for polarization diversity you use two orthogonal linear polarization aerials each positioned equally to to incoming wave-front. The software can then derive any polarization from that. Circular polarization is convenient to avoid cross-polarization losses, but see below. One issue with circular polarization is that each end of a link must use opposite handedness polarization, conveniently this is not necessary with EME since the reflection of the Moon reverses the circular polarization direction.
Circular polarization is used for most microwave EME but AFAIK it is not used for VHF/UHF EME, hence the use of MAP65 and dual polarization receiving systems. Note that using linear polarization for transmission is often good enough, particularly if the the linear polarization that matches the latest received signal is used. This works because the cross-polarization losses when the delta is less than 45 degrees is relatively small (<3dB). Note that the theoretical cross-polarization loss for 90 degree difference is infinite. Note also that using circular polarization for reception of linear polarized signals always incurs a 3dB loss so is not optimal compared with picking the nearest linear polarization from a pair of horizontal and vertical (or slant) polarized transmitting aerials.
On 06/06/2021 11:17, Amos Sobel 4X4MF wrote:
Bill My H/V Yagi antenna does have 2 separate H and V outputs which are separated by quarter lambda /90 degrees phase shift. It is possible combine it to one output with Circular Polarization. Is that equivalent to the polarization diversity of MAP65? I am told this process does add 3db of noise. Can Q65 overcome this type of noise? 73's Amos 4X4MF ============================================================================ ======================= 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"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