As their mobiles got smaller and smaller, Motorola cellular telephones featured three major design changes, leading up to the StarTac design of today. The bag, the brick, and the flip proved extremely popular.
A transportable or luggable phone, the bag phone contained a heavy cellular transceiver with a large battery enclosed in a leather bag. Since battery life wasn't good, most people plugged the unit into a car's cigarette lighter and used it while driving. Power output was twice that of the brick, the hand-held cellular phone that borrowed its name from Motorola's first Handie-Talkie. Dwarfing any present hand-held, except perhaps satellite phones, the brick's battery itself was larger than most cell phones on the market today.
When the first digital networks were built Motorola introduced the flip phone, part of their Personal Digital Communicator Series. It could work in analog or digital mode. Many are still being used although the StarTac, introduced in 1996, and now the MicroTac, have since replaced the original flip phone.
For a look at how Ericsson cellular telephones evolved, click here
We discussed how reducing radio size and weight in World War II was less important than the modulation technology hand-helds eventually used: F.M. Today, as every company produces smaller and smaller radios, the technology used to transmit information is the most important development: C.D.M.A. or code division multiple access. Sometimes called spread spectrum or frequency hopping, C.D.M.A., puts bits and pieces of several calls on different frequencies. It's the most efficient technology, allowing more calls in the same spectrum than older digital systems. And where did CDMA start out? Well, you may have guessed the answer.
Spread spectrum was first used during World War II to prevent signals from being jammed. By rapidly changing frequencies the Allies found the Germans could not interfere with their transmissions. This immunity to interference is yet another reason for C.D.M.A.'s great popularity, indeed, the entire wireless world is embracing this technology. When GSM based systems evolve they will use it, as well as the next generation of I-Mode. This new yet old operating method reveals again the important and continuing link between civilian and military communications.
Patent illustration 2,292,387, for a Secret Communication System, utilizing spread spectrum. Co-filed by the movie star Hedy Lamar