Retronetworking » OCTOI - Osmocom Community TDM over IP

still waiting for clarification on the GPS situation (RS485-PPS in one data centre or RF-over-fiber in the other). Sent another ping today.

laforge wrote in #note-2:

still waiting for clarification on the GPS situation (RS485-PPS in one data centre or RF-over-fiber in the other). Sent another ping today.

So, today I finally received confirmation: We will bein the data centre where RS-485 over CAT-5 is used for the clock between rack and roof.

• On the roof
  • GPS antenna
  • Ericsson GPS_02 (on DIN-Rail)
  • RS-485 overvoltage protector[s] (on DIN-Rail)
• In the rack
  • icE1usb
  • phantom voltage power supply (12V)
  • RS485 converter for 1PPS + NMEA
    • probably similar to the SIU Clock breakout

TBD: get some idea about the cable length and figure out if the 12V phantom supply really can run over that kind of distance

tnt - are you still willing / able to work on some kind of icE1usb internal RS485 board? Given that we need to feed the 12V phantom voltage into the same CAT5, having an external board with something like a current limit / fuse and a DC barrel connector for an external PSU would probably make equal sense.

Given that all of this has to go into a rack, it might even make sense to mount the icE1usb, RS485 bits 12V PSU etc. all in a 1U enclosure. At that point it becomes irrelevant if the RS485 converters are inside the typical icE1usb enclosure or not.

tnt wrote in #note-5:

We need "some" internal board anyway because the GPIO connector links to ... nothing.
It relies on a internal board to link some RJ45 pins to some of the available signals.

yes, that could have simply been a bridge

So I figured we might as well put the transceivers on there since that could then be re-used for other use-cases (or adapted for).

indeed. that other use case would probably need the inverse direction? so you'd at least need one direction-switchable transceiver and two fixed ones?

So I'll leave the RS4xx interface in your hands and assume we will have 2xRx and 1xTx pair on that spare RJ45 of the icE1usb.

• mechanical mounting of GPS antenna (picture of my setup at home attached; I still have some more of that model of GPS antenna MA-700G)
• over voltage protection (LP-GTR-NFF on coaxial plus something like discussed above for RS4xx)
• 12V power supply (phentom or not). The cable length is about 100m (!) no problem for the slow RS422/485, but that's about 20 ohms loop resistance for 12V. Need to test that.

installation confirmed for Monday, September 19th from 9am CEST onwards.

• some icE1usb firmware cleanups (#5625)
• migrating users over to the new hub (will create new issue)

C*NET ENUM DNS update has been requested and confirmed, but actual DNS is still serving old data :(