Hi John, Thanks for the info. I'll add Litelink to my list of suppliers to investigate. We have no particular urge to multiplex the signals on to the fiber unless there's a particularly neat/cheap solution to do that. There's no great appetite to go custom. We've got about ~30 nodes, and my first stab at getting an off-the-shelf solution turned up at a few k$ / node, not including any cleanup electronics.
Thanks again, Jack On Mon, 4 May 2015 at 19:25 John Ford <jf...@nrao.edu> wrote: > > 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 > > > > >
