# A point to note - LoRa low data rate optimisation flag

**URL:** <https://www.thethingsnetwork.org/forum/t/a-point-to-note-lora-low-data-rate-optimisation-flag/12007>\
**Category:** Uncategorized\
**Created:** [January 24, 2018, 3:04pm UTC](https://www.thethingsnetwork.org/forum/t/a-point-to-note-lora-low-data-rate-optimisation-flag/12007 "2018-01-24T15:04:26Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![rocketscream](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/rocketscream/32/45934_2.png) [@rocketscream](https://www.thethingsnetwork.org/forum/u/rocketscream)\
**Post date:** [January 25, 2018, 8:05am UTC](https://www.thethingsnetwork.org/forum/t/a-point-to-note-lora-low-data-rate-optimisation-flag/12007/2 "2018-01-25T08:05:13Z")

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Thanks for bringing this up and writing to me personally. It definitely doesn’t affect people running the LoRaWAN based library like LMIC BUT if you are running raw LoRa using earlier version of RadioHead library (prior to v1.81), you’ll seeing this short and limited range at high SF and small bandwidth.

The never been updated RFM95W datasheet (which is a bad copy of Semtech’s SX1276 datasheet anyway) adds much weight to this issue as the register definition was not updated leaving such important setting out of the picture totally. Chances that everyone was looking at that RFM95W datasheet instead of Semtech’s SX1276 was nearly 100%! That being said, I will update my existing range testing [report here](http://www.rocketscream.com/blog/2017/08/21/the-sx1276-modules-shootout-hoperfs-rfm95w-vs-nicerfs-lora1276-c1-vs-hpdteks-hpd13/) soon.

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