# RST Decoder Pro2 — Morse Decoder App for iPad

> Morse code decoder and practice app for iPad with advanced signal processing. (iPhone/iPad app by koji kamogawa.)

- Source: https://appshunter.io/ios/app/rst-decoder-pro2/id1525088013 (this page in markdown: same URL + `.md`)
- Developer: [koji kamogawa](https://appshunter.io/developer/1488210713)
- Category: Education, Utilities
- Price: $2.99
- Rating: 1.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 6 MB
- Languages: American English, Japanese
- Released: 2020-07-26
- Data updated: 2026-06-10
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/rst-decoder-pro2/id1525088013/reviews.md

## What is RST Decoder Pro2?

This is an App that decodes Morse code input from the microphone of iPad.
It is a Morse practice App that you can use to check if you are keying the correct code.
Signals with good S/N can be decoded correctly, but signals with bad S/N cannot be decoded correctly.
Also, the performance will be degraded for extremely slow or fast signals.
Usually about 5 to 10 characters are required for speed synchronization of Morse Code.
Adjust the input signal so that the peak value changes from level 6 to level 7.
Make fine adjustments to each parameter according to the reception status.

[Additional Functions]
-In addition to the decoder using BPF, a new decoder using FFT has been added so that it can be switched according to the usage.
-AFD (Auto Frequency Detector) function has been added to the decoder using BPF, and BPF can be set automatically by pressing the AFD button.
-The decoder using FFT automatically follows the strongest signal in the band by AFD (Auto Frequency Detector) and AGC (Auto Gain Control). You can also hold the AFD / AGC parameters by pressing the Lock button.
* There will be a time lag of about 1 to 2 seconds for AFD tracking.
* The Pro version also supports waterfall display.

[Control parameters]
1.Language select English and Japanese(KANA)
2.Audio Input Level
3.BPF ON/OFF
4.BPF of Center Frequency
5.BPF of Band Width
6.BPF of Shape
7. Notch ON/OFF
8. Notch  Frequency
9.CW Speed Control ON/OFF
10.CW Speed Control Low, Mid1, Mid2 or High
11.Delete All Decoded Text
12Realtime CW Signal Display
13.Input signal recording function.
14.Playback function from the file list.
15.Support the Garbage Data reduction function

[Note]
Since the signal after BPF is output to the audio output, it can also be used as an AF-CW filter.

[URL of this App(Free version)  working example video]
The GUI is slightly different, but the basic functionality is the same.
https://youtu.be/Pwp7W4m-m34

## Key features

- Morse code decoding via microphone
- BPF and FFT decoding methods
- Auto Frequency Detector (AFD)
- Auto Gain Control (AGC)
- Adjustable control parameters
- Real-time signal display
- Input signal recording and playback

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/rst-decoder-pro2/id1525088013/reviews.md

### 1/5 — Does not work on iPad Pro 12

*2023-05-20, version 2.0.0*

This app does not even start correctly on iPad Pro 12.

**Developer response:** Sorry, I found bugs. I will fix.
Is it now working properly? We are looking forward to your report.

## Frequently asked questions about RST Decoder Pro2

### What is RST Decoder Pro2?

RST Decoder Pro2 is an application designed to decode Morse code signals received through an iPad's microphone. It also functions as a practice tool to help users verify their Morse code keying accuracy.

### How does RST Decoder Pro2 decode Morse code?

It utilizes two primary decoding methods: a Band Pass Filter (BPF) and Fast Fourier Transform (FFT). The app allows users to switch between these methods and offers features like Auto Frequency Detector (AFD) and Auto Gain Control (AGC) for improved signal acquisition.

### What parameters can be adjusted in RST Decoder Pro2?

Users can adjust various parameters including language selection (English and Japanese), audio input level, BPF settings (ON/OFF, center frequency, bandwidth, shape), notch filter settings, CW speed control, and options to delete decoded text.

### Does RST Decoder Pro2 support recording and playback?

Yes, the application includes an input signal recording function and a playback feature from a file list. This allows users to save and review received Morse code signals.

### What are the system requirements for RST Decoder Pro2?

RST Decoder Pro2 is designed for iPads and has an age rating of 4+. It was last updated on May 25, 2023, with version 2.2.1.

### What is the price of RST Decoder Pro2?

RST Decoder Pro2 is a paid application, priced at $2.99. There are no in-app purchases or advertisements associated with this version.

### How accurate is RST Decoder Pro2 with different signal qualities?

The app can decode signals with good signal-to-noise (S/N) ratios correctly. However, performance may degrade with signals that have poor S/N, or are extremely slow or fast. Approximately 5 to 10 characters are typically needed for speed synchronization.

### Does RST Decoder Pro2 have ads?

No, RST Decoder Pro2 does not contain advertisements. It is a paid application that offers a clean, ad-free experience for its users.

## Version history (last 5 releases)

### 2.2.1 — 2023-05-25

Re-relase by using Xcode 14 version.

### 2.0.0 — 2023-02-15

I reviewed the parameter of the decoder part and improved the performance.

### 1.8.0 — 2023-02-05

Fixed a bug in slider processing.
It corresponds to the screen size of iPad Pro 12.9.
Fixed the app icon.

### 1.7.0 — 2021-11-14

Changed the space character insertion logic.
Added the garbage reduction function.

### 1.6.0 — 2021-11-04

-In addition to the decoder using BPF, a new decoder using FFT has been added so that it can be switched according to the usage.
-AFD (Auto Frequency Detector) function has been added to the decoder using BPF, and BPF can be set automatically by pressing the AFD button.
-The decoder using FFT automatically follows the strongest signal in the band by AFD (Auto Frequency Detector) and AGC (Auto Gain Control). You can also hold the AFD / AGC parameters by pressing the Lock button.

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## More apps by koji kamogawa

- [UkeDrum](https://appshunter.io/ios/app/ukedrum/id1488210714)
- [RST 599](https://appshunter.io/ios/app/rst-599/id1488919851)
- [WabunMorse](https://appshunter.io/ios/app/wabunmorse/id1490745806)
- [音耳せん](https://appshunter.io/ios/app/id1496478545)
- [RST 599 Pro](https://appshunter.io/ios/app/rst-599-pro/id1497452984)
- [RST 599x](https://appshunter.io/ios/app/rst-599x/id1498597799)

All apps by koji kamogawa: https://appshunter.io/developer/1488210713

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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 2026-06-10.*