Quick record on AM

N9HLL
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Quick record on AM

Postby N9HLL » Fri Nov 17, 2017 5:26 am

Is it just me or is it not possible to get a good recording either with the Quick record or Wave record screen on AM ? Completely distorted no matter what I have tried.
SSB works absolutely perfect in either selection.


Any suggestions ?

Thanks Rick (N9HLL)
Life is too short for QRP and less than 3kc
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N9HLL
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Re: Quick record on AM

Postby N9HLL » Fri Nov 24, 2017 2:31 am

Mods Please delete this thread, I guess it is either a problem on my end or nobody cares if you are not in the "loop".

Thanks
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Re: Quick record on AM

Postby w-u-2-o » Fri Nov 24, 2017 3:12 am

Rick,

Don't get discouraged. I think the issue is that you've simply hit on a niche problem for which few, if anyone, has any input. People are not ignoring you, they just don't have an answer for you.

I'll throw myself under this same bus: I never use quick record/playback in any mode, so have no experience to fall back on with which to help you. Add to this the fact that about 1% of my operating is AM and that just makes the knowledge vacuum worse.

73,

Scott
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Re: Quick record on AM

Postby W1AEX » Fri Nov 24, 2017 5:42 pm

Hi Rick,

I operate a lot of AM with my ANAN and have used the REC button in the software GUI to make recordings and then play them back over the air with the PLAY button. You do have to be transmitting before you hit the PLAY button for that to work correctly. I have also used the WAVE recording form to make I/Q recordings on AM which I then use to make screen captures with OBS or Camtasia for uploading to my YouTube channel. More often than either of those scenarios I use an old version of Adobe Audition to make an MP3 recording during an AM QSO and then I edit it to a reasonable size (under 10 meg) and save it so that I can attach it to an email for the station who wants an audio air-check. Those recordings reliably produce very "true to life" air checks that give an accurate representation of how the station sounds.

I have not had any issues with distortion during any of those procedures, however, initially, I found that my windows mixer settings were way too high and everything sounded over driven. Could be an issue there but if it's working fine with SSB then it doesn't sound like that's the problem.

Tell us a little more about your TX audio setup and RX audio setup and maybe we can figure out what's going on.

73,

Rob W1AEX
"One thing I am certain of is that there is too much certainty in the world."
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Re: Quick record on AM

Postby spinomaly » Sat Dec 02, 2017 1:03 am

I have the same issue with 3.4.5 and the 7000. I tried recording my voice on SSB and it plays back completely distorted.

Using Jabra headset into VAC1 and VAC2(off). CFC disabled.

recording.png
recording.png (312.84 KiB) Viewed 4080 times

recording2.png
recording2.png (407.57 KiB) Viewed 4080 times
Dr. Loren Betts
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Re: Quick record on AM

Postby w-u-2-o » Sat Dec 02, 2017 2:02 am

Loren,

Perhaps you might find my VAC tutorial helpful.

73,

Scott
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Re: Quick record on AM

Postby spinomaly » Sat Dec 02, 2017 2:30 am

Thank Scott. This is very helpful. I am not all that familiar with the details of audio in windows so this is great.
Dr. Loren Betts
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Re: Quick record on AM

Postby spinomaly » Sat Dec 02, 2017 3:34 am

Hi Scott,

Checking my settings shows I am inline with your document. I also get good audio reports. I am still not able to get a recording of my voice. It plays back distorted.
recording3.png
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Dr. Loren Betts
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Re: Quick record on AM

Postby w-u-2-o » Sat Dec 02, 2017 11:53 am

Unfortunately I never use the quick record/playback feature, so I am ill equipped to help you. Perhaps Rob will chime in again.

It should be noted that when PureSignal is enabled your transmit waveform will also include predistortion, and that can make it sound funny if you are listening on MON or using quick record. In this cases you may want to disable PureSignal temporarily.

I'm not sure what your screen shot is showing, but it doesn't look good. You may want to take a look at this thread regarding display configuration:

https://apache-labs.com/community/viewtopic.php?f=6&t=2545

Finally, if you did follow the recommendations in the VAC tutorial, then I hope you were able to change the sample rate on the Jabra from 44.1KHz to 48KHz,

73,

Scott
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Re: Quick record on AM

Postby DL2XY » Sun Dec 10, 2017 2:25 pm

Hi,

every things are working fine with record/playback, even in AM.
Just do not supress the carrier by having checked "Setup/DSP/AM/DC-BLOCK" during record!

