> Below is a list of programs for generating signals of various shapes and frequency characteristics, which are most often used by radio amateurs.
>SweepGen program
>Program-generator of time-varying and stationary test sound signals. Equipped with several working modes: manual sweep, fixed frequency, slow and fast adjustable sweep, white noise. The program is free.
>Digital Signal Generator
>
> Free program for developing various digital signals. Includes: white noise generator, triangular and rectangular pulse generator, sine sweep generator, sine wave generator and beat generator.
>NCH Tone Generator
>
> The program is capable of generating a large number of various waveforms: pulse, sawtooth, rectangular with very good fronts, triangular, sinusoidal, as well as all the main noises (purple, white, brown, pink, gray and blue).
>AudioWave Generator
>
>Software, which is a low-frequency signal generator (two-channel). The software is paid, the cost is 50 EUR, but there is a demo version of limited use.
>Test Tone Generator
>
> A program capable of creating various sound signals in a wide range of frequencies. Software cost from 30 EUR. There is a 30-day fully functional free version.
>Filtered Noise Generator
>
>Software designed to generate noise signals. The free version of the program works for 30 days. The full version is available from 20 EUR.
>PWM Generator
>
>Conventional pulse-width format signal generator. The program is shareware: 16 EUR. The free version of the program is available for 30 days.
>Multi Tone Generator
>
>Multitonovy two-channel generator of signals of audio frequencies. The trial version of the software is valid for 30 days. The full version is available from 20 EUR.
SoundCard Oszilloscope - a program that turns a computer into a two-channel oscilloscope, a two-channel low-frequency generator and a spectrum analyzer
Good day dear radio amateurs!
Every radio amateur knows that in order to create more or less complex amateur radio devices, it is necessary to have at your disposal not only a multimeter. Today in our stores you can buy almost any device, but - there is one "but" - the cost of a decent quality of any device is not less than several tens of thousands of our rubles, and it's no secret that for most Russians this is a lot of money, and therefore these devices are not available at all, or a radio amateur buys devices that have been in use for a long time.
Today on site , we will try to equip the amateur radio laboratory with free virtual devices -digital two-channel oscilloscope,
two-channel audio frequency generator,
spectrum analyzer. The only drawback of these devices is that they all operate only in the frequency band from 1 Hz to 20,000 Hz. The site has already given a description of a similar amateur radio program:“ “
- a program that turns a home computer into an oscilloscope.
Today I want to bring to your attention another program - “SoundCard Oscilloscope“. This program attracted me with good characteristics, thoughtful design, ease of study and work in it. This program is in English, there is no Russian translation. But I don't see this as a disadvantage. Firstly, it is very easy to figure out how to work in the program, you will see it yourself, and secondly, someday you will get good devices (and they have all the symbols in English, although they themselves are Chinese) and immediately and easily get used to them.
The program is developed by C. Zeitnitz and is free, but only for private use. A license for the program costs about 1,500 rubles, and there is also a so-called “private license” that costs about 400 rubles, but this is more like a donation to the author for further improvement of the program. We, of course, will use the free version of the program, which differs only in that every time it is launched, a window appears with an offer to buy a license.
Download the program (latest version as of December 2012):
(28.1 MiB, 50,675 hits)
First, let's understand the "concepts":
Oscilloscope- a device designed for research, observation, measurement of amplitude and time intervals.
Oscilloscopes are classified:
♦ according to the purpose and method of information output:
- oscilloscopes with a periodic sweep for observing signals on the screen (in the West they are called oscilloscop)
- continuous-sweep oscilloscopes for recording a signal curve on a photographic tape (called an oscillograph in the West)
♦ according to the method of processing the input signal:
– analog
– digital
The program works in an environment not lower than W2000 and includes:
- a two-channel oscilloscope with a bandwidth (depending on the sound card) of at least 20 to 20,000 Hz;
– two-channel signal generator (with a similar generated frequency);
- spectrum analyzer
– and it is also possible to record an audio signal for later study
Each of these programs has additional features that we will look at as we explore them.
We'll start with the Signalgenerator:
The signal generator, as I said, is two-channel - Channel 1 and Channel 2.
