Status LEDs - info

Just tested several Audiomoths in different housings. It is clear that disabling the LED doesn't have an impact on the clicks mentioned above. Like Andy stated, it is likely to be the writing to the SD cards. Unfortunately those clicks are much more present when put in a case. The plastic bag is intermediate and without any protection it is negligible.

Recording in tropical conditions require adding some housing. We hope this can be solved in the next batches....

Recording snippet with SD card write 'clicks' when put in a plastic housing

Sorry to hear that you had a poor session with the case. If it rains it could be worth trying the case again. Sometimes the microphone can miss-align with the drill hole so it's good to double check everything is aligned correctly before deploying.

Thanks Andy. I had a poor session when using my second moth in the acrylic case that came with the BCT pilot scheme. Thousands of 'Soprano Pips' that just were not there. Haven't experienced this with the original moth.

Great, thanks for checking that. The clicks you are seeing are SD writes that sometimes are amplified when AudioMoth is deployed in a grip sealed bag with low-level background noise. If you need more clarity in the recording I would suggest recording without the grip-sealed bag for now (if not raining). We will be releasing a low-cost acrylic case soon for outdoor recordings. The 18kHz and 40kHz represent the frequency response of the microphone, a lot of recorders have these bands centred at varying frequencies.

Andy: Not as much of an issue (as far as I know) but any idea about the smears at c. 18 kHz and c. 40 kHz as well? They seem to be intrinsic to the device as I've had them in recordings made 20 miles apart.

Thanks for getting back Andy. I'm using SanDisk Extreme 32GB. I tried it in a ziplock bag and without an enclosure. It seemed perhaps a bit worse in the bag. With the LED off it's still there but less noticeable. [And on 'default' the LED still flashes when configured 'off' (but not on 'custom').]

Thanks for the message. Interesting recording. What SD card are you using and is AudioMoth in an enclosure? Can you try recording with LEDs off to see if the problem still occurs? Cheers, Andy

I had one moth and got another from the recent batch. There's what looks like a sharp click coming out in the recordings, most noticeable at about 56-60 kHz, and pulsing every 85 ms or so when using a sampling rate of 192 and every 42 ms approx. when the sampling rate is 384. The red LED seems to flash about every 85 ms on SR=192. Are the clicks and the flashes linked? I've tried various recording locations and it's not extraneous noise, and it happens on both devices though it is weaker on the first one. The clicks from the second device are a bit of a problem as the software I'm using seems to be interpreting some (lots) of them as Soprano Pipistrelles.

No problem, glad you are thoroughly testing the device.

Thanks Andy,

Sorry not to have re-checked all of the info pages - as you say, the loss of schedule is there plain and simple.

As for the frequency of red lights, this makes sense (I am mostly testing at 8kHz, but this more rapid rate was indeed at your configuration default setting. Maybe just a note about this in the instructions would head off a worry that something is strange with different rates of signal?

Thanks for the refinements,

1) This information is stated in Step 7 of the "initial setup guide"

2) The flashes are weaker in 'standby' and 'sleep' to conserve battery. We will look into the 1/sec and 1/2sec flashing intervals.

3) We will look at adding more detail to explain each flash duration. The red flashes indicate each SD card write interval, the intervals between each flash depend on the set sample rate. Intervals between flashes are quicker at higher sample rates (>48kHz). The duration of the red flash is less when faster SD cards are used.

I have been running various configurations and tests and would like to suggest a few more refinements to the 'getting started' pages:

1. should be made clear that if batteries are removed, the loaded configuration is lost. (this would be a very good thing to change in the firmware, if possible. This behavior requires having a tablet or such to re-configure in the field, instead of the much more efficient change of SD card and power supply to resume recording).

2. the combination green + red LED signal (time not set or no recording schedule): the green LED is very bright compared to 'standby' or 'sleep', and also flashes close to 1/sec (instead of roughly 1/2sec in standby).

3. red recording LED: when in 'default' this LED flashes very rapidly (more than the 1/2sec for recording using a schedule or 'custom' mode). However, I am also finding that at least with recording durations <=60 min, the light also flashes rapidly.

Thanks for the quick reply.

Yes, default. I was not really paying attention to this option because with the system that I am currently using (produced by my group at Cornell), the 'schedule override' would do the same, but if there is any temporary break in power, it will go into standby forever. In Africa, where I work, primates might sometimes really physically shake up the recorder which might cause a brief power break. So I have always wanted a schedule so that if power is resumed, recording also resumes. Sounds like on the AudioMoth this would not be a problem.

Thanks, we will add a bit more detail on the quick start guide.

It should make 24 recordings if you change the schedule times to 0:00 to 24:00. AudioMoth won't wait an hour at the beginning of each day, it only does this immediately after the switch moves from USB to CUSTOM during a scheduled period.

If you require 24h of recording immediately after configuring the device, you can use the DEFAULT switch position (you don't need to add a recording schedule for this). This will record continuously with the configured record and sleep lengths immediately after the switch is flicked to the DEFAULT position.

This is helpful and would be great to have as part of the 'quick start' guide.

The delay in beginning to record is sort of unfortunate because there is no assurance that everything is OK in the field when turning the unit on, and I miss an hour of recording.

Question: when I set sleep=0 and record=3600 the configuration says I will get 23 files each day. Is that really correct and not true only for the first day? Does it wait an hour at the beginning of each day to begin recording?

If you set to sleep to 0s and record to 60s, AudioMoth will start to continuously record 60s WAV files after 60s. In this case the green LED will flash for 60s when the switch is immediately changed to CUSTOM, then it will start to continuously record with your set configurations. If you set sleep to 0s and record to 3600s, AudioMoth will start to continuously record 1h WAV files after 1h. In this case the green LED will flash for 1h when the switch is immediately changed to CUSTOM, then it will start to continuously record with your set configurations.

Hi Andy - thanks for the response. Neither the 'sleep' or the 'recording duration' made much sense to me because I was scheduling to record for 24hrs.

At least part of the issue must be the 'sleep' setting, which I left on the default, as I did for 'recording duration'. Setting sleep duration to be Zero seconds would be what I want - continuous recording. But what setting would be correct for 'recording duration'? When I set it for 60 s (with sleep=0) I get the standby green LED for quite a few flashes, then it went into record mode. When I set record time to 3600 (1 hr) it is still flashing green.

I am thinking that these parameters are not configured really with continuous recording in mind? Some more detailed info would be great.

Thanks for the message,

What sleep and record lengths have you used? Green flashes indicate a sleeping period, these would occur between a set recording schedule and between each individual recording at the set sleep length (e.g. shown below).

Red flashes indicate a recording, these flash at different rates depending on the sample rate, but should last the set recording length (e.g. shown above). Do your LED flashes relate to the sleep and record lengths you have set? I will double check the LED guide to see if it needs updating.

Thanks,

Andy