Async 192Khz USB - the SDR-Widget collaborative project


2004-08-02 10:04 pm

Take a look at this page here: SDR Widget project

We were searching for some time here on diyAudio for a high quality USB interface, well the page above just might be the ticket.

These guys managed to do 192Khz in Linux and OSX, still in development for Windows (in asynchronous mode).

The boards are already in the second revision. Check also a comparison on the noise spectrum in the link above.

Also you can find the complete documentation

This is really some great work in this project. Really cool stuff.


2004-08-02 10:04 pm
Ok, here are some more details regarding the first board:

The design is based on the AK5394A 24bit ADC and the Atmel AT32UC3A3256 processor

" The SDR-Widget-lite supports full RX and TX I/Q audio lines. It has been
successfully tested up to 192k sampling with the latest Linux kernels and
Mac OS. It is limited to 48k on Windows SDR software without a driver but an
experimental version of the firmware using the HPSDR protocol is being
developed to allow the SDR-widget-lite to run full speed on Windows.


The cost of the alpha boards was about 150$. Now, ADC included. I suppose this would go down a lot as a kit containing only the Atmel chip.

And take a look at the development roadmap:

This is the development roadmap for the sdr-widget as we march on to
year 2011:
(1) The current widget BETA will be shipped (hopefully) in Jan 2011.
After a couple of months of testing by the BETA users and getting
their feedback, we hope to move on to widget production. The "widget-
lite" has morphed into the "real and full" widget. There will not be
another "full" widget as such. The widget's main application is for
SDR - as a "sound card" for general Softrocks, and as a "sound card" +
controller for Mobo users.
(2) In the 1st half of 2011, we will be developing the audiophile-
widget. The current widget has superior sound capture (ADC)
capabilities. The playback quality is already very good. In fact, it
is so good that I'm using it for music playback of 96khz/24bit music,
with superior sound quality compared with my CD player (Cambridge
Audio DVD99, playing 44.1khz/16bit music). However, we are working on
an audiophile-widget with top end playback, comparable to the
specialty commercial USB-DAC's costing thousands of $.
The design has a USB-I2S module (scaled down version of widget,
without the rig control I/O's), which will be mated to a number of
versions of Analog Boards (AB).
Some versions of the AB will have both a DAC and an ADC. Some
versions will be DAC only. Other versions of the AB will have an FPGA
with DSP capabilities.
The DAC we are going to use will likely to be an ESS 32 bit DAC, the
ES9012. This is the top end DAC. The output stage will have AD797
opamps and the power supply will be rechargeable Li-on batteries for
best low noise performance. The batteries are automatically recharged
via the USB port when not in operation mode.
Another version of AB will not use batteries, but uses ultra low
noise "shunt regulators" for the power supplies.
One version of the AB will have an FPGA with digital filters and
processing, for things like upsampling, digital cross-over, etc.
The audiophile-widget is targeted at the DIYaudio community. However,
the version with ADC (which will likely be an AK5394A) can be used for
SDR use :)
In the 2nd half of 2011, we will consider developing RF front-ends
which make use of the widget "core" for a complete receiver or
(4) SRtg; (widget + all band Rx) - a very portable "USB stick", with
one end plugging into a USB port of a PC, and the end an ANT
(5) diversity-SR (diversity-widget + RF front-end with 2 QSD's) - for
2 RF ANT inputs for diversity reception.
(6) widget transceiver (widget + all band RxTx) - with standalone &
docking options - this will be something like the next generation SR +
Mobo + widget + SDR cube. In standalone mode (without PC), it is a
full all band transceiver controlled by a rotary encoder and buttons/
switches. When connected to the PC USB port, it allow the use of the
PC SDR programs with bigger and more detailed displays, more powerful
processing by the PC cpu etc.
There may be advanced features incorporated, such as diversity
reception, pre-distortion linearization transmit, 6M, 2M, 70cm
operation etc.
We are still conceptualizing the widget transceiver. So it may or may
not happen in 2011.
73 Alex

So, what do you think?
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The audio-widget is a fork of the SDR-Widget project with the focus on audio reproduction. Both projects are open-source with the Atmel firmware and hardware schematics available.

The audio-widget will be a consist of a separate USB-I2S controller module which will mount on a DAC card. DAC cards are planned for release based on the ES9012 and the TI PCM1794 chips.

The USB-I2S module design is complete and work is progressing on a ES9012 DAC card. The overall concept is to have the board set powered by a set of LiPo or LiPoFE batteries.

Join the mailing list or visit the mail archive to keep abreast of the projects progress.

George Boudreau
SDR-Widget hardware