The volume slider has a range from -80dB to 0dB, which is currently devided into 100 steps -> 0.8dB per step.
I think it would be nicer to have a multiple of 80 for the number of steps,
e.g. 160 which would give 0.5dB steps or 240 for 1/3dB steps.

missing documentations for setting up a development environment

This will sound idiotic but I'm trying to fork this app for an custom project and I can't get it to build.

when I just open the project in a text editor of choice (vscode) intellisense and Linting does not work because

Main.java is not on the classpath of project sig-gen, only syntax errors are reported

When I try to run the gradlew.bat script I get this error:

Error: Could not find or load main class org.gradle.wrapper.GradleWrapperMain
Caused by: java.lang.ClassNotFoundException: org.gradle.wrapper.GradleWrapperMain

I know of the Android Studio from Google and installed it and opened the project in it. Besides it being ridiculously cpu expensive I could not figure out how to get it build or even just error highlighting (Linting) to work.
I'm kinda lost.
How do you build this thing?

missing documentations for code and variables.

the Main.java is of most interest to me so I'll take an example from there. more specific the processAudio method at the very end.

duty, t, K, f, level, q, l
what are the number ranges for these variables?
what do they represent?
why is there so much Pi involved?
what is the purpose of these cryptic one letter variables?
if f stands for frequency, what does frequency stand for? poor naming and no meaningful comments!

If I'd design this code I'd assume I get

• a buffersize
• a sampling rate
• audio volume level as a float ranging from 0 to 1
• the frequency as a float ranging from 0.1 to 25000
• and the duty cycle as a float ranging from 0 to 1

Then I iterate over the buffersize. using the sampling rate I can calculate the time step between each iteration and increment a global ms variable each time by that amount. that variable I then can use to calculate the waveforms.
The output audio samples are a float ranging from 0 to 1

I would greatly appreciate comments that describe the valid number range and purpose so that I don't have to reverse engineer the whole app (if I could get it to build in the first place) just to make a few tweaks.

I wanted to try a 440Hz but could not get there, the closer I could get was 440.05.
This is on a smartphone, so maybe with a tablet it's easier, anyway I've been hoping I could tap on the frequency indicator to enter a number with the on-screen keyboard. Just a feature request.

I love what you're making for music players, thank you !

http://uploadax.com/viewer.php?file=25073166318540372259.png
Hi
As you can see there is a big problem on gui
galaxy-tab-10.1 gt-p7500
And 4.1.2 ker3.1.10-cyanogenmod+

woud be a nice feature if the duty cycle of the square wave could be modified.

after the latest update, instead of the tuning buttons floating near the "mute" button, they now directly cover it up

It would be nice for it to keep the screen awake instead of this happening, but it would also be nice if the app can play signal while screen is off.

Perhaps a user setting could choose the behavior.

It's very jarring to have the tone start playing immediately and can annoy people around. I think it should be muted by default or not play a tone until the frequency is changed.

Can't play square wave。It is a fixed frequency of square wave, playing on the phone. According to your project, I extract the code.

As follows:

protected class Audio implements Runnable
{
protected static final int SINE = 0;
protected static final int SQUARE = 1;
protected static final int SAWTOOTH = 2;

protected int waveform ;
protected boolean mute;

protected double frequency;
protected double level;

protected Thread thread;

private AudioTrack audioTrack;

protected Audio()
{
    frequency = 270.0;
    level = 16384;
}

// Start
protected void start()
{
    thread = new Thread(this, "Audio");
    thread.start();
}

// Stop
protected void stop()
{
    Thread t = thread;
    thread = null;

    // Wait for the thread to exit
    while (t != null && t.isAlive())
        Thread.yield();
}

public void run()
{
    processAudio();
}

// Process audio
protected void processAudio()
{
    short buffer[];

    int rate =
            AudioTrack.getNativeOutputSampleRate(AudioManager.STREAM_MUSIC);
    int minSize =
            AudioTrack.getMinBufferSize(rate, AudioFormat.CHANNEL_OUT_MONO,
                    AudioFormat.ENCODING_PCM_16BIT);

