The Bucket Brigade Device (BBD) is an analog shift register implemented using a chain of capacitors and transistors. It stores analog signals as charge packets on these capacitors, sequentially transferring them along the chain with the help of a clock signal. This creates a time delay proportional to the number of stages in the brigade. BBDs were historically used for audio effects like delay, chorus, and reverberation because of their simplicity and relatively low cost. However, they suffer from signal degradation due to charge leakage and require careful biasing and clocking for optimal performance. Despite being largely superseded by digital technologies, BBDs offer a fascinating example of analog signal processing.
Researchers have demonstrated a method for using smartphones' GPS receivers to map disturbances in the Earth's ionosphere. By analyzing data from a dense network of GPS-equipped phones during a solar storm, they successfully imaged ionospheric variations and travelling ionospheric disturbances (TIDs), particularly over San Francisco. This crowdsourced approach, leveraging the ubiquitous nature of smartphones, offers a cost-effective and globally distributed sensor network for monitoring space weather events and improving the accuracy of ionospheric models, which are crucial for technologies like navigation and communication.
HN users discuss the potential impact and feasibility of using smartphones to map the ionosphere. Some express skepticism about the accuracy and coverage achievable with consumer-grade hardware, particularly regarding the ability to measure electron density effectively. Others are more optimistic, highlighting the potential for a vast, distributed sensor network, particularly for studying transient ionospheric phenomena and improving GPS accuracy. Concerns about battery drain and data usage are raised, along with questions about the calibration and validation of the smartphone measurements. The discussion also touches on the technical challenges of separating ionospheric effects from other signal variations and the need for robust signal processing techniques. Several commenters express interest in participating in such a project, while others point to existing research in this area, including the use of software-defined radios.
This blog post presents a different way to derive Shannon entropy, focusing on its property as a unique measure of information content. Instead of starting with desired properties like additivity and then finding a formula that satisfies them, the author begins with a core idea: measuring the average number of binary questions needed to pinpoint a specific outcome from a probability distribution. By formalizing this concept using a binary tree representation of the questioning process and leveraging Kraft's inequality, they demonstrate that -∑pᵢlog₂(pᵢ) emerges naturally as the optimal average question length, thus establishing it as the entropy. This construction emphasizes the intuitive link between entropy and the efficient encoding of information.
Hacker News users discuss the alternative construction of Shannon entropy presented in the linked article. Some express appreciation for the clear explanation and visualizations, finding the geometric approach insightful and offering a fresh perspective on a familiar concept. Others debate the pedagogical value of the approach, questioning whether it truly simplifies understanding for those unfamiliar with entropy, or merely offers a different lens for those already versed in the subject. A few commenters note the connection to cross-entropy and Kullback-Leibler divergence, suggesting the geometric interpretation could be extended to these related concepts. There's also a brief discussion on the practical implications and potential applications of this alternative construction, although no concrete examples are provided. Overall, the comments reflect a mix of appreciation for the novel approach and a pragmatic assessment of its usefulness in teaching and application.
Researchers have developed a new transistor that could significantly improve edge computing by enabling more efficient hardware implementations of fuzzy logic. This "ferroelectric FinFET" transistor can be reconfigured to perform various fuzzy logic operations, eliminating the need for complex digital circuits typically required. This simplification leads to smaller, faster, and more energy-efficient fuzzy logic hardware, ideal for edge devices with limited resources. The adaptable nature of the transistor allows it to handle the uncertainties and imprecise information common in real-world applications, making it well-suited for tasks like sensor processing, decision-making, and control systems in areas such as robotics and the Internet of Things.
Hacker News commenters expressed skepticism about the practicality of the reconfigurable fuzzy logic transistor. Several questioned the claimed benefits, particularly regarding power efficiency. One commenter pointed out that fuzzy logic usually requires more transistors than traditional logic, potentially negating any power savings. Others doubted the applicability of fuzzy logic to edge computing tasks in the first place, citing the prevalence of well-established and efficient algorithms for those applications. Some expressed interest in the technology, but emphasized the need for more concrete results beyond simulations. The overall sentiment was cautious optimism tempered by a demand for further evidence to support the claims.
Obsidian-textgrams is a plugin that allows users to create and embed ASCII diagrams directly within their Obsidian notes. It leverages code blocks and a custom renderer to display the diagrams, offering features like syntax highlighting and the ability to store diagram source code within the note itself. This provides a convenient way to visualize information using simple text-based graphics within the Obsidian environment, eliminating the need for external image files or complex drawing tools.
HN users generally expressed interest in the Obsidian Textgrams plugin, praising its lightweight approach compared to alternatives like Excalidraw or Mermaid. Some suggested improvements, including the ability to embed rendered diagrams as images for compatibility with other Markdown editors, and better text alignment within shapes. One commenter highlighted the usefulness for quickly mocking up system designs or diagrams, while another appreciated its simplicity for note-taking. The discussion also touched upon alternative tools like PlantUML and Graphviz, but the consensus leaned towards appreciating Textgrams' minimalist and fast rendering capabilities within Obsidian. A few users expressed interest in seeing support for more complex shapes and connections.
