New RTL-SDR Receiver App for iOS Released

SDR Receiver on iOS Screenshot
SDR Receiver on iOS Screenshot

A new RTL-SDR compatible app for Apple iOS (iPhone, iPad) has recently been released on the Apple App store. The app is called "SDR Receiver", costs US$9.99, and is used together with an RTL-SDR (or Airspy HF+) server running on a separate networked device such as a Raspberry Pi or PC. Limitations by Apple mean that the RTL-SDR can not run directly on iOS  devices. The software description reads:

SDR Receiver, a new iOS app for RTL-SDR and Airspy HF+, is now available on the App Store. The app works with an RTL-SDR or Airspy HF+ that is attached to a host Mac, PC or Raspberry Pi running the rtl_tcp server or equivalent. The iOS device, which may be an iPhone or an iPad, communicates over the network with the host computer which may be anywhere on the network that is reachable by TCP/IP and that can sustain the required bandwidth. 

  • SDR Receiver demodulates AM, narrowband FM and wideband FM signals. Key features include:
  • Easily entered and managed lists of stations to simplify station selection.
  • Adjustable squelch that works for both AM and FM signals.
  • Adjustable LNA gain for RTL-SDR.
  • Adjustable audio high pass and low pass filters.
  • Signal strength indicator that shows power level in the signal passband.
  • Multiple sampling rates down to 240Ksps for RTL-SDR.
  • Sampling rate of 768Ksps for Airspy HF+.

Streaming from an RTL-SDR requires installation of the librtlsdr package including the rtl_tcp utility on the host computer. Streaming from an Airspy HF+ requires installation of server software on the host computer that supports the Airspy HF+ and that streams data according to the protocol used by the rtl_tcp utility. One such server has been made available by Ron Nicholson in source code form on GitHub.

Requires an RTL-SDR or Airspy HF+, a host computer and server software which are not provided with the application.

Another RTL-SDR client for iOS is "RTL_TCP SDR" by Ron Nicholson which we posted about back in March when it was still in beta testing. RTL_TCP SDR includes a spectrum analyzer and FFT display. SDR Receiver appears to have no spectrum display, so is mostly useful for listening to preset frequencies, whilst RTL_TCP SDR appears to be more useful for spectrum exploring.

14 comments

  1. Scott Harris

    Thank you so much Kertesz. I have the RTL2832U dongle. I will give this software a try. Thank you so much for the advice!

    • Kerteszradio

      Very welcome. Unfortunately nowadays we are sitting in the sunspot (sun activity cycle) minimum. In this period the sunspot number is below 70 so consequence this, the shortwave propagation is very poor. If the sunspot number increases above 70, the hf propagation will raise up.

  2. Scott Harris

    I bought and an RTL-SDR dongle because I wanted to use it to listen to shortwave radio stations. Can someone please recommend the best basic Windows and Android app for SWL purposes? Thanks, SH

    • Kerteszradio

      Dear Scott ! I using under Win the HDSDR software (hdsdr.de) it easy, and informative. I don’t know what a type your dongle, but if rtl-sdr and not V3 need the hardware direct sampling mod. Besides, even if the RTLSDR v3 dongle (alu case,1ppm etc) on a bigger antenna (10-15m longwire) overload the receiver. The V3 dynamic range in direct sampling is poor. The best advice : buy SDRPlay RSP1A. This not cheap as the rtl-v3 but suitable a high gain efficient shortwave receiving. In fact, even the V3 is entry-level hardware, if you decide to serious swl need a better performance receiver. Example RSP1A. This is my experience.

      • Scott Harris

        Dear Kertesz, what ExtIO do you use. The SW keps telling me I am missing the ExtIO Dll and I do not know how to install it properly. Any tips? Thanks, SH

  3. hotpaw2

    The other iOS app (mine), “rtl_tcp SDR”, supports LSB and USB on HF (via Direct Sampling or using an upconverter). The rtl_tcp SDR app also includes a CW audio filter. (I forgot to mention both of those capabilities in the App Store description.) But it’s also around $10 (depending on country), currently. https://itunes.apple.com/us/app/rtl-tcp-sdr/id1351164646?ls=1&mt=8

    The spy-server protocol looks interesting, but it’s not fully documented to allow it to be re-written in Swift.

  4. Anonymous

    The other iOS app (mine), “rtl_tcp SDR”, supports LSB and USB on HF (via Direct Sampling or an upconverter). It also includes a CW audio filter. I forgot to mention both of those capabilities in the App Store description. But it’s also around $10 (depending on country), currently. https://itunes.apple.com/us/app/rtl-tcp-sdr/id1351164646?ls=1&mt=8

    The spy-server protocol looks interesting, but it’s not fully documented to allow it to be re-written in Swift.

  5. Rick

    Sadly it uses RTL-TCP. Way to slow over 3G/4g. No ssb either. Would pay that price only if it used spy-server and supported ssb on Hf

  6. Daniel

    Price is about right considering how many people will use this and efford used to code this app. I guess person who is laughing at price is working for free.

    Is there any android version?

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