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Author Topic: "Smug" Question About SDR Synch Detector  (Read 22694 times)
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flintstone mop
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« on: January 18, 2010, 09:08:46 PM »

I thought the recovered audio from my R390A diode load was always superb to anything at MOP radio.............UNTIL I turned off the Sync Detector in the FLEX radio.
When the SAM or Sync Detector is on the lower frequencies seem like they are reduced and the bottom end is cut off at 100HZ. Anyone else make such a discovery?

Fred
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Fred KC4MOP
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« Reply #1 on: January 18, 2010, 09:19:22 PM »

I suspect your sound card is smug enough to pass audio below 100hz while the 390 may not be set up for hi fi.
I like to run the sound of the oil furnace through my PDM rig
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KF1Z
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Are FETs supposed to glow like that?


« Reply #2 on: January 18, 2010, 09:24:45 PM »

I think he's talking the other way 'round Frank...


I did not like powersdr's sync AM at all...

Granted that was an old version 1.14?

I think you're using a softrock right Fred?


If you haven't already, give  Winrad a try.
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N2DTS
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« Reply #3 on: January 18, 2010, 09:32:30 PM »

On the flex 5000, I don't hear much difference between sync detector and regular AM.
A little less distortion with a lot of qsb maybe.

In Power sdr, you can set the lowest freq it will pass (and the highest) on TX and RX.
I have mine set to 20 Hz.
(VERY smug here....)

Brett
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« Reply #4 on: January 18, 2010, 09:34:55 PM »

Sorry. Fred it may be the loop filter in the software locking to the carrier. The corner frequency is set fairly high for a fast lock. I've seen this same effect on a Sherwood sync detector. The lows don't really come in till you tighten up the loop.
When you have a tight loop or low corner the thing takes a real long time to lock.
It would be cool to have a loop change once there is a lock to help recover more lows. Alberto's (weak signals ver .99 sounds a lot better) but it takes longet to lock with a smaller capture range.
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WA1GFZ
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« Reply #5 on: January 18, 2010, 09:37:32 PM »

Gee Brett, I never checked the RX freq. It must be in the set up stuff. I have played with TX though.
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N2DTS
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« Reply #6 on: January 18, 2010, 09:38:58 PM »

Somehow, the flex seems to lock very fast, but sync or not, there seems to be no change in the frequency response.

Brett
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N2DTS
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« Reply #7 on: January 18, 2010, 09:45:19 PM »

Setup, general, filters, default low cut.
Like I said, I set mine at 20Hz.
Also in there is the MAX filter width, which I set to 10Khz (20Khz in AM).

Brett
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K9ACT
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« Reply #8 on: January 19, 2010, 12:03:57 AM »

Setup, general, filters, default low cut.
Like I said, I set mine at 20Hz.
Also in there is the MAX filter width, which I set to 10Khz (20Khz in AM).


It never ceases to amaze me what is all in there.  I have been running this for three years or more and never noticed that trick.

Yah I know, read the manual.

I don't know about Flex but with SoftRock SAM is a powerful tool that can make or break a QSO.  Turning garble into clear speech can be like magic.  I notice nothing but an improvement in audio quality when using it.  The only time I turn it off is when there is/are old buzzards with sloppy VFO's or sloppy habits.

Jack
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Blaine N1GTU
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« Reply #9 on: January 19, 2010, 06:22:03 AM »

there used to be a software bug a few years back that did this.
when i upgraded to a newer version it fixed it, you should be running the latest version anyway.
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N2DTS
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« Reply #10 on: January 19, 2010, 07:11:46 AM »

I like playing with buttons, so psdr is lots of fun for me.
I open every menu and see what is in there, change stuff and see what the result is....

Also nice is the ability to preset things and have a wide hifi setting for the audio, and a battle setting that narrows the audio and adds more companding.

Also, I dont like the auto level (under the alc/agc tab I think) that uses an automatic audio gain thing on TX, the compander works much better, less background noise.
The TX agc (leveler) is like a compressor without a threshold and boosts everything and only reduces gain on loud things.

Brett





Setup, general, filters, default low cut.
Like I said, I set mine at 20Hz.
Also in there is the MAX filter width, which I set to 10Khz (20Khz in AM).


It never ceases to amaze me what is all in there.  I have been running this for three years or more and never noticed that trick.

Yah I know, read the manual.

I don't know about Flex but with SoftRock SAM is a powerful tool that can make or break a QSO.  Turning garble into clear speech can be like magic.  I notice nothing but an improvement in audio quality when using it.  The only time I turn it off is when there is/are old buzzards with sloppy VFO's or sloppy habits.

Jack
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w1vtp
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« Reply #11 on: January 19, 2010, 08:10:49 AM »

Be careful about your AVC setting.  The low AF frequencies in RX can sound weird as the AVC tries to follow, say  10 HZ.  In a recent test with Steve, I was hearing 15 Hz and seeing 10 on the cone.
TX?  There is a setting for both the bottom and high end for that freq resp

SAM works great except on Timmy's SBE rig.  His wobbleulator really drives my SAM crazy

Al
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flintstone mop
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« Reply #12 on: January 19, 2010, 08:51:51 AM »

Gud Info here Thanks,
I'll print these replies and check the setup............so many things can be changed or tweeked. Forgot about the corner freqs and lock-up speed.
The sound card is the Delta44 and when the SAM is off the Steve, QIX lower freqs are there.
On a similar note the SoftRock I.F. board using the same Flex software gives the same response.
I have the Flex 1000. I don't know if I can use the very latest and greatest VER.

