History of broadcastingIt is generally recognized that the first radio transmission was made from a temporary station set up by Guglielmo Marconi in 1895 on the Isle of Wight. This followed on from pioneering work in the field by a number of people including Alessandro Volta, André-Marie Ampère, Georg Ohm and James Clerk Maxwell. The radio broadcasting of music and talk intended to reach a dispersed audience started experimentally around 1905–1906, and commercially around 1920 to 1923. VHF (very high frequency) stations started 30 to 35 years later.
Onion routingOnion routing is a technique for anonymous communication over a computer network. In an onion network, messages are encapsulated in layers of encryption, analogous to the layers of an onion. The encrypted data is transmitted through a series of network nodes called "onion routers," each of which "peels" away a single layer, revealing the data's next destination. When the final layer is decrypted, the message arrives at its destination. The sender remains anonymous because each intermediary knows only the location of the immediately preceding and following nodes.
Tamper-evident technologyTamper-evident describes a device or process that makes unauthorized access to the protected object easily detected. Seals, markings, or other techniques may be tamper indicating. Tampering involves the deliberate altering or adulteration of information, a product, a package, or system. Solutions may involve all phases of product production, distribution, logistics, sale, and use. No single solution can be considered as "tamper proof". Often multiple levels of security need to be addressed to reduce the risk of tampering.
TamperproofingTamperproofing, conceptually, is a methodology used to hinder, deter or detect unauthorised access to a device or circumvention of a security system. Since any device or system can be foiled by a person with sufficient knowledge, equipment, and time, the term "tamperproof" is a misnomer unless some limitations on the tampering party's resources is explicit or assumed. Tamper resistance is resistance to tampering (intentional malfunction or sabotage) by either the normal users of a product, package, or system or others with physical access to it.
Radio networkThere are two types of radio network currently in use around the world: the one-to-many (simplex communication) broadcast network commonly used for public information and mass-media entertainment, and the two-way radio (duplex communication) type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery services. Cell phones are able to send and receive simultaneously by using two different frequencies at the same time. Many of the same components and much of the same basic technology applies to all three.
