FREQUENTLY-ASKED QUESTIONS
I'm not confident soldering - can I buy a pre-assembled device?
Yes you can, go to shop.smithrobotics.co.uk - a UK company, they ship worldwide. They are currently (September 2024) assembling, testing and shipping pippyg and π•pistrelle, but not the USB microphone. Be aware that sales of the devices help two charities - the BTO's Acoustic Pipeline project, and Friends of Friendless Churches - so if you are in any doubt at all about a self-build, just buy a device pre-assembled.
Are the pre-assembled devices identical to the self-build ones?
Right now (September 2024) the devices you can buy are the same as the ones you can build. No doubt better built than yours, but notionally identical. However, Smith Robotics are working on improvements, so at some point they will diverge, but will always remain 100% software-compatible with the self-build hardware.
Can I download the schematics / Gerbers and make my own PCBs? I'd rather not use PCBWay.
Sorry, you're out of luck. Once the schematics or Gerbers leave my hands there is nothing to stop unscrupulous people from manufacturing these, selling assembled devices, making money for themselves and leaving me with all the support burden. So no, you can't. Just order the number you need from PCBWay, order the parts from DigiKey, it's extremely cost-effective and their PCBs are consistently good quality. Or even better, buy them pre-assembled and pre-tested from shop.smithrobotics.co.uk
Can I download the source code? Is it an open source project?
See "Can I download the Gerbers ..." - no and no, for the same reasons. However, the USB microphone software is provided as source code, mainly because the project started life as a Raspberry Pi / ARM example, and apart from changing the sample rate and introducing some filtering I haven't added much, so honestly I can't claim ownership.
OK, I'm feeling brave and want to build something but I'm confused by the PCBWay site - what exactly do I need to buy?
There's a guide on the PCBWay ordering process page (in fact there isn't yet, but there will be by the end of tomorrow 😀)
Thanks for that. My PCBs, stencils and 3D prints are on order - what else do I need to buy to build these?
There's a guide on the Self-Build Equipment page.
Thanks for that as well. One more question - once I have built / bought one, what else do I need?
For pippyg there's a guide on the How to use pippyg page
For π•pistrelle there's a guide on the How to use π•pistrelle page
For the "Bat Detector" USB microphone there's a guide on the How to use the Bat Detector USB microphone page
Can I use pippyg for non-ultrasound projects? Can I reduce the sample rate and use it to capture birds?
The simple answer used to be "no". However - there is a new, experimental "bird mode" for pippyg which can be turned on by reflashing your device using the file "pipistrelle-birdmode.uf2" that can be found in the deliverables package (from mid-September 2024 onwards). Testing has been minimal, but feel free to give it a try. When in bird mode pippyg triggers on pretty much anything that isn't ultrasound (I will work on fine-tuning that), and deep down in its bones the device continues to run, and sample, at 384kHz. Which is a bit overkilly, but does have a distinct advantage that the device can run some aggressive antialias filtering to get the 384kHz internal audio stream down to 48kHz for recording, and at the same time keep as much signal as possible up to the Nyquist limit of 24kHz, killing everything above. So when in bird mode you can happily capture "big bats" - Noctule, Serotine, Big Brown Bat, European Free-Tailed Bat, and the lower ranges of social calls of European pipistrelles - in extremely good fidelity, right up to the 24kHz Nyquist barrier. If you want to record birds give it a shot, and meantime I'll work on removing obvious non-bird / non-small mammal false triggers.
I can't work out what my pippyg is doing - is there a guide to what the flashing LED means?
Make sure you are on the most recent firmware image, and memorize the information in the "pippyg 3 minute guide" : https://www.youtube.com/watch?v=cGPcvGIN8y. Helpfully, the video tells you how to get hold of the most recent firmware image,
How can I work out what bats I have recorded? Is there a way to auto-ID the species?
Yes there is. Get an account with the BTO Acoustic Pipeline (www.bto.org/our-science/products-and-technologies/bto-acoustic-pipeline) - π•pistrelle and pippyg recordings are timestamped and geolocated (to the location of your phone at the time you chirped the device), and 5 second recordings are optimised for processing by the BTO Acoustic Pipeline. It is extremely accurate, but as with any auto ID system it can make mistakes, but it is an excellent resource for improving your bat ID skills.
I'm not in the UK and would like to change the set of species frequencies for manual heterodyning - is that possible?
