Discussion of technical tradeoffs? #2
Description
Is there a detailed discussion of design tradeoffs somewhere? (I've read the journal article at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0267730 and the project README.)
I was impressed that it made sense to choose a heavier GPS receiver in order to use a smaller battery, so you may well have considered the following as well, but ... I couldn't find the information.
Why use external flash memory instead of the LOCUS logging built in to the GPS chip used by the GPS module?
Why use a custom logging format? I assume it was to reduce memory memory usage, but then why not document how to customize it further, by dropping the last few bits (within the HDOP) or the first few (for animals not likely to leave the local area). Or by storing only differences from the previous fix, which should take fewer bits, at the cost of some software complexity.
Was the ATTiny needed, or would it have been reasonable to use just the GPS module? As best I could tell, this gave you more freedom for scheduled GPS fixes, but the combination of various low-power modes and conditional capture (including only when outside a home area, or moving faster than a certain speed) seemed like they might outweigh this in some cases.
What about just using the GPS chip (MTK 3337?) instead of a module (Quectel L70?) This might make it easier to get the right customizations on which data to save and when, but if it also required 5000 units or lots of hardware integration, that could explain why not...