How Geocaching Works
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NOTE: The coordinates above are not the ones where the cache is hidden.
[sve]Med GCVote kan du betygsätta den här cachen och andra du hittar.
[eng]With the use of GCVote you can rate this cache and your other founds.
This cache is located close to one of Ericsson's offices in Gothenburg. Once founded by Lars Magnus Ericsson, and developed from a small mechanical workshop, Ericsson has become a leading provider of telecommunication systems in general and 3G mobile systems in particular.
In WCDMA, a third generation (3G) mobile phone standard, the radio signal is modulated with QPSK, a modulation based on phase difference.
The digital bitstream of data, is splitted into two-bit symbols, which modulates the phase according to a constellation diagram. In the receiver the reverse apply, i.e. the phase of the signal translates to symbols (and bitorder) via the constellation diagram.
A key feature of WCDMA is the method that the transmitted signals in the air are separated with. All users are using all of the frequency band, at the same time. The separation lies within the use of coding. Each transmitter is given a unique code, which is used to encode the signal.
The receiver has to know this code to be able to read the wanted signal in the crowded frequency band.
Worth to mention is that the GPS satellites also use CDMA technique. Here the frequency band is smaller than in the 3G systems, but the idea is the same.
The codes, named Gold codes, used in the GPS system consist of 1023 bits. There exists 1025 Gold codes of this lenght, but only 32 are used. Each satellite is assigned with one specific gold code.
Using a correct set up in the receiver system, you're able to extract the information from the diagram below.
Med rätt inställt mottagarsystem, kommer du att kunna extrahera informationen ur diagrammet nedanför.
Kontrollera din lösning här/Check your solution here: Geochecker.com.
This cache is part of the Master of Mystery #14 Amsterdam!
- Master of Mystery
- QPSKConstellation diagram for QPSK.
- SignalQPSK modulated signal.
- WCMDA spread spectrumWith the correct Gold Code, you're able to pick up the signal.
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Coordinates are in the WGS84 datum