KiwiSDR Kickstarter Successfully Funded

Last month KiwiSDR started their fundraising campaign on Kickstarter. The kickstarter has now completed. The goal was to raise $50,000 USD and they have well surpassed that mark by reaching $70,757 USD. If you missed out on the Kickstarter then it is still possible to preorder by directly emailing the KiwiSDR team.

The KiwiSDR is a software defined radio with 30 MHz of bandwidth and a tuning range that covers 0 – 30 MHz (VLF to HF). It is intended to be a low cost web based SDR that can be accessed from all over the world via a browser interface. It is designed as a cape for the BeagleBone Black mini embedded computer, and uses a LTC 14-bit 65 MHz ADC and Xilinx Artix-7 A35 FPGA. It also has an integrated SDR based GPS receiver which is used to automatically compensate for any frequency drift from the main 66.6 MHz oscillator. It runs on the OpenwebRX web based software, which many RTL-SDR users have already been using to stream live radio to the web.

Right now the team is beta testing some sample boards and appears to be getting ready for the large production run.

In a previous post we mentioned that the KiwiSDR project had some ethical issues attached to it. The creator of the OpenWebRX software, Andreas, was upset over the fact that the KiwiSDR had forked his open source project and had said that they would not share any profits. However, it appears that KiwiSDR have now struck a deal with Andreas, with both sides being happy, thus resolving any ethical issues.

The latest KiwiSDR Board
The latest KiwiSDR Board
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RTL-SDR Blog Units Back in Stock + Polling on Future Upgrades

After a few delays our RTL-SDR blog TCXO/SMA/Metal Case units are back in stock at the Chinese warehouses. The restocking of Amazon USA will follow shortly, and they should be ready for purchase on Amazon by the end of next week. See our store for information on purchasing.

As some readers may know, we’ve been working on finding ways to improve upon and add features to the RTL-SDR’s we sell, whilst trying to maintain the attractive low cost. In previous batches we added upgrades such as a TCXO, bias tee, SMA connector and a shielded metal case with passive cooling. For future modifications we’d like to poll the community on what is most desired.

In the poll below please choose your top 3 desired improvements. If you desire something else please comment on this post. Thanks!

What RTL-SDR Improvements / Options / Products would you like to see in the future? CHOOSE UP TO 3.

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Our RTL-SDR Blog Unit
Our RTL-SDR Blog Unit
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Receiving up to 4.5 GHz with an RTL-SDR and a $5 Directv Downconverter

KD0CQ has recently been experimenting with trying to receive signals at frequencies of up to 4.5 GHz with an RTL-SDR and downconverter. Since a typical R820T/2 RTL-SDR’s maximum frequency limit is about 1.7 GHz, an external downconverter circuit is required. A downconverter converts high frequencies down into the range receivable by the RTL-SDR. For example a downconverter with a 2.4 GHz local oscillator would convert a 3.5 GHz signal down to 1.1 GHz, which can be easily received by an RTL-SDR.

The secret to doing this cheaply is revealed by KD0CQ. He shows that a very cheap $5 Directv SUP-2400 upconverter can be converted into a 2.4 GHz downconverter simply by removing some filters. He writes that he hasn’t uploaded the full set of steps to modify the SUP-2400 yet, but he intends to do so in the near future.

There is also a discussion about this mod on Reddit. Several posters have been discussing what applications a cheap downconverter could open up. Some mentioned applications include receiving various satellites in the C/S bands, DECT cordless phones @ 1.9 GHz, SiriusXM satellite radio @ 2.3 GHz, ISM @ 2.4 GHz, RADARs, RC aircraft control/telemetry/video and ham beacons.

The SUP-2400 Directv upconverter that can be converted into a downconverter.
The SUP-2400 Directv upconverter that can be modified into a downconverter.

$5 Microwave Downconverter for the RTLSDR KD0CQ

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Hearing Ethernet Packets with an ESP8266 and RTL-SDR

Over on YouTube CNLohr has posted a video showing an interesting side effect of implementing ethernet on the ESP8266. The ESP8266 is a very popular $7 wifi module for microcontrollers that has found a lot of extra use outside of its intended design. Previously CNLohr also showed how Analogue NTSC TV could be broadcast with the ESP8266. Recently it was found that (software based) ethernet capability could be hacked into it.

In his new video CNLohr demonstrates that AM radio can be broadcast by attaching a short wire antenna to the ESP8266 ethernet output, and then using an RTL-SDR to receive one of its harmonics at 150 MHz. He shows that by varying the size and speed of the packets he can change the received tones, and even create notes to play music. This essentially gives a simple way to ‘hear’ ethernet. 

Broadcasting AM Radio with Ethernet on the ESP8266

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Using the Airspy as a low cost Spectrum Analyzer with Spectrum Spy

Over on his blog VK4ZXI has been testing the Airspy with the Spectrum Spy software. The Airspy is a $199USD software defined radio that can be considered as a high end upgrade to the RTL-SDR as it has 10 MHz of bandwidth and a 12-bit ADC. The Spectrum Spy software allows the Airspy to be used as wideband spectrum analyzer. In a previous post we reviewed the Spectrum Spy software with the Airspy and found it to have an extremely fast refresh rate. Recent updates since the review have made it even faster.

