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HP 58540A GPS Time and Frequency Reference Receiver A First Look This is a tiny receiver! It is not much larger than a standard 3.5 inch floppy disk, and it weighs about one-pound. Threaded mounting holes on the enclosure bottom are provided for receiver mounting. It appears very similar to the Datum Starloc II GPS receiver, since the cabinet has essentially identical dimensions. Front Panel -- BNC
connectors for 10 MHz out, One PPS out Electrical Specifications Frequency:
10 MHz Frequency accuracy: less than 1 x 10-11 for a one day
average when locked to GPS. Serial Port Serial protocol is SCPI. Factory default 9600 baud, 8 data,1 stop bit, no parity. Mechanical Two small circuit boards are inside the receiver enclosure. The bottom one is the DC to DC converter. It changes the plus 24 Volt input into plus 5V and plus 12V. The top board is the GPS receiver itself. A shielded 8 channel GPS receiver, an oven oscillator, and surface mount control circuitry is located on the board. The circuit board has mounting holes and footprint patterns for four different oven oscillators. The oscillator used on this example is the SC cut MTI 230-0801 10 MHz oven oscillator, similar to that used in the HP Z3816A. . Conclusion I like this receiver. It appears to be a worthy time and frequency reference. The performance is probably along the lines of the Z3816A or better. The internal firmware is oriented more towards the use of the receiver as a movable device rather than a fixed position 10 MHz frequency reference. An examination of the manual showed that no commands exist for examining internal parameters like oven EFC, One PPS vs GPS Time Interval, or Predicted Uncertainty. Without these commands in the receiver firmware, plotting and control software such as GPSCon Pro will function well in handling the basic receiver commands, but the graphing and plotting portions of the software will not work. The receiver simply does not supply what is required. Also, the receiver does not offer a Status Command like the Z3801A and Z3816A receivers use, so the familiar screen status dump is not displayed. If the 58540A is the ONLY receiver type you will be using, perhaps you are best served by using a simple serial communications program such as HyperTerminal. The free HP SatStat software will do the same thing for you.
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