FDM-SW2 and WinBook TW100 - first impressions

I bought recently FDM-DUO, a QRP transceiver made by a small Italian company, Elad. The radio is really nice. The receiver is a bandpass sampling (no downconversion on RF side, sometimes called direct sampling), full SDR design, with all signal processing and demodulation done in FPGA and software on microcontrollers. The transmitter side uses more traditional approach, where the modulation occurs in digital domain at 0Hz IF, and after conversion to analog domain is upconverted to the band of interest.
It's not my first software radio platform (I've already enjoyed for about couple of years experimenting with bladeRF), but FDM-DUO has the big advantage of integrating the digital and analog circuitry with sleek, minimalistic, knobbed user interface in a small, handy package. The radio can be used as an SDR interface to an application running on a computer, but can also be used as a traditional, standalone HF transceiver.

Problem with USB connector on bladeRF part 2: The Fix

In the previous post I described the problem with the USB connector on my bladeRF. Now it's time to describe how I attempted to fix it.The first attempt was successful only partially, I had more luck the second time, but I will describe it in another post.

Working with SMD components at home

Few weeks ago, during one of the meetings of the Vienna Wireless Society ham club, I gave a presentation about working at home with SMD components. The presentation attracted quite a lot of attention, so I thought that it might be worth to share the video recording on the blog. There are two parts of the presentation. During the first part I gave a quick introduction about SMD components for people who have no experience with them. The second part was focused on working with surface mounted devices at home.

Problem with USB connector on bladeRF part 1: The Failure

A few weeks ago my bladeRF almost died. No, I did not electrocute it, I did not step on it, I did not try to make it work too hard, it did not suffer any kind of physical or intellectual abuse. All I did was to try to gently connect a USB cable. One moment I was pushing the plug into the connector, the next moment the plug was sitting completely loose in the metal frame.

Why do I buy on Ebay from Chinese sellers?

Ebay is an interesting place when it comes to shopping for electronic parts. You can find dirt cheap components from sellers on the far East, but you can also buy a reel of metal slugs instead of real ICs. Having had some bad experiences with shady sellers and long shipping times, I generally try to buy from US sources. The prices are not that great, but at least I don't have to wait 4-6 weeks for delivery, I tend to trust US sellers more (even if they sell the same Chinese crap), and I prefer to shop locally instead of pumping extra dollars into the Yellow Dragon's economy. However, there are days that I just want to say "fuck the political correctness" and go ahead and stuff the shopping cart with parts sold by all the Liang Mings of Ebay. Just like today.

Using VirtualBox to install OS for an embedded system

Embedded systems are fun to play with, but installation of the OS can be a real pain. In my case the OS was not a big problem (I'm using a plain, old, boring PC hardware, after all), but as usual, the devil lurks in the details. In my case none of the monitors I have at home was able to display the video signal from the board (23" Dell LCD went just blank, while 17" LCD at least showed a message about unsupported video mode.) The only device that worked properly was a projector. Being a lazy brat as I am, I decided to not to stand at the projector holding the keyboard in one hand and the board in the other, and hack the entire process without touching the target board at all. Enter VirtualBox, a full PC system in a small window on the monitor.

Keep your Red Pitaya cool

Red Pitaya is small measurement instrument built around Xilinx' Zynq SoC integrating a dual-core Cortex-A9 CPU, peripheral devices and FPGA fabric. The chip drives two 14-bit DA converters and two 14-bit AD converters at 125MSps. Switching transistors in CMOS circuits at such speed requires quite a lot of power, which is dissipated in a form of heat. The board gets hot. Even though the SoC and the converters are cooled by a heat spreader, after several minutes the input connectors and the heat sink become too hot to touch.