> Hi CASPERites, > > For HERA, we're looking at distributing timing signals (PPS & 10Mhz ref or > 500 MHz clock) over O(100m) fibers to various digitization nodes. > I figure some folks in CASPERland have experience with this kind of > system? > Did you use custom RF-over-fiber kit, or off-the-shelf PPS/10MHz > solutions? > Any words of wisdom/caution to share? > > Any responses much appreciated!
We have several different schemes for the different signals. Are you planning for one fiber per signal per node? or one fiber with the signals multiplexed on them? If the signals are one per signal, you can use some off-the-shelf solutions, but they are kind of pricey, and if you have a lot of nodes to supply, it might be worth working on something custom. We have used Math Associates stuff for this kind of work. Math Associates is now litelink, and they tout the affordability of their stuff, so maybe it's reasonable... On the 10 MHz, we send the 10 MHz reference over fiber, and at the far end use a crystal oscillator locked to the reference to clean up the noise from the fiber electronics. This is essential for interferometry, but maybe not for single-dish use. John > > Jack >
