--- Begin Message ---
- Subject: dual receiver SDRs for diversity reception / phasing
- From: Mark Connelly <markwa1ion@xxxxxxx>
- Date: Tue, 15 Jan 2019 18:20:39 +0000 (UTC)
- Delivered-to: irca@xxxxxxxxxxxxxxxx
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aol.com; s=a2048; t=1547576443; bh=jtSq3ifWWay7xfgHkfbGntD0MwCxN8tkiPBHkpF+wSY=; h=Date:From:To:Subject:References:From:Subject; b=VqnFy10GUfYwelvGx4/u8pmsithr90BXEgk+y0bkLaRY0Eqn3U2g/dziQ8it+aWvZ6Fvxt2Hh2yk8kltZrvpSDplnPyrV1GGWBbmgWtWmAsaNsJTW/fP7c1qlQa4A+ynoGj2uSd/rK1qRePZMo8iDYnBXDTKK+ibyF0SPBUOfvG1x2JtW1U1pb88MTLsGJLkQbgwthhnZLHoJRignSHLr1rHcPzwzVGGuC9r4zNeoaCDpgFQd31NPJOnu5zhDh/WHN2rvmGhEClrB7ScunAGLKd8Gjx4GuJxvzKRpzRpiRDCt+Q0ruE9rSrrv2YsOoOltEAfeGmFctv8cK2dAIkOIQ==
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
>>
--- End Message ---