What does LmHandlerSetSystemMaxRxError do?

[AD-NCD]

Hello, i was wondering how does LmHandlerSetSystemMaxRxError works? does it open window before it's starting time or after or does it shrink it from the middle? so if i set it to 100 msec what will happen? i check documentation and i couldn't find anything.
Thanks

[gopalsih]

Can someone please answer this , i have the same question.

[mluis1]

Please refer to

LoRaMac-node/src/mac/region/Region.h

Lines 940 to 993 in dcbcfb3

	/*
	* Rx window precise timing
	*
	* For more details please consult the following document, chapter 3.1.2.
	* https://www.semtech.com/uploads/documents/SX1272_settings_for_LoRaWAN_v2.0.pdf
	* or
	* https://www.semtech.com/uploads/documents/SX1276_settings_for_LoRaWAN_v2.0.pdf
	*
	* Downlink start: T = Tx + 1s (+/- 20 us)
	* |
	* TRxEarly | TRxLate
	* | | |
	* | | +---+---+---+---+---+---+---+---+
	* | | | Latest Rx window |
	* | | +---+---+---+---+---+---+---+---+
	* | | |
	* +---+---+---+---+---+---+---+---+
	* | Earliest Rx window |
	* +---+---+---+---+---+---+---+---+
	* |
	* +---+---+---+---+---+---+---+---+
	*Downlink preamble 8 symbols | | | | | | | | |
	* +---+---+---+---+---+---+---+---+
	*
	* Worst case Rx window timings
	*
	* TRxLate = DEFAULT_MIN_RX_SYMBOLS * tSymbol - RADIO_WAKEUP_TIME
	* TRxEarly = 8 - DEFAULT_MIN_RX_SYMBOLS * tSymbol - RxWindowTimeout - RADIO_WAKEUP_TIME
	*
	* TRxLate - TRxEarly = 2 * DEFAULT_SYSTEM_MAX_RX_ERROR
	*
	* RxOffset = ( TRxLate + TRxEarly ) / 2
	*
	* RxWindowTimeout = ( 2 * DEFAULT_MIN_RX_SYMBOLS - 8 ) * tSymbol + 2 * DEFAULT_SYSTEM_MAX_RX_ERROR
	* RxOffset = 4 * tSymbol - RxWindowTimeout / 2 - RADIO_WAKE_UP_TIME
	*
	* Minimal value of RxWindowTimeout must be 5 symbols which implies that the system always tolerates at least an error of 1.5 * tSymbol
	*/
	/*!
	* Computes the Rx window timeout and offset.
	*
	* \param [IN] region LoRaWAN region.
	*
	* \param [IN] datarate Rx window datarate index to be used
	*
	* \param [IN] minRxSymbols Minimum required number of symbols to detect an Rx frame.
	*
	* \param [IN] rxError System maximum timing error of the receiver. In milliseconds
	* The receiver will turn on in a [-rxError : +rxError] ms
	* interval around RxOffset
	*
	* \param [OUT]rxConfigParams Returns updated WindowTimeout and WindowOffset fields.
	*/
	void RegionComputeRxWindowParameters( LoRaMacRegion_t region, int8_t datarate, uint8_t minRxSymbols, uint32_t rxError, RxConfigParams_t *rxConfigParams );