KaikuSDR

Your receiver

KaikuSDR works with RTL-SDR dongles (for example the RTL-SDR Blog V3, V4 and V4 Lite), Airspy receivers (R2 and Mini), the Airspy HF+ (Discovery and Dual Port), the HydraSDR RFOne, the HackRF One, the bladeRF (2.0 and the first one), the Fobos SDR and the SDRplay RSPs (RSP1, RSP1A, RSP1B, RSP2, RSPduo, RSPdx and RSPdx-R2). Several receivers can scan side by side: the bands are shared between them, and while one of them stays on a transmission, the others of its kind sweep its other tunings too, so the whole band stays watched; they hand them back when it is free again. With no receiver, the app runs the demo.

RTL-SDR dongles ↑

A dongle is reached through rtl_tcp, a small free program that talks to the dongle and hands its signal to KaikuSDR. Getting it onto the computer is the only thing to do by hand; KaikuSDR starts and stops it for each dongle itself.

On a Mac

  1. Install rtl_tcp: with Homebrew, brew install librtlsdr in Terminal. Nothing else needs setting up: KaikuSDR finds it where Homebrew (or MacPorts) puts it. Kept somewhere else? Press Find rtl_tcp… under Add a receiver and point at it once: KaikuSDR remembers it.
  2. Plug in the dongle. In KaikuSDR, open Settings, and under Receivers press Add a receiver. The dongle is found, and KaikuSDR asks whether to start rtl_tcp for it, on a free port it offers (change it only if another program needs that port). Press Start rtl_tcp.

On Windows

Three things, each once per computer. KaikuSDR tells you which one is missing under Add a receiver, with the steps.

  1. The USB driver. Windows has no driver that lets a program use the dongle, so install one with Zadig, a free tool:
    1. Plug in the dongle. Download Zadig from zadig.akeo.ie and open it. When Windows asks whether it may make changes, answer Yes.
    2. In Zadig, open the Options menu at the top and choose List All Devices.
    3. In the list of devices, choose Bulk-In, Interface (Interface 0). Not Interface 1: that is the dongle's remote-control receiver, which is not needed. With several dongles the line appears more than once, and any of them will do; one installation covers all dongles of the same kind.
    4. Check that WinUSB is shown to the right of the green arrow, then press Install Driver (it may say Replace Driver). This takes about a minute. Close Zadig.
  2. rtl_tcp.exe. Press Get rtl_tcp.exe under Add a receiver. KaikuSDR downloads the RTL-SDR Blog's own Release.zip from github.com/rtlsdrblog/rtl-sdr-blog, checks that it is the right file, and keeps rtl_tcp.exe in a folder of its own; nothing else is installed or changed. Or get it by hand: download Release.zip (under Releases at github.com/rtlsdrblog/rtl-sdr-blog), right-click it in your Downloads folder and choose Extract All. KaikuSDR finds rtl_tcp.exe there by itself, beside the app, or in a folder of its own at the top of a drive such as C:\rtl (up to three folders down); nothing needs adding to the PATH. It only looks at the names of files in those folders, and nothing leaves your computer. Before starting it for a dongle, KaikuSDR shows which rtl_tcp.exe it found. Kept somewhere else? Press Find rtl_tcp.exe… (or Choose another… beside the one found) and point at it once: KaikuSDR remembers it, and uses it before any other.
  3. Microsoft's Visual C++ runtime, if the app asks for it. rtl_tcp.exe cannot start without it, and neither can speech detection or speech to text. Most computers already have it; if not, KaikuSDR shows a notice with a Download from Microsoft button: run the installer it fetches, then press Look again.

Then plug in the dongle (if it is not already), open Settings, and under Receivers press Add a receiver. The dongle is found, and KaikuSDR asks whether to start rtl_tcp for it, on a free port it offers (change it only if another program needs that port). Press Start rtl_tcp.

If Windows says Unknown USB Device in its own notifications, or KaikuSDR says it lists a USB device it could not start, unplug the dongle, wait a few seconds and plug it in again, straight into the computer rather than through a hub; then Look again.

If something is missing, Add a receiver says so: a dongle plugged in without rtl_tcp installed is named, with what to install, and Look again checks once more. Every other kind of receiver is spoken of the same way once it is plugged in.

KaikuSDR remembers your dongles, starts rtl_tcp for them again next time, and stops it when you quit. If it cannot, the receiver says why: the dongle not plugged in, another program using it, rtl_tcp not installed, or the port taken.

An rtl_tcp you start yourself (rtl_tcp -d 0 -p 1234), or one on another computer, works too: Add a receiver finds one running on your computer, or press Connect to an rtl_tcp server by its address… and type its address and port.

For shortwave (below 24 MHz) with an RTL-SDR Blog V3 and an antenna for it, set Direct sampling (shortwave) under Show advanced settings to Q branch. While it is on, only shortwave can be tuned: the bands above wait (the list says how many channels are out of reach), and your region's shortwave bands, the CW parts of the amateur bands, are offered in What to scan. Set it back to Off for everything else.

