WA8DRZ GPS Page
Amateur radio operators and other hobbyists used to rely on off-air reception of time standard stations like WWV for a frequecy and time standard. With patience and luck, one could manually adjust a local oscillator to one part in one million -- not very impressive. This process became much more accurate with the availability on the surplus market of Hewlett Packard OEM GPS receivers such as the Z3801A and others. These units were apparently used in CDMA cellular telephone sites and, for various reasons, a large number were replaced and appeared on the surplus market starting in about 2002. With one of these units, the amateur has a frequency and time standard several orders of magnitude better than before.
I have constructed an ensemble consisting of four of these units. The ensemble consists of two HP model Z3801A receivers and two HP model Z3816A receivers. They are connected to an HP 58532A GPS L1 Reference Antenna through HP L1 Distribution Amplifiers. A diagram of the antenna cabling is available here. Future plans are to add another antenna some distance from the current one.
Real-time statistics from the ensemble can be viewed here. On the left side you will see "short-term" graphs of the last 48 hours of data from each receiver. On the right are "long term" graphs showing the past 30 to 60 days, depending upon when I last truncated them. Also, links on the page will take you to several other screens of interest. Statistics for the individual receivers are available here for Receiver #1, here for Receiver #2, here for Receiver #3 and here for Receiver #4. All these screens are upadated once per hour. A nice explanation of the textual Status Screen can be found here
Hewlett Packard manufacured an extensive line of these products before selling the business to Symmetricom, Inc. Some of the models are listed at HP GPS Receivers, HP GPS Accessories and HP GPS Antennas.
Bill, K8CU maintains a web page that is chock full of information on these receivers. It contains tips for getting started and software to download. Definetly worth a visit. K8CU HP Z3801A Z3816A GPS Receiver Frequency Standard
