[Racal] Mystery Racal devices

[Tom B]

Hello All,

I have 2 boxes that I beleive are made by Racal.
One is marked model GG-6-C PPM generator.
The other is marked model DC-6/X (B Model) PPM Demultiplexer
They have a light blue front panel and no manufacturer's name on them.

My guess is they are used for Pulse Position Modulation.
I can send a photo if anyone wants to see them.
Anybody know what these things really are?

Tom Bryan
N3AJA