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Real-time Audio Spectrum Analyzer with Built-in Tracking Generator Copyright by InterFlex Systems But there's more... A Lot More This software turns your computer (laptop, desktop) and sound card (internal, or external USB) into an advanced Audio Spectrum Analyzer, tone generator, sweep tone generator, frequency response measurement device, oscilloscope, phase amplitude display analyzer, waterfall scope, and provides the features of an expensive bench Hardware analyzer at a far lower cost. It uses your computer for the data processing and analysis, and your sound card is the "front end" detector device used to both measure audio input (level and frequency) AND to either simultaneously, or separately generate single tones, dual tones, in-phase, out of phase tones, pink noise, sweep tones and tracking generator functions (generate a tone at the same frequency being "swept" by the analyzer section). This Audio Spectrum Analysis Program integrates the sound detection and computer processing power you already own and like a hardware analyzer, handles the calculations and data display (spectrum analyzer, oscilloscope, frequency generator, etc.) Also, as you would with a hardware analyzer, you provide the "device under test" (DUT) and use the built-in tracking generator to "sweep" the DUT, or simply look at the spectrum coming from, or going through a device (Microphone, Amplifier, Radio, etc.) Microphone response, signal hum and distortion, overdriving of audio circuits, frequency response of audio circuits (passive - e.g. filters, or active like amplifiers, pre-amps). People have reported using this program for low-level vibration analysis using transducers to detect vibration and hooking the output to the line or mic input of the sound card. Or use it to sweeping audio de-emphasis circuits used on FM radios. Look for PL(tm) tone levels and frequency, or detect phase issues with auditorium speaker systems, or noise levels in audio circuits and devices. SYSTEM REQUIREMENTS (What You Have) Your computer, laptop or desktop with CPU running 120 Mhz or faster (It's hard to even find a computer these days that slow). If you have a current system, it's likely to be 500 Mhz or faster. A sound card, internal or external (USB) that is recognized by Windows 98, ME, XP, 2000, etc. The program gets audio through the Windows audio drivers, and produces output audio just like any Windows program. So if your laptop has a MIC input and Earphone output, you can use it. If you have an external sound "Card" on a USB port (very low noise so great for analysis) that works too. If your sound can be controlled by Windows, it can be used for Spectrum Analysis with this RTGA (Real Time Generator Analyzer) program. All versions of Windows starting with Windows 95 and through Windows 2003. We don't support MAC OS, so don;'t ask. This is a Windows program, and a very tightly written, fast, and compact program which is why it works so well. InterFlex Systems AudioRTA Description You may find other freeware and shareware programs so be sure you understand the advantages of the unique built-in tracking generator. Also, you will get a vectorscope (phase analysis), and spectrogram, and the ability to read the signal level and frequency from a "popup" that appears when you put the cursor on the spectrum plot. The resolution is very high, and can be changed by changing the vertical and horizontal scales.Resolution can also be changed by slowing down the sweep rate, and by using averaging, one of the user selections. Bottom line: This program can be very helpful for those familiar with audio spectrum analyzers and what purpose they serve, and how to setup a Device Under Test (DUT) to analyze it's frequency response. It can also be very helpful to learn about audio analysis. You'd pay more for a short seminar than you'll pay for this entire program. Here are some of the specific features with a brief explanation of each: A Tracking Generator is a feature that produces audio output from your sound card at the same frequency that is being measured for the audio going to your sound card. The system "sweeps" a use selectable range of the audio spectrum from 20 Hz to 22 Khz and measures the amplitude of signals and allows you to produce a "frequency response" plot of the DUT (Device Under Test). Tone Generator also creates WAV files of sweep, two two-tone, single tone, sine, sawtooth, white and pink noise, to be used with other applications or to create a test CD to play on your system. Then analyze results using the spectrum analyzer. Note: If you need SQUARE wave signals. Sound Cards cannot produce square waves, there are too many harmonics, however if you need a square wave generator, you can use a 555 timer. Right Click HERE and choose "open in new window" or new tab to get information about building a square wave generator with a 555 timer chip. Try R1=1, R2=15, C=0.05 to produce about a 1 Khz square wave, or C=0.1 for about 460 Hz square wave. R1=1k, R2=1k, C=0.1 uF produced about 5 Khz square wave. Note: Instead of using Square Waves, you can use a triangle waveform which is also rich in harmonics with decreasing amplitude as the harmonic multiple increases. The Triangle Wave, if reproduced accurately by your device under test, is a good indication that your audio gear is likely to do as good a job with square waves. The Spectrum Analyzer section can be run by itself (without the tracking generator) to look at the audio spectrum for the DUT. Putting the cursor on a particular part of the plotted response, the dBm level is shown in a popup, allowing more precise information about the plotted response. The analyzer can be used in linear or log frequency mode, the sweep rate can be set, and the range of frequencies analyzed can be set by the user. Very useful for looking at dynamic range of audio, rolloff of amplifiers, microphones, speakers, etc. Noise level (can see noise down to -120 db) and extraneous hum, whistles, etc. On some FM receivers, the stereo chopping signal can be seen clearly as an artifact on the receiver output. Some