Yes, the "interesting frequencies" can be changed by modifying the configuration string and reflashing your devices - look at the software tools section of the deliverables zip file for more details on how to do this. It's pretty advanced but doable.
Is it normal for π•pistrelle to enter heterodyne mode when I trigger a recording?
It is. The available memory on the Raspberry Pi Pico is small, and there simply isn't enough to allow simultaneous recording and time expansion, so the device must enter heterodyne mode when recording. Similarly, the device must be in heterodyne mode when the pipistrelle chirp app is used to configure the real-time clock.
I am time-expanding and want to record, but my π•pistrelle is not reponding to the app so I can't chirp it. Help!
Same answer as above - for technical reasons the device must be in heterodyne mode when the pipistrelle chirp app is used to configure the real-time clock.
Can I use a FAT formatted SD card?
Can I use <enter name here> SD card?
Can I use <enter size here> SD card rather than 32GB?
No, your cards must be formatted ExFAT. I can't test them all, so try your own card and see. I recommend SandDisk Extreme 32GB, they are the best I have tested.
Can I use a hot air gun rather than a hotplate to make these devices?
Honestly, I don't see why not - I don't have a hot air gun so have never tried it, so feel free to try. Others have reported success.
My π•pistrelle can't see the SD card - it was fine yesterday but now it flashes green and fast on power-up.
Check your batteries. Check your SD card, and maybe clean the gold contacts with isopropyl alcohol. Failing that, try another SD card. If you have dropped your device onto a hard floor, typically the first failure is the SD card no longer works. It can be very hard to repair these, typically I salvage the Pico, the op-amp and the power switch, and just build a new one. If you bought your device from Smith Robotics, contact them to see if your device can be repaired.
I see regular pulses on my recordings, at about 23ms intervals - is that normal?
What you are seeing here is the device microphone picking up sounds that are generated by the microSD card. Yes, weird but true - microSD cards generate ultrasound when you write data to them. This can be annoying, but it's hard to avoid with a design as compact as pippyg where the microphone is extremely close to the microSD card, and the two are connected by a circuit board that is very good at conducting sounds. The best solution is to buy known quiet SD cards - SanDisk Extreme and SanDisk Ultra are quieter than most. Samsung Evo are VERY noisy. Excellent SD cards, just not ideal for a sensitive bat detector.
My recordings seem quite noisy, and nothing like as quiet as my <insert name of expensive passive detector here>
Two things here. Firstly, the Raspberry Pi Pico has just 8.7 ENOBs. Which means, technically, that it makes relatively noisy recordings, so that is a limitation on how good your recordings will be. Secondly, if you built it yourself, it cost less than £20. If you bought it, it cost way under £50. Seriously - a 384kHz passive detector for under £50!
Think about it like a car - if you REALLY NEED and REALLY WANT an AMG Mercedes, it will do an awesome job but it will cost you. Will a Ford Fiesta do the job instead? Because these devices are the Ford Fiestas of bat detecting and recording, but are provided at bicycle rather than automobile pricing. If you need better signal to noise ratio to pick up quiet bats, rather than spending big on a single premium device, why not go for saturation coverage and use 10 pippygs? It will still cost you less than a single high-end recorder that has to go in EXACTLY the right location to catch your quiet bat.
And closing words - sometimes you just need a really, really high quality, high sensitivity recorder. If that's you, you're shopping in the wrong place!
I see you can use a pippyg as an ultrasonic mic with the Bat Detector app - how?
You need to reflash your device with new firmware - it saves a lot of explanation if you just watch this video - https://www.youtube.com/watch?v=cGPcvGIN8yQ
I have heard there is updated firmware available - how do I reprogram my device? And do I need a Mac?
You need to reflash your device with new firmware - it saves a lot of explanation if you just watch this video - https://www.youtube.com/watch?v=cGPcvGIN8yQ
And of course you don't need a Mac, you can use any desktop computer that can mount a USB flash drive, even a Raspberry Pi can do it.
How do I use your sonogram generation tool sonogram.js?
Video guide : https://www.youtube.com/watch?v=EcnnL4D9rBE
My friend has one of your USB microphones and the Bat Detector app. I am crazy jealous - when will it be available on Android?
Honestly, I truly have no idea. Buy a refurbed / renewed iPhone or iPad on Amazon and impress your friends with your impeccable taste.