i have a gateway with ic880a on rpi installed with software from https://github.com/ttn-zh/ic880a-gateway. it works.
Then i have analysed the source poly_pkt_fwd.c and modify it to log more. The issue is, the packet forwarder never send Data on RX_SLOT2. I can’t found no configuration for the RX2 frequence 869.525 MHz / DR0 (SF12, 125 kHz) in configuration file or source files. Is this normaly and the poly_pkt_fwd newer Send on RX2 Slot? If true, why?
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Hi, I have found that the Downlink frequencies are governed by the ttn handler used.
that’s right for the RX_SLOT1, but I don’t get any packets from ttn for the rx2 slot. Does the packet forwarder have to manage this? (simply duplicat)
Do you always receive the message on RX 1?
Usually RX 2 is only used if RX1 was unsuccessful.
Only place I have seen this setting is on the Network server configuration. But this is not related to ttn…
Which handler do you use to forward the payload from Gateway to Server, and from Server to Application?
Perhaps have a look at the documentation on that, and then modify the Node’s RX2 frequency.
Also have a look what the delay is between the RX1 & RX2 windows. This can also result in loss of transmission.
the gateway cannot know whether rx1 arrived at the node. What the node receives does not matter at first. I log all packets that the gateway send over the air und and I have to find out that the gateway only sends packet at rx1 time and never at rx2 time.
For TTN RX2 is used when sending downlinks if the uplink used SF10 or higher and when the gateway exceeded the airtime for the RX1 frequencies. The network server does not know the RX1 packet could not be transmitted by the gateway for some reason or could not be received by the node. There is no feedback from the packet forwarder to the network server once the packet has been delivered to the packet forwarder.
That is right. The configuration of the packet forwarder only lists the uplink frequencies where the packet forwarder should listen. All downlink frequencies and related datarates are specified by the network server when it provides a downlink packet.
That is probably because you uplink with one of the faster spreading factors. If TTN can send the answer with SF7-SF9 it prefers answering in RX1 as that consumes less airtime. RX2 is fixed at SF9 so there is no way to optimize airtime in RX2.
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ok, I had assumed that the gateway should always send in RX1 and as a duplicate in RX2. But it is always sent in RX1 or RX2, right? I am reassured. thank you.
Yes, the network server decides which one of the two will be used.