Over on YouTube, ICAS enterprises have posted a video demonstrating “Signal Adaption” using an RSPduo. This is a good example of a feature we think will be enormously powerful, especially when SDRuno  is updated to provide accurate time and phase synchronization of the two input signals.

From what we understand, this experimental setup used Linrad software with RSPduo hardware to receive a weak Japanese beacon, and then inject an interfering signal, which could be removed. The Linrad software provided the Signal Adaption.  Signal Adaption can either combine the wanted signals on both antennas to improve S/N,  or it can be used to cancel out an unwanted signal.

The accompanying notes from the video read as follows:

“RSPduo/SDRunoを使用したノイズキャンセルの実験です。 This video shows an noise canceling experiment using RSPduo and Linrad in combination. 詳細は、下記URLを御覧ください。 Please refer to the following URLs for detais: 設定編 (settings) http://icas.to/sdrplay/play/nc-linrad-duo.htm  運用編 (operation) http://icas.to/sdrplay/play/nc-linrad-duo-2.htm ”

There are two links to Japanese description which we have translated into English using Google translate:

Settings: https://sdrplay.com/wp-content/uploads/2018/06/Linrad-demo-by-ICAS-Enterprises-Part-1.pdf

Operation:  https://sdrplay.com/wp-content/uploads/2018/06/Linrad-demo-by-ICAS-Enterprises-Part-2.pdf

Click here to view the YouTube Video

Other details of the set-up are understood to be as follows:

Settings of RSPduo/SDRuno:

-Tuned to the same freq with the same LO (listening to a 50MHz beacon.) -Assigned Ant 1 to instance 0, and Ant 2 to instance 1 -Fed to Linrad using the VBA cable – L and R

Settings for Linrad:

-0 deg: receiving with Ant 1

-90 deg: receiving with Ant 2

-injected an artificial QRM using VNWA signal generator -Adaptation is enabled.

-Clicking “O” on Linrad shifts the phase 90 degrees and the artificial signal disappears 🙂

Linrad, authored by SM5BSZ,  is available as Windows software from http://www.sm5bsz.com/linuxdsp/linrad.htm

Yas at ICAS also noted: “We do not have to use a hardware 90 deg shifter. I just used an LZ1AQ loop and a discone. Linrad has a capability to enhance the combined signal (adaptation) to the maximum (both antennas combined), which is set as the origin, while “O” button on Linrad shifts the phase by 90 degrees from the origin where the maximum signal at 0 degrees gets offset (namely, gone).”

We are grateful to channel partner SDR-Kits who are working closely on this with ICAS Enterprises and who also supplied the VNWA

We hope to write this up more fully as an application note. But meanwhile it is a good indication of the promising potential of the RSPduo.