Abstract
Before discussing software-defined radio, we need to define: what is a radio. For the purposes of this book, a radio is any device used to exchange digital information between point A and point B. This definition is somewhat broader than the standard concept of a radio in which it includes both wired and wireless communications. In fact, most of the concepts that will be covered here are equally applicable to both types of communications links. In most cases no distinction is made, since it is obvious that, for example, a discussion of antennas is only applicable to wireless links.
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Notes
- 1.
Analog radios are being rapidly phased out by their digital counterparts and will not be covered in this book. Even the two major holdouts, AM and FM radios, are slowly being converted to digital.
- 2.
An entirely different kind of radio is described in [279]. All of the functionality is (incredibly) implemented in a single nanotube.
- 3.
A received signal power of −100  dBm (~2 µV) is expected by small wireless devices, while −160 dBm (~2 nV) received power is common for space communications.
- 4.
Papers presenting very creative and elegant approaches to analog implementation of traditional digital blocks are always being published (e.g., [274]), but are more exercises in design rather than practical solutions. Exceptions include niche areas such as ultra-low power and ultra-high rate radios.
- 5.
Only receiver functionality is described here for brevity. Most functions have a corresponding equivalent in the transmitter.
- 6.
Typical offsets include differences in RF carrier frequency, transmission time, and signal amplitude.
- 7.
A simple demodulator maps a received value of +1 V to a data bit of ‘1’ and a received −1 V to a data bit of ‘0’. Modern demodulators are significantly more complex.
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© 2013 Springer Science+Business Media New York
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Grayver, E. (2013). What is a Radio?. In: Implementing Software Defined Radio. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-9332-8_1
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DOI: https://doi.org/10.1007/978-1-4419-9332-8_1
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