    // Find a suitable buffer size
    int sizes[] = {1024, 2048, 4096, 8192, 16384, 32768};
    int size = 0;

    for (int s : sizes)
    {
        if (s > minSize)
        {
            size = s;
            break;
        }
    }

    final double K = 2.0 * Math.PI / rate;

    // Create the audio track
    audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, rate,
            AudioFormat.CHANNEL_OUT_MONO,
            AudioFormat.ENCODING_PCM_16BIT,
            size, AudioTrack.MODE_STREAM);
    // Check audiotrack
    if (audioTrack == null)
        return;

    // Check state
    int state = audioTrack.getState();

    if (state != AudioTrack.STATE_INITIALIZED)
    {
        audioTrack.release();
        return;
    }

    audioTrack.play();

    // Create the buffer
    buffer = new short[size];

    // Initialise the generator variables
    double f = frequency;
    double l = 0.0;
    double q = 0.0;

    while (thread != null)
    {
        // Fill the current buffer
        for (int i = 0; i < buffer.length; i++)
        {
            f += (frequency - f) / 4096.0;
             l += ((mute ? 0.0 : level) * 16384.0 - l) / 4096.0;
             q += (q < Math.PI) ? f * K : (f * K) - (2.0 * Math.PI);

           switch (waveform)
            {
                case SINE:
                    buffer[i] = (short) Math.round(Math.sin(q) * l);
                    break;

                case SQUARE:
                    buffer[i] = (short) ((q > 0.0) ? l : -l);
                break;

                case SAWTOOTH:
                    buffer[i] = (short) Math.round((q / Math.PI) * l);
                    break;
            }
        }

        audioTrack.write(buffer, 0, buffer.length);
    }

    audioTrack.stop();
    audioTrack.release();
}

}
Direct calls in the project：

@OverRide
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

        audio = new Audio();
        audio.start();
        if (audio != null)
            audio.waveform = Audio.SQUARE;
    }
}

The sound of the play is not like the sound of square wave. I don't know where there's a mistake.
And the sound of the play is not always there, and it stops for a moment.

that would be better aligned with our loudness perception

my interface is not very nicely shown. the buttons overlap each other. the numbers are superimposed.

Signal Generator 1.22 (122) F-Droid
Andrion 9.0
Xiaomi Redmi Note 7

There are some buttons which I assume have a connection to the setting but the setting doesn't change anything and no matter what I chose, it turns out deactivated if I return to the main screen and go back to the settings.

Malwarebytes Anti-Malware detects this app as a Trojan.BankBot.rn

I have Android 12 and it works well on Android 11 but breaks up and loses volume on Android 12.
Great app.

Hi. I just upgraded to the latest version via f-droid and now the interface is broken, making the app pretty much unusable. See screenshot. I am running cyanogenmod ob a samsung galaxy S3. Let me know if there's any other relevant info you need 🙂

Please add support for icon shape
https://developer.android.com/guide/practices/ui_guidelines/icon_design_adaptive.html
https://material.io/guidelines/style/icons.html

Malwarebytes 2.1.1.6 (for Android) with the latest database is reporting that Signal Generator 1.10 has a virus (see screen below). I assume that is a "false positive" but can you look into this? I downloaded Signal Generator 1.10 from f-droid.org .

Hi Bill

Been using your app for a while. Thanks for the dial knob interface.

Do you think you can implement pulse width modulation with adjustable duty cycle.

Typical use case to test an electric motor with a headphone jack plugging into the motor driver.

Pwm duty cycle from as close to 1% to 100% with a slider of dial, if doable.

Will keep tracking your app.

I've been asked by trumpet teacher to buzz a target note, tuning to something.
Signal generator would be great for this, but I don't know note frequencies by heart so I thought it would be great to have "bookmarks" for easily jump to preferred frequencies.