audio systems have low level 60 Hz hum that is easy to detect with the analyzer, others have noise or hiss at low levels that is also easily seen well below the audible level. Distortion can be checked with a single sine wave tone input to an amplifier, and looking at resulting output spectrum for harmonics. Oscilloscope mode: useful to check amplitude of Left and Right channels, look for clipping, over driving audio, background noise, hum, etc. The Vector Scope is useful to check the Phase angle difference between input and output, and to check the linearity of gain on left and right channels. Also useful for stereo balance indicator, stereo richness and quality. Mono shows as vertical graphic, stereophonic sound (music) has a wide variety of plots, levels can be adjusted on source to fill both stereo channels and seen visibly on Vector Scope. The Spectrogram feature is a "waterfall" type display showing the intensity of signals at different frequencies over time. . Note: This program uses BOTH channels (Left and Right) for both output (separately controlled in phase, 180 degrees out of phase, or independent amplitude and type - sine, triangle, white noise, pink noise) and gives an analysis of either Left or Right or Both (using different colors on the plot). This allows you to test Left/Right balance, Left/Right comparisons of frequency response. Program Operation: The program screens can be reviewed at the InterFlex Web Site - click here to learn more about the program. Technical Audio Analysis: Check speakers, microphones, audio filter circuits, amplifiers for noise, distortion, linearity, clipping, hum, etc. A "must" for any audiophile wishing to know more about audio quality, gain, noise, for a wide array of audio devices. Check your Sound Card: This program will display the noise floor for various inputs to your audio card, Line, Mic, CD, Aux. Some are very quiet (Creative Labs Extigy) some are noisy (built-in cards on Laptops). Check for birdies (whistles caused by CPU, bus noise, etc.) on computers. Audio hum (from ground loops etc.) EchoLink Users: If you are an amateur radio operator and have EchoLink, you can use this program to monitor the audio coming in from repeaters, links, and other stations running IP sessions. On some sound cards select "what you hear" as the source, on others, a comparable "source" is available to monitor what is coming to your station. Also use it to analyze your MIC and Speakers. Voice over IP Users: Analyze outgoing and incoming audio and rolloff characteristics. Muffled audio has a fast rolloff of 20 db from 300 to 3300 Hz, better audio is flat. Audio with lots of excursions above and below the average is more intelligible, restricted spectrum means no dynamic range on the audio, and harder to understand. * Voice Spectrum using inexpensive microphone Click Here * Audio Monitored from EchoLink user: Click Here - I used "User" settings to sweep from 300 Hz to 5.0 Khz. Notice the range of audio levels from -20 to -40, pretty good dynamic range for voice audio. The noise floor for my audio card is -100 db. System Requirements: This program runs under Windows 95, 98, ME, NT, 2000, and XP. It uses the sound card for both input and output. You can specify which sound card input is to be analyzed by checking the box under "Recording Controls" in the "Volume Control" program with Windows. You can select to analyze the Line input, Mic input, Aux input, or CD input. Specifications: The Tone generator can produce white noise, pink noise, sine wave and triangle waves from 1 Hz to 22 Khz. The analyzer can display the spectrum for frequencies from 1 Hz to 22 Khz. The 1/3 octave display is the most basic and is used to view audio in "bands" to show the general distribution of energy across the audio spectrum. The more detailed display allows you to set the upper and lower "db" range on the vertical axis, and the mode you use can be Linear or Log, and the frequencies selected can be "voice" or "full audio" or can be set by the "User Settings" shown on the generator display. The program will analyze the characteristics of the audio card and compensate for errors (this is a function button on the "Input Controls" tabbed page). You can also measure the frequency response without the device under test, and save the results in the "Left" channel, then run another analysis with the device under test in the circuit and make "Left channel" the reference to compare. It is also possible to create your own "Left channel" reference files, they are text files with a .dat extension. If you have a microphone frequency response chart or graph, you can enter some points on the chart and the program will fit a curve to the points and use this as a "left channel" reference for your measurements. If you know how to use a Spectrum Analyzer, this can be a very useful tool. If you don't this can be a very educational tool. One application that came up was to use a vibration sensor to create a small voltage based on the vibration, to hook that to the MIC input of an audio card, and measure the spectrum of vibrations down to a few Hz. Sample Applications with Images: 1. Tests of two sound cards. One with noticeable tones being picked up apparently on the system bus, and the other external card with very low noise floor: Right Click, open in New Window. Close when done viewing. 2. Display of Harmonic Distortion - using 1000 Hz tone, notice, very low harmonics Right click on link, open in new window. Close when done Harmonic Distortion Display image 3. Using the built-in 2-channel Oscilloscope. 