Stereo demodulation = Binaural reception

Stereo demodulation is only possible on stereo capable hardware (eg. OVI40). Not possible on mcHF, because the Line OUT audio path is MONO. In the mcHF -when using the newest UHSDR firmware- you will therefore not notice anything new. Only with OVI40 or other hardware you are able to choose stereo demodulation modes.

We have implemented three Stereo demodulation modes:

• IQ: listen directly to I and Q without any demodulation
• Stereo SSB: listen to demodulated LSB on the right ear and demodulated USB on the left ear
• Stereo SAM: this is a Stereo version of sideband selected synchronous AM demodulation, i.e. a PLL which locks to the carrier of a station and sends the lower sideband (SAM-L) to the left ear and the upper sideband (SAM-U) to the right ear

What do you need Stereo demodulation for?

• just to hear selective fading acting differently on the lower and the upper sideband (if it were not for that, Stereo SSB would make no sense)
• for "spatially" identifying CW stations in the filter bandwidth: could lead to more efficient separation of CW stations which are very near to each other. You can actually hear if the stations are below or above your tuned frequency
• to spatially enhance your hearing experience (eg. when listening to music)
• to be able to "hear" what these famous "I" and "Q" signals are

Binaural receivers were once famous when phasing rigs became popular (Hayward et al. 2012). In March 1999, a binaural IQ phasing receiver was published in QST ("to fully appreciate this receiver, you´ve got to hear it", Campbell 1999). The IQ signals were preserved all the way to the headphones. Sorting the signals and interference was then left to the ear-brain processor. "Binaural receivers are a delightful way to listen" (Hayward et al. 2012).

"A number of experimenters have noticed that Binaural IQ receivers sound best with very little audio filtering. A versatile receiver might have a switch that provides wide open Binaural IQ for tuning around the band and then a number of narrow band options for communicating with individual stations." (Hayward et al. 2012).

Well, the UHSDR software together with a stereo capable hardware like the OVI40 now delivers exactly this option (together with two more stereo demodulation modes)!

Hayward, W., Campbell, R. & B. Larkin (2012): Experimental methods in RF design. - The American Radio Relay League ARRL.

Campbell, R. (1999): A binaural IQ receiver. - QST March 1999: 44-49. HERE