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luigifcruz / pico-stuff

I add my Pi Pico (RP2040) stuff here.
GNU General Public License v2.0
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Potential applications? #5

Open seamusdemora opened 1 year ago

seamusdemora commented 1 year ago

This isn't an actual issue, but a question:

What are some potential applications for a 500 kHz radio?

luigifcruz commented 1 year ago

From the top of my head, it can be used for any application that requires direct sampling.

seamusdemora commented 1 year ago

OK- but in terms of applications, what does "direct sampling" imply exactly?

Also, since posting this question, this has occurred to me: Could this repo serve as the basis for a WWVB receiver? The subject of a suitable antenna will likely figure into this, and AIUI there is a ferrite antenna design that is easily built by the hobbyist (REF the swiss guy)

seamusdemora commented 1 year ago

@luigifcruz

I've done a bit more research on this WWVB SDR implementation on Pi Pico. I wanted to share it with you hoping that it will pique your interest, but if you're consumed please let me know & I'll just drop this.

So it seems that WWVB has a new modulation scheme that is said to have far better performance than the older (simpler) scheme. I've attached some papers here. I'd like to hear your thoughts as to whether or not the Pico has the chops to to implement this receiver. Thanks for yr time.

WWVBTimeSignalBroadcast.pdf CMOSBPSKReceiver.pdf WWVBTimeSignalBroadcast.pdf

luigifcruz commented 1 year ago

The reception seems doable with the right RF front-end. But standard Raspberry Pi Picos have very poor ADC noise floor. I tried with my Airspy HF+ and YouLoop antenna but didn't see the signal. But this antenna is far from the ideal.

seamusdemora commented 1 year ago

That makes sense (even with my limited grasp of receiver design). The antennas I've seen used and built employ a ferrite core with a capacitor for tuning. There are some commercial sources for these antennas, and they're inexpensive - can I send you one for your experiments? I have some experience in antenna design, but it's all in VHF & UHF. I also have some decent test equipment incl VNA, SA, etc. I'd love to help, but you'll need to tell me what to do.

luigifcruz commented 1 year ago

The idea seems very interesting indeed. Let’s talk once I’m back in the US. I might have some cycles available for this project in the future.

— Luigi On Jan 30, 2023 at 8:52 PM -0300, Seamus @.***>, wrote:

That makes sense (even with my limited grasp of receiver design). The antennas I've seen used and built employ a ferrite core with a capacitor for tuning. There are some commercial sources for these antennas, and they're inexpensive - can I send you one for your experiments? I have some experience in antenna design, but it's all in VHF & UHF. I also have some decent test equipment incl VNA, SA, etc. I'd love to help, but you'll need to tell me what to do. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you were mentioned.Message ID: @.***>

seamusdemora commented 1 year ago

Look forward to hearing from you.