KiwiSDR Review

KiwiSDR Review

The KiwiSDR is a 14-bit wideband RX only HF software defined radio created by John Seamons (ZL/KF6VO) which has up to 32 MHz of bandwidth, so it can receive the entire 10 kHz – 30 MHz HF spectrum all at once. However, it is not a typical SDR as you do not use or connect the KiwiSDR directly to your PC. Instead the KiwiSDR is a cape (add on board) for the Beaglebone single board computing platform. If you’re unfamiliar with the Beaglebone, it is a small computing board that is similar to a Raspberry Pi. The KiwiSDR is designed to be a low cost standalone unit that runs 24/7, connects to your HF antenna and internet network, and shares your 10 kHz – 30 MHz reception over the internet with up to 4 simultaneous users.

The KiwiSDRThe KiwiSDR

The KiwiSDR kit retails for $299 USD (Amazon) (Direct) (MassDrop), and with that price you get the KiwiSDR cape, a Beaglebone Green board, an enclosure, microSD card and a GPS antenna. If you already have a Beaglebone lying around, then you can purchase the KiwiSDR board only for $199 USD.

Because the KiwiSDR is a network SDR, instead of connecting it to your PC it connects to your home internet network, allowing you to access it from any computing device via a web browser. Direct access to the SDR is not possible (actually it seems that it is, but it’s not easy to do), and all the computing is performed on the KiwiSDR’s on board FPGA and Beaglebone’s CPU before being sent to the network. Thus raw ADC or IQ data is never touched by your PC, your PC only sees the compressed audio and waterfall stream. So a powerful computer is not required to run the SDR. In fact, a mobile phone or tablet will do just fine.

In comparison, a $299 USD wideband non-networked SDR such as the LimeSDR uses a 12-bit ADC and can do up to 80 MHz of bandwidth over USB 3.0. But even on our relatively powerful PC (i7-6700 CPU, Geforce GTX 970 and 32 GB RAM) the LimeSDR can only get up to about 65 MHz on SDR-Console V3 before performance becomes too choppy.

But the real reason to purchase a KiwiSDR is that it is designed to be shared and accessed over the internet from anywhere in the world. You can connect to over 137 shared KiwiSDRs right now over at sdr.hu which is a site that indexes public KiwiSDRs. To achieve internet sharing, the KiwiSDR runs a modified version of András Retzler’s OpenWebRX software. OpenWebRX is similar to WebSDR, but is open source and freely available to download online. The standard OpenWebRX is also designed to support the RTL-SDR. Of course if you don’t want to share your receiver over the internet you don’t have to, and you could use it on your own local network only.

Some applications of the KiwiSDR might include things like: setting up a remote receiver in a good noise free location, helping hams give themselves propagation reports by accessing a remote KiwiSDR while they are TXing, listening to shortwave stations, monitoring WSPR or WEFAX channels, education, crowd sourced science experiments and more.

Hardware

The KiwiSDR PCB plugs directly into the expansion ports of the BeagleBone PCB. On the KiwiSDR PCB is the FPGA which handles most of the DSP processing, two shielding cans which contain the HF and GPS RF front-ends, two SMA ports (one for a wideband HF antenna, and one for a GPS antenna), an Ethernet port, and a 2.1mm DC 5V power jack. There is also a terminal block connector for directly connecting a long wire antenna and ground to the unit.

There is no WiFi on the KiwiSDR so it must be connected to an Ethernet cable, although it is possible to use a cheap wireless Ethernet to WiFi adapter or router like a TP-Link N300 to connect it to WiFi. The KiwiSDR doesn’t require much network bandwidth, so WiFi connection speeds are more than adequate.

The GPS antenna is used together with the KiwiSDR’s onboard software GPS receiver which is used to enhance the frequency stability of the KiwiSDR.

The enclosure that comes with the kit is made of acrylic glass and metal end plates. It’s unfortunately quite a badly designed enclosure, and it’s very difficult to get the final piece of acrylic in (some bending is required) but it at least protects the electronics. John does write that a proper aluminum enclosure is in the works.