1-Hz tone generated and measured. This is a very low frequency for a sound card, but on the Extigy card, it looks like a pure sine wave. Appears on both right and left channels. Triangle and Sine Waves Generated. This shows the Generator producing a Triangle wave on the left channel, and a Sine wave on the right. The scope displays these waveforms accurately. Stereo with Left/Right channels at different levels. The Scope shows that the two channels are not at the same "volume" level Internet Music Display There are many uses of the vectorscope, including measuring time delays, harmonics, separation of channels, etc. This shows the analysis of some mp3 music found on the internet. Clearly not monaural, it is stereo with different sounds on each channel, hence the complex display. Sweeptest this is a test of the speaker output into a fairly good mic. The speaker output goes up to -20 db, but it doesn't stabilize until about 650 Hz. Below that frequency, it appears to have a natural response at about 370 Hz, and below that, drops off rapidly. If you have speakers, a mic, some audio equipment to test, this is the program you can use to analyze the performance of your audio components. Q: This sounds pretty cool. Here is what I want to do: I have a two trace analog oscilloscope with which I am obtaining organ note voltages at the key actuators. I need to identify and measure the subharmonic/harmonic frequencies on that signal which are screwing up my fundamental tone voltage readings. The scope has an output for each trace with the following specs: "At least 50 mV/div into 1 Mohm to at least 25 mV/div into 50 ohms with negligible DC". My soundcard claims to be -3db down to 15 hz. Can I use the scope output into the sound card ? A: You can feed ANY voltage source into a sound card, either the mic input (for low voltages) or the line input (for line level voltages about 1 volt peak to peak). If they voltages vary in the range of 1 Hz to 22 Khz, they can be analyzed by this software. You can look at the time domain (oscilloscope reading voltage vs time) or frequency domain (amplitude vs frequency). You can also restrict the analysis range (both time and frequency). The sound card input has a very flat frequency response. Q: Is it posible to get the "TS" parameters for "raw" speakers with this software? A: You can get the resonant frequency by putting a resistor in series with the speaker (8 Ohm in series with an 8 Ohm speaker) and generating a sweep tone from the tone generator, and picking off the voltage across the resistor or speaker to ground, and sweeping this system. At resonance, the amplitude will be the highest, and you can simply read the frequency off the frequency response plot. For other parameters, you can often contact the speaker mfg for those values. "TS" parameters. After you build a cabinet and put the speaker inside, then you can use the Spectrum Analysis "Frequency Response" measurement capability using a good microphone to sweep the "device under test" to see if it behaves according to the expected results of using the "TS" parameters to design a speaker enclosure. A: Any transducer (including a microphone) that generates a varying voltage and is in the frequency range of about 5 Hz to 22 kHz will do as an input to a sound card. "Sound" in this case is a misnomer - what we mean is "in the spectrum of frequencies nornally associated with human hearing" - aka 20 Hz to 22 Khz. If your vibrations are in that range, no matter how complex, a plot of the spectrum will show the amplitude(s) of the vibrations. You can also limit the soectrum analysis to a smaller range within the 20 Hz to 22 Khz by setting a "User Range" (low and high end). You can also build a vibrator/actuator that is driven by a small variable voltage aka "sound" from the sound card fed to a mechanical device that can shake whatever you're analyzing to "sweep" the mechanical "device under test" to find such things as natural frequencies, resonance, etc., which can be useful if you're trying to "deaden" the noise, etc Q: Hi. I am interested in your analyzer, but not on this computer. I have a computer in my listening room with all my design programs, and other audio related stuff. I would use the analyzer on this unit, but it is not connected to the internet. Could I download this program to a disk, and install it? A: The program can be archived without any problems. You will get a Name and Key to copy/paste into the registration screen, and the information will be displayed in the banner. You are licensed to use the program on your computers. System requirements are modest - it will run on a laptop, and any Windows recognized sound card, including external USB sound devices like hte Creative Labs MP3 unit, which is excellent, low noise level, and works with any computer (including laptops) that have a USB port. Q. How does your program compare to the others I've seen ? A. This program has features that make it far more useful than just spectrum analysis. Because we have a sweep generator that can be set to sweep between frequencies of your choosing, at fast or slow rates, and the spectrum analyzer can be set to "track" the tone generator frequency, you can create frequency response plots for any DUT (Device Under Test) - other programs don't have this "Tracking Generator" feature. You can also use our program for phase angle and amplitude analysis between Left and Right channels which among other things provides an instant indication of "in phase" or "out of phase" speaker wiring if you have a microphone in front of each speaker fed into the stereo input to a sound card (or Left/Right Line input). Compared to paying thousands of dollars for a hardware audio spectrum analyzer, we use the measurement capabilities of the sound card combined with the processing power of a computer to accomplish audio spectrum analysis for under $100. This is a VERY cost effective program, and very useful for anyone with a need to analyze audio devices, filters, amplifiers, radios, etc. Also, because the sound card can measure frequencies above and below the human ear, you can determine a lot about your sound system that you cannot find out by listening to it alone. You'd spend more than this for a modest voltmeter and the SCOPE function is useful as an oscilloscope for measuring relative AC amplitudes. * Spectrum Analyzer with User Selected Ranges * Frequency Response Analyzer for any audio device * Phase Angle Analysis for Left/Right channels * Tone Generators (Single and Dual Tones) * Sweep Tones Generator (slow, fast, your range) * White Noise and Pink Noise Generator * Audio Frequency Oscilloscope All These Features for less than $100 |