Binaural Reception ?

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WB5AGF
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Location: Garland, Texas (north side of Dallas)

Binaural Reception ?

Postby WB5AGF » Tue Dec 18, 2018 4:13 am

(If the way I lead-in to the subject seems overly-complicated it is because I suspect that there are readers who do not have a background in high-frequency Amateur Radio/short-wave listening.)

Going back some years in shortwave/high-frequency radio publications (I'm remembering articles in the Amateur Radio publication 'QST') there have been implementations of a receiving technique that has sometimes been referred to as 'binaural reception' which presents the acoustic equivelent of a three-dimentional visual experience.

Before software there was hardware ..... And the hardware method of implementing binaural reception was, with a receiver of superhetrodyne design, to go to the I.F. (Intermediate Frequency) and from there on through and including the audio output stage have two independent and identical sections - call them 'A' and 'B'.

Set up 'A' for lower-sideband ('LSB') detection and feed its output to an audio amplifier which we will designate as being the 'left channel'.

Set up 'B' for upper-sideband ('USB') detection and feed its output to an audio amplifier which we will designate as being the 'right channel'.

Plug in stereo headphones into the receiver's audio output and put them on.

Now, as the receiver is tuned up-and-down the short-wave spectrum, the user experiences hearing signals first through either the left or right earphones and, as the receiver continues to be turned through the signal, the sound in the earphones 'moves' 'through' the earphones (either from the left to the right, or the right to the left, depending on if the receiver is being tuned from lower to higher frequencies or higher to lower frequencies).

I would like to know ... Is there a way to user the SDRuno software with the SDRplay receivers to implement binaural reception ?

(signed)

Paul, WB5AGF

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Paul
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Re: Binaural Reception ?

Postby Paul » Tue Dec 18, 2018 11:15 am

Hi, I've never heard of that.
It sounds (no pun intended) like a really useful function, if as I suspect it produces gradual tonal change, thus making the audibility of CW signals for instance capable of optimal adjustment.
This ability may already be present and well known to real amateurs. amongst whom I do not belong, being a humble and learning SWL-er.

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glovisol
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Location: Piedmont, Italy

Re: Binaural Reception ?

Postby glovisol » Tue Dec 18, 2018 6:30 pm

This technique has been with us a long, long time, this was done with crystal set receivers as well. The best article on this subjeect is here:

http://www.arrl.org/files/file/History/ ... mpbell.pdf

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pnoelw
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Re: Binaural Reception ?

Postby pnoelw » Tue Dec 18, 2018 9:10 pm

Paul
You could try setting 2 VRX to the same frequency, one on LSB and the other on USB. The in RX Settings/Out tab/output routing - one receiver to left and the other to right.
That should do the trick.
Noel.

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g1hbe
Posts: 475
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Location: Cheshire, UK

Re: Binaural Reception ?

Postby g1hbe » Tue Dec 18, 2018 11:30 pm

Pat hawker covered this technique in his TT column back in the mid 80's. There were some quite complex systems, but a simple system takes the audio from the headphone socket and filters it so that the higher frequencies are routed to the right 'phone and the lower ones to the left. This isn't quite the same as the systems described here, but it does something quite similar. As you tune across a CW signal, it will appear in one phone because of its frequency and as you continue to tune it will move across and appear central, then move across to the other phone as the frequency gets to the other extreme.
So if you are 'centrally' tuned to a CW signal, an off-frequency interfering signal (say high frequency) will appear to come from one side only and be easier to ignore than if it was co-incident with the central signal. I would imagine it gives a similar 'soundstage' effect as the other systems as well.
I can imagine this being of more use if you don't have a narrow IF filter available and your IF b/w is wide enough to allow several adjacent sigs through at once.
I must try it one day.

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Andy

WB5AGF
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Location: Garland, Texas (north side of Dallas)

Re: Binaural Reception ?

Postby WB5AGF » Thu Dec 20, 2018 3:14 pm

pnoelw wrote:Paul
You could try setting 2 VRX to the same frequency, one on LSB and the other on USB. The in RX Settings/Out tab/output routing - one receiver to left and the other to right.
That should do the trick.
Noel.


