired) in-band signaling long distance telephone network. The phone companies used this tone to control long distance line connections, when played it would disconnect one end of the call leaving the remaining caller in Operator Mode. John and his friends quickly realized that Operator Mode = Free Phone Calls and the rest is telecom history.
    This is a 2-stage multicache. Please read to the end before proceeding. **All coordinates used are in standard GPS format.** Both cache stages are placed on private property with the approval of the landowners, one is a residence the other is a business. Please respect private property and only hunt these caches between 6:00am and 10:00pm. Finding this cache requires a bit of technical aptitude and skill with Google. It was designed by a linux geek, about a phone geek, for geo-geeks. If you're able to locate this cache you might be a geo-geek too. Enjoy!

    Stage1 is a magnetic mini-altoids can, the coordinates to which have been encoded as DTMF telephone tones in .wav format audio files.
Alert: You are about to download files in order to obtain further details needed to find this geocache. As the cache owner, I represent that these files are safe to download although the files needed to complete this geocache have not been checked by Groundspeak or by the Geocache Reviewer for possible malicious content. As a result, you are downloading these files at your own risk.
The coordinates are: N latitude, W longitude (pound sign # replaces degrees symbol, asterisk * replaces decimal point). Find a way to detect and decode DTMF tones to locate stage1. You can check your results using Geochecker.
    Inside stage1 are the coordinates to stage2 encoded using a DTMF key-frequency-sum table (see below). DTMF is short for 'dual-tone multi-frequency' meaning every key on the telephone keypad consists of two different frequencies played simultaneously, an upper-band and lower-band frequency. The table is created by adding the upper & lower band frequencies together for each key and it works like a secret decoder ring. 
DTMF Key-Frequency-Sum Encoder/Decoder Upper Band Frequencies
1209Hz 1336Hz 1477Hz
Lower Band Frequencies 697Hz 1<=>1906 2<=>2033 3<=>2174
770Hz 4<=>1979 5<=>2106 6<=>2247
852Hz 7<=>2061 8<=>2188 9<=>2329
941Hz *<=>2150 0<=>2277 #<=>2418
When encoded using this table, 'N 42° 31.083' looks like 'N |1979|2033|2418|2174|1906|2150|2277|2188|2174|'. (pound sign # replaces degrees symbol, asterisk * replaces decimal point). Print or copy the table above (pdf) and bring it along to stage1 to decode the coordinates to stage2.
    Stage2 looks like a common outdoor wildlife enclosure. It's placed in an open grassy area behind a local business about 1200ft. from stage1. Entrance from the north is easiest. To open this electronic geocache, figure out the frequency of the (in)famous Cap'n Crunch® toy whistle and add 1000Hz, then create & record a sample of that tone (whistle_frequency+1000Hz sine waveform) and bring it along to the stage2 cache. Once there, find the 'key' located on the cache itself and insert the key into the keyhole & hold to power up the device. Then listen very closely and play the pre-recorded tone when prompted to open the lock.
    ** Note: when the key is removed from its holding place a small light should be visible. This is a battery indicator light and it must be present to operate the cache. If no light is seen after removing the key, either the batteries are toast or what was removed wasn't the key.
Q: What can I use to create the tone?
A: There are a number of software programs that will do the job. Audacity is an open source (free) sound editor for Linux, MAC & Windows that includes a tone generator. Linux users with ALSA installed can use the 'speaker-test' program. Or try a Google search like 'free tone generator'.
Q: What can I use to record and play back the tone?
A: Anything that can play the tone 'out loud' is fine. Some examples include personal tape recorders, digital voice recorders, mp3 players with speakers, a cell phone with speakerphone & the tone recorded to voice mail. You could even 'phone a friend' to have them create & play the tone for you.

    The contents of the cache include a log book, a small/medium-size jar for trading goodies and a camera to capture the smiles of successful geocachers. Please don't 'tinker' with the cache inner-workings and be careful to repack the cache properly or the contents may interfere with its operation. When leaving the cache be sure to close the door with a good push (listen for a -clack- sound) and return the key to its holding place which will turn off the light.
    For the FTF there's a SanDisk Cruzer Micro 1G USB 2.0 flash drive loaded with bootable Ubuntu Linux 8.04 Desktop Edition (FREE as in Freedom).

    ** Most of the materials used to build this unit were recycled from something else, or I fashioned them myself from scraps. (To be earth-friendly of course). I hope this inspires others to build electronic geocaches since disposable electronics are everywhere and can be easily reused.

Additional Hints (Decrypt)

Fgntr1 Uvagf:
D: Ubj qb V qrpbqr gur QGZS pbbeqvangrf gb fgntr1?
N: Gel n Tbbtyr frnepu yvxr "qrgrpg qgzs gbarf", "qgzs qrgrpgvba ncc" be "qgzs qrpbqre/qrgrpgbe".
D: Jung nz V ybbxvat sbe ng fgntr1?
N: Guvf pnpur jnf oebhtug gb lbh ol gur yrggre "C".
Fgntr2 Uvagf:
D: Jurer'f gur "xrl"?
N: Svyy va gur oynax: "Qba'g gbhpu gung fdhveery'f _ _ _ f, vg'yy znxr uvz penml!"
D: Jurer'f gur xrlubyr?
N: Svaq crnpr. Gura ybbx oruvaq vg.

Decryption Key


(letter above equals below, and vice versa)



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Current Time:
Last Updated: on 11/15/2017 3:34:14 PM (UTC-08:00) Pacific Time (US & Canada) (11:34 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum

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