3 ms·

Why do you need to merge these items at the point of collection? Why not just stream the sensor data off with temporal correlation data and assemble them elsewh

by 15155 2y ago

Why do you need to merge these items at the point of collection? Why not just stream the sensor data off with temporal correlation data and assemble them elsewhere? Either way, galvanically isolating 5W isn't too terribly hard either.

hcfman 2y ago
Because you can. Why split the architecture across multiple machines when it works on one. Do you have any recommended links to that galvanic isolation I could look at ? I’m encouraged by your view on this.
- 15155 2y ago
  I don't really want more Linux boxes floating around if I can help it. https://www.analog.com/en/products/adum6000.html https://www.analog.com/en/products/adum6000.html Things like this are a fancy way to go about it - otherwise very-filtered flyback will probably get you where you need to be.
  - hcfman 2y ago
    I've tested this device and that works. Nice clean power on the microphones whilst running over POE. https://thepihut.com/products/power-filter-board-for-raspberry-pi https://thepihut.com/products/power-filter-board-for-raspber... The chip you point to suggests a much simpler approach. Is it really that simple? There are a great many more bits on the board I point to. Why would they take a hard way if one simple chip can do it ?
    - 15155 2y ago
      The board you linked isn't a galvanic isolator, it's just a capacitor bank covering a bunch of different frequency ranges. The ADUM isolator I linked as well as flyback converters use transformers to provide a high-voltage isolation barrier between the source and device being supplied. Transformers are generally larger, more expensive, and less efficient than non-isolated DC circuits. The POE supply itself is isolated (with a transformer) and doesn't need to be noisy necessarily - but if you want even more quiet, another level of isolation can't hurt.
      - hcfman 2y ago
        Interesting. Do you know of any built products that use the approach you are suggesting ?
hcfman 2y ago
Streaming it away and then merge is exactly how it's intended to with jackd streams. You create a dummy slave off the first one, then you have clients off that. The point being that if I had take a potentially easy way of just recording directly from the device to write the files, then I would not easily at the same time be able to perform real time analysis of the stream. So the way I've done it you can indeed do this. Note, with manual examination of the sound files with raven lite, I'm able to reliably determine the start time of a sound to less than a millisecond of error (Jitter in the pipeline, otherwise it would be a lot more accurate). Making it entirely possibly to locate the position of bat calls in real time to quite a good degree of accuracy if you wanted.

by 15155 2y ago

hcfman 2y ago

Because you can. Why split the architecture across multiple machines when it works on one. Do you have any recommended links to that galvanic isolation I could look at ? I’m encouraged by your view on this.

15155 2y ago
I don't really want more Linux boxes floating around if I can help it. https://www.analog.com/en/products/adum6000.html https://www.analog.com/en/products/adum6000.html Things like this are a fancy way to go about it - otherwise very-filtered flyback will probably get you where you need to be.
- hcfman 2y ago
  I've tested this device and that works. Nice clean power on the microphones whilst running over POE. https://thepihut.com/products/power-filter-board-for-raspberry-pi https://thepihut.com/products/power-filter-board-for-raspber... The chip you point to suggests a much simpler approach. Is it really that simple? There are a great many more bits on the board I point to. Why would they take a hard way if one simple chip can do it ?
  - 15155 2y ago
    The board you linked isn't a galvanic isolator, it's just a capacitor bank covering a bunch of different frequency ranges. The ADUM isolator I linked as well as flyback converters use transformers to provide a high-voltage isolation barrier between the source and device being supplied. Transformers are generally larger, more expensive, and less efficient than non-isolated DC circuits. The POE supply itself is isolated (with a transformer) and doesn't need to be noisy necessarily - but if you want even more quiet, another level of isolation can't hurt.
    - hcfman 2y ago
      Interesting. Do you know of any built products that use the approach you are suggesting ?

hcfman 2y ago

Streaming it away and then merge is exactly how it's intended to with jackd streams. You create a dummy slave off the first one, then you have clients off that. The point being that if I had take a potentially easy way of just recording directly from the device to write the files, then I would not easily at the same time be able to perform real time analysis of the stream. So the way I've done it you can indeed do this. Note, with manual examination of the sound files with raven lite, I'm able to reliably determine the start time of a sound to less than a millisecond of error (Jitter in the pipeline, otherwise it would be a lot more accurate). Making it entirely possibly to locate the position of bat calls in real time to quite a good degree of accuracy if you wanted.