How do you get a GPS timing signal through over a mile of cable
Sometimes it's not possible to have a clock within a few metres of its own antenna.
Take for example a pumped storage plant that acts like a large battery. When there is a period of low demand, excess power in the network is used to pump water from the bottom of a mountain, hill or even a tower to a reservoir at the top. When power demand goes up, the water is released back down through generators to boost grid supply. That generator might be miles underground in the case of a large mountain system, and it contains equipment that needs precision timing for event logging and control.
A customer came to us facing this exact issue. They'd tried using GPS receivers directly transmitting over long distance fibre using a complex signal boosting arrangement - but it simply didn’t work. Due to the high frequencies of GPS, sending it directly over fibre multimode has a distance limit of about 100m. The multimode fibre cable link was already installed and would cost too much to replace. So they went searching for possible solutions.
" I just happened to be working on another project replacing the GPS systems at another hydro plant. We started talking and decided we’d contact you guys, see if you had a product that would do the job "
After consultation with our team, we decided that the TTM 01-G and TCG 02-G combined would be the best solution. We placed the TTM as "master" at the top of the mountain, receiving the GPS signal. It's a small clock that's perfect for generating an IRIG-B signal that travels well in multimode fibre. This new signal was sent down the existing cable run.
Deep in the mountain the TCG 02-G became the "slave" unit, taking the time signal from the TTM above, regenerating and boosting it, and sending it through a number of outputs to nearby equipment. We sent the clocks through for testing first as the signal distance was outside of the official tolerances.
"Tekron offered to send us a unit to test with before we bought it, which is unusual and really great. Bam, it worked immediately. Don’t know many companies that would loan us equipment just to see if it works first"
Timing is key at the mountain. If the time sync is off they can’t troubleshoot problems correctly, which can lead to all kinds of issues and expense. The Tekron solution has saved them time and gives them the chain reaction data they need to figure out any problem.
"Once we got the IRIG signal down to it, it just started working right off "