Revision as of 01:38, 26 July 2017

Why my LoRa module shows RF96? what frequency is it?

The RF96 mark means this module is the HopeRF RFM95W-868-S2 or RFM95W-915-S2 module. Both modules use the Semtech SX1276 IC on it.

Meanwhile, if the LoRa module has a RF98 mark, which means it is hopeRF RFM98W-433-S2 module and use the sx1278 chip.

What is the frequency range of the Dragino LoRa products?

The Dragino LoRa products base on SX127x solution normally has three version: 433, 868 and 915. This means the device is best tuned at this frequency. The exactly work frequency is set in the software.

Below is the table shows the model info:

Some countries may need different frequency such as ~920Mhz. In this case, User can choose the 915Mhz version, the performance is similar.

I have a Dragino LoRa product with 868Mhz, Can i use it in 915Mhz?

Yes, in our product, the 868Mhz and 915Mhz module use the SX1276 HF Radio path, the difference of these two modules are 3 inductors which can let the module work best in 868MHz or 915Mhz.

So if user use the 868Mhz model as 915Mhz, the software is complete the same. the difference will be the Radio performance which is not siganificant between 868Mhz and 915Mhz.

I have a Dragino LoRa product with 868Mhz, Can i use it in 433Mhz?

No,in hardware side, the 433Mhz module use the LF Radio path, and 868Mhz use the HF radio path of semtech chip. To save sapce and support PA mode, there is no radio path for LF in the 868Mhz module. So it won't work.

How can i increase the distance for two LoRa devices?

Check the use environment

First , User should notice: Radio link quality and performances are highly dependent of environment.
Better performances can be reached with:

• Outdoor environment.
• No obstacles.
• No high level radio interfere in the ISM band you use.
• At least 1 meter above the ground.

Radio performances are degraded with:

• Obstacles: buildings, trees...
• Inner buildings environments.
• High ISM band usage by other technologies.
• Radio communication are usually killed with bad topographic conditions. It is usually not possible to communicate through a hill, even very small.

Check the Antenna

• Check if the Antenna has a good connection to the Antenna connector
• Check if the Antenna has the good performance in the require frequency. (need special device, so may not possible to check in most case.)

Check the Frequency Setting in Software

• Check if in the software, the correct frequency is set.

Check the Modem Setting in Software

Check if the modem is set to the correct modulation, Different modem setting will affect heavily in the distance and datarate. User can refer How Modem Config Affect Distance to see how it works.

To configure modem setting in RadioHead Library, use can consult below place in the software:

• RH_RF95::ModemConfig in RH_RF95.CPP

PROGMEM static const RH_RF95::ModemConfig MODEM_CONFIG_TABLE[] =
{
   //  1d,     1e,      26
   { 0x72,   0x74,    0x04}, // Bw125Cr45Sf128 (the chip default)
   { 0x92,   0x74,    0x00}, // Bw500Cr45Sf128
   { 0x48,   0x94,    0x00}, // Bw31_25Cr48Sf512
   { 0x78,   0xc4,    0x00}, // Bw125Cr48Sf4096
};

• setModemConfig in RH_RF95.CPP.. Try to use different Radio Setting for LoRa to get the best distance.

 setModemConfig(Bw125Cr45Sf128);