New Accessory for Flex6700 - Cognitive Processor Bus Interface

Stu Phillips - K6TU

Give polarization diversity a try first...  175' is still almost 6 wavelengths on 10m...

Stu K6TU

PS: in my Homer moment of the day - doh!  600 feet separation is just over 1 wavelength on 160m...  imperial/metric, metric/imperial... doh!

Richard McClelland, AA5S

Getting a 6700 in the shack is the greater challenge but your suggestion seems quite sound.

Sergey R5AU

Well, BTW, what we are need in 6700- need to be implemented possibility to choose of the DAX  channel separately for each paired slice. I guess it will be improved in the upcoming versions, ex.: to test with http://www.sm5bsz.com/linuxdsp/linrad.htm

KY6LA_Howard

I agree with Stu... in a previous incarnation I used polarization diversity which definitely worked

Being real estate challenged with only 1/2 Acre and a large SteppIR MonstIR dominating the lot, I cannot achieve meaningful horizontal separation

So Stu has inspired me to get a vertical installed so that i can get Polarization Diversity.

Andrew VK5CV

Ken,
I do have my 1500 on the 10MHz output of the GPS unit in the 6500. Havn't tried both at once yet. Different latencies and frequency errors though.
I do have an MFJ analogue noise reducing phasing box and that worked vey well on the 1500 with a noise antenna, a 40m sloper 40m from the 160m inverted L. The panadapter makes adjustment for narrow band signals a snip.
The other noise source of use may be the common mode on the feedline. Diverse in terms of wanted and unwanted but not space. A bit of a challenge for transmitting though. I really wish I had room for a shared apex loop array but the block is 150 x 50ft.
I do have a mate with a 6700 and a pixel loop a few km away but no GPSDO as yet. We both have access to seaside properties 45 km away.
Lots of fun ahead.
Andrew

Ken - NM9P

When I ran W1AW/9 (Indiana) a few months ago on 40 SSB I ran primitive polarization diversity...called an antenna switch!  

But I was amazed even then how changing from my 160 OCF Dipole to the Full sized Elevated Vertical Ground Plane would bring a station out of the noise or the pileup!  

Ian1

Stu Thanks for the great briefing I spoke with Bob Heil a while back he has a phase shifting in his headphones and it does work. Based on what your describing I could indeed make a 6500 perform the same way without a 2nd SCU needed. On Fri when I Fly back to Florida I am going t o look for a 2nd Antenna Site on my property for trying this out. Thanks Again Ian

Stu Phillips - K6TU

Ian,

I don't believe that you can do this with a 6500 - with only one SCU you have a tie between a single receive antenna port and all the slices serviced by that SCU.

The second SCU allows a second slice to be sourced from a different receive antenna.

The headphone mechanism you describe is like binarual audio - one channel is phased shifted 90 degrees before being fed into one ear piece.  Its the same as steaming I data to one ear and Q to the other as PowerSDR did when you turned binaural on.  The effect is similar audibly because its the audio phase difference in the signals from the two antenna/receivers that enables the brain to create the sound stage.

You can certainly manually switch between the two antenna but you aren't going to get the same diversity real time reception provided by the 6700 - the signals bounce around way too quickly for manual switching to work.

Diversity on the 6000 requires the two SCUs - only present in the 6700.

Stu K6TU

dl9eri/oe9eri

You can do this with an DXE NCC-1 connected to the 6500 or 6300 and the DXE-RTR-1A as Antenna-Switch - so it does not need two SCUs..... It works here with my 6500 and I use it for noise-blanking of house-made QRM or 360 degree phasing of two different antennas.

Ian1

Stu Can a 2nd or 3rd receiver not be from a different antenna source? This is what he is speaking of. Ian

George O'Brien

There is an excellent writeup by W8JI on the whole topic at   w8ji.com/polarization_and_diversity_htm

I recommend jumping down to the section entitled "Diversity Receivers and Reception".  A significant quote is "To be effective, signals cannot just be directly mixed either at audio, IF or radio frequencies."  He achieved the stereo diversity by phase locking two separate receivers, heavily modified Drake R4C's, even to the point that the crystal filters were hand selected for equal group delay over the filter passband.  At the time of article, Tom Rauch wrote "I currently use an Elecraft K# since it is the only system that phase-locks two identical receivers..."  Today, with the Flex 6700 and perhaps also with the Flex 5000 (I don't know that the two receivers are phase locked) we have similar capabilities.  Are the results worth the effort?  He says "The difference can be worth as much as a signall being nearly readability 5 in stereo to readabillity 2 without."

