Hard-Core-DX.com

Is SDR phasing live any better than hardware 
phasing?  If it's not, then all you're doing is 
replacing a piece of hardware with perhaps a 
heavier duty computer, are you not?
Phasing files as they are played back would be 
the technological game changer.   I suspect that 
doing that means recording a different kind of 
.wav file that includes a counter in its header, 
so that samples recorded from one locked receiver 
can be matched up with samples from the other 
during playback.   More informed folks than I 
could comment on the feasibility of that, or whether it exists already.
Would it make any difference to the average 
DXer?   I don't seem to have time to play back 
some of the files from my good openings at home, 
let alone from DXpeditions.  The 
enhanced  ability to winkle out more DX from 
files that I'm not listening to anyway may not be 
all that helpful, hi.  (of course, if I stopped 
bloviating, there might be more time...)
I seem to recall one SDR manufacturer a few years 
ago thinking that there would be little market 
for such a device, even if you provided all 
manner of hand-holding software, which is the 
quite expensive to produce, especially if you want it to function well.
best wishes,
Nick

At 04:06 2019-01-16, Mark Connelly via IRCA wrote:

I would be willing to have a receiver that just 
saved half the MW bandwidth, e.g. 700 kHz, in 
capture files if it had the I/Q streams from the 
two receivers.Â  But with receivers doing 3, 6, 
and more MHz of capture these days, why can't we 
get the whole 510-1710 stretch?
Basic requirements:
*** Phasing can be done after the fact on 
capture files both manually and, when channels 
are reasonably similar, automatically.
*** The two receivers can be slaved to each 
other for diversity and phasing applications or tuned independently.
*** There must be the provision for separate antenna inputs.
*** User can save null solution data to an INI 
file that can be recalled later.Â  This file 
should be plain text suitable for importation 
into antenna-testing technical articles, DXpedition reports, etc.
You need to be able to adjust both gain of each 
channel and the delta-phase / delta-time between 
them.Â  You are not always using identical gain 
and pattern antennas. In fact you could be using 
two opposite ends of the same SuperLoop or 
DKAZ.Â  East end could have 880 WCBS at S-9 and 
882 UK at S-8; west end might have WCBS S9+20 
and UK S-5.Â  So why should you not be able to 
put 20 dB attenuation on the west end to make 
WCBS S-9 and then phase it against the east end 
to provide vastly cleaner pick-up of 882 UK?Â  I 
can certainly do that with the Quantum Phaser and several homebrew models.
If you can adjust after the fact on capture 
files you can run several different gain / phase 
scenarios on, let's say, a graveyard 
channel.Â  By moving the null around the 
compass, as with a conventional rotatable loop, 
you could pull as many as 6 to 8 different ID's 
out of a single channel at a particular time.
You could also think about applying a gain / 
phase curve.Â  Let's say you used an (A vs. B) 8 
dB delta gain / 100 ns delta time solution to 
take down 770 WABC and 6 dB / 90 ns to take out 
880 WCBS.Â  In-between frequencies could be 
adjusted "on the curve".Â  820 WNYC, in a 
similar direction as 770 and 880, could be 
expected to null at something like 7 dB delta 
gain / 95 ns delta time.Â  This sort of 
mathematical manipulation of the data streams 
could help to broadband the nulling pattern when 
using two antennas that don't quite fit the 
textbook scheme of spatially-separated elements 
of identical gain and pick-up pattern.
Phasing only during live DX is not the game 
changer or killer app here.Â  It's nice maybe to 
eliminate one box on the table but what we 
really want is post facto phasing as well as live DX use.
The baby steps are being taken but 
ready-for-prime-time software and hardware 
hasn't arrived yet as far as I can tell.Â  Ham 
DXpeditions / contest stations, MW guys in 
Finland etc. would be all over it if it had.
Mark Connelly, WA1ION
South Yarmouth, MA
<<
A couple of drawbacks for the Afedri:
(1) As of a year ago (I have not checked since), 
the phasing only worked on the live signals. No 
phasing was possible on a recorded file.
(2) It has only a 12 bit converter so is not top of the line.
And something that needs verification: the 
Afedri was only spec'ed to record 900 kHz of 
bandwidth. I see it has recently been changed to 
1100 kHz. That's enough for me if it performs as advertised.
Chuck
>>
<<
Did I miss something?Â  As far as I can tell, 
nothing discussed here comes close to what we 
need - the ability to phase null synchronized RF 
spectrum captures.Â  Everything described here 
is no different than using two receivers (SDR or 
analog) on different antennas, or 
