Coherent IQ Streams for Adaptive EME

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Conrad_PA5Y
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Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Fri Apr 27, 2018 1:18 pm

Well I finally found some time to test Bryan W4WMT's patched PowerSDR v3.4.9. It is patched to provide 2 x I/Q pairs via VAC1 when Direct I/Q output to VAC is selected. This uses VAC1. Enabling diversity forces the RX1 and RX2 to be coherent.

Unfortunately I have been unable to set up VMB to accept 4 channel ASIO and so cannot proceed any further.

My test setup consists of a 6m antenna>LNA>BPF>Splitter to RX2 and EXT1 inputs. Each leg of the splitter feed has a phase shifter and equal phase cables. My idea is to check for repeatability of reported phase in MAP65 and Linrad once I can get a signal into them. This needs VAC and I need some help. Once repeatability is proven then I will connect the 2m dual RX path in parallel with my existing adaptive RX system.

Unfortunately my UMC404c GUI has no VU meters so I cannot even use that to see if I have a valid stream. I see no VU meter activity in VMB when I select I/Q output to VAC.

In order to have the correct sample rate for MAP65 I have used 96000 as the primary sample rate with 512 buffer, VMB audio engine is configured to be the same. If I de-select IQ, I can route audio as normal.

Sorry it took me so long to find time for initial testing.

73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Fri Apr 27, 2018 1:47 pm

Conrad_PA5Y wrote:Unfortunately I have been unable to set up VMB to accept 4 channel ASIO and so cannot proceed any further.

Conrad,

Please elaborate on this difficulty.

VMB should accept up to eight channels on either of the two "virtual" channel strips, B1 and B2. There is no explicit setup required, it just does it automatically when it sees a multi-channel cable instance. How do you know it is not working?

There is no need for ASIO unless you require low latency, which should not be necessary for nearly all digital mode, EME or similar operations. Therefore, if ASIO is not working, why not try MME or WDM?

It might be instructive to find some plain old multi-channel audio applications to use to prove that VMB is moving multi-channel audio on B1 and B2. Unfortunately, this is not a problem that I've studied, so I can't immediately provide any suggestions. But it is an option for proving out VMB functionality.

I know we can get this to work.

And there is always Muzychenko VAC to try, as well. You might even want to try that first.

73,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Fri Apr 27, 2018 2:19 pm

I set up ASIO because it was mentioned explicitly by Bryan in his initial email on the subject, Have no idea whether this works with any sound API other than ASIO'. So I thought that I would try that first, I will try Muzychenko VAC some time this evening.

What I don't understand is why the VU metering in VMB ceases to indicate anything when I/Q output to VAC is selected, this applies to the standard PowerSDR mrX PS v3.4.9 as well as the patched version.

I have limited time today but a lot more tomorrow. It would be useful if someone other than me tried.

73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Fri Apr 27, 2018 5:40 pm

Conrad,

It may be that VMB does not like the formatting of the IQ data stream. Perhaps this is a peculiarity of its ASIO implementation. Perhaps it might work under MME or WDM. That would be an easy, two minute thing to try if you already have it set up. Or perhaps IQ doesn't work with VMB at all.

I've never tried to pass IQ through VMB myself. When I tested the resampler with CW Skimmer, all of my VMB channels were allocated for existing phone and digi uses, so I simply added some M-VAC channels to the system (VMB and M-VAC happily coexist). The M-VAC channels work fine to pass IQ data. So you may have discovered that VMB just doesn't like the IQ data format. If you try M-VAC and it works, that would be my guess.

73,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Bryan W4WMT » Fri Apr 27, 2018 6:46 pm

Hi Conrad,

The IQ levels coming out of VAC1 are pretty low on my sound card’s VU meters. I assume this is because the raw DDC streams are not being pumped by AGC. So make sure to turn up all your gain controls, the signal might be easy to miss.

