ANDROID AUDIOMOTH APP WILL NOT SET TIME

AudioMoth app installed on Amazon Fire HD 8 Plus (10th gen).

AudioMoths 1.0.0 & 1.1.0 (two of each)

Firmware versions 1.5.0, 1.6.0 & 1.8.0 (same behaviour in every case)

In each case, with AudioMoth in Custom mode and time not set: Red LED constant & Green LED flashing once per second as expected. When chime is played Green LED momentarily flashes rapidly then returns to slow flashing with constant Red LED. Thus the devices are detecting the tone sequence but not recognizing the instruction to set the time.

The tablet is playing an audible chime with the phrase C5:1 D5:1 E5:1 C5:3 and analysis of the chime confirms the presence of an 18kHz tone encoded in 5, 7.5 and 10ms bursts. This indicates that the tablet is correctly playing a tone sequence but whilst the devices are responding to the tones the clocks are not being set. I have experimented with varying both the volume of the tablet sound output and also the distance between the tablet speaker and the AudioMoth microphones with no effect.

The time can be set using the PC Time app, whereupon the devices behave correctly when set to Custom mode.

EDIT: I've also tried programming the AudioMoths to use both UTC and local time - no difference

Unfortunately my Android 'phone is too old to run the AudioMoth app and I only have 32 bit laptops running XP so I can only use the tablet to set the time when in the field.

16 comments

16 Comments

davidlee_malvern

Aug 04, 2022

@Alex Rogers Thanks for your replies. It appears that the problem is with the AudioMoth app downloaded from Google Play. Your alternative firmware makes no difference - the app will still not set the time. However the chime from the webpage works perfectly when played from the internal speaker of the same tablet at about the same volume as the app (works even with firmware 1.6.0). Not a viable solution in the field though as it will depend on finding a wi-fi hotspot!

The tablet doesn't have cellphone capability and my phone is too old to play the tones from the webpage (I can open the page but the tones won't play).

Alex Rogers

Aug 16, 2022

Replying to

Here's an updated version to try. No need to record the signal, just see if it works: https://www.dropbox.com/s/kqzrgtsl63oao93/app-debug.apk?dl=0 The tone from the app seems to be fine and I can decode all the bits correctly. However, there is a difference in how the tone starts playing which causes an offset in the bits for some reason. This then causes the data to be corrupted and the CRC check at the end to fail. The version above changes the way that samples are fed to the audio card. Rather than streaming the samples, it completely fills a buffer, and then just plays the buffer. This might solve the issue. It's still a bit strange why it doesn't occur on other devices, as the Kindle Fire processor doesn't seem particularly faster or slower than that on other devices.

davidlee_malvern

Aug 16, 2022

Replying to

@Alex Rogers

Thinks for continuing to try - unfortunately this version of the app still will not work. I'm beginning to think that the problem may be the Fire OS - it's only BASED on Android 9.0 so something important may have been crippled by Amazon.

Alex Rogers

Aug 16, 2022

Replying to

It's quite strange as the effect is really subtle. It seems to be just the first byte that is corrupted. The start bits are correct, the first byte seems to have some corruption with additional phase changes, and then all the rest of the message is fine. I might have to try to find one to test the app on to see if I can figure out what it is doing.

Alex Rogers

Aug 04, 2022

Try the firmware version below which should be a bit more flexible to varying volume levels. https://www.dropbox.com/s/vmya2cdeygiyja8/AudioMoth_1_8_1_RC2.bin?dl=0

Tablets sometimes don't reproduce the high frequencies as well as their speakers are often larger than smartphone speakers. Touching the tablet against the PCB close to the microphone also helps sometimes.

Alex Rogers

Aug 04, 2022

Replying to

You can also try the website here which will run in a browser on your smartphone. https://audiomothchime.herokuapp.com We'll look at adding the chime to the openacoustics.info website.