Hi, I am trying to connect an HTI-96min hydrophone to the audiomoth PCB. I also wanted to power the unit with a battery pack. I was successful in soldering everything but ran into a problem. After configuring the device with the app and switching to Custom mode the green LED was flashing as it should but when it was supposed to record the red led blink twice and then both lights were flashing as if it had not been able to read the configuration. It recorded an electric signal but no sound. I have attached pictures of the Configuration file and the work I did. I think I may have soldered the mic in the wrong configuration or maybe the hydrophone needs a separate power source. I have attached a word document showing my work as well as the sounds recorded. I believed cable 1 was positive, Cable 2 negative, and Cable 3 signal.
Please advice. Thank you
Hi Alex.
These are all very helpful comments. I ran a bench test and everything was working fine. When I came back from the field I was tired and clumsily pushed the switch from custom to default by accident and then to USB/off again. That may have erased all the previously collected data.
I also tried to look at the comments in the files like the picture you sent but cannot see it. I am using windows and I thought I could reach that windows through the Properties menu. Thank you for your response. I will do another attempt at the field test and keep you posted.
Hi, One of the files here was recorded before you set the time. It was recorded in DEFAULT mode and then stopped recording when the switch was immediately moved back to USB/OFF.
The second file has the correct time but is zero length which means it was not closed properly. This most often occurs if the SD card was removed whilst a recording was underway. To keep the current file the switch should be moved back to USB/OFF before removing the SD card. It can also happen if the batteries are removed or are very flat during recording. I don't think this is the issue here as the original battery voltage looks good. Finally it can happen due to the SD card filling up whilst recording or a genuine SD card write or read error. This configuration will generate 16GB of data per day but it doesn't sound like it ran for very long. Rather than deleting files from an SD card we generally always reformat the card as some operating systems just move the file to a hidden folder rather than actually clearing the space in the file allocation table. What happened when you switched to CUSTOM in the field? If the green and red LED ever flash at the same time this is indicating an SD card write or read error. I'd test out the device at your desk - recording through the internal microphone - to double check that everything is okay. Also, check the header comments in the WAV files as it will tell you why the successful files were different lengths. The AudioMoth will cut the recording short if the battery voltage goes too low. The recording will also be shorter than requested if the switch was moved to CUSTOM in the middle of a record/sleep cycle. You have the recording period set to 555 s. I assume that this should be 595s so that you have a 10 minute cycle? If so, all recordings, apart from the first one, will end up starting on a round multiple of 10 minutes (e.g. 15:00L 15:10, 15:20, etc. with file names YYYYMMDD_150000, YYYYMMDD_151000, YYYYMMDD_152000, etc). Alex
Hi, Alex Rogers. I hope you are well. Recently I went out to the field to test the audiomoth SNR on underwater recordings taken with the H2A and compare it to other underwater acoustic dataloggers available in the market. Unfortunately, after I had program the audiomoth I waited for the first programmed recording cycle to start and it did work well. I headed out to the field to run the test's but the audiomoth stopped recording and I do not know why. Attached are the recorded files (the two that cannot be uploaded are the ones that worked, but they are different lengths). I will appreciate any feedback on this issue. Thank you!
Yes, AudioMoth Dev is essentially a standard AudioMoth with a permanently fitted jack for an external microphone, and all the connections brought out to JST headers so it is easier to extend.
Yes, AudioMoth Dev is essentially a standard AudioMoth with a permanently fitted jack for an external microphone, and all the connections brought out to JST headers so it is easier to extend.
Will the Aquarian H2A also work with the Audiomoth Dev?
We used these - https://uk.rs-online.com/web/p/instrument-cases/9060385/. They are a bit expensive but very rugged as they are aluminium.
Hi Alison. I am using an Aquarian H2C fitted to an audiomoth. Currently I am doing the waterproof testing to see if the unit holds. Next steps, which are comin soon is to compare SNR between the unit I am building and acoustic dataloggers currently available in the market. Thank you.
Hi Alison, I'd be happy to help. What advice do you need?
Hey @Alex Rogers, do you know of anyone using the Auidomoth with the Acquarian H2A hydrophones? I'd like to get some advice on this approach. Thanks!
I doubt that this hydrophone will work with AudioMoth. I can't see any wiring diagrams for it but it sounds like it has an internal pre-amp and isn't configured as a regular microphone which takes a bias voltage and returns the signal on the same wire. The AudioMoth jack is wired to accept normal 3.5mm audio microphone connections, and is compatible with Acquarian H2A hydrophones that use the same format.
Sorry this was the chart I was going to send you. It is an HTI-96min with pre amp
HI Alex . Thanks to your help I was able to get the audiomoth to record on schedule. However I believe I need at least 5-10V to power the hydrophone I wish to attach and I believe that is why audiomoth cannot turn on the hydrophone. If I connect only the signal cable to audiomoth and power the hydrophone independently. Will the pieces be able to communicate with each other through the signal cable? Thank you
the signal cable?
Yep. The battery voltage quoted is measured directly from the battery and then during recording the AudioMoth monitors the supply voltage within the chip and applies a 2.8V threshold to that voltage. During SD card writes the current can be up to 50mA and the internal resistance of the batteries goes up over time creating more of a voltage drop. We normally use 3 alkaline cells which give a voltage of about 4.6V when fully charged and 3.6V when close to flat. However, 3 x NiMH cells in series and single LiPo batteries which spend most of their life between 4.2V and 3.7V work well also. Alex
Thank you very much Alex. What would be the recommended voltage, 4.6V?
Hi Carlos, I'm not sure of the connections to the hydrophone without seeing the details of the device, but the flashing of both LED is because the AudioMoth has stopped the recording early due to the battery voltage being too low. The 3.0V battery is too low, and really needs three cells in series to work with AudioMoth. Alex