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Re: Codec & ADC's
The short answer is that the 8-bits, or at least part of them are useful.? I'm attaching a plot of the output of the PCM1808 while receiving "no signal" to help explain what is happening.
The magenta trace is the direct 24-bit output of the ADC coming through AudioInputI2S_F32 path.? The blue trace is derived as the nearest I16 value to the 24-bit value.? Examine a couple of vertical pairs and it becomes obvious.
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OK, two things happen.? The conversion increases the noise by a dB or so, as computed from the variances of the two data sets.? Probably more important is that the 16-bit noise no longer has a continuum of values, but in this case they are quantized to either -6, -7 or -8.? If that quantized signal is amplified up and applied to the human ear, it does not sound right and to some ears is offensive.? The classic solution is to add dither noise, which improves the sound, but also reduces the S/N and uses up dynamic range.?? All of this is avoided by the using the 24-bit data generated by the PCM1808, and the benefits are real.
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On the question about the Teensy adapter with the SGTL5000.? If you look back at Figures 1 and 2 of the Codec page, you see that the SGTL5000 spectrum, when not in an idle tone, is about 6 dB noisier than the PCM1808.? When you are including idle tones, the spectrum is way higher.? So, running the SGTL5000 with 24 data is probably going to be of minimal value.?
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Fun stuff. |
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Re: New SI5340-based RF Board in development
Just had a look at what the Si5340 is. It will have a place in high performance radios, but it's not going to replace the Si5351 in all applications. It's a much more expensive part; the cheapest version is over $16 in quantity one (the Si5351 is a bit over $2) and doesn't do fractional dividers so its frequency flexibility will be more limited. The least expensive one that does is over $21. It's in a 44-QFN?package that isn't as friendly to hand soldering as the Si5351 is (10-MSOP isn't ideal for hand soldering but 44-QFN is worse), and takes up more board real estate so it may not be well suited to small portable designs. Finally, it appears to be a much more power hungry device; the typical power consumption is listed on the datasheet as 680 mW. It requires both 1.8V and 3.3V power rails. The Si5341 is basically the same device, but with 10 outputs. But not ten fully independent outputs, as there are only five MultiSynth blocks. The Si5340 has four, so each output can be programmed completely independently. Doing an RF board with the Si5340 is very much in the spirit of the T41 project. We'll get to see how much the higher performance synthesizer makes in real world operation. Well done, AE0AM. On Mon, May 12, 2025 at 2:44?PM jjpurdum via <jjpurdum=[email protected]> wrote:
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Re: New SI5340-based RF Board in development
¿ªÔÆÌåÓýYou know, the other benefit of this approach is that you can use the fourth output for RX2 and that could easily be a second RX chain placed as a daughter card. ?Has me thinking. ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com email:??bill@... ? On May 12, 2025, at 1:37?PM, John Bennett via groups.io <jkb@...> wrote:
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Re: New SI5340-based RF Board in development
¿ªÔÆÌåÓýI like that part a lot and have used it for several things. ?The only downside side is that you must iss 7474¡¯s to generate the quadrature, and while it covers the MF and LF frequencies in a better way, the 7474¡¯s are not reliable above 30 Mhz (from my testing and basis their datasheet). ??Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com email:??bill@... ? On May 12, 2025, at 1:37?PM, John Bennett via groups.io <jkb@...> wrote:
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Re: Morse Code Tutor pcb...
