I have a custom design using the S2-LP and SE2435L amplifier, largely similar to the STEVAL-FKI915V1.
About one year ago we produced a first batch of prototypes and it all worked perfectly on the Sigfox side. Now I am testing a second version prototype, where the RF portion is mostly unchanged. On one of the protypes I have an S2-LP with date-code B818 (taken form last year's batch) while on another 4 prototypes I have a newer S2-LP with date-code B851. Sigfox requires the maximum RMS modulation phase error to be 10° and 30° Peak. On the prototype with the old S2-LP I am getting very low phase error (I am checking this with the Sigfox RSA software/dongle) and everything works normally. On the prototypes with the newer S2-LP I am getting large and varying phase errors. The packet envelope for the new S2-LP prototypes is highly distorted as a result.
I swapped the old S2-LP with the newer S2-LP on the other boards and the problem moved, wherever I used the old S2-LP the issue goes away but when I place a new S2-LP on the same board the issue appears. In general, transmission power level, frequency and all other aspects appear normal on both new and old, it is only this phase error that seems to be the problem.
Unfortunately I only have one of the B818 batch S2-LP to test with so I cannot conclusively say that it is batch related but definitely there is something different between this B818 part that I have and the newer B851 parts that I have.
I am not seeing any errata notices related to newer S2-LP batches. Is there any difference between batch B818 and B851 ? (Both ordered through DigiKey) Anyone having issues with newer S2-LPs? Any idea?
Firmware is based on S2-LP_SigFox_DK_1.4.1 is there any need to update to v1.6.1 to resolve this?
Thanks