Bookmarks would probably be the most flexible way to deal with it, so there's no enforcement of any scale of tuning..

I like running the program in the background while I do other things. Unfortunately, after a couple minutes audio spontaneously stops. When I go back to the app, audio starts again.

Expected Behavior

The app should stop it's noise when making or receiving a Call. It should also stop making its noise when opening a media file.

Actual Behavior

It keeps making its noise irrespective of incoming or outgoing calls. It also interferes on audio and music

*Test Tools

• Operating system : Android 6.0
• Phone : Infinix hot s
• Signal Generator App version 1.15

How to produce the bug

Open the app, Select any audible frequency, minimise the app and place a call. It would stop its noise for few seconds and start again to interfere with the call

Recording of the bug is shown below......

https://youtu.be/ZaIL2WbldQM

Hi Bill,

Congratulations for this excellent app! It's the only one I could find that changes pitch in real time; also logarithmically, and without artifacts.

One awesome accidental feature that worked up til version 1.06 was the possibility to extend the frequency range beyond the limits of the rotary knob by using the left and right arrow buttons above it.

This was very useful for temporal and rhythmic applications by using the squ and saw tones which click like a metronome at very low frequencies. Also excellent for hearing the transition between the temporal and spectral characteristics of sound. Unfortunately, this feature was lost (or fixed) after version 1.06.

How about extending the frequency range down to around 1 BPM = 0,01667 Hz, the slowest tempo which, according to some, can hold human attention? Maybe make this into an option in the Settings menu which will activate both the frequency knob and arrow buttons?

Thank you in advance!
Bo C-sen

Title says it: for example, macrodroid script sends and intent to this app to change frequency generated.

I need gen 270Hz square wave. i define waveform = 1 and frequency = 270.0, but it play bad wave. Where did I make a mistake?
MyApplication.zip

I get a warning from malwarebytes that the app got recognized it as a trojan.

The app doesn't show any controls. It's blank.

Attempting to play waveforms containing harmonics with frequencies above the Nyquist rate results in aliasing. The output will lose it's intended form.

To reproduce, choose a waveform other than sine, set the frequency to around 10Khz, and slowly increase it via the knob. You will will hear weird sounds being produced due to this phenomenon.

One possible solution would be to band-limit the generated waveform before handing the signal to the system, using a low pass filter.

https://www.reddit.com/r/fdroid/comments/g7qoyp/signal_generator_apk_malware/

I've gotten used to the idiosyncratic interface of sig-gen, but after trying to show it to another person, I think it could use some improvement.

Currently tapping on the displayed frequency does nothing. It should pop up the dialog asking to enter the frequency directly.

Also, there is a hollow rectangle icon which confuses people. They think it is a glyph representing a phone screen. I suggest removing the rectangle icon once tapping on the frequency works.

Using Signal Generator 1.30 (via FDroid) I noticed quite severe power usage -- see the attached screenshot.

Watching videos for 10 hours takes ~5% of the battery, but 2 mins of sig-gen 23%? I guess there's something amiss.
Do you re-calculate the waveform a million times a second or so?

Please add a changelog link to fdroid repository. Thanks

There's some random extra buttons

I created bookmarks for 30 and 40 Hz. I expected that I could use the left and right arrows to move between them, the same as with any other bookmark. Left arrow works. However, when I am at 30, the right arrow does nothing and the frequency stays at 30.

Likewise, with a bookmark at 25 Hz, I cannot use the right arrow to go from 25 to 30 Hz.

The problem does not occur for bookmarks over 10 Hz apart. (For example, 29.99 to 40 Hz).

Thank you for this extremely handy tool! Just the other day I found a new use for it: teaching a young nephling the difference between audio waveforms.

Please follow the system theme.

hi bill,
thanks for your signal generator. i am sorry this is more a feature request, since i din't kjnow how to contact you. i would like to play around with it a bit to try reduce my tinnitus with it. as i understand it therefore it would be necessary to change/revert the phase of the sinus signal. maybe you are interested in that. regards!