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Author Topic: Changable SDR software  (Read 3997 times)
WB6RQN
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Posts: 484




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« on: June 08, 2011, 08:42:32 AM »

I am creating this new thread to take the off-topic traffic from the KX3 thread. We got a bit sidetracked talking about if and how SDR software [ever] gets changed.

73 de Brian, WB6RQN/J79BPL
« Last Edit: June 09, 2011, 07:30:21 AM by WB6RQN » Logged
K3SF
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Posts: 51




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« Reply #1 on: June 10, 2011, 06:27:20 AM »

hi brian

i think sometime people think a bit too conventionally about sdr radio..oh listening to a single ssb or cw  or digital signal..there is a time for this type of activity..like when you want to make a contact

BUT

i think the big advantage is the ability to collect a large amount of spectrum data analyze and report what happening..SIMULTANEOUSLY

an example of this is cwskimmer..my setup is able to look at 196 khz using my sdr-iq and report in near realtime the activity of the current band being monitored..no way i can listen to 196khz and decode over 100 cw signals simultaneously...i then link it to to macloggerdx using the dxcluster spot feature and set an alarms  for countries i still need...

i use this setup cause it gives me the capability to have a local cluster of those station MY receiver hears and not some vague dxcluster posting...

once a station is noted as needed..i can fire up my more conventional sdr radio ( TT Orion)
by the way .. i can do this all remotely too..from an ipod touch, ipad or even my laptop

to me the  sdr radio is only part of an overall ham radio station...and how i want to enjoy the hobby
i have spent many hours sitting in front a radio and tuning and tuning and tuning..
listening to a lotta static in my ham life time...now i do like the assistance sdr and computers can offer to the  hobby

just my 2 cents ( which has been greatly devalued by inflation ;-))  )


Paul K3SF








have seen similar capability for digital modes too

ssb (voice and languages are  hard problems) is much more difficult but that would be the challenge for sdr..but the s/w would  have all the spectrum data from sdr ...











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WB6RQN
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Posts: 484




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« Reply #2 on: June 10, 2011, 07:07:32 AM »

Paul, I think you have precisely the right idea. I am working on a project right now that requires receiving several channels concurrently. Narrow-band radios won't do. It looks like we are probably going to use a direct-sampling SDR to meet the requirements.

SDR is changing radio. It is changing radio because it makes new applications possible. One of the major problems is that we don't yet know what those applications are. CW Skimmer is the first application to come along that makes use of the ability to receive and decode multiple channels concurrently.

When this forum gets going on comparing narrow-band radios to the Flex, Perseus, and other SDRs, I get so frustrated because, to me, it is like the early days of motor vehicles where they would have races between horses and cars, and then later between cars, motorcycles, and airplanes. Today those races seem silly because it is now so obvious that there really is no comparison. But back then ...

73 de Brian, WB6RQN/J79BPL
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ZENKI
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« Reply #3 on: July 07, 2011, 03:44:52 AM »

Well SDR radios, why dont they sound  as great as the best analog receivers?

SDR receivers are noisy, lack body and just dont sound good.

I have a number of SDR receivers and  many  of the greatest commercial analog radios. At the moment the analog radios have unbeaten quality. All my SDR  radios sound washed out, thin and lack body when compared to the analog radios. They also amost 3 times more noisier under QRN conditions. They all grind your ears to death with self generated QRN thats never as bad on a analog receiver. ALL SDR receiver have a very bad case of group delay which makes the bands sound noisier than they really are.

A whole generation are going to miss out on the potential that analog design can still offer receiver performance.  I am not in hurry to throw my analog babies out with the bath water.  When I can find a SDR receiver that can out perform and sound better than the TS830S in QRN/ low band conditions I will buy it. In the meantime I have saved myself from several migraine headaches by not using any SDR receiver in low band/QRN contest conditions. Turning on a TS830S on  a band that has QRN is like turning on a QRN filter. SDR radios cant handle QRN very well and are very noisy. The AGC systems on SDR radios need some  new design techniques that dont turn the receiver into a GITMO torture device for your ears!

I am PRO SDR, yes but wont say they beat the pants off analogue receiver not yet!

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KE5JPP
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« Reply #4 on: July 07, 2011, 03:58:00 AM »

SDR receivers are noisy, lack body and just dont sound good.

You must own the wrong SDR receiver then, because my experience is the exact opposite of yours and I think that is the case with most people who actually have used SDRs.  You actually have to learn how to set the controls in the software.  Try actually backing off the AGC gain setting, because it sounds like you have it cranked all the way up!  It is not like your old tube analog receivers where you just turn it on and live with whatever the analog designer decided for you.

Gene
« Last Edit: July 07, 2011, 04:01:53 AM by KE5JPP » Logged
KE5JPP
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« Reply #5 on: July 07, 2011, 05:02:06 AM »

an example of this is cwskimmer..my setup is able to look at 196 khz using my sdr-iq and report in near realtime the activity of the current band being monitored..no way i can listen to 196khz and decode over 100 cw signals simultaneously...

