iSDR 4+

A Software Defined Radio App

Digital Confections LLC

Designed for iPad

    • 2.7 • 10 Ratings
    • $0.99
    • Offers In-App Purchases



PLEASE READ THE ENTIRE DESCRIPTION BEFORE PURCHASING. iSDR is the first and only software-defined radio application compatible with the Apple iPhone®, iPod touch® and iPad™. iSDR is for experimenters and amateur radio enthusiasts looking to construct a truly portable software-defined radio receiver. Additional hardware is required to receive live signals. Currently, iOS devices will not work with RTL-SDR USB dongles, and they are not supported by iSDR.

PLEASE NOTE: Receiving live on-air signals using iSDR requires purchasing or constructing a "quadrature sampling detector (QSD)" RF front-end device, and connecting it between an antenna and the microphone input jack. Alternatively, iSDR can be used to implement a panadapter for use with a compatible radio receiver. Without a QSD RF front-end or a connected radio, iSDR will only play I/Q recordings of actual radio signals. Additional recordings can be loaded into the app using iTunes file sharing - some recordings are available free to download from the Internet. Visit the support web site for more information.

iSDR includes a sample I/Q recording featuring 30 seconds of a ham radio contest. This is for demonstration purposes only. It is not meant to fool you! It is to allow you to experience how the app works without having to do anything yourself: just turn it on. You can download and play your own files if you like. Please see the support page for details. AND PLEASE contact us directly if you experience any issues with using this app. We will respond promptly when provided with details.

When iSDR is used to receive live radio signals, receiver performance will depend largely on the quadrature sampling detector and antenna that you use.

iSDR is a software-defined receiver application for use on mobile handset devices and iPad. Despite its extreme portability, the app utilizes the same digital signal processing techniques found in PC-based SDR receivers. It does frequency domain filtering using a theoretical "brick wall" sinc filter algorithm to provide steep and deep bandpass filtering. iSDR doesn't utilize any DSP hardware but instead uses the iOS device's processor to implement DSP algorithms.


o Six receive mode settings: USB, LSB, CW, AM, FM* and Binaural.
o Selectable bandwidth settings for each mode.
o Signal strength meter covering 120 dB of dynamic range with peak and average power indication.
o Three AGC settings: fast, slow, and off.
o Three display modes: Spectrum, Waterfall and Oscilloscope.
o File sharing** supports downloaded audio-format spectrum files synced using iTunes.
o Most PCM file formats are supported, including .wav and .caf.
o Embed the center frequency in your file names and iSDR will automatically display the correct frequency!
o Tune quickly using a single touch to the display screen, or tune precisely using the rainbow tune bar.
o Change radio settings with a simple double-tap action to the red cursor, mode text, AGC indicator or signal grid!
o Up to 44.1 kHz of available spectrum bandwidth.
o Dimmable semi-log or linear spectrum grid (native Settings app only).
o Adjustable CW offset (native Settings app only).
o Monaural microphone input automatically adjusts the display to 22 kHz bandwidth.
o Automatically detects if external audio is available for receiving live signals (menu selectable).
o Reverse I/Q stereo input logic (menu selectable).

*FM mode is not supported for monaural signals, and will not appear as a mode selection unless stereo audio (live or recorded) is available. Narrowband FM only: 16 kHz or 11.2 kHz bandwidth.

Please contact Digital Confections with your questions and suggestions!

What’s New

Version 5.1

o Fixes a crash when using native Settings
o Provides WiFi functionality without in-app purchase
o Updates for iOS 9 and above
o Support for iPhone 11 and iPad Pro

Ratings and Reviews

2.7 out of 5
10 Ratings

10 Ratings

SignalRanger1 ,

Great beginning!

This is a fantastic idea for an app, and I am glad it's freeware! Some points for improvement:
1. The user interface needs to be more user friendly. For instance, trying to lock the frequency at a certain point almost always ends up affecting/moving the reception slider bar instead.
2. There should be a recording function.
3. The sound should play even when the app is minimized.
4. There ought to be an official front end that can be purchased separately for this app. It should be pre-built, tested for use with idevices, and should include an antenna. A separate antenna with a ferrite rod should be optional for good AM reception.

Keep up the good work!

InTruthIBelieve ,

Very useful!

Exactly what I was looking for. I plan to use this app with KX2, QCX, and QSX in the future. Although I currently have none of these radios, the demo file gives me a very good understanding of what this app can do. Mind blown with the sdr/dsp stuff.

Dr MonkeyBrains ,


This is junk. Will not work at all. Just get a blank black screen. Would like my money back

App Privacy

The developer, Digital Confections LLC, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.

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