• LoRa®
  • Peer to Peer LoRa Range
2020/09/24 13:59:02
NorthWestGuy
Hello,
 
I have a couple of SAMR34 Xplained demo boards. I have created peer-to-peer communications between the two, with no gateway (my applications does not want a gateway). I have been testing them but am not getting much range. My settings are power=20, boost=enabled, frequency=915.5MHz, SF=12, BW=500kHz. I am sending a basic packet of 13 bytes. I only get about 300m los. If I decrease the BW to 125kHz the range increases to about 1 km. My antennas are elevated 1 meter off the earth ground. I am using better antennas than the ones that came with the SAMR34 kits. I have used a similar demo module by Multi-tech which has a peer-to-peer mode that is built-into the original program (entered by AT commands). With the same exact RF settings and antennas as the SAMR34, the Multi-tech module gets 3km in a semi-urban environment! I must doing something wrong with the SAMR34 for such little range, but what? I am sure there is something basic missing.  Does the LoRa scheme include a header and preamble and if not what I should be sending?
 
Please chime in if you have any success with a peer-to-peer network. Microchip has essentially no documentation on this mode. 
 
Thanks,
Rich
 
void transmit_radio_packet(void)
{
static char SerialData = 'f';
static uint16_t Message_Num = 0;
if (SerialData == 'f')
SerialData = 'a';
else
SerialData = 'f';
// exit receive mode
radio_exit_receive_mode() ;
printf("Message #: %i\r\n", Message_Num) ;
buffer[0] = 0xff; //synch
buffer[1] = 0xff;
buffer[2] = 0x00;
buffer[3] = 0x49; //system 1234567890 address
buffer[4] = 0x96;
buffer[5] = 0x02;
buffer[6] = 0xd2;
buffer[7] = 0b00000001; //unit mask
buffer[8] = SerialData ; //command
buffer[9] = (char)Message_Num;
buffer[10] = (char)(Message_Num>>8);
buffer[11] = 0x23;
buffer[12] = 0xc3;
radio_transmit_uplink(buffer, 13) ;
}
2020/10/11 21:58:41
WeHongKongers
Hello,
LoraWAN is not for peer-to-peer!
 
If you want to receive weak RF signal, you have to increase the sensitivity of your receiver.
 
125kHz does seem a typical usage of LoraWAN. It should be 19200 bps.  Check the MPLAB X IDE's suggested values.
 
2020/10/12 00:32:44
Chris A
As a comparison with 2483 modules in p2p open space at SF11, BW 250kHz, CR 4/5, I get about 1km.
 
The way LoRa works the over the air bit rate gets very low at these settings.  I forget without checking but I think the over the air rate was in the order of 1kbps. The BW and the over the air rate are not the same thing!
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