The ADC is a LTC2248 14-bit 65 MHZ chip, and it uses a standard non-TCXO oscillator as the clock. However, remeber that drift is not a problem as long as you have the GPS antenna connected which will compensate. The FPGA is a Xilinx Artix-7 A35 FPGA.

Heat generated does not seem to be an issue.

KiwiSDR Setup

The KiwiSDR is fairly easy to setup for personal use, but you will need some basic networking knowledge to get it to work over the internet.

When you receive the kit, the Beaglebone’s onboard memory should be already preloaded with the latest KiwiSDR firmware. The kit comes with an SDcard, but this card is only in case you accidentally mess something up and need to revert to the original software. To get going on your local network all you need to do is connect the KiwiSDR to an HF antenna, an Ethernet cable which is on your network and a 5V power supply. Then run the KiwiSDR scanner at kiwisdr.com/scan to auto-detect the device, and connect to it!

You can then later connect to YOURKIWISDRIP:8073/admin to access the admin page to control things like passwords, KiwiSDR owner info, what’s displayed on your KiwiSDR interface, your location, and set where or not you want to share your KiwiSDR publicly, or password protect the unit so only certain people can use it.

5V Power Supply

One minor issue is that the KiwiSDR takes 5V DC via a barrel connector which is on the KiwiSDR PCB. The DC power adapter also must be able to supply at least 1.5A. There is a standard microUSB connector on the BeagleBone PCB, but it not capable of powering the unit with enough current, so the 5V barrel connector is the only way to apply power. The KiwiSDR does not come with a DC power adapter so you will need to purchase your own 5V DC supply.

KiwiSDR recommend that a 5V linear power supply be used to avoid the noise caused by switch mode power supplies. Most power supplies that we’re used to (e.g. phone chargers) are switch mode supplies. Linear supplies are generally used by Audiophiles to power their audio equipment to avoid audio noise, and can be found quite easily on Aliexpress or eBay (an example supply – note that you need to specify to the seller what output DC voltage and what input AC voltage you require). They start at about $50 USD including shipping, so this is a potential additional expense. In our testing we did see a noticeable reduction in noise at around 1 – 5 MHz once we changed from switch mode to linear mode power supplies for both our active loop antenna and the KiwiSDR. The image below shows the difference during a daytime test.

Below are some pros and cons of the KiwiSDR:

Pros Cons
  • Wideband 0 – 30 MHz
  • 14-bits, not easy to overload with broadcast AM
  • Access from anywhere on your network or over the internet anywhere in then world
  • Up to 4 users can listen to the KiwiSDR at once
  • Relatively cheap
  • The developer is actively working on new features
  • No need to assign a dedicated PC server
  • No need for powerful PC hardware. Runs on mobile devices too.
  • Easy to use web software
  • Voice and music audio quality is not great thanks to compression
  • No recording functionality – can only listen live.
  • Software features and extensions still in infancy.

We recommend the KiwiSDR for people who are able to set up a good wideband antenna in an area with good reception and low RF noise, have a sufficient internet data plan, and want to share their excellent reception over the internet. But if you are only interested in DXing, or SWLing for long periods of time, then you might want to consider a regular HF capable SDR or radio as the sound quality will be a lot better. Of course the KiwiSDR can always be used as a supplementary radio, to help you listen while away from your main radios such as when at work.

The best way to decide if a KiwiSDR is for you is to head on over to sdr.hu and try out a few KiwiSDR receivers over the internet. Note that many of the KiwiSDRs that are shared are quite subpar in terms of their reception. This is not indicative of the KiwiSDR, but rather of the subpar antenna systems used. Also of course, most receivers will really only come alive at night local time, so check the time zones and locations first. The sdr.hu rating system also does not accurately reflect the best receivers. After searching for a while you should be able to find some with good reception.

Some recommended KiwiSDR receivers to try: https://www.rtl-sdr.com/a-review-of-the-kiwisdr-10-khz-30-mhz-wideband-network-sdr/

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