EMRFD Message Archive 14467
Message Date From Subject 14467 2017-12-26 10:02:18 jwolczanski Binaural receiver finished I've actually pulled my high-performance 40 meter super heterodyne from the operating position and have put the binaural receiver (BR) on-line in its place. I surely would not recommend the BR for contesting. I can hear signals about 8kHz either side of zero beat, but it's rather remarkable to hear the desired signal clearly discernible in the 3D "sound space" that exists between my ears (my wife suggests there's lots of room...).
I up-loaded a file entitled "Final wrap-up - Binaural Receiver.pdf" at:
The only selectivity this radio has is from the diplexer which is from "Solid State Design for the Radio Amateur" (page 77). What a delight to listen to the band with this radio.
For serious 40 meter hamming, I've recently completed one of those QCX transceivers offered by QRPLabs. The receiver portion is quite remarkable. The opposite sideband rejection is claimed to be at least 50dB and it must be at least that. I've heard one monster signal on 40 meters the other day - - and there was just a barely discernible trace of signal on the opposite sideband.
The QSK feature on the QCX transceiver seems noisy to me at audio higher gain settings. I might built & install a little LM-380 amp to see if that helps.
Life is good!
Merry Christmas and Happy New Year!
14468 2017-12-26 17:18:13 iq_rx Re: Binaural receiver finished Very nice Jerry. Best Regards, Rick KK7b 14486 2018-01-07 02:00:34 peter_dl8ov Re: Binaural receiver finished OK, now you have me interested after I read the descriptions of the binaural receiver in use. In the conventional R2Pro receiver there are adjustments for gain and phase, in fact, EMRFD has a circuit where these adjustments can be made for each sideband.
In a binaural receiver are the adjustments for gain and phase not required, it just needs to be as close as possible to 90 degrees?
What does AM sound like on a binaural receiver?
14487 2018-01-07 14:43:23 iq_rx Re: Binaural receiver finished Hi Peter,In an IQ receiver where you are using precise amplitude and phase relationships to cancel the opposite sideband, sideband suppression is directly related to how well you maintain those relationships. So for a conventional phasing receiver, it is important to be as close to equal and 90 degrees as possible.In a binaural IQ receiver, you are presenting the two ears with nearly equal amplitude signals and a relative phase relationship that mimics what the ears hear in a natural environment. The ear-brain perceives that as space, and signals downconverted from above the LO frequency sound like they are arriving first at one ear and signals from below the LO frequency sound like they are arriving first at the other ear. So in a binaural receiver, nearly equal and nearly 90 degrees phase difference is about right. There is no real benefit to making fine adjustments in relative amplitude and phase.Binaural independent sideband and (and perhaps also binaural I Q channels) for shortwave AM broadcast signals is an ancient technique. Pat Hawker described the technique in Amateur Radio Techniques in the early 1970s, with a reference in EBU Review that I have never been able to find. It requires phase locking to the carrier, and the two sidebands are presented in stereo to the two ears. I built a receiver to do this a decade or so ago, and it is really quite remarkable when listening to shortwave double sideband AM broadcasting from far away. I had a favorite folk music program from China and another one from Australia that I listened to in stereo many mornings, on both headphones and speakers.Selective fading occurs when different frequencies in the two sidebands of a shortwave broadcast signal arrive out of phase and cancel. Binaural listening to the two sidebands greatly reduces this effect, and in addition, results in a perception of "concert hall" space as the ear-brain interprets the sounds in the two ears as arriving via different paths. That is what happens in the concert hall with a single source on stage, so perceived stereo when listening to a distant AM shortwave broadcast station binaurally with independent sidebands is very natural and pleasant.There is renewed interest in amateur radio AM in the US at least, and I hope some folks will experiment with locked carrier/binaural ISB systems.Enjoy the experiments.Best Regards,Rick kk7b 14491 2018-01-08 03:29:28 w0ep Re: Binaural receiver finished I received a fancy SDR receiver for Christmas. It seems like it would be
possible to set the software to do things like this... but I don't know
14492 2018-01-08 05:38:17 jwolczanski Re: Binaural receiver finished VERY glad that Rick chimed in with an explanation of binaural receivers.
I'm still using the binaural receiver daily along with my 2/10 Watt 40 meter TX. Together they have "VOX like" T/R switching. The binaural receiver is a delight, and if/when conditions get too tough for the wide-open bandwidth, I can switch to my little 40-meter QCX kit transceiver that I built a few weeks ago.
I sent a recording to a ham I was chatting with and he sent me this:
"Hey Jerry.It played it on the I phone with stereo ear buds. It’s a wild effect. you hear multiple cw signals at the same time. It sounds like your at field day and you hear 4 guys at tables behind you pounding brass. Each cw tone sounds like it’s coming from a different direction or different table. Some left some right and other spots in between. You can tell your brain to listen to one table just like you can listen to one person talking in a crowed room. I can see how this could work. Thanks for showing me this! Freakydoodle but interesting :-)Neat - and I added a new word to my vocabulary - "freakydoodle"!JerryKI4IOWarrenton, VA
14493 2018-01-08 07:38:12 Bill Carver Re: Binaural receiver finished For Christmas my stepson bought his kids a "designer" puppy, a cross between a Bernese Mountain dog and a poodle: a "Bernedoodle".
From that I tried extrapolating to what a "Freakydoodle" must be. All I could come up with is a cross between one of those wierdos that populated the fringes of the Berkeley (CA) campus and a poodle. It's been quite a few years, but I guess anything is possible.
"Hey Jerry.It played it on the I phone with stereo ear buds. It’s a wild effect. you hear multiple cw signals at the same time. It sounds like your at field day and you hear 4 guys at tables behind you pounding brass. Each cw tone sounds like it’s coming from a different direction or different table. Some left some right and other spots in between. You can tell your brain to listen to one table just like you can listen to one person talking in a crowed room. I can see how this could work. Thanks for showing me this! Freakydoodle but interesting :-)
Neat - and I added a new word to my vocabulary - "freakydoodle"!