Sorry I don’t have VMB here to help test. Maybe I should get a copy.

73, Bryan W4WMT
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 10:03 am

Good morning.

I tried with M-VAC and I could see some activity on the control panel metering. I could not get MAP65 to open any of the PORT AUDIO devices that were needed. I suspect that 4 channels is the problem. It must be 96000 SR so and although the control panel was reporting 96000/16 the M-WAC MAP65 happily takes 4 ch directly from the UMC404HD Via ASIO at 96000 using the ASIO driver. Unfortunately the UMC404HD ASIO driver is single client which of course is why VMB cannot route audio to MAP65 via ASIO. I will try the MME and Direct X drivers but I believe that only 2 channels are available.

Bryan you are correct the metering is not bouncing around much and so from the start of this testing I use a beacon that is -80dBm and fixed AGC. At this stage I just want to get the IQ audio into MAP65 then we can really test it.

As Scott says there must be a way of making this work, VMB should be the best bet. I feel that I am missing something fundamental.

More to follow

Regards

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 10:47 am

Update.

I am not sure why I could not see the 4 channels in VMB previously but now I can, I am also able to confirm that the 4 channels are successfully passed to the UMC404HD ASIO output albeit at a very low amplitude. Next step is to see if I can get the signals into Linrad somehow.

Regards

Conrad
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 2:02 pm

It WORKS!!

Image

As expected this produces either 135 or 45 deg reported polarity as both inputs are in phase with equal amplitudes

However we are not out of the woods yet, There are a few issues, more later.

Also it is reliable with respect to phase accuracy and repeatability. Stopping and starting PowerSDR many times produces the same results, reported Pol of 45 or 135 deg, this PROVES coherence.

The problem was gain.This is how to make it work.

Setup>Audio>Primary

Buffer size 1024
Sampling rate 96000

Setup>Audio>VAC1

Driver ASIO
Input Voicemeter AUX Virtual ASIO
Output Voicemeter AUX Virtual ASIO (not used yet but set it the same to ensure no weird clock stuff)
Buffer Size 1024
Sample Rate 96000

PHASING CONTROL

Receiver Source RX1+RX2
Phase = 0
ENABLED

VF0 Sync ENABLED
AGC Fixed 120 - so max sensitivity

Tuned to 50.180 to test that IQ freq is accurate in MAP65 an arbitrary freq in a quiet part on the 6m band was chosen. I have an off air feed - more realistic.
Image

VMB settings
Image

MAP65 Audio Settings
Image

Test setup
Signal off air so that I have realistic noise floor
Path antenna>LNA>BPF>Splitter to IC746 (to listen off air) and to a 2nd splitter with equal length cables to RX2 and EXT1 - RX1 has EXT1 as input
Gain is approximately 20 -3-1-3 so 16dB from the LNA and splitter combination.
TX from WSJT-X into IC7300 into a dummy load, power and audio input set to produce EME level signals

This works but we have ghost signals every 47Hz as seen below:

Image

These are not present on the TX signal - here is an image from the output of the IC746 used to monitor off air at the same time.

Image

It is a very nice quality near perfect signal as the drive levels are so low, no ALC etc,

Positives

The output stream is coherent and can therefore be used for adaptive EME

It is reliable and repeatable with respect to phase

Negatives

47Hz ghosts are being created somewhere in the ANAN>VAC>VMB path.

The minimum sensitivity in MAP65 appears to be -25, this is not optimal it should be -27 to -28 this is likely to be SRC in VMB it is typical of VAC feeds.

Tonight I will try to connect it to the 2m EME system via the transverters although I am inclined to wait until we figure out where the 47Hz ghosts are coming from.

73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby W9IP » Sat Apr 28, 2018 3:13 pm

Dear Conrad -
This is wonderful news. Thank you for taking the time to carefully report your setup, and of course thanks to Bryan W4WMT for doing the patch!
73,
W9IP
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Sat Apr 28, 2018 3:44 pm

Congratulations on the forward progress. The screen shots are great. It would be very handy to see a shot of the VAC1 setup window.

