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Amos Sobel 4X4MF
Bill
Flex radio does tell me that my request to make their SmartSDR deliver the 2xDAXIQ stream compatible with the requirement of MAP65/Q65 have been put in their enhancement database for sometime implementation. I will pray for that. In the mean time please consider using the IQ streams delivered by Flex Radio and many other SDR radios as an input to WSJT-X Q65. This is half way to your MAP65 requierment and does contain more “Flash” than the common data stream.
Amos 4X4MF
From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of Bill Somerville
Sent: Sunday, June 6, 2021 3:23 PM To: main@WSJTX.groups.io Subject: Re: [WSJTX] WSJT-X 2.5.0-rc1 and MAP65 3.0-rc1 H/V signals #general
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
On 06/06/2021 10:55, Amos Sobel 4X4MF wrote: BillPlease explain what do you mean by 4 channel audio device feeding aninterleaved pair of I/Q channels.My Flex 6600 radio can deliver 4 channels of I/Q data out of 2 separate ADCconnected to 2 separate antennas. Would that suffice?73'sAmos 4X4MF-----Original Message-----From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of BillSomervilleSent: Sunday, June 6, 2021 12:38 PMTo: main@WSJTX.groups.ioSubject: Re: [WSJTX] WSJT-X 2.5.0-rc1 and MAP65 3.0-rc1 H/V signals #generalAmos,as discussed previously MAP65 when used for polarization diversity requiresa pair of synchronized I/Q channels which must be interleaved, that is notpossible if your starting point is two separate stereo channels containingI/Q data. Either a 4 channel audio device feeding an interleaved pair of I/Qchannels, or Linrad is supported using an interleaved pair of I/Q channelsvia UDP in Linrad's own message format.73BillG4WJS.On 06/06/2021 07:04, Amos Sobel 4X4MF wrote:
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