Absolutely not too much detail @MichaelMaggs  ! Those cross correlation maps look really interesting, well done. I'll have to have a play with those myself. I had never heard of them before, maybe opensoundscape can do some of this stuff.

Thanks for taking the time to provide this details :-)

Assuming that you had the source of the sounds is within the polygon of microphones, at what kind of distance are you able to sound localize say Koalas well ?

Hi @kimhendrikse,

With our recorders (mic quality is important!), and depending on terrain, their calls can easily be seen on a spectrogram 400 - 700m away, which has been determined with data from large arrays and recognizable individual calls appearing on multiple recorders.

So if your recorders were spaced ~300m away from each other (an offset grid of equilateral triangles is the best for overlay efficiency but certainly not always practical) then you should be ok. But I've not confirmed this distance experimentally with triangulation yet. I need to touch base with Richard Hopkinson and Roger Martin again as they are currently trialing this on Koalas. We're going to run our own Koala trials soon hopefully and see how far we can push recorder spacing.

Okay, super! Really nice thread you started. It’s great to get these insights.

With my own experiments, as you mentioned, accuracy is very good within the polygons. But in addition I found surprisingly good distance outside of the polygons in the case of a square layout along the axis of the square beyond the vertice.

I concur about the quality of the microphones. I’m using microphones that get good reviews from people who do nature recordings.

Looking forward to hearing about the Koala trials.

Re: the conversation about alternatives to knots/tying nylon line, I wonder if something like these PCB mount screw terminals would be strong enough to hold line in place for a long time, but also not sever it? They could be mounted either side of the nichrome coil, with holes for the nylon to come through from underneath, pulled over the nichrome and then through the screw terminal, where it can be secured in place. The metal screws could potentially be replaced with nylon to make it a little 'softer' on the line maybe? Below is an absolutely amazing diagram of the idea! Could even make a PCB for it all (or mod the current drop-off PCB to have this at the front)...the only thing is they aren't the smallest things in the world...so good for larger drop-offs maybe (certainly ok for AWDs I reckon) but not smaller critters...

I've been trying to find something off the shelf along those lines @Rob_Appleby

This is a cubesat example that's neat but not really meant to withstand the load an animal would put on it.

Seems like most tensioning examples out there are custom made but I'm convinced it can be done with off the shelf parts.

Regarding worries of damaging the line you can use ptfe tube or polyester/fep heatshrink for added abrasion resistance.

Hi Brett,this ocean lab sychelles is great to hear from you! I love your remote monitoring buoy project, especially the recycling of DFAD buoys and the design of custom-built ones that are full of interesting features. The expandability of the navigation buoys enabling it to be configured as hydrophones, cameras, or water quality monitors is a great feature. The technical marvels, such as recycling DFADs' circuits, making your own hydrophone, and designing a super-efficient system, are terrific. Moreover, it is encouraging to witness the deployment of your early system, particularly the live video and water quality data you have collected. You will definitely make a positive impact on the Wildlabs community with your knowledge of electrical engineering and software development. I care to hear more of your discoveries and any news that you will be sharing. Keep doing what you excel at!

These would be infrasound, so no the sealed volume doesn't need to be buried.  It only needs to be a few cc total volume for a single element.  I found an old poster that may help describe some of it.  Ignore everything but the description of the microphones themselves.

I included a photo of a single element that we used early on.  You do need a tiny hole (like 30 gauge needle) somewhere in the capsule so it is not completely sealed.  Otherwise for some microphone elements, you end up distorting the diaphragm.  Somewhere online at researchgate.net is the poster below that shows where we were at one time.  Of course we were looking at 5 Hz rather than the higher frequencies, but the microphone's response was flat well beyond what was our interest at the time.

I think your idea for a seismic sensor, a piezo disk is terrific.  It is an inexpensive sensitive sensor provided the input impedance of the preamp is high enough.  I've sometimes used a small tungsten weight glued to the disk to improve the sensitivity.

Best wishes for a successful program.  It is a worthy challenge.

A quick search comes up with the following answer. Let us know if that helps.

Annex III of the European Environmental Agency (EEA) does not directly regulate the protection or hunting of specific species. Instead, it's important to look at Annexes II and IVof the EU Habitats Directive (Directive 92/43/EEC) for species protection and hunting regulations in the European Union.

Roe deer (Capreolus capreolus) is not listed in Annex IV (which covers strictly protected species), meaning it is not afforded the strictest protection that prevents all forms of exploitation. However, Annex III of the Bern Convention, which relates to species that may be exploited but require careful regulation, includes species like roe deer.

In many European countries, roe deer hunting is permitted under specific regulated conditions. These regulations aim to ensure sustainable hunting practices and maintain healthy population levels, with hunting seasons and quotas determined based on local wildlife management policies.

In summary, roe deer are generally not strictly protected across the EU, and hunting is allowed under regulation, though specific conditions depend on national and regional legislation.

Disclaimer: I can't guarantee that the above is not a hallucination :-)

Seeing that the performance improved with the addition of a decoupling cap and increasing the size of the bulk caps would lead me to think that:

1. The bulk cap may have been undersized for whatever load was being put on the power supply. If there is a lot of ripple (noise) in the power supply, this is often due to undersized bulk capacitors. 
2. The addition of the decoupling capacitors is needed to shunt the high frequency artifacts to ground. It seems like there may not have been enough decoupling caps or there should have been more located near the location where the noise is occurring, ie: mic, analog pins, ADC pins, etc

For the mic power circuit, if there's a resistor there, it limits the maximum current the power supply can source to the mic circuit. Not sure if this does anything at all. Normally, if there is a circuit on the power rail, I'd use an inductor for high frequency noise suppression as a resistor just acts as a current limiter. The only thing I can think of is that it's a low pass filter but you'd still be restricting the power supply. 

Anyways, my $0.02.

Akiba

FreakLabs 

I would love to see my bat detector designs in use in Africa - drop me a line, let's see if we can get something to happen - I'm pipistrelledetector at gmail dot com

http://www.pippyg.com