This blog post explores using Go's strengths for web service development while leveraging Python's rich machine learning ecosystem. The author details a "sidecar" approach, where a Go web service communicates with a separate Python process responsible for ML tasks. This allows the Go service to handle routing, request processing, and other web-related functionalities, while the Python sidecar focuses solely on model inference. Communication between the two is achieved via gRPC, chosen for its performance and cross-language compatibility. The article walks through the process of setting up the gRPC connection, preparing a simple ML model in Python using scikit-learn, and implementing the corresponding Go service. This architectural pattern isolates the complexity of the ML component and allows for independent scaling and development of both the Go and Python parts of the application.
HN commenters discuss the practicality and performance implications of the Python sidecar approach for ML in Go. Some express skepticism about the added complexity and overhead, suggesting gRPC or REST might be overkill for simple tasks and questioning the performance benefits compared to pure Python or using GoML libraries directly. Others appreciate the author's exploration of different approaches and the detailed benchmarks provided. The discussion also touches on alternative solutions like using shared memory or embedding Python in Go, as well as the broader topic of language interoperability for ML tasks. A few comments mention specific Go ML libraries like gorgonia/tensor as potential alternatives to the sidecar approach. Overall, the consensus seems to be that while interesting, the sidecar approach may not be the most efficient solution in many cases, but could be valuable in specific circumstances where existing Go ML libraries are insufficient.
Voyager 1, currently over 15 billion miles from Earth, successfully transmitted data using a backup thruster control system not activated since 1981. NASA engineers recently rediscovered the system's functionality and tested it, confirming Voyager 1 can still send scientific data back to Earth via this alternative route. This extends the spacecraft's operational lifespan, though using the backup system requires slightly higher power consumption. While the primary thruster control system remains functional for now, this rediscovery provides a valuable backup communication method for the aging probe.
Hacker News commenters generally expressed awe and excitement at Voyager 1's continued operation and the ingenuity of the engineers who designed and maintain it. Several commenters highlighted the remarkable longevity and durability of the spacecraft, given its age and the harsh environment of interstellar space. Some discussed the technical details of the trajectory correction maneuver and the specific hardware involved, including the attitude control thrusters and the now-resurrected TCM thruster. A few questioned the phrasing of "breaking its silence," pointing out that Voyager 1 continues to send scientific data. Others reflected on the historical significance of the Voyager missions and the small, but important, course correction that ensures continued communication with Earth for a few more years.
Summary of Comments ( 29 )
https://news.ycombinator.com/item?id=42146718
HN users generally found the bucket brigade device fascinating. Several commenters discussed practical applications like its use in early audio delay lines and the challenges of clocking it consistently. Others appreciated the clear explanation and visualization of the device's operation, highlighting its simplicity and elegance. Some compared it to charge-coupled devices (CCDs) and discussed their similarities and differences in functionality and implementation. The practicality of using actual buckets filled with water was also debated, with some suggesting the analogy, while visually appealing, might not accurately represent the underlying physics of the electronic device. A few users linked to relevant Wikipedia pages and other resources for further exploration.
The Hacker News post "The bucket brigade device: An analog shift register" has generated several comments discussing various aspects of the technology.
Several commenters focused on the practicality and applications of bucket brigade devices (BBDs). One commenter questioned their utility, asking why one would use a BBD instead of just storing samples digitally. This prompted a discussion about the historical context of BBDs, with others pointing out that they predate readily available digital solutions and were used in applications like early synthesizers and guitar effects pedals due to their simplicity and relatively low cost at the time. Another commenter mentioned the use of BBDs in toys and musical greeting cards. This highlighted the BBD's suitability for low-fidelity audio where digital solutions might have been overkill. Someone else mentioned the distinct "analog" sound of BBDs, specifically their characteristic warble and degradation, which became desirable in some musical applications, contributing to their continued niche usage.
The technical aspects of BBD operation also drew attention. One commenter clarified the functionality, explaining that the charge isn't actually moved across the entire chain of capacitors, but rather small amounts of charge are passed between adjacent capacitors, analogous to a bucket brigade. This clarified the name and underlying principle for other readers. Another comment delved deeper into the physical implementation, describing the use of MOS capacitors and the impact of clock frequency on the delay time.
One commenter reminisced about experimenting with BBDs and other analog components in their youth. This added a personal touch to the discussion and underscored the historical significance of these devices for hobbyists and early electronics enthusiasts.
A recurring theme in the comments was the contrast between BBDs and digital delay lines. Commenters explored the trade-offs between the simplicity and unique sound of BBDs versus the fidelity and flexibility of digital approaches. The limitations of BBDs, such as their fixed maximum delay time and susceptibility to noise, were also mentioned. One commenter even discussed the specific challenges of clocking BBDs and the impact of clock imperfections on the output signal.
Finally, a couple of comments highlighted related technologies, including the use of CCDs (charge-coupled devices) for similar signal processing applications, and drawing parallels with the operation of peristaltic pumps. These broadened the context of the discussion and provided additional avenues for exploration.