Some observations and concerns that might help fix your ghost problems:

1. You should not have any A1 sends checked in VMB. This would send audio to your UMC audio interface, and since you have no audio to send, only IQ data, which is not audio per se, these should all be turned off.

2. Your output device in MAP65 should be Voicemeeter Virtual ASIO (not Voicemeeter AUX Virtual ASIO).

3. Turn off the B1 send on the Voicemeeter Virtual ASIO channel. You do not need it to send to itself!

The only sends that should be on are the B2 send on the Voicemeeter Virtual ASIO channel (the left one, this is channel B1) and the B2 send on the Voicemeeter AUX Virtual ASIO channel (the right one, this is channel B2). B1 sends to B2 (for transmit). B2 sends to B1 (for receive).

4. Your sample rates are not showing correctly in VMB at the top of the channel strips. You can fix this by launching the Virtual IO and Virtual AUX IO control panels (they are under the VB Audio folder in the Windows Start menu, and setting the sample rates to 96KHz. You will need to restart Windows after this.

Please let us all know if things still work after the above adjustments.

Assuming the setup survives those changes, that leave one MAJOR problem, which is that the output levels are all out of whack. You should NOT have to crank all of the gain controls up. This is flat out wrong. Question: do you have RX1 AF and RX2 AF set to 100? If not, please try that first, and set AGC to something normal (medium rate, guideline a few dB above the displayed noise floor). If that does not fix the low amplitude problem then there is something wrong in the PowerSDR code. I had no problem in CW Skimmer with levels when I tried it after the resampler came out (but before Bryan gave you this experimental version, which I don't have).

73,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 4:29 pm

Scott thanks, see comments below.

w-u-2-o wrote:Congratulations on the forward progress. The screen shots are great. It would be very handy to see a shot of the VAC1 setup window.

Some observations and concerns that might help fix your ghost problems:

1. You should not have any A1 sends checked in VMB. This would send audio to your UMC audio interface, and since you have no audio to send, only IQ data, which is not audio per se, these should all be turned off.

OK done result no difference.

2. Your output device in MAP65 should be Voicemeeter Virtual ASIO (not Voicemeeter AUX Virtual ASIO).

OK done result no difference

3. Turn off the B1 send on the Voicemeeter Virtual ASIO channel. You do not need it to send to itself!

Sorry but if I do not send to B1 there is no input to MAP65 not with my mapping

The only sends that should be on are the B2 send on the Voicemeeter Virtual ASIO channel (the left one, this is channel B1) and the B2 send on the Voicemeeter AUX Virtual ASIO channel (the right one, this is channel B2). B1 sends to B2 (for transmit). B2 sends to B1 (for receive).

I have not looked at the TX at all yet but this will of course work. I can configure it like this you were not to know as you did not see my VAC1 setup

4. Your sample rates are not showing correctly in VMB at the top of the channel strips. You can fix this by launching the Virtual IO and Virtual AUX IO control panels (they are under the VB Audio folder in the Windows Start menu, and setting the sample rates to 96KHz. You will need to restart Windows after this.

This fixed the ghosts, well spotted, furthermore the SNR went up I still cannot decode below -26 but this is happening with much lower level signals I will post some more images in another post illustrating this

Please let us all know if things still work after the above adjustments.

Assuming the setup survives those changes, that leave one MAJOR problem, which is that the output levels are all out of whack. You should NOT have to crank all of the gain controls up. This is flat out wrong. Question: do you have RX1 AF and RX2 AF set to 100? If not, please try that first,

RX1 and RX2 volume makes absolutely no difference, I think that the IQ stream is output before any demodulation in PSDR so it is not surprising, I didn't think that RX1 and RX2 volumes had any effect on VAC?

and set AGC to something normal (medium rate, guideline a few dB above the displayed noise floor). If that does not fix the low amplitude problem then there is something wrong in the PowerSDR code.

