Hi Tabitha, What recording settings were you using when you saw these differences? I've measured the consumption across some different firmware versions and I can't see any difference. Were these AudioMoth 1.2.0 devices? Alex

Yes. The key output for synchronisation is the pulse per second (PPS) output which is synchronised very accurately to UTC. The TX from the GPS module is then useful for reading the time and positions. You generally don't need to be able to send commands to the module as most of the time the default settings are fine.

Same issues here. A MEMS is a great idea to pot, but you really need a piezoelectric element for this to work and not a MEMS based on capacitance (btw they're all capacitance, except for one now discontinued...). It was originally made by Vesper, but the company was bought out last year and the MEMS is no longer made. 

This is because you're no longer really doing a typical microphone, this would be a contact type hydrophone. For waterproofing, you can actually get a waterproof MEMS. As long as your not submerging this for an extended period, it should do the job. Be sure to keep the cable short between the PCB and the mic as you'll get noise as I've experienced. 

For generally answering your question on the "best" epoxy to with sound transparency, in general the harder the material the lower the acoustic impedance. I use Epotec 301 resin with a hardness of 85. Your shape will also influence the resonance frequencies, meaning the flat frequency response will now be distorted and you'll probably have distorted audio. . 

You generally don't want to pot MEMS microphones since they're designed to pick up on air pressure changes and adding any material in front of the microphone just introduces another transition layer where pressure waves need to propagate through. Also, potting the MEMS microphone can be tricky since if you get any material in the port, you could damage the microphone or drastically reduce its performance. If you want to seal something with epoxy, take a look at contact microphones. Higher frequencies will be attenuated but depending on the application, it could work. 

There are companies, however, that design fabrics that are waterproof/resistant but have a relatively low acoustic impedance. SAATI has a variety of samples that you can request and GORE makes Acoustic Vents that could work. You can design a mechanical housing around your MEMS microphone with small perforations that are covered by one of these materials. I did this for one of my latest projects and it holds up just fine in heavy rain conditions. 

Hey Sol, 

No problem at all. Depending on your configuration, the Audiomoth software would have to work on a PCB with an ESP32 chip which is the unit on the audiomoth/hydromoth, so you would have to make a PCB centered around this chip. You could mimic the functionality of the audiomoth software on another chip, like on a raspberry pi with python's pyaudio library for example. The problem you would have is that the H1A requires phantom power, so it's not plug and play. I'm not too aware with the H1e, but maybe you can control the microphone through the recorder that is programmable through activations by the RPi (not that this is the most efficient MCU for this application, but it is user friendly). A simpler solution might be to just record continuously and play a sound or take notes of when your 10 min deployment starts. I think it should last you >6 hours with a set of lithium energizer batteries. You may want to think about putting a penetrator on the PVC housing for a push button or switch to start when you deploy. They make a few waterproof options. 

Just somethign else that occured to me, but if you're dropping these systems, you'll want to ensure that the system isn't wobbling in the seagrass as that will probably be all you will hear on the recordings, especially if you plan to deploy shallower. For my studies in Curacao, we aim to be 5lbs negative, but this all depends on your current and surface action. You might also want to think about the time of day you're recording biodiversity in general. I may suggest recording the site for a bit (a couple days or a week) prior to your study to see what you should account for (e.g. tide flow/current/anthropogenic disturbance) and determine diel patterning of vocalizations you are aiming to collect if subsampling at 10 minutes. 

Cheers, 

Matt

Hi Sol,

If the maximum depth is 30m, it would be worth experimenting with HydroMoth in this application especially if the deployment time is short. As Matt says, the air-filed case means it is not possible to accurately calibrate the signal strength due to the directionality of the response. For some applications, this doesn't matter. For others, it may.

Another option for longer/deeper deployments would be an Aquarian H2D hydrophone which will plug directly into AudioMoth Dev or AudioMoth 1.2 (with the 3.5mm jack added). You can then use any appropriately sized battery pack.

If you also connect a magnetic switch, as per the GPS board, you can stop and start recording from outside the housing with the standard firmware.

Alex

Vinegar is also a great solution! Let it sit overnight and then just scrub it off. As a warning if you don't clean it, your sensitivity does decrease. You might actually see this if you keep it out there for a month that the amplitude of your calls decrease over the month/you might detect fewer calls. 

Hey! I would recommend a few things:

1) set up at least two in the same site kind of back to back or side to side if you have that many. Directionality can influence the number of calls you get and it's just good to know your error rate. 

2) Experiment with breaks and recording duration. You wont collect anything if the write time is not long enough to record to your SD card and you'll get empty files. 

3) Clean your device every time you take it out or see visible biofouling. Also, add silicon grease every time to your O-ring. Take it out with an O-ring pick and clean the plastic seal, looking for any type of sand/mud/debris. We've had a few flooding incidences, but this is probably because we open them all the time.  

4) lower the frequency rate the more data you can collect, so keep it as low as your frequency of interest without clipping your calls. Fish are lower than pretty much everything (2kHz-3kHz). 

I hope this helps! 

Oh wow, thank you so much!!!

I will keep that four advices in mind!

Hi Ian,

I have hours of an unidentified creature recorded during overnight recording sessions with mutliple hydrophones. We think it is platypus but there is nothing to compare against that isn't from captive sounds. I am waiting on the Hydromoth to become available again so I can do longer term monitoring.

Totally agree.

Inititally sceptical until I saw Helena and Graeme were involved.

MJ

Thanks @Freaklabs, I think you'll really enjoy getting involved with this too as we're looking for input from makers in the community to get the most from the approach and to capture features and usability ideas from a large number of people.

I've a new modular drop-off tag build using @Rob_Appleby's original SensorDrop board that I think would be great for this project too to see if we can drop different compartments, or do various different timed events with the one TimeLord board.

Most importantly, we have to make it play a MIDI version of the DoctorWho theme song when you arm the device. That has to be the #1 feature if you ask me!

 

Reminds me that we should look at both terrestrial and marine applications when we get stuck in to the demo builds to make sure we cover use cases 

'Most importantly, we have to make it play a MIDI version of the DoctorWho theme song when you arm the device. That has to be the #1 feature if you ask me!' 

Seconded!

Yes, I agree with Panji......make sure you have notes of where you put them and remember that photos of trees without leaves look completely different 6 months later......not that I would ever make that mistake.........well not again......especially after spending 2 days trying to find 3 ARU's.