Yes .... That's the idea .... My 'problem' is that I am unaware of a way to then be able to tune the two VRX's at the same time. I went looking to see if there was some other software that could sample signals coming from an SDRplay receiver but all that I've managed to do so far is to get HDSDR to 'listen' .... I still do not know how to be able to set up two demodulators (one on LSB and the other on USB) and then tune them simultanously from a single control. (signed) Paul, WB5AGF

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WB5AGF
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Location: Garland, Texas (north side of Dallas)

Re: Binaural Reception ?

Postby WB5AGF » Thu Dec 20, 2018 3:20 pm

Paul wrote:Hi, I've never heard of that.
It sounds (no pun intended) like a really useful function, if as I suspect it produces gradual tonal change, thus making the audibility of CW signals for instance capable of optimal adjustment.
This ability may already be present and well known to real amateurs. amongst whom I do not belong, being a humble and learning SWL-er.


re> "It sounds (no pun intended) like a really useful function" - One of the articles in ' QST ' (can't remember which one) talked about the human ear/brain having the ability to separate out a desired signal from others when given the sort of acoustic-spatial signal that binaural reception provides. (signed) Paul, WB5AGF

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pnoelw
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Re: Binaural Reception ?

Postby pnoelw » Thu Dec 20, 2018 3:55 pm

Hi Paul - I think you can....try this

Set up the 2 virtual receivers as previoulsy described ie same frequency; one on LSB and the other USB; one output to left speaker and the other to right speaker.
Make sure you are offset from the LO frequency
In the main panel turn off "LO Lock"
In RX Control for RX00 hover your mouse above the Hz digit and turn the mouse wheel. Both receivers will move in synch.

I've tried to attach a screen capture and hope it appears!

Good luck.
Noel

[img]
binaural2.jpg
[/img]
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Roger
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Re: Binaural Reception ?

Postby Roger » Thu Dec 20, 2018 6:54 pm

WB5AGF wrote:
Yes .... That's the idea .... My 'problem' is that I am unaware of a way to then be able to tune the two VRX's at the same time. I went looking to see if there was some other software that could sample signals coming from an SDRplay receiver but all that I've managed to do so far is to get HDSDR to 'listen' .... I still do not know how to be able to set up two demodulators (one on LSB and the other on USB) and then tune them simultanously from a single control. (signed) Paul, WB5AGF


There is a way to have the two VRX's track the same frequency even when you switch bands using the keypad. What is required is to set up a communications link between the two VRX's to pass the frequency (not mode like USB/LSB etc.) between them.

The first step is to setup a Virtual COM port pair between them much like you do when syncing SDRuno with a ham transceiver. I use COM0COM because it is freely available but some folks like VSPE. In my setup I use COM6: and COM7:.

The next step is to have the main VRX connect to OmniRig for communication. This is described in the User Manual. You have to download OmniRig and setup the correct parameters. OmniRig will be setup as a Kenwood on Rig2 using COM7:. The settings are shown in the screenshot below. In VRX 1 you select OmniRig in the settings and Rig 2. You then enable RSYN2 in the window bar as shown. VRX1 is now sending the frequency info out to OmniRig and OmniRig is sending it out on COM7: which means it can be received on COM6:.

You then add a second VRX and you connect it to COM6: using the CAT option in the settings. The CAT option in SDRuno uses the Kenwood protocol and that is why OmniRig was configured for a Kenwood radio above. Now press Play and the two VRX's will track in frequency. Use VRX1 as the master to change bands and frequency. You set the USB and LSB modes in each VRX.

For audio you will need to configure VRX1 to use the left audio channel and VRX2 to use the right channel as described in the post above.

Have fun.....
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AB9IL
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Re: Binaural Reception ?

Postby AB9IL » Sat Jan 19, 2019 10:26 pm

Bear in mind that there is more to true binaural reception than the frequency - amplitude relationship between channels. There is also the matter of phase, which affects the perception of a sound's bearing. So a sound seems to come from the right not only because it is louder in the right ear, but also due to a phase lag in that same sound in the left ear.

Before the age of dsp, those old binaural reception techniques used crude methods to generate quadrature RF oscillator signals and tweak the audio taken from the product detector. Today, quadrature signals are easy to create, and the Hilbert Transform can phase shift a signal by 90 degrees in DSP.

I often wonder why binaural CW mode isn't a common feature in SDRs, as it is not hard to implement. For fun, try listening to 40 meter CW on a KiwiSDR site in I/Q mode and use some EQ on your computer to favor low notes on one side and highs on the other. That is some rough binaural, but it works.

Cheers,
Phil AB9IL
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