Consider the purpose of its main switches and windows:
1
– buttons for turning on generators;
2
– output waveform setting window:
sine– sinusoidal
triangle- triangular
square- rectangular
sawtooth- sawtooth
white noise- White noise
3
– output signal amplitude regulators (maximum - 1 volt);
4
– frequency setting knobs (the desired frequency can be set manually in the boxes under the knobs). Although the maximum frequency on the regulators is 10 kHz, any allowed frequency can be entered in the lower windows (depending on the sound card);
5
– windows for setting the frequency manually;
6
– switching on the “Sweep-generator” mode. In this mode, the generator output frequency periodically changes from the minimum value set in the “5” boxes to the maximum value set in the “Fend” boxes during the time set in the “Time” boxes. This mode can be enabled either for any one channel or for two channels at once;
7
– windows for setting the end frequency and time of the Sweep mode;
8
– software connection of the generator channel output to the first or second input channel of the oscilloscope;
9
- setting the phase difference between the signals from the first and second channels of the generator.
10
-at setting the duty cycle of the signal (valid only for a rectangular signal).
Now let's take a look at the oscilloscope itself:
1
– Amplitude -
vertical channel sensitivity adjustment
2
– Sync– allows (by checking or unchecking) to perform separate or simultaneous adjustment of two channels in terms of signal amplitude
3, 4
– allows you to spread the signals along the height of the screen for their individual observation
5
– sweep time setting (from 1 millisecond to 10 seconds, while 1 second is 1000 milliseconds)
6
– start/stop oscilloscope operation. When stopped, the screen saves the current state of the signals and the Save button ( 16
) that allows you to save the current state on the computer in the form of 3 files (text data of the signal under study, a black and white image and a color image of the picture from the oscilloscope screen at the moment of stopping)
7
– trigger- a software device that delays the start of a sweep until certain conditions are met and serves to obtain a stable image on the oscilloscope screen. There are 4 modes:
– on/off. When the trigger is off, the image on the screen will look “running” or even “smeared”.
– auto mode. The program itself selects the mode (normal or single).
– normal mode. In this mode, a continuous sweep of the signal under study is carried out.
– single mode. In this mode, a one-time signal sweep is performed (with a time interval set by the Time control).
8
– active channel selection
9
– edge– signal trigger type:
- rising– along the front of the studied signal
– falling– by the decline of the signal under study
10
– Auto Set- automatic setting of the sweep time, the sensitivity of the vertical deviation channel Amplitude, as well as the image is forced to the center of the screen.
11
-Channel Mode– determines how the signals will be displayed on the oscilloscope screen:
– single– separate output of two signals on the screen
- CH1 + CH2– output of the sum of two signals
– CH1 - CH2– output of the difference of two signals
– CH1 * CH2– output of the product of two signals
12 and 13 – choice of displaying channels on the screen (or any of the two, or two at once, the value is displayed next to Amplitude)
14
– channel 1 waveform output
15
– channel 2 waveform output
16
– already passed - recording a signal to a computer in the stop mode of the oscilloscope
17
– time scale (we have a regulator Time stands at 10 milliseconds, so the scale is displayed from 0 to 10 milliseconds)
18
– Status– shows the current state of the trigger and also allows you to display the following data on the screen:
- HZ and Volts– displaying the current voltage frequency of the signal under study
– cursor– inclusion of vertical and horizontal cursors for measuring the parameters of the signal under study
– log to fill– second-by-second recording of the parameters of the signal under study.
Making measurements on an oscilloscope
First, let's set up the signal generator:
1. Turn on channel 1 and channel 2 (green triangles light up)
2. Set the output signals - sinusoidal and rectangular
3. Set the amplitude of the output signals to 0.5 (the generator generates signals with a maximum amplitude of 1 volt, and 0.5 will mean the signal amplitude is 0.5 volts)
4. Set the frequencies to 50 Hertz
5. Switch to oscilloscope mode
Signal amplitude measurement:
1. Button under the inscription measure choose the mode HZ and Volts, tick the labels frequency and voltage. At the same time, the current frequencies for each of the two signals (almost 50 hertz) appear on top of us, the amplitude of the total signal vp-p and effective signal voltage Veff.
2. Button under the inscription measure choose the mode Cursors and tick the box Voltage. In this case, we have two horizontal lines, and at the bottom of the inscription, showing the amplitude of the positive and negative components of the signal ( BUT), as well as the total range of the signal amplitude ( dA).
