The walkie-talkie technology was first produced in the trembling twenties, and was born in the laboratory of Westinghouse. An eccentric inventor named John Kermode "whimsically" wants to realize the automatic sorting of postal documents. At that time, every idea about the application of electronic technology was very novel. His idea is to make a walkie-talkie mark on the envelope. The information in the walkie-talkie is the address of the recipient, just like today's postal code. For this reason, Kermode invented the earliest walkie-talkie sign. The design scheme is very simple, that is, one represents the number "1", two represents the number "2", and so on. Then, he invented the walkie-talkie reading equipment composed of basic components: a method to determine the reflected signal band and space (which can emit light and receive reflected light), that is, the edge positioning coil; And a method of using the measurement result, namely a decoder. Kermode uses a newly invented photovoltaic cell to collect reflected light. "Empty" reflects a strong signal, while "bar" reflects a weak signal. Unlike today's high-speed electronic components, Kermode uses magnetic coils to measure "bars" and "spaces". Just like a child connecting a wire to a battery and winding it around a nail to clamp paper. Kermode uses a coil with an iron core to attract a switch when receiving the "empty" signal, and release the switch when receiving the "bar" signal to connect the circuit. So the earliest walkie-talkie readers were very noisy. The switch is controlled by a series of relays, and the "on" and "off" are determined by the number of "paper strips" printed on the envelope. In this way, walkie-talkie symbols sort letters directly. Shortly thereafter, Douglas Young, a collaborator of Kermode, made some improvements on the basis of Kermode code. Kermode code contains so little information that it is difficult to compile more than ten different codes. Young code uses fewer bars, but uses the change of the space between bars, just like UPC intercom symbols today use four different bar sizes. The new walkie-talkie symbol can encode 100 different areas in the same space, while Kermode code can only encode 10 different areas.
The appearance collection of Motorola GP328 interphone (15 pieces) is not recorded in the patent document of 1949 for the first time. Prior to this, there was no record of walkie-talkie technology and no precedent for practical application. Noam Woodland and Bemmad Silver's idea is to use Kermode and Yang's vertical "strips" and "spaces" to bend them into a ring, much like the target of archery. In this way, by scanning the center of the pattern, the walkie-talkie symbol can be decoded regardless of the orientation of the direction of the walkie-talkie symbol. In the process of constantly improving this patented technology, the science fiction writer Isaac-Azimov described an example of automatic identification using a new information coding method in his book Naked Sun. At that time, people thought that the intercom symbol in this book looked like Fang Gezi's chessboard, but today's intercom professionals will immediately realize that it is a two-dimensional matrix intercom symbol. Although this walkie-talkie symbol has no direction, no positioning and no timing, it is obvious that it represents a digital code with high information density.