868 MHz support

[King-anderson]

Hi,
thanks for sharing the project knowledge, with details.
how can i find the L and C values for the RF part tuned for 868 MHz (EU)?

[linux4life798]

Hi msadeghz,

That's a good question. In it's current configuration, the LoRaBug should be able to operate in the EU 868MHz band. They typically just group in the 868 and 915MHz bands together in the reference designs.
For testing in the 868MHz band, I would need to defer to some of the other OpenChirp EU members to comment on their experiences.

Details

The LoRaBug follows the SX1276RF1JAS (JAS) reference design with some small tweaks.
The JAS reference design covers the 433 and 868/915MHz bands, whereas the competing EU reference design, SX1276RF1IAS (IAS), covers 169 and 868/915MHz bands.

With respect to the 868MHz band, the primary difference between the IAS (which is said to be primarily targeted for ETSI/EU applications) and the JAS, is that JAS design has the PA_BOOST configured to supply the 868/915MHz frequency range. This means the LoRaBug is theoretically capable of outputting +20dBm to 868/915MHz, compared to the +14dBm of the IAS ref design.

You can read about the differences between the reference designs in the SX127x Reference Design Overview.

Notes and References

• Some of the tweaks came from the SX1276MB1LAS reference design.
  • http://www.semtech.com/apps/filedown/down.php?file=SX1276MB1LAS_e311v02a_prod_folder.zip
  • https://os.mbed.com/components/SX1276MB1xAS/
• SX127x Docs & Resources tab on http://www.semtech.com/wireless-rf/rf-transceivers/sx1276/
• SX127x Reference Design Overview

Best,

Craig