3. We set the horizontal lines in the position we need relative to the signal, on the screen we will receive data on their amplitude:
Measurement of time intervals:
We perform the same operations as for measuring the amplitude of the signals, with the exception - in the mode Cursors tick the label Time. As a result, instead of horizontal lines, we will get two vertical lines, and below the time interval between the two vertical lines and the current signal frequency in this time interval will be displayed:
Determining the frequency and amplitude of the signal
In our case, there is no need to specifically calculate the frequency and amplitude of the signal - everything is displayed on the oscilloscope screen. But if you have to use an analog oscilloscope for the first time in your life and you don’t know how to determine the frequency and amplitude of the signal, we will also consider this issue for educational purposes.
We leave the generator settings as they were, with the exception of setting the signal amplitude to 1.0, and setting the oscilloscope settings as in the picture:
We set the signal amplitude control to 100 millivolts, the sweep time control to 50 milliseconds, and we get a picture on the screen as from above.
The principle of determining the signal amplitude:
Regulator Amplitude we are in position 100 millivolts, which means that the vertical division of the grid on the oscilloscope screen is 100 millivolts. We count the number of divisions from the bottom of the signal to the top (we get 10 divisions) and multiply by the price of one division - 10*100= 1000 millivolts= 1 volt, which means that the amplitude of the signal we have from the top to the bottom is 1 volt. In the same way, you can measure the signal amplitude in any part of the waveform.
Determination of the temporal characteristics of the signal:
Regulator Time we are in position 50 milliseconds. The number of divisions of the oscilloscope scale horizontally is 10 (in this case, we have 10 divisions on the screen), we divide 50 by 10 and get 5, which means that the price of one division will be equal to 5 milliseconds. We select the section of the signal waveform we need and consider how many divisions it fits (in our case, 4 divisions). Multiply the price of 1 division by the number of divisions 5*4=20
and determine that the period of the signal in the area under study is 20 milliseconds.
Determining the signal frequency.
The frequency of the studied signal is determined by the usual formula. We know that one period of our signal is 20 milliseconds, it remains to find out how many periods there will be in one second - 1 second/20 milliseconds= 1000/20= 50 Hertz.
Spectrum analyzer
Spectrum analyzer– a device for observing and measuring the relative distribution of the energy of electrical (electromagnetic) oscillations in the frequency band.
Low Frequency Spectrum Analyzer(as in our case) is designed to operate in the audio frequency range and is used, for example, to determine the frequency response of various devices, in the study of noise characteristics, and tuning various radio equipment. Specifically, we can determine the frequency response of the assembled audio frequency amplifier, adjust various filters, etc.
There is nothing complicated in working with a spectrum analyzer, below I will give the purpose of its main settings, and you yourself, by experience, will easily figure out how to work with it.
This is what the spectrum analyzer looks like in our program:
What is here - what:
1. View of the analyzer scale display vertically
2. Choice of displayed channels from the frequency generator and display type
3. Working part of the analyzer
4. Button to record the current state of the waveform when stopped
5. Working field enlargement mode
6. Switching the horizontal scale (frequency scale) from linear to logarithmic
7. Current signal frequency when the generator is in sweep mode
8. Current frequency at cursor position
9. Signal harmonics indicator
10. Setting the filter for signals by frequency
View Lissajous Figures
Lissajous figures- closed trajectories drawn by a point that simultaneously performs two harmonic oscillations in two mutually perpendicular directions. The shape of the figures depends on the relationship between the periods (frequencies), phases and amplitudes of both oscillations.
If applied to the inputs " X" and " Y» oscilloscope signals of close frequencies, then you can see Lissajous figures on the screen. This method is widely used to compare the frequencies of two signal sources and to tune one source to the frequency of another. When the frequencies are close, but not equal to each other, the figure on the screen rotates, and the cycle period of rotation is the reciprocal of the frequency difference, for example, the rotation period is 2 s - the difference in the frequencies of the signals is 0.5 Hz. If the frequencies are equal, the figure freezes motionless, in any phase, however, in practice, due to short-term signal instabilities, the figure on the oscilloscope screen usually trembles a little. You can use for comparison not only the same frequencies, but also those that are in a multiple ratio, for example, if the exemplary source can produce a frequency of only 5 MHz, and the tunable source - 2.5 MHz.
I'm not sure that this function of the program will be useful to you, but if you suddenly need it, then I think that you can easily figure out this function on your own.