I have a feeling that this may be 'normal' behaviour. In MAP65 Audio settings there is a tick mark for +10dB. As for the AGC settings I am trying to recreate an EME scenario, traditionally we NEVER use AGC when on EME as it results in lower sensitivity, besides turning it on will only reduce the IQ amplitude not increase it

I had no problem in CW Skimmer with levels when I tried it after the resampler came out (but before Bryan gave you this experimental version, which I don't have).

It is easy to fix, we have an EME button that adds the required amount of again, as its virtual nothing will overload, it would merely be a level shift.

73,

Scott


73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby Bryan W4WMT » Sat Apr 28, 2018 4:51 pm

Hi Conrad,

Glad to hear you fixed the 47 Hz ghosts.
That part had me worried.
Are you going to have enough gain to get the job done when you go on the moon for real tonight?

73, Bryan W4WMT
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Re: Coherent IQ Streams for Adaptive EME

Postby Bryan W4WMT » Sat Apr 28, 2018 4:58 pm

Something to watch out for: it’s been reported here before that “Diversity” mode will sometimes lose coherence when QSYing with the VFO. If so, that’s a bug that needs fixing.

73, Bryan W4WMT
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Sat Apr 28, 2018 5:09 pm

2. Your output device in MAP65 should be Voicemeeter Virtual ASIO (not Voicemeeter AUX Virtual ASIO).

OK done result no difference

No, it wouldn't, not until you go to transmit. But it seemed important to get it correct up front.

3. Turn off the B1 send on the Voicemeeter Virtual ASIO channel. You do not need it to send to itself!

Sorry but if I do not send to B1 there is no input to MAP65 not with my mapping

Did you turn off the correct B1 send? You should not have both the B1 and B2 sends turned on on channel B1 (Voicemeeter Virtual ASIO). This makes no sense. If you really have to have both of those sends activated on that same channel I would sure like to understand why.

The only sends that should be on are the B2 send on the Voicemeeter Virtual ASIO channel (the left one, this is channel B1) and the B2 send on the Voicemeeter AUX Virtual ASIO channel (the right one, this is channel B2). B1 sends to B2 (for transmit). B2 sends to B1 (for receive).

I have not looked at the TX at all yet but this will of course work. I can configure it like this you were not to know as you did not see my VAC1 setup

You documented your VAC1 setup as follows:

Code: Select all

Setup>Audio>VAC1

Driver ASIO
Input Voicemeter AUX Virtual ASIO
Output Voicemeter AUX Virtual ASIO (not used yet but set it the same to ensure no weird clock stuff)
Buffer Size 1024
Sample Rate 96000


With that setup, and with MAP65 input and output set to Voicemeeter Virtual ASIO, then on channel B1 you should only need the B2 send active, and on channel B2 your should only need the B1 send active. If this is not the case, I'd really, really like to understand why not???

Thanks,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 5:27 pm

The moon has just risen here so I will attempt to connect up the coherent dual channel 144>28MHz transverters - then we will really see. Bryan I think that I will have enough gain. Also the frequency is fixed, there is never any need to change it. It will be 144.125 on 2m EME, always. For TX I do not use MAP65, it is a band map only, I use the IC746 for TX for now.

In MAP65 when using ASIO both input and output must be the same, it seems that this version of PowerSDR has the same requirement.

A few more screenshots.

Image

b]Strong signal no ghosts[/b]

Image

Same but WSJT from IC746

Image

Now some weak signals

Image

Same but WSJT from IC746 now set as I use it for 6m EME

Image

73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 6:32 pm

Now for some 2M EME - I think it is working fine, I have some gain imbalance on CH1 and CH2 but it could be real, at low elevations often V signal on CH2 has a higher noise floor so before I address this I thought that I would share some things.

