Hey there,
we are looking into performing CHIRP (see here), preferably using one of the sonars that are meant to be mounted on the BlueBoat.
However, the specsheets seem to speccify only one set frequency - not a variable frequency band.
Does anyone have any experiences in this regard?
Greetings Johannes
Hi @jkohl, welcome to the forum 
Are you looking for something that already uses CHIRP, or are you wanting to test implementations and processing algorithms?
If the latter, the only option I’m aware of is implementing CHIRP in the open source variant of firmware for our Ping Sonar (which has a BlueBoat integration kit available).
If you want something that already exists I’m less sure on the extent of possibilities, but as some relevant links:
Objects have modes of vibration that have corresponding resonant frequencies, at which the object most “wants” to vibrate. In the context of sonar transducers those are the frequencies that will be easiest to induce, and easiest to detect when sent from another transducer or returned as an echo.
Sonar control electronics are then often placed and tuned to prioritise one or two of those vibration modes, which are considered the nominal frequencies of the sonar. That doesn’t mean they can’t use other frequencies nearby, but the further you get from a resonant frequency the less efficiently transmission and receiving occur - often with quite a sharp drop-off.
As I understand it transducer specifications typically report the nominal frequency, as it gives a sense of the length of the sound waves being used, which is a limiting factor on how precisely it can resolve responses from a distance, and also indicates that other things vibrating near that frequency will likely show up as noise in its signals. An echosounder being advertised as using CHIRP technology may report the bandwidth it uses to do so (around its nominal frequency), but that still doesn’t give a sense of how strong the returns are in that expanded region, just that they decided to use it, so it’s not as critical information.
Hey @EliotBR, thank you for the response!
I indeed intended the question for the second option as I figured using a Sonar meant for the BlueBoat and adapting existing software for it would be easier then mounting a device which was not intended for this boat.
However, the options you have provided for this seem promising, so I will look into them.
If something turns up regarding the Side Scan Sonars CHIRP-capabilities that would be great, I also could not find a mention of it in the guide of this product.