Audio signal recording function
I have already said that the program allows you to record any sound signal on a computer for the purpose of further study. The signal recording function is not difficult and you can easily figure out how to do it:
An application that allows you to transmit sound of different frequencies through several channels is indispensable when setting up professional music systems.
Sound frequency generator - the name of the program speaks for itself. There is another name for the application "Sound Generator". The system allows you to transmit sound with the additional ability to customize the characteristics of the signal. An important plus of the application is the ability of multi-channel sound transmission. When the generator is turned on, nine separate panels light up with the function of possible frequency settings for each channel. Their location can be changed or fixed in the desktop area.
Application characteristics
The sound application is compatible with both 24 and 32 bit cards, and the sampling rate must be 384 kHz. It is possible to transmit noise and harmonic sinusoidal signals. It is easy to change the sound phases by mechanically switching the system. Often these functions are used when using professional equipment.The audio frequency generator is a narrowly focused application. This is due to the following features:
- The frequency range is not limited, it depends on the technical capabilities of the sound system;
- the generator provides for the operation of two or more oscillators with the function of simultaneously changing the characteristics of sound transmission;
- playback modes of Brownian, white and pink noise are provided, as well as the transmission of amplitude modulation and sweeping frequency of electrical oscillations;
- the audio application has the lowest percentage of distortion;
- the processed sound can be saved to a computer.
D.I. HALTS:
The method is perverted, to be honest, I would quickly assemble a signal generator of the desired shape on R2R. But it happens that one is not there, then the other, but there is almost always some computer junk lying around.
Disclaimer:
I want to warn you right away that barbaric manipulations with the computer immediately cover the guarantee for iron with a fur organ, and with a small radius of curvature of the hands, the whole computer or important parts. If you doubt the firmness of your hand and your capabilities, then it is better to collect Frankenstein from the trash purely for experiments.
I needed to debug one device on an AVR microcontroller. More precisely, the reception of data from the ADC. When the signal of this data should be ultra-low frequency, on the order of 1 Hz. Oddly enough, it is quite difficult to receive a signal of such a frequency using regular means. The sound card has filters on the output that do not allow such a low-frequency signal to break through. According to this, a decision was made to upgrade the sound card.
In order not to take risks, it was decided to implement this on an external sound card. But this experience is also true for built-in sound cards, but it is worthy of the Jedi.
A sound card was bought on a hammer Sound Blaster Live. After a quick look, it became clear that it is impossible to understand the circuitry of a 4-layer board without good grass. But it is quite obvious that all output and input analog signals first go to the op-amp, and then to the DAC / ADC. Well, OU googled quickly. Then I turned my attention to the microcircuit, into which all the signals tentatively come. She was the second largest. I drove the label into Google, and lo and behold! Datasheet found!
Chip pinout.
We are interested in the line output of the DAC (underlined in red). I chose only the right channel. If someone decides to make an oscilloscope, then you will need to solder to the line input (blue rectangle). Of course, through the appropriate decoupling scheme (which is googled on the Internet).
In order not to burn the DAC with my hellish experiments, I decided to protect it a little. And I strongly recommend doing this.
soldered resistor
To output a signal from a computer, I used the VGA connector, which, by some miracle, lay in my desk. What is good about this wire: it has 5 separately shielded wires. I just put a wire on 1 pin (RED signal). Since the screens of all signals are connected to the ground and so, I did not bother with the output of the ground. Of course, ideally, you need to output the analog ground of the sound card (where it is, it looks in the datasheet on the same chip), but I was broke.
Installed zvukovuha, and the nest of our generator
As a generator, I use the primitive program "Tone Generator", which can be downloaded from here. It allows you to generate sine, saw, square wave, white noise and some strange signal.
Which is enough for my purposes.
After it was installed in the computer, I decided to use an oscilloscope to make sure that the generation was on, and I soldered it correctly.
Pure sine of our generator.
Well, the offset without a capacitor, my DAC is about 2 volts. Let's check how the ADC of my microcontroller eats.
Generator, and a program that reads the ADC values of the microcontroller.
Do not pay attention to the fact that the sine taken by the controller is so broken - there is a very small sampling rate.
To shift the zero point, as well as reduce the signal amplitude by half, you need to put one 10k resistor to ground. Thus, together with the resistor on the sound card, a voltage divider is formed.
For this, I take my leave, successful experiments.
