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Hi Amos,
in order to do polarization diversity
reception I/Q samples for both polarizations must be delivered in
sync to the MAP65 application. The only practical way to do that
is as a multichannel (4 in this case) feed. Inside MAP65 the
application connects to an audio device and receives buffers full
of audio samples, with a 4-channel audio device the samples for
each of the 4 channels are delivered together. That is I and Q
from he vertical receiver, and I and Q from the horizontal
receiver interleaved in frames that have 4 samples each. If the
pair of I/Q channels are received via two separate audio devices,
i.e. a pairs of interleaved stereo channels, there is no easy way
to match the arrival time of the two polarizations. Only when the
arrival times are exactly synchronized can polarization diversity
be carried out.
One way MAP65 users do this is with the
Link RF IQ+ direct conversion dual SDR, that device consists of a
pair of ADCs clocked with a common clock source and then the pair
of I/Q outputs at 96,000 Hz Sa/S are fed to a 4-channel external
sound card which also has ADCs using a common clock source, which
in turn delivers interleaved 4-channel audio to MAP65 via a USB
connection.
Other options are available, and using
Linrad to wrangle I/Q outputs from any pair of SDRs that are known
to be synchronized is one option. Linrad delivers the pair of I/Q
data streams as interleaved samples via a UDP network protocol
that MAP65 supports.
The bottom line here is that
polarization diversity requires synchronized sampling of the two
polarization channels. I am not an expert with Linrad, but it may
be possible that Linrad can combine the output of two slices of
I/Q data from your FlexRadio SDR, maintaining any synchronization
they might have. That would require, at least, that the FlexRadio
Signature series SDRs use a common clock for all ADCs, but I
believe you stated earlier that is not the case, YMMV.
73
Bill G4WJS.
On 06/06/2021 10:55, Amos Sobel 4X4MF
wrote:
Bill Please explain what do you mean by 4 channel audio device feeding an interleaved pair of I/Q channels. My Flex 6600 radio can deliver 4 channels of I/Q data out of 2 separate ADC connected to 2 separate antennas. Would that suffice? 73's Amos 4X4MF -----Original Message----- From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of Bill Somerville Sent: Sunday, June 6, 2021 12:38 PM To: main@WSJTX.groups.io Subject: Re: [WSJTX] WSJT-X 2.5.0-rc1 and MAP65 3.0-rc1 H/V signals #general Amos, as discussed previously MAP65 when used for polarization diversity requires a pair of synchronized I/Q channels which must be interleaved, that is not possible if your starting point is two separate stereo channels containing I/Q data. Either a 4 channel audio device feeding an interleaved pair of I/Q channels, or Linrad is supported using an interleaved pair of I/Q channels via UDP in Linrad's own message format. 73 Bill G4WJS. On 06/06/2021 07:04, Amos Sobel 4X4MF wrote:Joe I am preparing to work EME using Q65 on 2m: I have a CROSS H/V long Yagi. I have a Flex 6600 Radio which can support 2 antennas In parallel 1. To enable the use of Q65, do I need a 2 channel Transverter to enable 2 instance processing of WSJT-X v2.5.0 with possible software combination of the H/V data? Or 2. Prefer a combination(X) of the H/V signals into one circularly polarized signal at the antenna level and use 1 instance of Q65 with possible switching between H/V/X signals? Amos 4X4MF -----Original Message----- From:main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of Joe Sent: Thursday, June 3, 2021 12:31 AM To:WSJTX@groups.io Subject: [WSJTX] WSJT-X 2.5.0-rc1 and MAP65 3.0-rc1 #general Dear WSJT-X and MAP65 Users, We are pleased to announce that a public Release Candidate WSJT-X 2.5.0-rc1 is ready for download by beta testers. WSJT-X in this release is nearly identical to that in WSJT-X 2.4.0. The Q65 decoder has been enhanced to measure and compensate for linear frequency drift in Q65 signals. In addition, the Windows installation package now includes version 3.0 of program MAP65. Potential interests of users in this release candidate can be sorted into three main categories: 1. If you are currently using MAP65 for EME, we strongly recommend installing WSJT-X 2.5.0-rc1. On the Windows platform this action automatically installs MAP65 3.0.0-rc1 as well. MAP65 3.0 is a major upgrade that incorporates the Q65 mode, complete with support for LiveCQ and other features enjoyed by MAP65 users for many years. 2. If you are currently using an earlier version of WSJT or WSJT-X for EME, or using the Q65 protocol for any purpose, WSJT-X 2.5.0-rc1 offers a faster and more robust decoder for Q65. If you are using JT65 or JT4 for EME on any band, we recommend switching to the Q65 mode and encouraging others to do so using WSJT-X 2.5.0-rc1. 3. If you are not currently interested in Q65, EME, or MAP65, there is little reason for you to try WSJT-X 2.5.0-rc1. For your present purposes WSJT-X 2.4.0 is just as good. Please note that MAP65 is installed automatically only on the Windows platform. Please let us know if using MAP65 in Linux or macOS would be important for you. If you need more information on recent additions to the capabilities of WSJT-X and MAP65, these short papers may be of interest: "Quick-Start Guide to FST4 and FST4W" https://physics.princeton.edu/pulsar/k1jt/FST4_Quick_Start.pdf "Quick-Start Guide to Q65" https://physics.princeton.edu/pulsar/k1jt/Q65_Quick_Start.pdf "Quick-Start Guide to WSJT-X 2.5.0 and MAP65 3.0"https://physics.princeton.edu/pulsar/k1jt/WSJTX_2.5.0_MAP65_3.0_Quick_Start.pdf "Q65 Sensitivity in MAP65 3.0" https://physics.princeton.edu/pulsar/k1jt/Q65_Sensitivity_in_MAP65.pdf Links for downloading WSJT-X 2.5.0 can be found on the WSJT-X Home Page, https://physics.princeton.edu/pulsar/k1jt/wsjtx.html Scroll down to find "Candidate release: WSJT-X 2.5.0-rc1". WSJT-X and MAP65 are licensed under the terms of Version 3 of the GNU General Public License (GPLv3). Development of this software is a cooperative project to which many amateur radio operators havecontributed.If you use our code, please have the courtesy to let us know about it. If you find bugs or make improvements to the code, please report them to us in a timely fashion. We hope you will enjoy using this beta release of WSJT-X 2.5.0 and MAP65 3.0.0, and exercising the new mode Q65. As a beta tester you should report on your experiences with new features, successful and otherwise, on one of the relevant WSJT forums. Bugs should be reported by following instructions found here in the User Guide: https://www.physics.princeton.edu//pulsar/K1JT/wsjtx-doc/wsjtx-main-2. 5.0-rc 1.html#_bug_reports -- 73 from Joe, K1JT; Bill, G4WJS; Steve, K9AN; and Nico, IV3NWV
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