73 Walter
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Re: Quick record on AM

Postby K9RX » Sun Dec 10, 2017 4:06 pm

Rick,

PLEASE tell me how you get it (QUICK REC/PLAY) to work on SSB!

I posted a thread on this as well some time ago although regarding SSB/CW and it is still an outstanding issue here. The Quick Record/Playback simply doesn't work that I can tell. I have options set at Receive from audio ... I hit QUICK record ... then hit play and I see what appears to be I guess an I/Q display as the signal is folded at the center line ... if receiving and trying to record CW it is the signal inside the passband - and there are two of them center/spaced the CW pitch frequency up and down from the center line... and the level is REALLY high, changing the only level control under WAVE (TX) doesn't effect it ... I've not been able to get this to work. It is frustrating as I'd LIKE to use it to record audio on air and play it back without having to go for the full WAVE panel option (which also acts weird at times)... I'm SURE I'm doing something wrong as too many use this - but for the life of me I can't see how something so simple can be done wrong. [using the QUICK RECORD/PLAY doesn't use any software outside of PSDR right? Someone mentioned Windows settings - that doesn't apply here - right? or is that what I'm missing/screwing up?]

Gary
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Re: Quick record on AM

Postby spinomaly » Sun Dec 10, 2017 4:11 pm

I am having the exact same issue but it is also affecting the Wave panel.
Dr. Loren Betts
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Re: Quick record on AM

Postby spinomaly » Sun Dec 10, 2017 5:12 pm

Update. If I change to IQ in the Wave Record Options dialog it appears to work. I will take a look at the code to see what is going on.
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Re: Quick record on AM

Postby w-u-2-o » Sun Dec 10, 2017 5:26 pm

This is your chance to change the program to make it work how you want, Loren! And no doubt we'll all benefit from it! Great stuff! :D

73!

Scott
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Re: Quick record on AM

Postby DL2XY » Sun Dec 10, 2017 11:41 pm

After severe testing and examining the source i have come to the following conclusions:

There are two distinc ways to record wave data.

IF (IQ)- Record:
This one is meant to take a snapshot of a wider bandwith for later examination (you can even tune within the recorded bandwith) or as input file for other SDR-Applictions.


AF (Audio)-Record:
This one is meant to be transmitted at playback. It records only the current Passband and normalizes the Level to the current AGC-Threshold.
The normalization is done to have the correct level for retransmission or for playing the File on Media-Players.

The Point:
"Quick REC" (and "REC" on console) always do AF-Record!

The Problem:
Playing the file in RX-Mode injects the wave data in normalized form ( max. level, ca -15 dBm) to the receiver input. The AGC will catch up with this strong signal, but that leads to massive Compression!

The Solution:
Rising the AGC-Threshold to -15dBm during playback will solve the compression and loudness difference.
I also have adapted the spectrum display range and the waterfall sensivity for good visual appearance.

Remember: If recording AM, do not activate DC-Block or ANF. This will lead to loss of Carrier!
Also always adjust AGC-Threshold to peak signal before recording to avoid additional compression.

Here are the changes in source i have done for my "personal build".
Modifications are marked with "DL2XY" in comment.
File: wave.cs (Line 1028...)

Code: Select all

        private bool temp_record = false;
        private bool temp_play = false;
        private bool temp_mon = false;
        private bool temp_txeq = false;
        private bool temp_cpdr = false;
        private bool temp_dx = false;

        private int temp_rf = -20;                  //DL2XY
        private int temp_GridMax = 0;               //DL2XY
        private int temp_GridMin = -100;            //DL2XY
        private float temp_WaterfallHigh = 0;       //DL2XY
        private float temp_WaterfallLow = -100;     //DL2XY
        private int att = 0;                        //DL2XY

        private void chkQuickPlay_CheckedChanged(object sender, System.EventArgs e)
        {
            string file_name = console.AppDataPath + "\\SDRQuickAudio.wav";
            if (chkQuickPlay.Checked)
            {
                temp_txeq = console.TXEQ;
                console.TXEQ = false;               // set TX Eq temporarily to OFF

                temp_cpdr = console.CPDR;
                console.CPDR = false;

