Part 1 of this FAQ looked at the optical rotary encoder, a low-cost, high-resolution, easy-to-use sensor for indicating incremental shaft position (although it can be “upgraded” to indicate absolute position as well). Q: What is the basic principle of the magnetic encoder? A: The magnetic encoder uses a rotating gear made of ferrous metal and […]
Rotary encoder basics and applications, Part 1: Optical encoders
Across a wide range of applications, it is necessary to need to accurately sense the motion of a rotary shaft and know its position, speed, or even acceleration. To do this, a component called a shaft or rotary encoder is added to the motor/shaft assembly. (Note that the term “rotary encoder” is often shortened to […]
Signal-channel diversity and fading, Part 2: Frequency Diversity
In Part 1 we looked at space diversity, which is the simplest form of signal-channel diversity. It has been used with success since the earliest days of wires and wired links, and it sees new uses in 5G MIMO and other advanced RF systems. We next look at the other very common form of signal-channel […]
Radio receiver architectures, Part 2—Zero-IF and SDR
Part 1 of this FAQ looked at two basic receiver architectures: the tuned radio frequency approach (now largely obsolete due to performance shortcomings), and the superhet design which has been used with great success for about 100 years. Part 2 looks at two other architectures – the zero-IF design and the software-defined radio – which […]
Solid-state temperature sensing, part 2: application
In Part 1, we looked at the basic principle and function of the solid-state temperature sensors, as well as the first widely available model, the AD590. Part 2 looks at some application considerations. Q: What are the interface considerations? A: A basic solid-state sensor has a PTAT current-only output. This means that the subsequent circuitry, […]
Solid-state temperature sensing, part 1: principles
Temperature is by far the most commonly measured physical parameter in industrial, commercial, and even residential settings. It’s obviously about much more than just “what’s the temperature, so I will know what coat to wear?” Temperature readings are needed to control processes and systems via a negative feedback loop, PID algorithms, and comparators (References 1 […]
Radio receiver architectures, Part 1—TRF and Superhet
A transmitter has much-less challenging task than the receiver. The former operates on a higher-level, known signal in a known setting, while the latter must find and decode a largely unknown signal corrupted by internal and external noise, interference from other signals, distortion, low signal levels, and constantly changing parameters. This FAQ looks at the […]
RS232 and Related Standards, Part 2
Part 1 looked at the basics of RS-232. This part continues that examination, along with some extensions to the standard and test issues. Q: What are some of the issues associated with RS-232 and its performance? A: The standard allows for many user choices in how the DTE and DCE are configured: number of data […]
RS-232 and related standards, Part 1
High-speed, high-performance “just plug and go” wired-communications interfaces such as Ethernet and USB are in wide use. In contrast, the technically ancient RS-232 standard and related standards seem like antique museum pieces with no design-in interest. However, that is a simplistic view of the reality. Although not necessarily the first choice or obvious choice in […]
Current feedback amplifiers, Part 2
Part 1 of this FAQ look at the operation of the CFB op amp and compared it to the VFB op amp. Part 2 continues the discussion of these two op amp topologies and their characteristics. Q: How do you choose between VFB versus CFB? A: Today’s CFB and VFB amplifiers have comparable performance, but […]