58540A GPS Time and Frequency Reference Receiver
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.
-- BNC connectors for 10 MHz out, One PPS out
-- TNC connector for GPS antenna input
-- DB9 for RS-232 serial control
-- Dual color Alarm LED
-- Three pin Amp Mate-N-Loc power connector for 24 Volts, 1
Amp max input. Mating connector is AMP 350766-1 (male shell).
Pins are AMP 350690-1.
10 MHz Frequency accuracy: less than 1 x 10-11 for
a one day average when locked to GPS.
Time: One PPS Absolute accuracy less than 110 nsec with
respect to UTC when locked to GPS.
Serial protocol is SCPI. Factory default 9600 baud, 8 data,1
stop bit, no parity.
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.
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.
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.
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 Symmetricom
SatStat software will do the same thing for you.
to Mike Pinault, W7GHZ for loaning his receiver.