I use CW Skimmer Server with my QS1R to skim 192 kHz segments of 7 different ham bands simultaneously.  This is directly supported and written specially for the QS1R by the author of CW Skimmer.  This is where direct sampling receivers really set themselves apart from conventional narrow band receivers.

Gene
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WB6RQN
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Posts: 484




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« Reply #6 on: July 07, 2011, 09:10:48 PM »

Well SDR radios, why dont they sound  as great as the best analog receivers?

SDR receivers are noisy, lack body and just dont sound good.

Huh. I must admit, I really liked my Hammarlund HQ-180AC. It had a lovely sound on SW and AM BCB stations.

But I disagree WRT SDR. I have listened to a LOT of receivers. I find that, if the detection is linear then most of the quality of sound is dependent on the audio section. And most receivers have truly abysmal audio sections. Put a good audio amp behind the detector and you will find your receiver sounds a lot better.

73 de Brian, WB6RQN/J79BPL
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WB6RQN
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Posts: 484




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« Reply #7 on: July 08, 2011, 09:07:40 AM »

Put a good audio amp behind the detector and you will find your receiver sounds a lot better.

73 de Brian, WB6RQN/J79BPL


It should be noted that many SDR's do not have a audio amp and require either headphones OR  user provided powered speakers. Or they run the audio thru the PC sound card...

Stan K9IUQ

Not true Stan. As soon as the signal is converted to a baseband analog signal every stage thereafter is an audio amp. Even if those stages only produce headphone-level or line-level signals, they constitute an audio amplifier. And it even includes the amp in the powered speakers if that is what follows in the signal chain. All of it contributes to the perceived "goodness" of the audio quality.

I have a great deal of experience designing, modifying, and repairing high-end audio equipment. I know how difficult it can be to build a solid-state preamplifier and amplifier that provides an audio quality that is "comfortable" for long-term listening. Personally I prefer vacuum-tube amplification for baseband audio which is why I believe that older receivers with vacuum-tube audio amplification stages are perceived to "sound better". Regardless, it is very possible to construct good sounding solid state amplification but I am quite confident that most receiver/transceiver manufacturers do not take the time, expense, or trouble to do so. Hence -- edgy, fatiguing audio.

73 de Brian, WB6RQN/J79BPL
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KE5JPP
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« Reply #8 on: July 09, 2011, 04:26:01 AM »

I have a great deal of experience designing, modifying, and repairing high-end audio equipment. I know how difficult it can be to build a solid-state preamplifier and amplifier that provides an audio quality that is "comfortable" for long-term listening. Personally I prefer vacuum-tube amplification for baseband audio which is why I believe that older receivers with vacuum-tube audio amplification stages are perceived to "sound better". Regardless, it is very possible to construct good sounding solid state amplification but I am quite confident that most receiver/transceiver manufacturers do not take the time, expense, or trouble to do so. Hence -- edgy, fatiguing audio.
73 de Brian, WB6RQN/J79BPL

This is true of any solid state receiver, not just a SDR.

Gene
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WB6RQN
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Posts: 484




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« Reply #9 on: July 09, 2011, 08:44:23 AM »

I have a great deal of experience designing, modifying, and repairing high-end audio equipment. I know how difficult it can be to build a solid-state preamplifier and amplifier that provides an audio quality that is "comfortable" for long-term listening. Personally I prefer vacuum-tube amplification for baseband audio which is why I believe that older receivers with vacuum-tube audio amplification stages are perceived to "sound better". Regardless, it is very possible to construct good sounding solid state amplification but I am quite confident that most receiver/transceiver manufacturers do not take the time, expense, or trouble to do so. Hence -- edgy, fatiguing audio.
73 de Brian, WB6RQN/J79BPL

This is true of any solid state receiver, not just a SDR.

Gene

I agree. It never ceases to amaze me just bad most receivers built in the last 30 years sound and how fatiguing they are to listen to for long periods. I can tolerate edgy audio when trying to dig out a weak signal but for the sheer pleasure of listening to a broadcast, I so miss my Hammarlund.

Many years ago when I was working for Audio Dimensions in San Diego we tried an experiment in an attempt to prove to people that we knew what we were doing when it came to broadcast sound reproduction. We advertised on KFSD, the classical music station, and hosted a show wherein we replaced the studio's audio chain with our own. We used equipment of my design from turntable directly to the FM exciter input. We then played high-quality recordings with minimal compression. The difference in perceived quality was striking. You could hear it on a cheap clock radio. Smiley The biggest problem was to prevent overdeviation because suddenly the peak-to-average ratio was 10dB or more. I had to use a 'scope to monitor instantaneous signal levels during the broadcasts.

The key point is that the "audio" chain is far more important to the overall quality of the transmission system than most people realize and that even "professional" audio equipment (the studio mix board, compressor, and limiter) is far worse than anyone realized.

73 de Brian, WB6RQN/J79BPL
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