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Here's my theory. Unfortunately I'm not able to duplicate this problem on my DE.

The digital to analog "output" side of the CODEC has two channels - since it's a Stereo CODEC. One side is used to send filtered and demodulated audio to the audio chain and then to the speaker. The other side is used to send IF signals to the transmitter strip. The software audio drivers that control the output side of the CODEC are manipulated by a parameter called the "Master" Volume level.

In receive the "Master" volume level is set by the radio's volume control. In transmit, the "Master" volume level is first set to 0 for 1 millisecond, then it is set to 95.

The audio buffers contain around 10 - 20 milliseconds of audio. If receiver audio is still being buffered and sent to the CODEC when the transmitter is engaged, that receiver audio will be sent to the speaker at a volume level of 95.

As part of the latest fixes incorporated into sbitx_sound.c, the size of the audio buffers was probably increased. So that burst of receiver noise at a volume level of 95 would be more noticeable. I can check to see if the buffer sizes can be minimized, which would reduce the length of time the receiver noise is heard. A better solution would be to somehow clear the receiver buffers, or to control the left and right side volume levels separately. Neither option may be possible, however.

Will try to have some test code to try in a couple days. Since my DE doesn't exhibit this issue, if one or two who are hearing this noise would be willing to be beta testers, please let me know.

73; Steve, N3SB

I should add to this search, that I'm also happy to consider a V.3 or V.4 board.? I have all of the stuff to bring them up to spec.

Thanks.

On Mon, Feb 5, 2024 at 11:26 AM, Robert D. Bowers wrote:

The problem with your argument is this: "Whatever the market will bear!"

I'm sorry, but I need to point out that my argument included options for spending the same, spending more, or spending less, and still ending up with a working sbitx radio.? The 'spend more' option means spending approximately $5-$45 more than the current Pi 4 models.? My 'spend less' option saves $20 for those who want to put in the work to enable support of a low-end CPU.

I'm sorry you've been treated badly by the ham radio community.

Since we're sharing personal stuff, I'll point out that I'm?I'm the child of immigrants who were raised in refugee camps in post-WWII Europe who came to the US knowing no English.? There was no one opening doors for me.? I had to find the right door and knock on it at it at the right time.? There definitely was a lot of luck and IMO even divine providence in the process, not to mention stress and hard work.? Yet I feel fortunate, I know many in worse shape, including many in my own family.??

My first ham radio stuff (Knight-Kit R-55 and T-60) came from a yard sale and was bought using money I earned on a paper route while in middle school.? My second radio was a used TS-520S bought with money saved after working in a factory each summer when I was in high school.

I've been on the Elmer side of the equation in recent times.? I've put out a FlexRadio 1500 and a Hermes Lite 2 for extended loans to local hams getting started.? I've done bug fixes and tons of wiki updates for the sbitx community.

So, again, sorry you were treated badly, but not everyone in ham radio was born with a silver spoon in their mouth and looks down on others.
?
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Regards,
Dave, N1AI

The amendment was made for the following reasons:
Update sbitx_sound.c to fix sound bugs and reduce CPU load #69

The side effect appears to be undesirable.
I also reverted to v3.01 sbitx_sound.c.
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Gyula HA3HZ

The amendment was made for the following reason:
Update sbitx_sound.c to fix audio glitches and reduce CPU load #69

It seems that the side effect is undesirable.
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Gyula HA3HZ

To me it sounds like the RX audio is being opened up as the TX is coming on.? Just a burst of RX audio before being muted again. Perhaps a change in theRX/TX key timing?


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Mike WB5LLI

Hi,
I did some measurements with the oscilloscope. No signal (just noise) on the AUDIO-MOD line, I tested it on the node between pin 2 of Q6 and R56. Does this test help?
By the way, I connected a DSI touch screen to the Raspberry and nothing changed, so the issue it’s not HDMI audio related.
Thanks!
L.

Ashhar,
Unfortunately, he didn't win... I run wsjt-x in the background and <...> is visible just like on the sBitx v3.02 screen.
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Gyula HA3HZ

Further update…

Pi4 now booting but very strange fault, I have no RX. The set produces noise as if it is receiving but only noise. Even more strange, sometimes after booting, it will receive ok!

I have removed some of the TX/RX switching FETs - Q10, Q101, Q23, Q22, Q9, Q28. I don’t believe they are all damaged but I am sure if at least one.?

From the schematic, I can’t see anywhere in the RX chain that would inhibit RX.

Anyone?

The problem with your argument is this: "Whatever the market will bear!"

If the radio starts using the new processor, it won't be long before there is pressure to make all of the radios use the new processor. Then because of demand, the price of that new processor will go up - maybe skyrocket.? Therefore the poorer among us (I'm one of them) will be priced out of the market.

I nearly trashed all of my radios four separate times - because of statements like "If you can't afford new, maybe you don't belong in Ham Radio!" That, by the way, is a quote I've heard a few times.? It reflects a common attitude which I regularly encounter.

