RAK5860 GPS/Data limitation - WHY?

WisBlock
1

I am just curious why Quectel would build their BG77 to allow GPS OR cellular data, requiring one to be switched off in order to use the other. This is a severe limitation when building devices for realtime tracking, adding a huge delay (40-60 seconds) between data acquisition and upload. To fix this, it requires the addition of another GPS module like the RAK1910, adding more complexity and expense to the device.

I would be grateful if any of you (especially those of you who worked on developing the RAK5860) know why Quectel would impose such a limitation. Is it for cost savings to use the same antenna front-end, or power savings, etc?

As a product suggestion: it would be really great to get a RAK LTE/CAT1 modem built on top of a Quectel or SimCom module that does support both GPS and data simultaneously.

Thanks for any info.

2

I am not a cellular module expert, but it is the same for the BG95 which is the successor for the BG96. From what I know, the cellular and the GNSS engine share parts of the chip inside (RF path???) and that’s the reason why you can’t use both together.

3

@beegee Thanks for your reply. Yes I understand that the circuitry is shared. I’m just confused about why they would need to share it… surely the cost differential is very small, and the capability is drastically hindered by this. Maybe they didn’t expect it to be used for GPS positioning, but you’d think it would be obvious that if the GPS capability is there, the module could be used in such devices. Oh well…