Chapter 1:Introduction to Software-Defined Radio

SDR functional steps overview
Figure 1.3

Modulation

convert the binary information into unique electromagnetic waveform properties such as amplitude, carrier frequency, and phase

Networking Layers and Models

2 major models: OSI 7 layer protocol and TCP/IP 5 layer protocol
Figure 1.4

TCP/IP Layers (highest to lowest, levels 5 through 1)

  1. Application Layer: Interfaces user with the data from the communication system. For instance, the application layer would include data originating from or intended for software running Web browsers, email clients, and streaming media interfaces. These applications are usually addressed via designated socket
  2. Transport Layer: Responsible for transporting application layer messages between the client application and server application. This layer ensures reliable data transmission
  3. Network Layer: Responsible for moving network layer packets from one host to another host. Defines format of datagrams and how end systems and routers act on datagram, as well as determine routes that datagrams take between sources and destinations
  4. Link Layer: Handles problem of exchanging data between two or more directly connected devices. Reliability: This includes error detection and error correction as well as addressing of different communication systems
  5. Physical Layer: Sends individual bits from one communication system directly to another communication system. It also covers the physical interface between data transmission device and transmission medium. Most of SDR application is in this layer
Example: 802.11 WiFi protocol:
Figure 1.5

Zero IF architecture (ZIF)

Uses a single frequency mixing stage with the local oscillator (LO) set directly to the frequency band of interest, translating the received signal down to baseband in phase (I) and quadrature (Q) signals Figure 1.7