iSDR vs ISS Detector
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
iSDR
This app allows experimenters and amateur radio enthusiasts to build a portable software-defined radio receiver using their iOS device. It processes radio signals using the device's processor and offers various display and filtering modes. Additional hardware is required for live signal reception.
- Six receive mode settings (USB, LSB, CW, AM, FM, Binaural)
- Selectable bandwidth settings
- 120 dB dynamic range signal strength meter
- Three AGC settings (fast, slow, off)
- Spectrum, Waterfall, and Oscilloscope display modes
- Supports downloaded audio-format spectrum files via iTunes
- Embed center frequency in file names for automatic display
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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. Features 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!
ISS Detector
Easily track the International Space Station and other satellites. Receive timely alarms before passes and get weather condition checks for optimal viewing. Enhance functionality with optional in-app purchases to discover more celestial objects.
- ISS tracking and alerts
- Weather condition checks
- Alarm notifications
- Track Starlink trains
- Track Hubble telescope
- Track amateur radio satellites
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Have you seen the International Space Station? It is visible with the naked eye! This is the easiest way to spot the station. ISS Detector will tell you when and where to look for the ISS. You get an alarm a few minutes before a pass. You will never miss it. ISS Detector will also check if the weather conditions are right. A clear sky is perfect for spotting. Premium will enhance the functionality of ISS Detector. With the subscription you can add many famous satellites and amateur radio satellites. See the Starlink satellite trains, Hubble space telescope, rocket bodies, Vanguard 1 and many bright satellites. Available categories in Premium: Radio Amateur Satellites: Track dozens of ham and weather satellites. Starlink: Track Starlink satellite trains. Famous Objects: Hubble Space Telescope, rocket bodies, bright satellites and more. Comets: Find comets in the night sky. You might need binoculars or a telescope to see them Planets: Find all the planets Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is price: ISS Detector at Free against iSDR's $0.99. ISS Detector also leads on rating (4.6 vs 2.5) and ratings volume (633 vs 11). iSDR's advantage is ads (none vs shown) and iOS requirement (9.0 vs 16.0). On review sentiment, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
ISS Detector is free to download; iSDR costs $0.99 up front. iSDR sells 1 one-off in-app purchase and ISS Detector sells 11 in-app purchases, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.
ISS Detector holds the better App Store score, 4.6 against 2.5. That said, the two scores are not equally well evidenced: ISS Detector has 633 ratings behind it against 11, so its average is the more settled of the two. Written reviews point the same way: 52% of iSDR's written reviews are positive against 55% of ISS Detector's.
iSDR ships an update every 3 months, ISS Detector monthly. The most recent releases landed on October 4, 2026 and October 15, 2026 respectively.
| Parameter | iSDR | ISS Detector |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 2.5 (11 ratings) | 4.6 (633 ratings) — better |
| Positive reviews | 51.7% of reviews | 55.1% of reviews — better |
| Number of ratings | 11 | 633 — better |
| Update frequency | Every 3 months | Monthly — better |
| Ads | No — better | Yes |
| In-app purchases | Yes | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 9.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 36 MB | 33 MB |
| Age rating | 4+ | 4+ |
| Developer | Digital Confections LLC | Derk Vrijdag |
Customer experience
iSDR
ISS Detector
In-app purchases
iSDR
- Wi-Fi Radio ControlFree
ISS Detector
- Premium Access2 variants$0.991 Month
- Donation$1.991 Month
- Premium Access$1.991 Month
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- Premium Access$2.991 Year
- Premium Access7 Days trial$5.991 Year
- Donation2 variants$5.991 Year
- Premium Access7 Days trial$11.991 Year
- Starlink and Famous objects$3.99
- Amateur Radio Satellites$3.99
- Comets and Planets$3.99
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- Combo package$5.99









