OpenRadio Part 2 – Prototype Works!

Since the first post on the OpenRadio project Mark has been moving ahead and leaps and bounds. In just a few late nights work he has assembled and tested the radio, managed to receive off air signals, and even tested the PSK31 transmitter! Fine business Mark.

Mark writes:

Hooked it up to a real antenna tonight:

That’s me decoding actual 20m PSK31 signals!

Signal path is:
Antenna —RF—-> OpenRadio SDR —-IQ–>|Laptop|—-IQ—> Spectravue
(IQ Demod) —SSB—> fldigi

Mark managed to build the radio in 1-2 hours, including taking plenty of photos to document assembly and aid others. Now not everyone will have Mark’s radio assembly skills. However even allowing for a learning curve and a few coffee breaks we are on track for a one-day (say 6 hour) mini-conf assembly time.

A working prototype verifies the hardware design, so we are now getting ready to re-spin the PCB and start putting the kits together.

In other news Edwin from Dragino has added the OpenRadio kit to his store. We estimate the kits will be available for shipping in December. Kim, Mark and I, are still deciding if we will bring a bunch of kits to LCA, or have delegates pre-order them from Dragino. More on that shortly.

Links

OpenRadio Wiki

OpenRadio – a one day Software Defined Radio project

For the 2015 Linux Conference, I am working with Kim Hawtin and Mark Jessop on a 1 day Open Radio Mini-conference.

In this mini-conf a classroom of people will solder together their very own software defined radio (SDR) transceivers in just a few hours. It will be capable of receiving signals on the HF . . . → Read More: OpenRadio – a one day Software Defined Radio project

JackPair – Secure Phone Calls using Codec 2

I’ve just found out about a new Kickstarter for JackPair, a device that enables secure phone calls over a mobile phone. It uses Codec 2.

Over the past 12 months I have been approached by a couple of groups interested in building a similar product (but not JackPair). These groups asked me to develop a . . . → Read More: JackPair – Secure Phone Calls using Codec 2

SM1000 Part 7 – Over the air in Germany

Michael Wild DL2FW in Germany recently attended a Hamfest where he demonstrated his SM1000. Michael sent me the following email (hint: I used Google translate on the web sites):

Here is the link to the review of our local hamfest.

At the bottom is a video of a short QSO on 40m using the SM-1000 over about . . . → Read More: SM1000 Part 7 – Over the air in Germany

Degrowth Economy

Just read this article: Life in a de-growth economy and why you might actually enjoy it.

I like the idea of a steady state economy. Simple maths shows how stupid endless growth is. And yet our politicians cling to it. We will get a steady state, energy neutral economy one day. It’s just . . . → Read More: Degrowth Economy

SM1000 Part 6 – Noise and Radio Tests

For the last few weeks I have been debugging some noise issues in “analog mode”, and testing the SM1000 between a couple of HF radios.

The SM1000 needs to operate in “analog” mode as well as support FreeDV Digital Voice (DV mode). In analog mode, the ADC samples the mic signal, and sends it . . . → Read More: SM1000 Part 6 – Noise and Radio Tests

Timing Estimation for PSK modems

Jim, KG4SGP just sent me an email asking about how timing recovery (timing estimation) works in the FDMDV modem. In fdmdv.c, this is performed by the rx_est_timing() function.

At the receiver, we need to “sample” the PSK modem signal at just the right time. A timing estimator looks at the received signal and works out the . . . → Read More: Timing Estimation for PSK modems

SM1000 Part 5 – Mysterious Triangle Waves

Getting close to Beta now.

I have just spent a week tracking down a mysterious 256 Hz low level (30mVpp) tone that ended up being a software configuration error in the DAC initialisation code! However before that I thought it was a noise issue caused by PCB layout, or the wrong sort of bypass capacitor. . . . → Read More: SM1000 Part 5 – Mysterious Triangle Waves

SM1000 Part 4 – Killing a PCB and PTT Working

Last Sunday the ADC1 net on the first SM1000 prototype went open circuit all of a sudden. After messing about for a few hours I lifted the uC pin for that net and soldered a fine wire to the other end of the net. That lasted a few days then fell off. I . . . → Read More: SM1000 Part 4 – Killing a PCB and PTT Working

Do Anti-Depressants work?

In the middle of 2013 I had a nasty bout of depression and was prescribed anti-depressant drugs. Although undiagnosed, I think I may have suffered low level depression for a few years, but had avoided anti-depressants and indeed other treatment for a couple of reasons:

I am a man, and men are bad at looking after their . . . → Read More: Do Anti-Depressants work?