The RTL-SDR Blog V4 Lite has a newer tuner (the R828S) that only the updated rtl-sdr-blog driver knows: install that driver's rtl_tcp, and the dongle works like any other; its gain steps may differ a little from the ones the app shows.

Airspy ↑

Airspy receivers need libairspy, a small free library: on a Mac, brew install airspy in Terminal. Plug the Airspy in, then Add a receiver offers it by its serial number.

On Windows: from airspy.com's Windows package, install the Airspy USB driver, and place airspy.dll next to KaikuSDR.exe (or in a folder on the PATH). Then plug the Airspy in and press Add a receiver.

Airspy HF+ ↑

The HF+ Discovery and Dual Port need libairspyhf: on a Mac, brew install airspyhf. On Windows: from airspy.com, the HF+ USB driver, and airspyhf.dll placed next to KaikuSDR.exe or in a folder on the PATH. They tune shortwave (9 kHz–31 MHz) and the VHF bands (60–260 MHz), and nothing between. The gain slider is the HF+'s attenuator, under a switch for the device's own gain control, which is very good on shortwave; under Show advanced settings there is also the +6 dB preamplifier.

HydraSDR RFOne ↑

The RFOne needs libhydrasdr from hydrasdr.com. On Windows, from the same place: its USB driver, and hydrasdr.dll placed next to KaikuSDR.exe or in a folder on the PATH. It behaves like an Airspy R2 with a wider range, to 1.8 GHz, and is set up the same way: plug it in, then Add a receiver offers it by its serial number.

SDRplay RSP ↑

An RSP needs SDRplay's own API software, free from sdrplay.com: it installs a small service that runs in the background and that KaikuSDR talks to. KaikuSDR does not bundle it, because SDRplay's licence keeps it for their own devices; note that their service may report your device to SDRplay. Plug the RSP in, then Add a receiver offers it by its serial number. Its gain slider is the IF gain, in decibels; under Show advanced settings there is also the front-end gain step, the notch filters for broadcast FM and DAB, the antenna socket on an RSPdx or RSP2, and power to the antenna.

On Windows: the same API installer for Windows from sdrplay.com/api, which also installs the USB driver and sdrplay_api.dll where KaikuSDR looks for it.

An upconverter or downconverter ↑

With a converter in front of a receiver, such as a Ham It Up that moves shortwave 125 MHz up, set the receiver's Converter offset under Show advanced settings (125 for that one; a downconverter is a negative number). From then on the chart, the lists and the log show the frequency at the antenna, and the receiver is tuned that much higher.

HackRF One ↑

HackRF needs libhackrf: on a Mac, brew install hackrf in Terminal. On Windows: from the HackRF release on GitHub, hackrf.dll (and the libusb-1.0.dll beside it) placed next to KaikuSDR.exe, and the USB driver once with Zadig (choose WinUSB, as for a dongle above). Plug it in, then Add a receiver offers it by its serial number. Its one gain slider is in decibels; under Show advanced settings it also has an RF amplifier (+14 dB, for weak signals far from strong transmitters — the app asks first, because a strong signal nearby can then harm its input).

bladeRF ↑

bladeRF needs libbladeRF: on a Mac, brew install libbladerf. On Windows: Nuand's bladeRF installer from nuand.com, which installs bladeRF.dll, the USB driver and the FPGA images. It also needs its FPGA image, which KaikuSDR does not include: install Nuand's bladeRF software with the image for your board, or let the bladeRF load its image from its own memory (set up once with bladeRF-cli -L). Without it, the app says so and what to do.

Fobos SDR ↑

Fobos needs libfobos, RigExpert's free library for it (there is no Homebrew package): get it from the Fobos SDR's page at RigExpert. On Windows, from the same page: its USB driver, and fobos.dll placed next to KaikuSDR.exe or in a folder on the PATH. Then Add a receiver offers it by its serial number.

Settings for each receiver ↑

Under Receivers in Settings, each receiver is a row: what it is, what it is doing and what it scans, with a warning mark when something on its page wants doing. Press the row for the receiver's own page. All receivers takes you back.

The page starts with the receiver's status: its sweep rate, how much of its data is arriving, its strongest level, and the fix beside any trouble. Its settings follow, in groups:

  • Gain: how much it amplifies. Automatic gain (overload protection), on by default, turns the gain down when strong signals would overload the receiver, and back up when they are gone.
  • Frequency: the bandwidth, how much of the band it takes in at once (wider sweeps a band with fewer tunings), and the frequency correction (ppm).
  • Antenna: power to the antenna (bias tee; the app asks first, because it can harm equipment that is not made for it), and whatever else the receiver has there.

Show advanced settings brings out the rarely needed ones. Remove this receiver is at the bottom of the page, and asks first; the receiver's settings are remembered in case it is added again.

The guide's contents