This psychoacoustic soundstage cannot be achieved through phase shifting of the same antenna and adding to the opposite ear.  Two separate antennas with either different polarizations H and V or if with the same  polarization separated by 2 lambda or more provide the RF signals required.

Finally, Tom has two sound files that help you hear what to listen for when testing for diversity capability.

George O'Brien

We shouldn't confuse beam steering and noise cancellation that these devices provide with stereo diversity reception that Stu experienced. 

Tom Warren

Is this technology akin to that used with the large interferometers, arrays of dishes?

Tom

Bill Sharp

Huh? I don't even understand what you said. "Cognitive Processor Bus" ????  I don't know what it is ......but I think that I want one. No, now I'm sure of it.... I must have one. Or maybe two?! Ham radio is just getting way to sophisticated for me I guess. )

George O'Brien

In radio astronomy signals from widely separated antennas are summed while maintaining their phase coherence through nanosecond synchronization via accurate and stable atomic clocks.  This allows them to act like an extremely wide aperture antenna.  What the researchers are trying to achieve with this extremely wide aperture is to increase the angular resolution or resolving power.  These antennas are sometimes on different continents.

Charles - K5UA

Pyschoacoustic sound stage......... About 4 years ago I worked about 6 hours of CW in a Field Day contest using a friend's K3 . Did not know about the psychoacoustic capability of the K3 that was engaged when I sat down for my turn at the radio. The CW note was odd sounding in the headphones, almost raspy. Didn't think too much about it in the heat of the contest. Took a one hour catnap after 6 hours and when I rolled out of the bed I hit the floor with a bad case of vertigo and tinnitus. The vertigo lasted about 6 months, and i still have the tinnitus. Coincidence. Maybe. Just know I'll never want to be exposed to a psychacoustic soundstage again. Just wanted to mention this in case anyone else runs into this problem. Not sure anyone knows what activates vertigo and tinnitus, so would not rule out psychoacoustic input to the auditory system as a catalyst to the very irritating condition. Would be interested to hear if anyone else has experienced this effect after hours of exposure to psychacoustic auditory input.

George O'Brien

Here's a real world example of diversity receive at work.  I've captured the signal of a station in Hawaii, NH7O, that I just completed an 80 meter QSO with.  He was in the noise and barely leaves a trace in the waterfall but with DIV turned on we were able to have a readable exchange.  The signal is so hard to see that I placed a yellow circle around it. BTW my QTH is northeast SC, grid EM84RQ. I was using a Pixeloop on slice A antenna RXA.  Slice B (on second SCU) used an inverted L (50 ftvertical section + 95 ft horizontal section sloping upward to 65 ft) antenna ANT1.  Slice C used ANT1 on transmit.  1000 watts output power RST exchanged 449.

George O'Brien

Charles, I'm sorry to hear of your bad experience. Subsonics can have severe effects and I don't know what constant phase shifting might do to certain people. Most of us who use diversity reception characterize the sound as "hollow" an almost ethereal quality. With a good setup one can feel immersed in the sound. Noise is much less intrusive and listening fatigue is significantly reduced.

Stu Phillips - K6TU

Don't confuse noise cancellation which is the function of the DXE NCC-1 and diversity reception.  They are two different things.

Noise cancellation uses a second sense antenna plus an external unit to generate an anti-phase noise source that mixed with the primary antenna, cancels some of the noise signal.  Errors in phase and magnitude introduced by the external unit (usually done in the analog domain) result in less than perfect noise reduction.  That said, these units work and work fairly well.

A 6700 could support software that did this perfectly in the digital domain using two SCUs - not possible with a single SCU at least in terms of conventional anti-phase noise reduction.  There are some possibilities for the 6500 and 6300 that don't depend on having a second SCU - but this is, as Gerald correctly described it, is a science experiment.

Diversity reception is a while different critter - I'll look and see if I can find some better descriptions that the one I've provided here.

Bottom line; DIVERSITY reception currently requires two SCUs - that means 6700 and 6700R only.

Stu K6TU

James Kirk

http://kc.flexradio.com/KnowledgebaseArticle50386.aspx?Keywords=diversity

James Kirk

Call Hupy and Abraham

James Kirk

https://www.youtube.com/watch?v=SD0V2D5S1dU

Ken - NM9P

Impressive!