The question that biz me these days is – Do we need decent RF receive frontend?
I would like to share my opinion. Remarks tips and suggestions are welcome.
The main objective of Lora transceiver is to be cheap and brodaly available. The specs says that Lora has tremendous Link budget – unfortunately in practice the link budget is much lower. I think the main reason for this is the cheap receive frontend.
- Input filters have very wide bandwidth.
- Huge power levels near the 868MHz band – mostly from GSM base stations and UHF/DVB-T – channels 55-69. Some are not evident - e.g. my neighbour has wireless home cinema system at 864MHz
- Oversimplified Receiver – LNA, Mixer, and digital IF processing . It looks that it uses direct conversion or very low IF – Am I right?
The questions are : Will I get better performance with decent 868 MHz frontend? Does somebody try this route? Does it worth it?
With decent I mean
- High Q input Filter
- Narrow band LNA
- Reasonably high IF frequency to reject any mirror channels.