Hernandez, November 30, www. Firstly, the past 6 White House administrations i.
Real-time Spectrum Analyser Having experimented with Fast Fourier Transforms FFT over the years, I realised that I could combine that routine with the sound sampling code sections to make a real-time audio spectrum analyser.
Like the other programs on this page, it uses the output from the 'Recording' mixer panel as its input. Audio is sampled at Please visit my dedicated Spectrum Analysis page at: The dedicated page has current updates e. Aug of the Spectrum Analysis with many more new features.
System frequency-response analysis For ages I'd been meaning to knock up a program to measure the frequency response of the computer speaker-microphone system. When working on the acoustic radar see below I had problems which I put down to resonances and a very non-flat response - so this analysis program couldn't wait any longer!
OPL3-SA motherboard sound chipset bass and treble controls one notch from minimum Altec Lansing ACS90 speakers without subwoofer Unbranded multimedia microphone with volume switch in mid position - II Microphone placed approx 5mm in front of centre of speaker The top dark green trace represents the outputted signal; 9-cycle cosine-enveloped, sinewave bursts at 20Hz, 25Hz, 31Hz, 40Hz, Bursts are separated by a silence period of the same duration as the preceeding burst.
The horizontal scale changes dynamically across the screen to make all bursts appear the same width! The middle, blue and red, trace represents the received signal, again on a linear amplitude scale.
The colouration is blue where a sound was expected, and red where it wasn't in the outputted silence periods. The bottom graph shows on a log decibel scale the amplitude of the received signal, after appropriate bandwidth filtering green trace.
The red trace below shows the amplitude of the received signal, similarly filtered, during the 'silence' periods - owing to background sounds etc, take the significance of this trace with a pinch of salt!
The peak at 50Hz is caused by AC mains electricity pickup. Ideas for future development: This showed that the electrical response was flat to within 3dB across the range 20Hz to 20kHz - but only when the soundcard bass and treble controls were set to one notch above minimum on a scale of With the controls in their mid position, there was a distinct dip of 6dB in the frequency response at around kHz - the region in between that affected by the tone controls!!!
Owing to its very experimental nature, this program is not available for download. Note on decibel notation Decibels are used to quote ratios of signal amplitudes: More specialist higher quality soundcards offer bit sampling, and so dB of dynamic range - exceeding that of the human auditory system!
The charts on this program use the maximum obtainable amplitude as the reference 0dB point.
Acoustic radar In the same way that radio waves can be used to detect and range distant objects, such as aircraft or ships at sea, soundwaves can be used - albeit usually over shorter distances. Soundwaves travel at approximately metres per second in air at room temperature. What is universally used in radar systems is a pseudo random bit sequence PRBS - in the case of sound, a hissing noise which contains all frequencies up to a certain limitwith the special property that it only correlates matches with itself at time-offsets of zero or the loop-period of the sequence - which can easily be made extremely long.
If you have several echos, the received sequence will match a little at the time corresponding to each echo, but not at all in-between. I wrote a program to sound a PRBS, and correlate the received signal from the microphone. Direct correlation for microphone 3 inches in front of speaker The problem was that resonances in the speaker and microphone were causing sound waves at certain frequencies to predominate.
A single frequency will correlate with itself at time intervals which are multiples of the period, T, of each cycle. My 'multiple reflections' were separated by about 0.
There is also evidence of a resonance at around twice that frequency. Early echo-plot With the microphone and speaker side by side, and a hard object held about 0.While the Chinese companies will not be directly involved in the construction or financing of the Trump properties, the theme park is a critical part of the 3,hectare development, which MNC.
Video Displays in all Sizes. Most early computer displays used bulky CRTs - cathode ray tubes - like those inside televisions at the time.
Some scanned horizontal lines in sequence, like a TV, and others could draw in an arbitrary order. The decision to buy a new gaming console comes with a lot of expectations about how it is going to improve your gaming experience.
A gaming console should have better processing capabilities, great graphics as well as better-looking and bigger games. Some researchers also connect gadget addiction to problems with fertility, supporting their point with the over-exposure to electro-magnetic fields emitted by gadgets, but this thesis needs to be checked.
The Google play store (previously known as the Android market) is a digital application distribution platform for Android and an online electronics store that is developed and maintained by Google.
Gadgets thesis CHAPTER.
Uploaded by. Janeth Dico. CHAPTER 1 THE PROBLEM Introduction As the world grows into technologically sophisticated, there is a great demand for the hottest electronic gadgets. These are cell phone, laptop, camera, MP3 player, and several cool electronic gadgets.
Cell phones support a wide variety of other services such.