Technical Topics



GPS Receiver Control Software version 2.026, 14 March 2022 for:

Hewlett-Packard HP Z3801 - Z3805 - Z3812 - Z3816 - 58503A - 55300A

Jackson Labs CSAC - M12M

Symmetricom UCCM-P

Datum 2000

Navsymm Proteus

Trimble UCCM


Features and Benefits

  • Complete HP GPS receiver control with long term performance graphing that automatically records all receiver parameters and reveals internal receiver trends.
  • Built-in SNTP Network Time Server delivers accurate time to all computers in a local network.
  • Remote control using TCP/IP (Server and Client) allows any local area network PC to control GPS receiver for true remote administration.
  • Complete satellite maps with plots of their transit paths.
  • Handles unlimited multiple GPS receivers.
  • Plots data from auxillary serial devices and supports up to 18 COM ports.
  • Statistical analysis for receiver graphs.
  • Four display modes.
  • Full graphical auto-scaling.
  • Easy graphics export.

  • Display Modes

    There are four display modes. These are Status, Time, Map, and Graph.

    Status Display

    In Status mode, the Z3801A receiver status is updated at intervals of about three seconds using a large easy to read font. All of your chosen parameters are still being logged in the background. If you have selected the optional web site output status file, your HTML web page is also being updated with the latest data.

    GPSCon has a helpful command selection method. A scroll down bar selects an alphabetical listing of the receiver commands. Any command variables are indicated, and you may then simply enter the remaining part of the specific command. This scroll down selector makes issuing commands to the receiver easy.

    Time Display

    In Time mode, the receiver time is always updated using large characters. This display mode will occasionally revert to the full Status mode whenever the log files require an update.

    Map Display

    GPSCon can produce an azimuth and elevation map of the satellites, with plots of their transit paths. This map may be animated at an increased speed to show the movement of the satellite paths much faster than real time.

    The Map display mode shows a projection of the satellite paths onto a circular disk with your specific position located at the display center. Concentric circles indicate lines of equal elevation. The PC mouse will position the cursor to indicate the precise location at the bottom of the map display. Actively tracked Individual satellites are indicated by circles. Non-tracked satellites show a square indicator. Each satellite is allocated a unique color based upon the assigned PRN. Placing the cursor on a satellite will display all relevant satellite information.

    The satellite display graph shows the long term paths of the satellites. The GPSCon software will color the path according to the reported signal strength of the satellite. Green is a predicted path only. The software measures the lowest and highest satellite signal strengths, then assigns Blue as the lowest level, and Red becomes the highest. This color will then gradually change between these two values, and this represents the total dynamic signal strength range.

    Statistical analysis available for TI and EFC.

    This version adds useful statistical analysis routines to evaluate the receiver TI and EFC parameters. Now slight changes in receiver performance may be described numerically. This is helpful when either comparing receiver performance to another receiver or evaluating changes to the receiver since an actual number may be compared rather than simply looking at the two graphs.

    The EFC analysis generates a figure of merit that is calculated in a similar way to an Allan Deviation. This is a new display line labeled "ad". In addition, a least squares fit is performed on the EFC data. This is used to generate the best straight line fit to the EFC data, and is labeled "sd" on the display. A line is drawn which shows the best straight line fit to the EFC curve. It is the RMS deviation from this line which is used to calculate the "sd" of the EFC.

    The TI analysis is performed as follows. The algebraic sum of all the TI samples is accumulated, and then divided by the number of samples. The result of this is printed as the "av=". Also every sample has the square of its difference from the mean added to an accumulated total. This total is divided by the number of samples minus 1 and its square root is evaluated. The result of this is labeled "SD=".

    The Control Panel Advanced Settings display contains a convenient check box to enable these new statistical analysis aids.

    The LPF is a low pass filtered plot of the TI. It takes a smoothed long term view of the TI, which is probably what the receiver does when deciding how to control the EFC. The value printed is the value currently plotted at the right hand edge of the graph. The 'smoothness' is controlled by the low pass filter coefficient which is selectable from the selection box on the panel.

    Graph Mode reveals internal receiver parameters

    Graph mode presents a detailed graph of the receiver Electronic Frequency Control (EFC), TIme Interval Value (TI), Predicted Uncertainty (PU), and the number of satellites tracked. Plotting inputs from another receiver or serial device on a different serial control port may also be displayed. The cursor may be positioned to indicate the specific time and date, and the specific data value that corresponds to the cursor position. This is helpful when identifying data segments on long term graphs. In either Map or Graph display modes, the Z3801A receiver full status is presented in a small window using a small fixed pitch character font.

    Graham Baxter, G8OAD

    The picture above illustrates the Graph mode in greater detail. The Z3801A receiver EFC is red, TI is blue, PU is green, and the satellite count is olive green.

    SNTP Time Server

    Get GPSCon Software now.

    Accurate time distribution facility across a network is built into the software. The beauty of GPSCon, SNTP, and the Z3801 lies in the simplicity of implementation with confidence in the accuracy. If you would like to implement practical time keeping for the PC clocks in your network, read more details here.

    Excellent for general maintenance issues

    Graham Baxter, G8OAD

    The graph above illustrates the effect of unplugging and then reconnecting the HP 10811 outer oven power connector.

    Suitable for advanced experimenters

    Doug Hogarth, K4UTC

    Advanced experimenters use the flexibility of GPSCon Pro to monitor a variety of interesting receiver parameters.

    Monitor multiple receivers on different serial ports, with unlimited program instances

    GPSCon Pro can monitor as many receivers as you have. The graph below illustrates the absolute EFC from two different receivers plotted on a single chart. The strong correlation between the two suggests that a common outside influence is causing the shifts in their EFC values.

    Bill Jones, K8CU

    The screen shot below shows the GPSCon settings to generate the above graph.

    International Web Plots

    GPSCon Pro is used in these countries

    Spain France Italy San Marino Taiwan South Korea Australia Potrugal 
    Germany Ireland Denmark Switzerland United States Japan Netherlands Sweden 
    Canada England Belgium Austria Thailand Brazil Greece

    Some users in these countries are using the optional Web site generation feature of GPSCon Pro software. This is a built in feature of sending Z3801A receiver plots to an Internet server. This makes any GPS receiver performance plot available for all visitors to view. You can compare many other receiver charts with your receiver performance. In many cases, frequent updating of their long term plots is now being made, making these charts nearly real time.

    See a current listing of participating users.

    System Requirements

    Requires Windows 10, 8, 7, VISTA, WinXP, W2000 (professional or server). It is not designed to run under Windows 95, 98se or ME.

    The computer needs an RS232 serial port capable of supporting the baud rate of your GPS receiver. For the Z3801A this is 19200 baud.

    You need a few megabytes of disk space to allow the data files to grow. The display looks best in 1024 * 768 with either 16 or 32 bit color depth.


    "Incredible product, great price and online delivery is great! Thanks!!"

    "Excellent software - thanks!"

    "GPSCon is thoroughly cool."

    "A Very Useful and Innovative Product! Thanks!"

    "Thanks! Very good software."

    "Great communications and super service, Thanks"

    "GPSCon is a real nice addition to a fine piece of equipment."

    "Awesome software. No problems or delays, Instant downloads. Very professional."

    "Great program, super follow up, recommended!"

    "Great payment & download system - works great - looks great - thanks!"

    "My best upgrade so far. GPSCon ROCKS."

    "This is great software! You really did an outstanding job."

    "Currently tracking the output of 5 receivers...
    2xZ3816A, 2xZ3801A, 1x58503B.
    As I said, love the package!"

    Buy Now