Firstly look at the screenshot of LiveCQ which shows what other stations are receiving. The best comparison for amplitiude and phase is PA9RX, he has a good receiver, his phase accuracy is very good and we have similar sized antennas.

Image

Now MAP65 at around the same time

Image

You will see that 7P8Z has a pileup and he calls RX1AS with a POL of 34 deg, he has a signal of -16 in MAP65, there is some vertical component in his signal. Now if we look at the H pol only from WSJT10 and the IC746 which is a VERY sensitive setup we see -18 for when 7P8Z calls RX1AS, so I would say it is working quite well. I will listen for a long time tonight and really check things out.

Image

The transverter inputs and adaptive don't seem to work so I set the ANAN to 10m for now, that is almost certainly me being stupid. I am sure of it.

Finally a little more band map and liveCQ comparisons as the moon gets higher, I am sure it works fine, some fine tuning perhaps but it is nearly there.

Image

Image

HB9Q has a 15.6m dish BTW

73

Conrad PA5Y
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 6:45 pm

Forgot to mention - very important, in the phasing control receiver source RX1 must be selected and RX1 should be the H channel. This is 0 deg and needs to be set like this to get the correct phase relationship. If you set RX1 and RX2 as the source then you always get 45 deg :lol:
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Sat Apr 28, 2018 8:18 pm

Conrad,

Do you have more than a single B1 and a single B2 send selected in VMB? If so, why?

It would really help me to know and understand this, please.

Thanks,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Ton_PA0TBR » Sat Apr 28, 2018 8:23 pm

Hi Conrad & Bryan,

Very nice to see that you got it working. Congratulations!
Good to see that 4 channels on a single VAC was the answer.

73,
Ton pa0tbr
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sat Apr 28, 2018 9:35 pm

There is a phase error of around -40 deg, compared it for several hours with my normal system and that is what I observed. I do not know the root cause of this. Perhaps the length of the RX path or perhaps filters in one path and not the other, I am tired now but will continue to experiment

Conrad
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Sat Apr 28, 2018 10:36 pm

Conrad,

Do you have more than a single B1 and a single B2 send selected in VMB? If so, why?

It would really help me to know and understand this, please.

Thanks,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sun Apr 29, 2018 5:42 am

Hello Scott now I have this setup. Which I believe is more in line with your expectations, I now use different ASIO feeds from PowerSDR to MAP65. Perhaps best explained with screen grabs. There is only a single B1 selected. Notice that the sample rate and buffers indicators above the virtual inputs in VMB are indicating 96000/2048 and are in red. I cannot get this to go white unless I drop the sample rate. However as you know if the sample rate is not 96000 I get ghosts. This configuration works other than there is an error in the reported phase in MAP65 coming from somewhere.

If I put a dummy load on RX2 input and the EXT1 input that I am using for RX1 then I see a 2dB difference in the noise floor also. I have a feeling that there is a phase error being caused by the path difference between the RX1 and RX2 ADCs. The ability to adjust the phase and amplitude would be useful. I don't seem to be able to do this with the phasing control. Does the phasing control have any effect on the IQ streams? In order to fully understand what is going on I have to set up a few controlled experiments with delay lines. This will also take me some time to prepare.

Image

Image
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Re: Coherent IQ Streams for Adaptive EME

Postby Bryan W4WMT » Sun Apr 29, 2018 11:42 am

Hi Conrad,

I don’t recall which rig you have there, but if it is pre-OrionII you may be seeing phase shift through Alex on RX1 that doesn’t exist on RX2. Possible?

73, Bryan W4WMT
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sun Apr 29, 2018 12:17 pm

Hi Bryan its an ANAN-100D so yes that is also my suspicion. What we need is a way of compensating and the easiest way is with a piece of cable. The size of the error must be caused by a filter and not just PCB track lengths. This is an error at 28MHz so 40 deg is significant length of cable.

