# Godafoss Audio Spectrum Waterfall QRSS CW FSKCW

> Audio spectrum waterfall display for slow transmission signals. (iPhone/iPad app by Black Cat Systems.)

- Source: https://appshunter.io/ios/app/godafoss-audio-spectrum-waterfall-qrss-cw-fskcw/id912139024 (this page in markdown: same URL + `.md`)
- Developer: [Black Cat Systems](https://appshunter.io/developer/301047032)
- Category: Utilities, Music
- Price: $2.99
- Rating: 4.30/5 from 4 App Store ratings · 2 written reviews indexed
- Age rating: 4+
- Requires: iOS 6.0 · 1 MB
- Languages: American English
- Released: 2014-09-12
- Data updated: 2026-08-12
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/godafoss-audio-spectrum-waterfall-qrss-cw-fskcw/id912139024/reviews.md

## What is Godafoss Audio Spectrum Waterfall QRSS CW FSKCW?

Godafoss displays a waterfall of the audio spectrum, letting you view QRSS CW, DFCW, FSKCW, and other slow transmission speed signals. You can place your device’s microphone near the speaker or headphones of your radio to pick up the sound, or directly connect if you have an appropriate cable.

A frequency axis is displayed to the right or bottom of the screen, depending on the direction the waterfall is running.

You can pan the range of audio frequencies by touching the screen and sliding with your finger, in the same direction as the frequency axis.

You can also pinch and zoom to adjust the span of frequencies displayed, up to a maximum of 0 to 20 kHz.

If you don’t want to accidentally change the frequency range, tap the Lock button so it is highlighted. Panning and pinch/zoom will not affect the frequency range, so you don’t accidentally change them.

When first started, Godafoss defaults to an FFT size of 4K, with a Hanning window. You can change these and other settings by tapping the Setup button, and a set of controls will appear:

The first two are sliders that set the minimum and maximum audio levels for the waterfall colors. Adjust these to get the best looking display for the signals of interest. Often you want a blue background, the minimum dB slider should first be adjusted for this. Then adjust the maximum slider for the strongest signal, often it is desired to make this red or pink, but you have the flexibility to set it how you wish.

The FFT size sets the number of sound samples used to compute the spectrum. Higher values provide better frequency resolution, but update more slowly, and can smear faster signals.  

The window type controls what windowing function is applied to the data before the FFT is run. The window modifies the received audio data to reduce what is called “leakage” from non periodic signals. Leakage smears the signal over a wider frequency range. Experimentation will help you find he best settings. The following windows are available:

Rectangular
Hanning
Hamming
Tukey
Cosine
Lanczos
Blackman

Speedup allows multiple FFTs to be run on the same set of audio samples, shifted slightly in time, This can be useful when a larger FFT size is required, but the signal rate demands a faster update rate on the waterfall. A speedup of 1 means no speedup is applied, a speedup of 10 means that 10 FFTs are performed on each data sample. 

Finally, you can change the direction the waterfall runs, to the left, right, up, or down.

Note that making changes to any of these settings only affects newly received audio, previously received audio already displayed on the waterfall is not affected.

You can take a screenshot of the waterfall by tapping on it three times. The screen will flash to let you know the picture has been taken, and it will be saved to your Saved Photos album. Then you can share your received signals with your friends.

## Key features

- Waterfall audio spectrum display
- Adjustable frequency axis and zoom
- Lockable frequency range
- Customizable FFT size and window types
- Speedup for faster waterfall updates
- Screenshot capture and sharing

## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/godafoss-audio-spectrum-waterfall-qrss-cw-fskcw/id912139024/reviews.md

### 2/5 — It works but not for what it is need

*2021-06-16*

The audio cable function does not work

### 5/5 — Godafoss

*2016-08-10*

Works great and is not bloat ware! Less than a Meg in fact.

## Frequently asked questions about Godafoss Audio Spectrum Waterfall QRSS CW FSKCW

### What is Godafoss used for?

Godafoss displays a waterfall of the audio spectrum, allowing users to view slow transmission speed signals like QRSS CW, DFCW, and FSKCW. It helps visualize these signals by converting audio input into a visual representation.

### How does Godafoss receive audio?

You can place your device's microphone near a speaker or headphones of your radio to pick up sound. Alternatively, you can directly connect the device if you have a compatible audio cable.

### Can I adjust the frequency range in Godafoss?

Yes, you can pan the audio frequency range by touching and sliding the screen. You can also pinch and zoom to adjust the displayed frequency span, up to 0 to 20 kHz. A lock button is available to prevent accidental changes.

### What are the customization options for the waterfall display in Godafoss?

You can customize settings like FFT size, Hanning window, and speedup. You can also adjust the minimum and maximum audio levels for the waterfall colors to optimize the display for specific signals.

### How often is Godafoss updated?

The latest version, 1.1, was released on May 8, 2017. While not frequently updated, the existing features provide robust functionality for its intended purpose.

### What devices is Godafoss compatible with?

Godafoss is compatible with iPhones, iPads, and iPods. It is designed for iOS devices.

### Does Godafoss have ads?

No, Godafoss does not contain advertisements. As a paid application, it offers an ad-free experience for users.

### What is the price of Godafoss?

Godafoss is available for a one-time purchase of $2.99. This grants users full access to all its features without any recurring fees or in-app purchases.

## Version history (last 2 releases)

### 1.1 — 2017-05-08

This app has been updated by Apple to display the Apple Watch app icon.

Updates for iOS 10.3
Added Blackman Harris window

### 1.0 — 2014-09-12

No release notes.

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All apps by Black Cat Systems: https://appshunter.io/developer/301047032

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-12.*