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Originally posted by scrungy_doolittle
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Don't use serial ports... use SDI OR I2S serial interface. Yes the data rate is relatively high compared to i/o in micro processors... you have to start thinking in bits not bytes... 12.8MHz in both the 20bit@48K and 24bit@192K parts. FPGA can handle that easily in real time. The 192K part is a Cirrus Logic CS5381 (mainly because I have one). TI has one with similar specs (may be made by Burr-Brown). -
I just received a notice on TI part MSP432 which is a micropower, and also features 14-bit ADC that supposedly consumes only 375 µA at 1MSPS. It could work.
I have no idea what it takes to make them tick. Guess there are no free tools of any kind.Comment
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This is a Cortex processor, I also just read about it.Comment
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Ti do free tool called code composer studio, Ive used that and its fully featured and quite good. They also have a grphical front end called Grace. IAR systems do a code limited one also free. Some of the more basic devices are on ti dev boards like tiva c etc. There is a high level library funtion rich ide cloned from arduino called Energia, mainly for 430 devices - Ive used that and its real simpleComment
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They have ugraded the Energia IDE for 432
DL here
http://energia.nu/download/
Ti do a Launchpad pcb with this devive on for 12 USComment
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Digitizing full raw RX signal is the best, but requires a lot of resources (speed). You can't beat analog's resource efficiency for some things. I think some mix of analog and digital is the answer.
What are the parameters that need to be extracted from RX signal? Phase to TX and amplitude. Phase can be extracted using microcontroller's comparators detecting zero crossing (maybe with opamp comparator if need be). This operation is super fast. Amplitude can be detected with support of peak detector opamp and ADC.Comment
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At this point signals will be moved into phase and amplitude space, filtering can be done at this point. The data load will be much smaller as there will be 2 data values (phase, amplitude) per each RX period. That about 10K x 2 values to handle every second (assuming RX freq around 10kHz). Microcontroller should be able to handle it.Originally posted by Daren View Post
I don't know if this approach will be better than full analog (lIDX for example), but it has two advantages: less parts and easily to evolve firmware. The phase/amplitude changes will be now available instantaneously so uC maybe able to extract some data that is lost on analog.Comment
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I am not sure how much of this relates but I see the same terms being discussed and I suppose if I were to contemplate what i'm reading and seeing I'd get it after awhile. I have recently been playng with an sdr dongle off ebay on a pc and raspberry pi2 soon. Check this website out for a discussion of I/Q sampling: http://whiteboard.ping.se/SDR/IQ
Does this 90 degree sampling scheme help us (or is it applicable?).Comment
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No quite true, but there are not many easily integrated tools. This is an arm processor. It has been a ***** getting the STM tools to work, but I have been able to use the new stm cube version to create code, compile and download. But now when I try to compile I'm getting redefinition errors, so am not quite certain what is happening.Originally posted by Davor View Post
I've been dealing with a personal crisis since last thursday. Wife left after 32 years. Went incommunicado until yesterday. The day before I finally had some success with the STM stuff.
Gnu tools are all free.. The only significant difference between this part and the STM's is a 14 bit sar ADC vs a 12 bit sar ADC. The ti part only runs at 48 mhz, vs 96 mhz for the stm. and it only has 256K of memory, vs 512K. And you can never have enough memory. It might be more power efficient, but specwise other than the ADC, it is not even close to the STMF411. And contrary to a comment above, multiplexing channels into an adc is simple and efficient. 1 sample time skew is not that bad.Comment
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Think you need more than just phase to TX and amplitude. It seems to me that you need to digitize both the transmit and receive. Every thing else can be extracted. The mix of analog would just be a filter and amplifier.Originally posted by Daren View Post
The pic24FJ128GC010 that I was considering using, has two opamps built into it, and 2 comparators in it as well. With maybe two more parts (an audio amp, and a signal amp with a settable gain, and feeding that into the opamps of the part, you basically have 4 parts. Power supply, processor, audio amp, and preamp. And it does 10 msamples per second, with dual dacs and built in oversampling if you want.
That being said, what success I have had with the STM has been achieved with the latest version of stmcube that knows how to create a project for the openstm.org toolset. I still have some compilation issues to work through, and I am sure Luca Spelgatti will be able to help clear those up. UNFORTUNATELY STMCUBE only generates basic stuff. they drew the line between application and set up at the wrong spot in my opinion. You should be able to specify buffer sizes and modes, but STM thinks that is application specific. shrug.Comment
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That's precisely how VLF rigs with processors operate. In a way it is also a way analogue VLFs operate, but more often than not the phases are aligned slightly different. Those differences in phases are easily obtained from IQ scheme. On the plus side, the IQ scheme has 2 channels with completely orthogonal noise, so there is a possibility to further improve the S/N of VLF Rx.Originally posted by bklein View PostComment
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Great! I'll study it more.
Newbie question though - would there be a way then to use a frequency up-converter or mixer/LO setup to visualize our signals real-time using this software?Comment
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For the record, I finally got the open STM32 software to work with a project generated with the new STMCUBE on the Nucleo F411 board. It works on my desktop windows 7, but not on a win 8 laptop running classic shell.
So now it is off to the races.
1. Download the tool chain from openstm32.org
2. Download the Latest version of the STMCUBE software from STM.
Install both.
If you have a already created project, the secret is the import. Then on the general option in the popup menu, select import an existing project.
I was able to take the modified project that one of the guys put in this thread, and compile it and download and single step.
It took the newest version of STMCUBE to make it work. Now I have to climb the learining curve on the STM32 family, but at least I am now able to compile, and build.Comment
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Thanks for the update.Comment
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