Maybe the phase error can be measured with the oscilloscope in Linrad by porting the IQ streams. I will see if I can bring a 2 channel Vector signal generator home from work. I think that there is one that can share a common modulation source and have variable delays and amplitudes applied to each coherent source, that will be the best.

I will also see what the Phase meter is capable of.

No QSOs for me today :-)
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Re: Coherent IQ Streams for Adaptive EME

Postby Bryan W4WMT » Sun Apr 29, 2018 1:41 pm

Just as a “proof of concept” kind of thing, can you figure out how to disable Alex on RX1 and see if the phase difference goes away?
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Sun Apr 29, 2018 2:32 pm

Not without doing some reading. I don't have any spare time today
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Re: Coherent IQ Streams for Adaptive EME

Postby AB2EZ » Sun Apr 29, 2018 3:37 pm

Conrad
et al.

I am very much enjoying reading and following this discussion.

Thank you
Stu
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Re: Coherent IQ Streams for Adaptive EME

Postby Ton_PA0TBR » Sun Apr 29, 2018 7:11 pm

Hi Bryan,

Conrad said that he is using the EXT1 and RX2 inputs.

Receiver 1 is disconnected from the LPF by relay K36 when EXT1 is selected.
The HPF can be bypassed in the Ant/Filters - HPF/LPF menu

73,
Ton PA0TBR
Last edited by Ton_PA0TBR on Mon Apr 30, 2018 9:01 pm, edited 1 time in total.
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Re: Coherent IQ Streams for Adaptive EME

Postby w-u-2-o » Mon Apr 30, 2018 1:04 pm

Sorry for the delay in responding. I was 100% otherwise occupied yesterday with no time for the internet.

Thanks for posting those screen shots, Conrad, and I'm so glad to see that everything is as expected with VMB. In particular, it is good to see that gains are now nearly all near 0dB with just the 10dB checkbox selected in MAP65. This is much closer to what I expected.

A few ideas for you:

1. Go back into the Virtual IO and Virtual AUX IO control panels and double the buffer sizes to see if this will rid you of the red indicators in VMB. A restart will be required.

2. No need to have MUTE activated on any channel.

3. You can probably eliminate any amplitude differential by using this tool with VMB:

https://forum.vb-audio.com/viewtopic.php?f=8&t=394

4. Defeat the preselectors and check your phase offset and amplitude offset. It would be interesting for us all to know how it changes with the preselector bypassed. Bypassing the preselector should make it near 0 for both phase and amplitude, but I guess we'll see!

To really make this work right, the plumbing inside of PowerSDR (or Thetis) needs to allow the "diversity" phase/amplitude control be effective when using the radio this way.

73,

Scott
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Re: Coherent IQ Streams for Adaptive EME

Postby Conrad_PA5Y » Mon Apr 30, 2018 1:43 pm

Hello Scott, I will have limited time tonight and also the moon rise is getting very late and lunar conditions are worsening. What I can maybe do is come up with a test signal and a variable delay line in 1 leg. I would like to do this so that I can get meaningful and repeatable measurements.

Just to be clear what must I do to bypass the pre-selector for RX1?

I think that I can maybe test that on Wednesday evening although not off the moon, it will be too late before moonrise.

I am pretty certain that we can make this work without a massive amount of development. Trimming the amplitude and phase for the inputs will be useful. You can imagine that the chances of having 2 mast mounted LNAs, 2 band-pass filters, RX cables from the mast with perfectly matched phase is unlikely. I spent a lot of time on this and I have a small but acceptable error. To be honest it is not hugely important, not as important as seeing the signal at max combined amplitude.

Then we get to the real sticky wicket, how to TX on the correct frequency and return to 144.125 on RX. We have CAT tools that are tied to MAP65 but I am not sure about this yet. We will need Split, will we maintain coherent operation?

One thing at a time...

73

Conrad PA5Y

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