Echolocation Solution

How it works

Each loop contains a morse code segment and a vocal segment. For each station, the voice speaks in a different language. In the event that the language is not familar, the morse code segment identifies the language. It has the format of a radio station callsign, e.g. KZZZ, with the last three letters giving the ISO 639-3 language code for the station. The codes and languages are:

Loop Callsign Language
A KCMN Chinese, Mandarin
B KDEU German
C KRUS Russian
D KENG English
E KFRA French

Following the morse code, the station reads two decimal numbers as digits and punctuation. For example, "one-two-point-three-four [pause] negative-five-six-point-seven-eight." The numbers are:

Loop First Second
A 40.08 116.58
B 52.56 13.29
C 55.41 37.91
D 38.85 -77.04
E 49.01 2.55

These are GPS coordinates, and in a terribly unlikely coincidence, all point to capital airports. Furthermore, the language is that primarily spoken in the country where the airport is found. The airports are:

Loop Airport
A Beijing Capital International Airport
B Berlin Tegel Airport
C Domodedovo International Airport
D Ronald Reagan Washington National Airport
E Paris-Charles de Gaulle Airport

The final step of the puzzle is to recall that airport codes have three letters and that three streets, Meridian, 2nd, and 3rd, were highlighted on the map. Indexing the street on which the station is found into the airport code gives a letter of the solution, with ordering by location from north to south.

Loop Street Airport Code
A Meridian PEK
B 3rd TXL
C 3rd DME
D 3rd DCA
E 2nd CDG



Design notes

One of my cherished experiences from school is fox hunting with the ham radio club. The basic idea is that you get a directional antenna, a variable attenuator, and a handie-talkie. You turn the antenna and watch the signal meter on the HT to watch how it changes as you turn the antenna, get a fix, and head in that direction. As you get closer, the signal gets stronger and the meter spends most of the time pegged at its maximum. The attenuator is dialed up and the signal strength is reduced so that the meter gives a useful reading again. Eventually this leads you to a general area and a search on foot reveals the beacon's location. (Find your local hams and try it!)

I wanted to create a puzzle using this mechanic, though it would have to be simplified to keep cost of parts and labor under control. I prototyped a directional antenna tuned to the FRS/GMRS band and modified an inexpensive FRS radio to use the antenna and remove its transmitting capability. The main accomplishment of this experiment was to prove to myself the importance of the attenuator. Without an attenuator, the setup would only be useful at some distance from the beacon. The lack of a real signal meter would have eventually been a problem too.

Just as I was giving up on the concept, the plan for 3G-connected laptops with GPS came together. It was recast as a software application using the laptops' location capabilities. (Having a zero-fabrication puzzle was especially attractive after subjecting the staff to Chiasmata fab.) While I worked on the technology, Ben designed and recorded an actual puzzle to be carried over the stations. The final touch was to have the numbers read by native speakers of each language.

GC notes

After leaving the casino we realized that the bag of printed maps and software "release notes" were still in Redmond. The crew back at GC saved the day by hurriedly uploading electrontic copies to the content system which then began to trickle down to all the team laptops.