LowPowerLab Forum

Hardware support => RF - Range - Antennas - RFM69 library => Topic started by: brolly759 on August 21, 2019, 12:13:23 PM

Title: Best settings for long range?
Post by: brolly759 on August 21, 2019, 12:13:23 PM
I have been playing around with changing the bit-rate from 1200 to 4800(default) to get the best range in a long distance vertical run. Obviously 1200 gets the best distance but for a battery powered solution where I need ACKs, it takes too long. Ideally I would like to use the default settings but extend the range if its possible with a settings change. Here are my settings and findings, is there anything I can do differently?

4800 - Default settings

radio.writeReg(0x58, 0x2D);

2400 settings:

 radio.writeReg(0x58, 0x2D);
 radio.writeReg(0x03,0x34);      //RegBitrateMsb 2400 bitrate
 radio.writeReg(0x04,0x15);      //RegBitrateLsb 2400 bitrate
 radio.writeReg(0x05,0x00);      //RegFdevMsb     2000
 radio.writeReg(0x06,0x52);      //RegFdevLsb     2000
 radio.writeReg(0x19,0x40|0x10|0x05);      //RegRxBw  DccFreq:010, RxBw_Mant:24, RxBw_Exp:5
 radio.writeReg(0x18,0x00|0x00|0x01);      //RegLna  LnaZin:50ohm, LowPower:Off, CurrentGain:MAX

1200 settings:

 radio.writeReg(0x58, 0x2D);
 //radio.writeReg(0x03,0x68);      //RegBitrateMsb 1200 bitrate
 //radio.writeReg(0x04,0x2B);      //RegBitrateLsb 1200 bitrate
 radio.writeReg(0x05,0x00);      //RegFdevMsb     2000
 radio.writeReg(0x06,0x52);      //RegFdevLsb     2000
 radio.writeReg(0x19,0x40|0x10|0x05);      //RegRxBw  DccFreq:010, RxBw_Mant:24, RxBw_Exp:5
 radio.writeReg(0x18,0x00|0x00|0x01);      //RegLna  LnaZin:50ohm, LowPower:Off, CurrentGain:MAX


I got rid of sendWithRetry and used standard send and receive in while loop to time the difference in TX / RX timing.

4.8Kbps Timing Test:

13   [RX_RSSI:-35
ms to receive message: 7
ms to Transmit message: 4
_____________________________
14   [RX_RSSI:-35
ms to receive message: 6
ms to Transmit message: 6
_____________________________
15   [RX_RSSI:-35
ms to receive message: 6
ms to Transmit message: 4
_____________________________


2.4kbps Timing Test:

251   [RX_RSSI:-33
ms to receive message: 92
ms to Transmit message: 84
_____________________________
252   [RX_RSSI:-33
ms to receive message: 88
ms to Transmit message: 84
_____________________________
253   [RX_RSSI:-34
ms to receive message: 145
ms to Transmit message: 84
_____________________________

1.2kbps Timing Test

3   [RX_RSSI:-34
ms to receive message: 172
ms to Transmit message: 168
_____________________________
4   [RX_RSSI:-34
ms to receive message: 172
ms to Transmit message: 166
_____________________________
5   [RX_RSSI:-33
ms to receive message: 170
ms to Transmit message: 168