This topic was migrated from the BotBlox ticketing system after being summarized and anonymized.
We recently had a customer looking to use UbiSwitch in a LEO spacecraft network. Most of their subsystems used standard 100BASE-T or 1000BASE-T, which was straightforward. The tricky part was an RF transmitter using a 10GBASE-R, 10.3125 Gbps CML SERDES interface rather than an SFP+ cage.
At first glance, this looks incompatible with the UbiSwitch BaseBoard, since its 10G ports are presented through SFP+ cages.
But electrically, the interfaces are actually compatible.
UbiSwitch’s three MAC ports can operate in 10GBASE-R mode, and the customer’s SRX-8 transmitter exposes its 10GBASE-R interface directly as four coaxial connections:
- RX+
- RX−
- TX+
- TX−
So the problem wasn’t really Ethernet compatibility. It was how to physically get the signals from one connector format to the other.
The solution
The cleanest production solution would be a custom UbiSwitch baseboard that routes the 10GBASE-R signals directly from UbiSwitch’s Samtec headers to the connector used by the transmitter.
But for a quicker off-the-shelf approach, we came up with:
UbiSwitch BaseBoard SFP+ → SFP-to-SMA breakout → 4 × SMA-to-SMPM cables → SRX-8
The SFP-to-SMA breakout exposes the four electrical high-speed signals, which can then be connected directly to the transmitter:
- UbiSwitch TD+ → SRX-8 RX+
- UbiSwitch TD− → SRX-8 RX−
- UbiSwitch RD+ ← SRX-8 TX+
- UbiSwitch RD− ← SRX-8 TX−
The important part is that there’s no conversion to 10GBASE-T or optical Ethernet. The link remains 10GBASE-R/SFI electrically all the way from UbiSwitch to the transmitter.
There are still a couple of practical considerations. Running the signals through the breakout and coax cables can reduce signal integrity, so this setup would need to be validated. It’s also important to confirm whether the transmitter has the required AC-coupling capacitors internally.