In his first post VK4ZXI compares the Airspy + Spectrum Spy with the RTL-SDR running RTLSDR-Scanner and Rtl_power, two spectrum analyzer programs written for the RTL-SDR. In his tests he finds that the RTL-SDR and Airspy can obtain similar scans, but the Airspy can scan and refresh the spectrum at much faster speeds than the RTL-SDR, thanks to its 10MHz bandwidth.

Airspy + Spectrum Spy receiving the entire digital TV band over 100 MHz.
Airspy + Spectrum Spy receiving the entire digital TV band over 100 MHz.

In his second post VK4ZXI uses the Airspy + Spectrum Spy together with a cheap BG7TBL noise source to measure the response of a cavity RF filter. This is the same BG7TBL noise source that we used in our “Measuring Filter Characteristics and Antenna SWR with an RTL-SDR and Noise Source” tutorial. The results from the cavity filter measurement show that the Airspy can potentially perform on a level close to an expensive spectrum analyzer.

Measuring the response of a UHF cavity filter with Airspy + Spectrum Spy.
Measuring the response of a UHF cavity filter with Airspy + Spectrum Spy.
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A new RTL-SDR based Portable ADS-B Kit for Pilots is on Kickstarter

Back in March we posted about the FlightBox, a portable RTL-SDR ADS-B 1090ES and 978UAT receiver built for use by pilots in small aircraft. 1090ES provides ADS-B which allows a pilot to see on a map where other aircraft are, and 978UAT provides other services such as weather radar. The FlightBox is essentially a Raspberry Pi 2 combined with two RTL-SDR dongles, two antennas, a GPS receiver and is preloaded with the stratux software. The two channel FlightBox receiver currently sells for $250 USD.

Recently a new similar ADS-B product for pilots made by a different company has been released on Kickstarter. The new product is made by a company called RF-Connect and is similar to the FlightBox, but is powered by an Odroid C1. RF-Connect are also the programmers behind the ADS-B on Android app which was one of the first apps to be able to receive FIS-B weather data and display it on a map. 

The product receives 978UAT and 1090ES ADS-B signals using two RTL-SDR dongles, and then transmits the data via WiFi to an Android or iOS tablet running flight navigation software.

The Kickstarter early backer price is $150 USD for a single channel 978UAT only capable receiver or $200 USD for the dual channel 1090ES and 978UAT receiver. This contrasts with the FlightBox price of $200 and $250 USD for similar products, however the standard backer price for the RF-Connect ADS-B receiver is the same as the FlightBox.

The RF-Connect ADS-B Receiver transmitting data to a tablet.
The RF-Connect ADS-B Receiver transmitting data to a tablet.
The parts inside the ADS-B Receiver. Two RTL-SDR dongles, GPS receiver, two antennas, WiFi dongle, Odroid.
The parts inside the ADS-B Receiver. Two RTL-SDR dongles, GPS receiver, two antennas, WiFi dongle, Odroid.

RF-Connect have also uploaded a video showing their ADS-B on Android app in action.

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Massdrop: Group Software Defined Radio Purchasing

Over on the r/rtlsdr subreddit forum many users are attempting to combine their purchasing power to initiate a ‘massdrop’ for a higher end software defined radio. Massdrop is a service that allows for large group purchases to be made. When a large group comes together to buy the same product the product manufacturer will often be able to offer better wholesale prices due to the increased sales volume.

The Massdrop service also allows for the group to vote on the most desired product. Currently the group is voting for several SDR’s including the SDRplay, HackRF, BladeRF, Airspy, USRP, Red Pitaya, Apache Labs and Perseus SDRs. Currently winning the vote at the time of this post going live is the SDRplay, with the HackRF coming in a close second. Once 200 total votes are reached a representative from Massdrop will contact the manufacturer of the most desired SDR and try to work out a deal for the group buy. There are 147 total votes at the moment, so they are almost at the threshold of being able to initiate negotiations.

If you want to take part in the Massdrop sign up to their website at www.massdrop.com and then visit the SDR voting link at https://www.massdrop.com/vote/Software-Defined-Radios1 (you must be logged in to see the SDR voting page).

If you’re interested in learning more about these higher end radios then we have a list of several SDR’s available here, and a review of the Airspy, SDRplay and HackRF here.

Current voting at the time of posting for the Massdrop.
Current voting at the time of this post for the Massdrop.
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OpenFest 2014: Software Defined Radio and RTL-SDR by Harald Welte

Recently some talks from the OpenFest 2014 conference have been uploaded to YouTube. One of the talks uploaded is titled “Software Defined Radio and RTL-SDR” and is by Harald Welte. Although a couple of years old, the talk is still valid and quite clearly explains some concepts about how software defined radio works, and then goes on to talk about the RTL-SDR dongle and some of it’s applications. The introduction reads:

This talk is about getting started with the basics of software defined radio (SDR). It introduces the fundamental concept of SDR constrasting classic radio systems, and continue to cover the rtl-sdr project, a software/driver architecture for the ultra-cheap RTL2832U based hardware. There will be practical demonstration using some of the readily-available Open Source projects implementing receivers for various radio systems.

If you are interested in his talk, then his slides appear to have been uploaded here.

Software Defined Radio and rtl-sdr - Harald Welte

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