I always wanna a real gateway since I meet LoRa, I've using it to transmit data from high altitude balloon for a long time, and amazed by the performance.
But I'm limited by the fact that without a real gateway, I could only have a single channel transceiver, which limit to a specific frequency and Spread Factor, thus I cannot receive two balloons at the same time.
For LoRa gateway, Semtech provide SX1301 and SX1308 baseband IC, both chip can provide up to 49 LoRa decoder, so I can build a 8 freq x 7~12 SF decoder in a single chip, baseband IC also needs RF frontend, Semtech provide SX1255 for 433Mhz band and SX1257 for 900Mhz band.
Normally I can buy LoRa gateway from some factory, but there is two problems,one is that when the project started, there is no gateway for 433Mhz band, and the other problem is that it is very hard to buy one, or the price is too high.
So, build one.
Current version is made for Raspberry Pi Zero, using SX1301 and SX1255.
SX1301 can attach two SX125X, but because of board size limit, I just place one SX125x on Channel B for simplicity, also the RF circuit is come from SX125X datasheet, rather then the complex RF circuit from SX1301 ref design. If you want a 900Mhz one, simply replace SX1255 for SX1257, also you need to change RF filter setting, but that all you need to modify hardware.
Current version is working now, but since I removed channel_A, SX1301 HAL and its testing software from Semtech need some kind of modification to remove channel_A , currently working on the software side now.