Fred
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Fred KC4MOP
flintstone mop
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« Reply #13 on: February 27, 2010, 01:55:07 PM »

Sorry. Fred it may be the loop filter in the software locking to the carrier. The corner frequency is set fairly high for a fast lock. I've seen this same effect on a Sherwood sync detector. The lows don't really come in till you tighten up the loop.
When you have a tight loop or low corner the thing takes a real long time to lock.
It would be cool to have a loop change once there is a lock to help recover more lows. Alberto's (weak signals ver .99 sounds a lot better) but it takes longet to lock with a smaller capture range.

Bringing this back to the top coz I remembered a certain SONY short wave receiver, a little hand held model ICF2000??? not sure and it had a lack of bass response when the sync detector was turned on.
I checked in my setup of the SDR FLEX and there is no tweeking corner freq for locking. I do notice a slow locking or loss of lock listening to WBCQ and their 5.110 freq. It's supposed to be "compatible A.M." with a reduced carrier, about 6 dB. You need the sync detector to keep the distortion reduced from that mode of A.M. broadcast.
Prolly why the Sherwood is so expensive. There are more processes taking place to assure high quality audio no matter what's going on in the RF world.

Fred
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Fred KC4MOP
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« Reply #14 on: February 27, 2010, 02:16:38 PM »

The ETON XM1's sync detector is wonderfull. I used it last night to listen to a cooking show in the philipines Smiley  It does not alter the Sound at all.  Just a steady signal. You can change it from DSB, LSB or USB am. 

Sounds like the ole Flex needs to go back to the Shop

C
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Pete, WA2CWA
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CQ CQ CONTEST


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« Reply #15 on: February 27, 2010, 02:31:31 PM »

Wait until PowerSDR 2.0 hits the streets. It will roll your socks.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
KF1Z
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Are FETs supposed to glow like that?


« Reply #16 on: February 28, 2010, 01:02:02 PM »

Hard for me to listen to AM in PowerSDR.

I've tried all the settings there are, but it just doesn't sound as good as say Winrad does, with the same hardware.

I do have three versions of PowerSDR that were re-written by people other than Flex...

One is SLIGHTLY improved... one is the same, and one is total crud.

The big problem with WinRad, is the filter can only be opened up to 5.5kc (11kc total)... not enough for a lot of the good sounding stations out there.


Oh well, if I wuz a software guru... there wouldn't be these problems... I'd be able to customize it mmyself..... and not need to complain about someone else's hard work!
 Grin
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Steve - WB3HUZ
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« Reply #17 on: February 28, 2010, 08:46:42 PM »

Can you put all 11 kHz off to one side (upper or lower sideband)? This would give you all the audio freq response you should need.
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WA1GFZ
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« Reply #18 on: February 28, 2010, 09:47:28 PM »

All I2PHD software sounds better than Power SDR on AM. I wish it worked for HPSDR so I could use it.
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KF1Z
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Are FETs supposed to glow like that?


« Reply #19 on: February 28, 2010, 10:17:50 PM »

Can you put all 11 kHz off to one side (upper or lower sideband)? This would give you all the audio freq response you should need.

Nope, for some reason he hasn't added that keen feature.

You can't pull it all, nor can you pull just one side, like you can with pretty much all the other SDR software.



I am using a hacked version of Power SDR (pic below) for another SDR transciever... it's kinda fun...  AM still leaves a lot to be desired, though it's acceptable.


* GS.jpg (102.47 KB, 800x600 - viewed 827 times.)
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K5UJ
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« Reply #20 on: February 28, 2010, 11:34:31 PM »

Fred,

Tubes.  Sherwood Sync Detector.  All you need to know.  Everything after that is down hill.

If they did that movie today with Dustin Hoffman, The Graduate where the guy says "Plastics," today he'd be saying "Tubes."

Rob
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"Not taking crap or giving it is a pretty good lifestyle."--Frank
W3RSW
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Rick & "Roosevelt"


« Reply #21 on: March 01, 2010, 01:37:58 PM »

Quote
I am using a hacked version of Power SDR (pic below) for another SDR transciever
which other transceiver?

interesting.
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RICK  *W3RSW*
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« Reply #22 on: March 01, 2010, 02:24:06 PM »

I really like the sync detector in my K3.  It tracks carriers for several kHz's in either direction, and allows selecting the sideband with the least interference in the bandpass.  I have the 13 kHz filter in the K3, and I can open up the receive audio to 5 kHz.  Listening several weeks ago to one of the guys who was demonstrating low pass filtering, I clearly heard  the difference between his 3.5 kHz and 5+ kHz filtering.  Being able to eliminate slopbucket jammers on LSB by changing to USB on the sync detector is also a nice option.

Also, running the K3 on AM, with enough carrier (10 watts or so) to an Ameritron AL811H amp putting out about 125-150 watts carrier, I get reports of great audio.

The K3/Ameritron helps in this case, until I get the Valiant and DX100B with CRL/Symmetrix/Omnia processing going, resuscitated.

73
Ted  W8IXY
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KF1Z
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Are FETs supposed to glow like that?


« Reply #23 on: March 01, 2010, 03:06:36 PM »

Quote
I am using a hacked version of Power SDR (pic below) for another SDR transciever
which other transceiver?

interesting.


Genesis G40, and G80  ( 5 watt output, mono band rigs) ....  
Now working on the G59 (  160 through 6 meter transciever... only 10mw as is, the GPA10 will give it a whole 10 watts of scrote.)  
That kit just came in the mail today.

About 750 through-hole, and 30 smd components...  FUN!

G80 below:


* G80.jpg (228.05 KB, 800x740 - viewed 857 times.)
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KA1ZGC
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« Reply #24 on: March 01, 2010, 04:30:08 PM »

About 750 through-hole, and 30 smd components...  FUN!

 Shocked

You're working with ESD-sensitive semiconductor components on a piece of cardboard? Say it ain't so!

That's a big no-no in any ISO shop.
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