ASSA Radio Astronomy Group

A comparison between the Thunderbolt GPS Disciplined Oscillators was made to confirm their serviceability and get an idea of any major differences between them. For the test results in the following images, the antennas were placed next to each other but there was no attempt to test concurrently. Note that the tests were run on an Ubuntu 10.04 system (Lady Heather is a M$ Windows O/S program) running CrossOver Linux Standard 9. Similar operation would be expected (but not tested) using the Wine Microsoft Windows Compatibility Layer with Ubuntu.

Peters Trimble Thunderbolt

ASSAs Trimble Thunderbolt One

ASSAs Trimble Thunderbolt Two

Typical 10MHz and 1PPS Outputs for a Trimble Thunderbolt

One thing that is obvious is the differences in the age of the GPS DO units. I bought mine in 2009 as a single unit item (without power supply, antenna or cables) and it was manufactured in 2005. The two ASSA units bought in June 2010 from the same source as "standard easy kits" with everything included were manufactured in 2002 & 2003. If you can't read between the lines, beware of the lack of fine print in the item descriptions. Not all things are equal in the land of eBay.

Recent Updates - August/September 2011

The two ASSA GPS Disciplined Oscillators are currently undergoing a bit of a revamp, being fitted to better 19½" 1U rack enclosures (ex triple fan cases) than the earlier enclosures used. This allows more air circulation around both the Trimble Thunderbolt and its DC Power Supply for cooler operation over summer. While they were back in the workshop, I was able to take some new output waveform images and carry out a good phase noise test as shown above (coming soon).

The GPSDO in it's new case from the front.

The GPSDO from the rear, lid off. Way easier to connect to than the original configuration.