phasing/combining two antennas into one 
receiver, for the purposes of live monitoring 
and making single RF spectrum captures.Â  While 
it is possible to make two RF spectrum captures 
using two SDR receivers simultaneously, then 
perfectly synchronizing playback of the two RF 
spectrum captures for diversity reception (i.e. 
audio from one RF spectrum capture in the left, 
the other in the right), it's difficult to get 
the audio from each spectrum capture in sync and 
the results usually not worth the effort.Â  The 
WiNRADiO Excalibur has three receivers in one, 
but they all operate off the same antenna.Â  So 
the Excalibur can be used for 'diversity 
reception' of parallel frequencies by tuning Rx1 
to 1053 TalkSport and Rx2 to 1089 TalkSport, 
then combining the audio using the Mix functions 
of the Excalibur for example, but it's not 
really diversity reception by definition which 
would have two SDR receivers each with their own 
antenna.Â  I see nothing groundbreaking here.
--
Bruce Conti
B.A.Conti Photography www.baconti.com
Â¡BAMLog! www.bamlog.com
>>
<<
Hi Mark, I have one of the newer Afedri V3.0 
dual input radios here. I bought it out of 
curiosity and am pleased with how well it 
phases. It only has a 1.2Mhz span width in dual 
channel mode, but that gets most of MW. It works 
as well as phased loops/flags but without as 
much loss. I use it with HDSDR after setup with 
the connection tool provided with the Afedri 
radio. SDR# is another software that works, but 
I haven't figured out how to get more than a 192K span from it.
In the Afedri, the 2 ports can be combined, with 
the ability to change the phase but not the 
signal levels. So, your antennas need to be the 
same and cable lengths need to be equal also (or 
length adjusted to prebalance the phase).
Dave AichelmanÂ Â Â Â  N7NZHÂ Â Â Â  Grants Pass, Oregon
__._,_.___
>>
The subject of SDRs containing two phase-locked 
receivers came up recently on the Topband (160m 
ham) list ( 
http://lists.contesting.com/archives//html/topband/2019-01/threads.html ).
The discussion dealt primarily with diversity 
reception: audio from antenna A's RF goes to 
your left headphone, antenna B to the right.? In 
some cases a weak or interfered-with signal that 
isn't quite readable on either channel 
independently can "pop out of the mud" when both 
channels are presented, one to the left and one 
to the right as mentioned. Typically you're on 
the same frequency, mode, bandwidth, and AGC for 
this.? Maybe you use USB one channel and LSB the 
other if the interference is different owing to 
antenna pick-up patterns.? For MW DX, sometimes 
two different frequencies would be fed to the 
headphones for quick comparison of parallel 
audio content (e.g. Spain 684 & 855, Cuba 670 & 710, Japan 747 & 774).
More of interest to me is phasing based in the 
receiver.? This should be available under 
complete (manual) operator control of each 
channel's gain and phase / time delay.? There 
should be a way to save successful null or peak 
set-ups to a look-up table text file that can be 
invoked later to speed up DXing.? The file 
should also be importable into Excel / Word / 
Access / PowerPoint for producing technical 
articles.? Additionally the receiver should 
provide a degree of auto-nulling, at least when 
the two synchronized receivers are getting the 
same dominant "pest" signal (or noise) a 
reasonable amount above co-channel and adjacent interference.
The subject has been chatted up here before and 
I think that one or more receivers 
hardware-capable of this were out there but 
there was no clear software solution, at least 
anything that has been adequately "road tested" 
by cutting edge contester hams and the top MW 
talent in Scandinavia, North America, and east Asia.
If there is new information on this topic, feel free to comment.
Mark Connelly, WA1ION
South Yarmouth, MA
These are some posts recently appearing on the 
Topband list under the "Re: Topband: Dual RX SDR 
receivers (diversity capable)" header.
<<
Have you looked at
http://www.afedri-sdr.com/index.php/new-afe822x-sdr-net-dual-channel ?
73
Nick
VE7DXR
>>
<<
Cross Country Wireless SDR-4++ dual diversity SDR general coverage receiver
Digitally signed mail - John? M0ELS
>>
<<
Hi Bjorn
If you are interested, I have a dual Softrock 
160m SDR receiver (two receivers in one diecast 
box) that was built up about ten years ago or so 
for diversity reception, using Alex VE3NEA?s 
Rock 2.0 diversity version ? see http://www.dxatlas.com/Download.asp.
Owing to family/business pressures I never got 
around to using it. My recollection is JC N4IS 
may have built up something similar?
The receiver is just sitting on a shelf here and 
I am happy to part with it. Also have a M-Audio 
D44 professional soundcard that was going to used with it.
Vy 73
Steve, VK6VZ
>>