Sputnik! vs SDR
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Sputnik!
Track the International Space Station and bright satellites with precise timing and location data. Get second-by-second countdowns, set reminders, and view satellite paths in the night sky. Supports offline calculations and sharing sightings.
- Accurate satellite and ISS sighting predictions
- Starlink satellite train detection
- Second-by-second countdowns
- Sighting reminders
- Compass direction and elevation display
- Night sky path visualization
- Offline calculations
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Sputnik! is an easy to use tool for predicting when the International Space Station will pass by your location or when a bright satellite will be visible in the skies above. Sputnik! features: - Predictions of satellite and ISS sightings accurate to the second. - Detection of Starlink satellite trains. - Second by second countdown to the satellite sighting. - Set reminders of upcoming satellite sightings. - Displays compass direction and elevation for your device to easily find the part of the sky where the sighting will occur (requires capable device). - Rotate your device to landscape orientation to show exactly where the satellite will pass in the night sky. - Share sightings via Twitter, Facebook, Mail, Messages and others. - Automatic download of up to date satellite orbital data. - Offline calculations, no need to be connected to the internet once orbital data has been downloaded. - Input your location automatically by GPS, select from a map or enter coordinates manually. - Save your favorite places for easy access. - Audio cues for the last seconds before the satellite passes by. Sputnik! on Apple Watch: - Easily find the next and last sighting at your current location. * Sputnik! is ad-supported *
SDR
Control your Icom transceiver remotely or locally from your iPhone. Operate in all modes, log QSOs, and utilize integrated digital modes like FT8/FT4 and SSTV. No extra hardware is needed for global access.
- Remote transceiver operation
- All mode control
- Auto logging logbook
- Integrated FT8/FT4 tool
- Integrated SSTV receiver
- Integrated CW decoder and keyer
- DX-Cluster integration
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Software Defined Radio Client for Icom Transceivers and your iPhone SDR-Control Mobile is a full featured iPhone App to operate your Icom Transceiver at home or from around the world without additional Hard- or Software. Important: This App requires one of the following Icom Transceivers: IC-705, IC-7610, IC-9700, IC-7760 or the IC-R8600 Receiver or the new IC-7300 MK2 FACTS AND FEATURES: ■ Native iOS 26 app, backward compatible to iOS 17 ■ Compatible with any iPhone ■ Complete operation of your Icom Transceiver in all modes ■ Use the App local or to remote access of your Transceiver from any place without additional Hard- or Software ■ Logbook with auto logging, ADIF Im-/Export ■ UDP Log submission when using external logging software ■ Integrated full featured FT8 / FT4 Tool ■ Integrated SSTV receiver (NEW) ■ Integrated CW Decoder ■ Integrated CW Keyer ■ DX-Cluster integration ■ Call sign lookup integrated ■ Displays Calls on Map with heading and distance information ■ And much more... WHAT YOU NEED: - An Icom IC-705, IC-7610, IC-9700 or IC-7760 Transceiver or IC-R8600 Receiver or the new IC-7300 MK2 - The Transceiver needs to be connected to your Network (WiFi or LAN) - No USB cable needed or supported - An iPhone that runs at least iOS 17 Find out more here: https://ham-radio-apps.com Read the Manual: http://go-to.me/sdrcontrol-mobile-manual
Screenshots
Verdict
The clearest difference is price: Sputnik! at Free against SDR's $44.99. Sputnik! also leads on rating (4.7 vs 4.5) and ratings volume (731 vs 64). SDR's advantage is in-app purchases (none vs 1) and update cadence (every 2 weeks vs every 5 months). On ads 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
Sputnik! is free to download; SDR costs $44.99 up front. Sputnik! sells 1 one-off in-app purchase. SDR asks for nothing beyond the download.
Sputnik! holds the better App Store score, 4.7 against 4.5. That said, the two scores are not equally well evidenced: Sputnik! has 731 ratings behind it against 64, so its average is the more settled of the two. Written reviews point the same way: 92% of Sputnik!'s written reviews are positive against 84% of SDR's.
Sputnik! ships an update every 5 months, SDR every 2 weeks. The most recent releases landed on October 15, 2026 and October 11, 2026 respectively.
| Parameter | Sputnik! | SDR |
|---|---|---|
| Price | Free — better | $44.99 |
| Rating | 4.7 (731 ratings) — better | 4.5 (64 ratings) |
| Positive reviews | 92.2% of reviews — better | 84.1% of reviews |
| Number of ratings | 731 — better | 64 |
| Update frequency | Every 5 months | Every 2 weeks — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Ad-supported — better | Paid |
| Devices | iPhone, iPod, Apple Watch — better | iPhone |
| Requires iOS | 14.0 — better | 17.6 |
| Further details — not scored | ||
| Size | 35 MB | 47 MB |
| Age rating | 4+ | 4+ |
| Developer | Applicate Ltd | Marcus Roskosch |
Customer experience
Sputnik!
SDR
User reviews
Sputnik!
From 731 App Store ratingsWhat we love
- 🚀 Accurate satellite tracking
- 👍 Easy to use interface
- 🔭 Supports tracking of various satellites (ISS, Hubble, Starlink)
- ⏰ Provides countdown and reminders for sightings
Room to improve
- 🐛 App not working/crashing for some users
- 🔍 Unclear information about satellite visibility (e.g. what 'enters Earth's shadow' means)
- 🔧 Difficulty updating satellite data
- 🙈 Dark mode text visibility issues
SDR
From 64 App Store ratingsWhat we love
- 🚀 Works perfectly with ICOM radios
- 👍 Intuitive and easy to use
- 🌟 Feature-rich and comprehensive
- 💯 Stable and reliable performance
- 📱 Great for remote operation
Room to improve
- 🐛 FT8 decoding issues (lower signal levels)
- 🐛 Dialogs do not scale with larger text setting
- 🐛 UI elements can be cramped on iPhone
- 🐛 Some buttons are small and hard to press
- 🐛 Frequency display overlaps buttons
Bugs and requests
Sputnik!
Reported bugs
3 issues- App reporting 'No Sightings' for all categories
- Null check errors when selecting satellite sightings
- Issues with location settings and data updates
Requested features
4 requests- Add support for more satellite types
- Improve sky chart visualization and orientation
- Provide filtering options (e.g. by elevation, magnitude)
- Implement automatic data updates
SDR
Reported bugs
12 issues- Dialogs do not scale with larger text setting
- Frequency display overlaps buttons
- FT8 decoding issues (lower signal levels than WSJTX)
- App crashes and leaves radio in transmit
- Logbook export not functional after update
Show 7 moreShow fewer
- Function button for horizontal scrolling not fully displayed
- FT8 decode is useless and unreliable
- Messed up radio, requiring reset
- RX audio unusable outside home network (prior to 1.5.1)
- Struggles with audio RX packets on remote cellular networks
- Cannot work over mobile data with certain carriers (EE)
- FT8 alerts sound but don't display
Requested features
14 requests- Develop for IC-7800
- CarPlay support
- Apple Watch add-on
- Windows version
- JS8call support
Show 9 moreShow fewer
- More digital modes
- Display memory bank names
- Initiate memory scan from app
- WSPR implementation
- Tool for WSPR
- More FT8/FT4 features (e.g., setting transmit frequency directly in FT8 view)
- Send image to unit
- KISS TNC support
- Control digital modes (reflectors, etc.)
In-app purchases
Sputnik!
- Go ad-free$0.99
SDR
No in-app purchases