                temp_dx = console.DX;
                console.DX = false;

                temp_play = Audio.RecordTXPreProcessed;
                Audio.RecordTXPreProcessed = true;  // set TRUE temporarily

                temp_mon = console.MON;
                console.MON = true;

                att=console.RX1AttenuatorData;                              //DL2XY get Attenuator setting for reference
                temp_rf = console.RF;                                       //DL2XY save AGC
                temp_GridMax = Display.SpectrumGridMax;                     //DL2XY save Spectrum Grid Max
                temp_GridMin = Display.SpectrumGridMin;                     //DL2XY save Spectrum Grid Max
                temp_WaterfallHigh = Display.WaterfallHighThreshold;        //DL2XY save Waterfall High
                temp_WaterfallLow = Display.WaterfallLowThreshold;          //DL2XY save Waterfall Low
                console.RF=0;                                               //DL2XY set AGC to Max
                Display.SpectrumGridMax = att;                              //DL2XY shift Spectrum Grid to Max
                Display.SpectrumGridMin = att + temp_GridMin-temp_GridMax;  //DL2XY keep Spektrum Span
                Display.WaterfallHighThreshold = att;                       //DL2XY shift Waterfall to Max
                Display.WaterfallLowThreshold = att + temp_WaterfallLow-temp_WaterfallHigh; //DL2XY keep Waterfall Span

                if (!OpenWaveFile(file_name, false))
                {
                    chkQuickPlay.Checked = false;
                    console.MON = temp_mon;
                    Audio.RecordTXPreProcessed = temp_play; //return to original state
                    console.TXEQ = temp_txeq;               // set TX Eq back to original state
                    return;
                }
                chkQuickPlay.BackColor = console.ButtonSelectedColor;
            }
            else
            {
                if (Audio.wave_file_reader != null)
                    Audio.wave_file_reader.Stop();
                chkQuickPlay.BackColor = SystemColors.Control;
                console.QuickPlay = false;
                console.MON = temp_mon;
                Audio.RecordTXPreProcessed = temp_play; //return to original state
                console.TXEQ = temp_txeq;               // set TX Eq back to original state
                console.CPDR = temp_cpdr;
                console.DX = temp_dx;
                console.RF=temp_rf;                                 //DL2XY restore AGC
                Display.SpectrumGridMax = temp_GridMax;             //DL2XY restore Spectrum Max
                Display.SpectrumGridMin = temp_GridMin;             //DL2XY restore Spectrum Min
                Display.WaterfallHighThreshold =temp_WaterfallHigh; //DL2XY restore Waterfall High
                Display.WaterfallLowThreshold = temp_WaterfallLow;  //DL2XY restore Waterfall Low
            }
            Audio.wave_playback = chkQuickPlay.Checked;
            console.WavePlayback = chkQuickPlay.Checked;
        }



73 Walter
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Re: Quick record on AM

Postby w-u-2-o » Mon Dec 11, 2017 2:20 am

Great stuff, guys! Interestingly, I've always disabled DC Block in Setup > DSP > AM/SAM as a matter of course, so never observed this problem, but didn't understand why until now. :)

73,

Scott
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Re: Quick record on AM

Postby DL2XY » Mon Dec 11, 2017 10:22 am

Hi Scott,

If you strip the carrier from an AM Signal (this is what DC-Block or ANF are doing) it won't be AM anymore but DSB.
If you try to AM-demodulate a DSB signal (this is what you do if you playback former signal in mode AM) you will get heavy distortion.

Playing back the same recording in modes DSB or SSB will sound fine, but you have lost any dynamic information since the carrier acts as reference level for momentary loudness in AM modulation.

The problem with stripped AM carrier only take place if playing back in RX-Mode. At retransmission in TX-Mode the carrier will be restored by the AM-Modulator. But also you will loose original dynamik range information, the output will be compressed depending to AGC setting during record.

73 Walter
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Re: Quick record on AM

Postby W1AEX » Wed Dec 20, 2017 3:11 pm

"PLEASE tell me how you get it (QUICK REC/PLAY) to work on SSB!"

Gary,

The REC/PLAY function is for re-transmitting a signal back to another station. If you hit PLAY while you are in receive mode it will do exactly what you have described. After making a recording, switch to transmit, and then hit PLAY to re-transmit what you have recorded:

1. Press REC to start recording
2. Press REC again to stop recording
3. Begin transmitting
4. Press PLAY and what you recorded will be re-transmitted

I made a short video below to demonstrate it. Hope it helps!

