Echolocation with HC-SR04 ultrasonic distance sensor

Ultrasonic echolocation is common practice in many areas, including nature itself. We all know how bats or dolphins navigate – they emit ultrasonic waves, and depending on the time delay of reflected echoes, they can determine the distance from obstacles or catch. From an engineering perspective, it is relatively easy to measure distances with ultrasound – all you need to know is sound speed in the air and time delay between sent and received pulses. L is the measured distance; CAIR – ultrasound speed; t – the time between transmitted and received pulses. The accuracy of measured distance mainly depends on air temperature. The following formula can calculate sound speed in the air approximately : For instance, at 25ºC, the speed of sound in dry air CAIR = 346.13 m/s. If you want greater accuracy, you should also measure temperature to adjust sound speed.

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Ultrasound wave propagation and parameters

Ultrasound waves are acoustic pressure waves that interact with propagation media. Ultrasound visualization is typically based on wave reflectance from regions with different acoustic properties. When a wave meets different acoustic media, part of it transmits further while others reflect. This happens due to different acoustic impedance. The ration between reflected and transmitted energy purely depends on the difference in acoustic impedance in both regions. As you can see each material can be characterized by its acoustic impedance Z which is equal to ultrasound speed v and material density r.

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Testing NEO-6M GPS receiver module

If your project requires a global positioning feature, then you should use one of many GSP modules. There are many receiver modules and expansion boards available for your choice. They vary in PCB size, functionality, antennas used, and price. In most cases, you are probably looking for a simple, small-in-one solution where GPS receiver and antenna would be on the same package. Recently I have picked one that might fit most needs – GPS receiver NEO-6M module with ceramic antenna and TTL serial interface. It is a very compact GPS module with the most needed features:

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Using wavelet transform in biomedical engineering – heart signal analysis

In previous post, we cleared out that wavelet transform is used to analyze short-time and non-stationary signals. Since base wavelet function has to parameters – translation and scaling, it is possible to achieve good time and frequency localization. In other words, we can equally analyze the slow signal and fast signal structures without losing resolution and so evaluate signal frequency characteristics and time dynamics. Heart signal analysis is one of the most common problems in biomedical engineering. Practically every part of ECG signal carries some sort of information about heart conditions, possible pathologies, and diseases. So equally, frequency and timing characteristics of ECG signal is essential. As you know standard ECG signal consists of several typical waveforms like P-QRS-T, where in P and T waves low frequency component dominates, and in QRS, mid and high. The common condition of hear is myocardial ischemia when blood flow through coronary arteries to the heart is reduced, what prevents receiving enough oxygen. This can damage the heart muscle and lead to a heart attack. In order to notice this pathology it is we need to analyze S-T segment of ECG waveform. Insignificant changes in the signal can indicate ischemia. In order to find…

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Fixing Renault Scenic II fan controller block

Renault Scenic II fan fails quite often. In some cases, you may notice that not all speeds selected from the dashboard works or works occasionally. But most often fan stops working at all. Of course, the first step to check fuses. If fuses seem to be OK, then the only way to look is at the fan speed controller (sometimes called fan resistor). The easiest and most expensive way is to call service and leave them to do repairs. But if you have some engineering blood, you can do it yourself by spending less than an hour of your time and probably only a couple of bucks.

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Ultrasound waves and propagation

It has been more than 100 years since ultrasound has been used for analyzing materials and echolocation. A bit later, it was adapted for medical diagnostics. Ultrasound became popular and widespread due to the number of benefits. Probably one of the essential features is that it is non-destructive. The other is simplicity and precision. Of course, when we talk about price and simplicity we have X-ray or tomography in mind. Ultrasound can be used in many areas and environments. You can measure geometrical properties of internal structures and physical properties like density and tension. In medicine, ultrasound visualization is mainly used as a non-invasive medical imaging technique using high-frequency sound waves to produce images of internal body structures. It is commonly used to view and diagnose conditions related to pregnancy, the abdomen, and the heart. The images are created by transmitting sound waves into the body, which bounce off internal structures and are detected by a transducer, then processed by a computer to create real-time images. Ultrasound is generally considered safe and painless and does not involve ionizing radiation.

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5 Creative Voice Tech Applications

Applications using voice technology are increasingly becoming popular in the modern-day society. Developers are working hard to make technological innovations meant to improve people’s everyday lives. Using voice technology today, you can learn about your community, send an email, buy movie tickets, and much more tasks through speaking to your smartphone. The following are some of the most creative apps of voice technology. Siri Assistant App The app runs on iOS mobile operating system and was developed by Apple. It works as a personal assistant app for knowledge and navigation. The most innovative feature of the app is that it uses natural language user interface to perform various tasks such as making recommendations, searching the web, answering questions, and making phone calls. The creative use of natural language ensures the user doesn’t have to remember particular keywords and phrases. In addition, Apple assured its users that the app uses a cloud-based voice recognition technology to analyze commands, process and interpret voice collected from the cloud.

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When there is (not) enough of screen resolution on your device?

We face lots of screens and displays today, starting with computer monitors, TVs, and smartphones and ending with more sophisticated virtual reality (VR) displays like Oculus Rift. Most of them already use high-resolution displays. For instance, Ultra HD 4k displays are becoming more and more available in the list of monitors. But what does this mean, and is this enough or too much? Many tests and debates are running about proper screen resolution when you have good picture quality and not waste only numbers. This is not what are we are going to discuss. Everyone has to find their own optimal solution. Why not do this rationally instead of chasing numbers. Fig. 1 Screen door effect From the practical side, resolution alone doesn’t have significant meaning when choosing screens and displays. You could take the other two parameters into account – distance from screen and screen size. All those parameters go along with human visual acuity – the smallest thing he can spot. When you go to the eye inspection, you are given a character chart to point to the smallest symbols you can see. The number next to that line represents your visual acuity. For healthy people, the parameter…

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How not to struggle with writing

Many people seem are naturally good at writing. They write great reports and articles that way so other enjoy reading. If you look more into the writing process, you start seeing that it takes lots of practice, planning and discipline to do it great. So in order to get on to right track you should analyze the routine the successful writers do when they write. The main roadblock in writing great essays is pressure. The need to write it fast and good simply freezes the brain. The fear of failure may take over. But there is good news – you can write and write well. All you need is to get over the pressure and build a simple strategy that will help accomplish the task. A probably most important part of writing is to get rid of fears and brain freezes. If you have failed in writing earlier, brain remembers and starts blocking again. Then you probably grab chocolate or cigarette, hoping to release tension. And later, you find that this doesn’t help much.

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Transferring files with SCP between raspberries

I was playing with Raspberry Pi Model B for quite a long time. I tweaked few settings, and wrote couple helper scripts. After some time second Raspberry Pi 2 arrived. I realized that most settings and scripts that were working on previous should do fine on a new one. I needed to copy few files from one Raspberry to another. For this purpose, I decided to use Secure Copy (SCP). This is a file-sending command over SSH. Raspbian OS already come with SCP installed, so you can use it right away. (it is missing you can install it by running the command sudo apt-get install scp).

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