Hi Vern: Good for you!! It's never too late to learn CW. BTW, the G4FON software () is very good for learning, too. (The video is worth watching.) It uses the Koch method for learning (with a Farnsworth dealy) and I think it works! It teaches you to learn Morse by the rhythm of the letters, rather than counting dits and dahs. There
have evidently been several variations of the Tutor done, but the one by
Bruce Hall, W8BH, seems to be the most complete, including the Gerbers
and code. I have those, but not the permission to release them. Write to
Bruce and see if he will release them. Jack, W8TEE
On Monday, May 12, 2025 at 02:36:31 PM EDT, Vern VanZ via groups.io <n7gtb@...> wrote:
Greetings All, I don't see much mentioned lately regarding the MCT, but having recently purchased the 'Microcontroller Projects for Amateur Radio' book (via Amazon); I've decided I would like to build an MCT of my own.? I've been a licensed ham since 1971 and would like to take one last(?) crack at CW. I've been searching the web for either a kit, or at the very least a PCB (as mentioned in the book) but so far haven't found anyone (in my hemisphere) currently offering one that goes with the text.? I also understand that the gerbers, schematics, source code etc., have been made available in the files section and github.? I just thought I'd ask before messing up square feet of perf board, whilst attempting to wire up the pieces-parts. I also considered trying to have a PCB made, but I've only ever done that once. The results were good enough, I simply don't need a handful of boards when one will suffice. :) Sorry for the ramble. Any advice...? Thanks. 73, Vern - N7GTB -- Jack, W8TEE |
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Re: New SI5340-based RF Board in development
Very interesting, John. Do you plan to release the Gerbers for the board and the supporting software? Please keep us posted on your progress going forward. Jack, W8TEE
On Monday, May 12, 2025 at 02:12:04 PM EDT, John Bennett via groups.io <jkb@...> wrote:
In the spirit of posting efforts currently underway, I have been working on a new RF board and associated driver software. In a nutshell, the new board uses the Skyworks SI5340 instead of the SI5351. This change addresses several issues. The SI5340 offers rock solid performance from 100 KHz to 250 MHz with LVCMOS outputs (employed by the prototype RF board), dramatically reduced phase noise and jitter, much improved clock symmetry (upon which the performance of Tayloe mixers depends), and much simpler application-level control software (no mucking about with the PLL, Multisynth, or phase at the application level). The new RF board replaces the 5351 with the 5340, and restores true split operation (the SI5340 has four outputs, three of which are used for RX, TX, and CWTx). The most challenging part of the software was the algorithm for setting output frequency, that is, given a desired frequency, find near-optimal numerator and denominator values for the various dividers used within the SI5340. My software employs a mediant-based algorithm attributed (incorrectly) to Farey, and efficiently produces results comparable to those produced by ClockBuilder Pro (the stand-alone program for configuring Skyworks parts). Current status:
1) Driver and driver example code complete and tested with main board and SI5340 EVB
2) T41 software (forked from V66.9) patched to ifdef choice of SI5340 or SI5351 RF Board compiling and in test
3) New RF board hardware under construction (PCBs back from China; parts on hand)
For the curious, prototype schematic and board pic are attached.
73,
John Bennett
AE0AM
-- Jack, W8TEE |
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New SI5340-based RF Board in development
In the spirit of posting efforts currently underway, I have been working on a new RF board and associated driver software. In a nutshell, the new board uses the Skyworks SI5340 instead of the SI5351. This change addresses several issues. The SI5340 offers rock solid performance from 100 KHz to 250 MHz with LVCMOS outputs (employed by the prototype RF board), dramatically reduced phase noise and jitter, much improved clock symmetry (upon which the performance of Tayloe mixers depends), and much simpler application-level control software (no mucking about with the PLL, Multisynth, or phase at the application level). The new RF board replaces the 5351 with the 5340, and restores true split operation (the SI5340 has four outputs, three of which are used for RX, TX, and CWTx). The most challenging part of the software was the algorithm for setting output frequency, that is, given a desired frequency, find near-optimal numerator and denominator values for the various dividers used within the SI5340. My software employs a mediant-based algorithm attributed (incorrectly) to Farey, and efficiently produces results comparable to those produced by ClockBuilder Pro (the stand-alone program for configuring Skyworks parts). Current status:
1) Driver and driver example code complete and tested with main board and SI5340 EVB
2) T41 software (forked from V66.9) patched to ifdef choice of SI5340 or SI5351 RF Board compiling and in test
3) New RF board hardware under construction (PCBs back from China; parts on hand)
For the curious, prototype schematic and board pic are attached.
73,
John Bennett
AE0AM |
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[FlexRadioSmartSDR] Hamvention Software Defined Radio Forum, Room #3, Saturday, 5/17 @ 4:10 pm ET
¿ªÔÆÌåÓýFYI for those going. ?Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com email:??bill@... ? Begin forwarded message:
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Re: Codec & ADC's
¿ªÔÆÌåÓýOne thing you could do is power your ADC from a battery. ?That will be the reference test case. ?Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com email:??bill@... ? On May 11, 2025, at 5:01?PM, Bob Larkin <bob@...> wrote:
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Shirley Dulcey KE1L
K9HZ
jjpurdum
