Valiance Backbone for CW - VBC -

Overview

VBC is a CW (Morse code) decoder for iPhone and iPad. It detects the carrier from audio received through the built-in microphone and decodes the signal. FFT-based signal detection is used to reduce false decoding caused by atmospheric noise, speech, beeps, and other non-CW sounds.

As of August 6, 2026, VBC reached a best ranking of No. 25 in the paid Utilities category for iPhone in Japan.

Example App Store ranking (2026/08/06)

Before You Start

Main Features

Decode Screen

Upper Display

• Cyan: Audio waveform
• Yellow: FFT / noise level
• Red: Threshold
• Operate the frequency display area to switch between automatic (AFRC) and manual (MFRC) frequency control.

Meaning of Decoded Characters

• Lowercase: Normal decode (example: cq)
• Uppercase: Recognized even though spacing was shorter than expected (example: CQ)
• ^Uppercase: Valid connected code (example: ^KN)
• [A/B]: Candidate display when connected characters are ambiguous (example: [CG/KP])

Main Buttons

• RUN / PAUSE: Resume / pause decoding
• RECORD / STOP: Start / stop recording
• FILTER / CENTER: Set decode bandwidth and center frequency
• SETTING: Settings screen
• MAIL: Send log by email
• SIZE: Change decoded text size

Settings

The settings screen has two pages. Swipe horizontally to switch pages.

• Peak search: Search for a signal peak and change the decode frequency
• Wait for Space Before Peak Search: Wait until a Morse-space interval is detected before performing peak search
• Automatic Speed: Automatically tracks CW speed
• Automatic Microphone Gain: Automatically adjusts input level
• Automatic Threshold: Automatically adjusts the threshold
• Signal Weak ↔ Strong: Adjust sensitivity toward weaker signals. Setting it too far toward Weak may also increase noise pickup.
• Noise reduction: Automatically detects and reduces the noise level
• Japanese Morse: Automatically switch between Japanese and International Morse
• Uppercase ↔ Lowercase: Switch the display style for normal decoded characters
• New Synchronization Method: Use the new synchronization method
• CW Signal Detection: Distinguishes CW signals from noise (ON recommended)
• Reduce CPU Load: Reduces graphics load for older devices
• DEFAULT: Restore factory defaults

Tone Display / Zero-In

Measures tone frequency and sound pressure level, and displays the offset from the center frequency by color.

• Green: Center
• Blue: Within ±5 Hz
• Yellow: ±10–25 Hz
• Red: More than ±30 Hz

You can set the zero-in frequency with the picker view. It can also be used to check callback frequencies when a DX station is operating split (UP).

Calibration / Frequency response measurement

VBC can compensate for the frequency response of your transceiver, speaker, or headphones. In addition to the FLAT / SPK / HEAD presets, you can save your own measured response in CAL1 through CAL3.

1. Select CAL1, CAL2, or CAL3.
2. Slowly vary the CW pitch or receive frequency to sweep the target frequency range.
3. When measurement is complete, press "Save CAL".
4. If decoding becomes worse, compare with FLAT and perform the measurement again.

Email / Recorded Files

• Tap the recipient field to enter an email address. You can also select an address from Contacts.
• Recorded files are displayed newest first. After selecting a file, choose one-time playback or repeat playback.
• Use the trash button to delete a file and the information button on the right to manage file information.
• Very large logs can slow down the app, so delete unnecessary log data when appropriate.

VBC Ver 1.60 – Main Changes

New Features / Content

• Added practice audio based on an actual radio contact
• Official iPad support
• Expanded font-size settings to up to four levels
• Added a development support menu

Usability / UI

• Moved log sending to the toolbar for faster access
• Added a send-complete message
• Recorded files are now shown newest first
• Selected file is highlighted with a blue background
• Improved scrolling through past logs while decoding
• Increased help text size
• RUN button is now shown only when needed
• Redesigned the UI for settings, calibration, text-size control, and related functions

Latest Device Support / Fixes

• Optimized layout for newer iPhones with a notch and no Home button
• Added app icon sizes for current device requirements
• Fixed incorrect storage destinations for CAL1–CAL3
• Fixed an issue where peak detection failed when Filter was set to None

Support / Reference Videos

For bug reports or feature requests, contact vbc@noble-system.com.

• Actual QSO with a DX station (YouTube)
• Tone Frequency Measurement Accuracy (YouTube)
• Callback Frequency Check (YouTube)

SECoreTextView is used for text display to support iOS 8 and later. Created by kishikawa katsumi. Copyright (c) 2013-2015 kishikawa katsumi.

Direct Connection Without Using the iPhone Built-in Microphone

This is an example configuration described in the original documentation.

• 1/6 W resistor, 1 kΩ
• 1/6 W resistor, 100 kΩ
• 10 kΩ linear potentiometer (B taper)
• ELECOM MPA-EHPS10BK (iPhone extension cable)
• Earphone jack

Connection Circuit

Lightning Adapter

Complete Connection Example