time field empty when no GPS present

[jpmeijers]

Looking at the PROTOCOL https://github.com/Lora-net/packet_forwarder/blob/d0226eae6e7b6bbaec6117d0d2372bf17819c438/PROTOCOL.TXT#L133-L135

And then at the code https://github.com/Lora-net/packet_forwarder/blob/d0226eae6e7b6bbaec6117d0d2372bf17819c438/lora_pkt_fwd/src/lora_pkt_fwd.c#L1609-L1637

time should contain an ISO time, irrelevant if the gateway is GPS synced or not. Maybe it's NTP synced, and the should be good enough to indicate at what time a packet was received.

tmms should contain the GPS timestamp in case a GPS is present.

tmst contains the concentrator clock counter value used to schedule downlinks accurately.

My opinion is that this line https://github.com/Lora-net/packet_forwarder/blob/d0226eae6e7b6bbaec6117d0d2372bf17819c438/lora_pkt_fwd/src/lora_pkt_fwd.c#L1613 should be removed.

[jpmeijers]

I was expecting to see the time field being added when fake_gps is enabled, but that does not seem to work.

Fake GPS off (metadata from TTN):

{
   "gtw_id":"eui-60c5a8fffeXXXXXX",
   "timestamp":11257844,
   "time":"",
   "channel":5,
   "rssi":-38,
   "snr":9.5,
   "rf_chain":0
}

Fake GPS on:

{
   "gtw_id":"eui-60c5a8fffeXXXXXX",
   "timestamp":600364156,
   "time":"",
   "channel":5,
   "rssi":-38,
   "snr":9,
   "rf_chain":0,
   "latitude":"<REDACTED>",
   "longitude":"<REDACTED>",
   "altitude":190
}

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