73,

Rob W1AEX

"One thing I am certain of is that there is too much certainty in the world."
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Re: Quick record on AM

Postby K9RX » Wed Dec 20, 2017 7:08 pm

Rob,

Well that's exactly how I thought it would - should work ... are you saying that listening to it, i.e hitting "PLAY" without being in TX is not what it is suppose to support? As that is all I've ever done. After hearing what it does - plays back at a very high volume, I've always been reluctant to actually try it ...

Gary
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Re: Quick record on AM

Postby K9RX » Wed Dec 20, 2017 7:27 pm

Rob,

THANK YOU SIR!!

As noted I've never actually tried it since listening to it and seeing what is displayed is discombobulating at best ... but I tried just hitting MOX and PLAY and IT WORKS! (It STILL sounds loud but I suspect it is actually as loud as when it was recorded) ... I recorded someone and then went to a clear frequency, announced, and played it briefly.

Gary
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Re: Quick record on AM

Postby W1AEX » Wed Dec 20, 2017 10:02 pm

Hi Gary,

Glad that worked out. As Walter (DL2XY) mentioned, the REC and PLAY buttons in the GUI only record audio and are intended for re-transmitting a received station's audio. It's important to enter TX mode before hitting the PLAY button for this to work as intended. The "Wave File Controls" menu shown below can record wave files in I/Q format for playback through the OpenHPSDR receiver and also can record audio in uncompressed WAV format (use the Options drop down menu) which can either be played back by a program such as WinAmp or processed into MP3 format by programs like Audition or Audacity (if the LAME codec is installed) to make the file size manageable.

You can adjust the transmitted volume by opening up the "Wave File Controls" form as a recording is being re-transmitted and setting the level to what is appropriate. The ALC meter would be a good indicator to assure that peaks are reaching 0 dB in the same way as your own transmitted audio.

I think Walter's comments about playing back AM through the REC and PLAY function are spot on. If the DC Block is being used the AM signal will sound very compressed and when it is re-transmitted it will not sound accurate. I have never heard the explanation for this before but I think he got it right!

73,

Rob W1AEX

Image
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Re: Quick record on AM

Postby K9RX » Thu Dec 21, 2017 2:08 pm

I would however suggest that there isn't anything that mentions the use of QUICK REC/PLAY and just looking at the results on the pan during play - and in so doing not to expect this to be 'meaningful' ... I've had the radio operational since May or early June and have tried to get this 'resolved' over that time period - this is the first that i've heard that it is only intended to be used on TX (and by implication DON'T "look at it" without being in TX).

Note- although it may seem like "common sense" that one be in transmit I would take exception to that - as one that wants only to be clean (TX) having seen what it does and heard how much LOUDER it is when I did just play it back there was no way I was going to transmit that - thus my seeking to get a better understanding of why it seemed not to work.

Note that I can indeed adjust the gain setting and have done that - but it seems like the ALC isn't really the appropriate means of adjusting this at least once you hit a point where its always at 0 dbm. Looking at the wattmeter seems a bit more 'accurate' ... my talking at a normal level and seeing how the watt meter responds (for me an external LP100 set to peak mode) and then setting the gain when playing back to be roughly the same. This shows a gain of about 23 db (interestingly the same as what my MIC gain setting is - although I believe that is strictly a coincidence) ... and I can adjust it higher than that - the signal when played "sounds" louder and harsher even though the ALC acts about the same as far as I can tell.

and for those looking to use this and reading this thread - be aware that when you record you want to be sure you open up the filter to encompass the whole signal of the station you're recording (and if it is on turn off the RX EQ) ... then when you play back it will automatically xmit using that same bandwidth (and turn off all the local audio settings, TX EQ, COMP, LEVELOR, CFC, automatically).

Again thanks for clearing this up for me - I can now reciprocate with others that share my recorded transmissions.

Gary
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Re: Quick record on AM

Postby N9HLL » Tue Dec 26, 2017 2:35 pm

Well Since I started this and have not been back to it for a bit...
The DC block was the issue....Thank you Gents.....That is the beauty of the Forum, You can always learn something

Rick
N9HLL
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