I've got plenty of horror stories of the greed I've encountered in Ham radio.? I do have a few stories of decency too - for instance, my newest HF radio is a BitX40 that was given to me about a couple of years ago (Other than that, I have a Kenwood TS520 and Alinco DX-70 which I have had for a few years and which don't always work right).? My HT is one of those Chinese radios, and I've caught hell for having it (accused of supporting slavery) - when it was the only HT I could afford (I lost most of my radios especially HTs and equipment due to arson - total loss no insurance).

?People keep lamenting about how the hobby (it's more than that when you consider emergency communications and experimentation) is dying, but don't see the forces behind that dying - a good example is the demand that (homebrew/kit/whatever) radios meet the same specs as the big corporations meet and all the effort some big corporations have made to try to take over our bands.? Poor people can expand the "hobby", but are often (if not usually) made to feel unwelcome. Poor does not equal incapable or unintelligent - it just means lacking resources.

Bob

Actually the sbitx comes with Pi 4 2GB which is currently $45 list price, Pi Zero 2W with headers is $21, so switching would save $21.

If you can get headers cheaply and do your own soldering, you may be able to save another $6.

Ref:??

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Regards,
Dave, N1AI

On Mon, Feb 5, 2024 at 12:37 AM, Gerald Sherman wrote:

I noted a recent email suggesting that we go with the latest processor and matching software.? That might be nice, but it's just like with cars,? We might all like a new Rolls-Royce or Ferrari (take your pick of other similar manufacturers), but the budget says we might have to settle for a second hand Ford.? I'd even settle for that today - my driving days are over - lost my driver's license - age-related medical issues.? Let 's all do the best we can with what we have, and help some of the less fortunate ones enjoy the hobby too.? I very recently provided some software I created, and it will be going up on the local radio club's web site, in case anyone thinks I don't do anything any more.

I get where you are going, but it's not as simple as that, IMO.

We might as well ask: why pay attention to cars at all, when all you should want is a faster horse?? Horses can eat the local grasses, not imported oil.? ?Horses leave behind manure, which is bio-degradable, not greenhouse gasses.? Horses even reproduce, so if you mange your stable correctly you will never need to buy a new horse ever again!? They also make lots of work for grooms and stable boys, providing employment to the community.? Sounds like trading in your car for a horse is the way to go.

Why play with radios at all?? Haven't we had everything we've needed in terms of radio technology years ago?? Why not sell everything and give the proceeds to the less fortunate?

Why have hobbies at all?? Why not spend every waking moment in the service of others?

Where does it end?

Don't we get to try to make the world a better place for ourselves and others, learn a few things, and share that with others?

Why not consider that the 2023 Pi 5 8GB is $85 whereas the 2019 Pi 4 8GB is $80 so only $5 more, can go 2x-3x faster, can do the same workload while consuming less electricity, and can provide fast access to an entire family of devices via PCIe?

This is why this is different than cars.? Your 2023 car does not cost just 6% more than your 2019 car while going 2x-3x faster with the same number of passengers aboard, being more energy efficient, and being able to travel on better road networks too.?

The PCIe can connect to not just fast storage, but fast networks, fast AI co-processors, fast graphics processors, etc.?

Pi 5 could be a path two a whole new series of innovations that might benefit future generations.

Moving on to Pi 5 helps one be ready for Pi 6 because we all know that's coming some day too, and presumably will be better in many areas.

But if you want to save $5, Pi 4 is still an options, as is selling it all and giving the proceeds to charity.

Or if you want a hobby, perhaps you should try to get a team of people interested in a port to the Pi Zero 2W and its 0.5GB of memory.

You should be able to get that to work, and if so it will cut $60 or so off the price of sbitx.
?
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Regards,
Dave, N1AI

Today I was peacefully radioing in ft8 mode on 21 MHz when the image below appeared on my screen.
Since I had done the same thing 10 minutes before, only then another station called at the same time, so I answered it.



I was invited again by this station with an unknown call sign, even though I know that the sbitx ft8 encoder is not capable of encoding everything, so I avoid special call signs. Special: understand /p or / prefix or more numbers and more letters than regular callsigns.
So whoever deciphers it, I owe them a coffee or a drink. :-)






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Gyula HA3HZ

Oh, I forgot to add that during TX I can correctly hear the signal through the speaker (CW and FT8), if that can be helpful to the diagnosis.
L.

Ashhar,
I was thinking about checking the signal "AUDIO-MOD" coming out from the WM8731 and following its path through Q6. What do you think?
If I understand correctly, all the signals are generated by the WM8731 codec and sent both to the LHPOUT (pin 9), to be sent to the earphone jack and speaker, and to RHPOUT (pin 10) to be sent to the TX stage through Q6, that's been enabled by the "TX" signal, correct?
Tonight I'll check and I'll report here. In the meantime, just wondering, could there be any reason why the RHPOUT output has been muted by software (maybe some corruption of the files during shutdown or something similar)?
Thanks!

L.

I have a version 6 board I need to sell, could that work for your project?? No issues with the board, just lost interest.? ?I paid 180.00 for it.? I have some speakers and an audio output module that can be added.??

Hi Ashhar,
yes, I have an oscilloscope, I can do tests.
thanks!
Lorenzo