Technical Topics



Several free software choices are available for the Z3801 or Z3816A. This screen photo of Satstat shows actual operation of the receiver at my location.

Satstat in operation

The Z3816A GPS receiver is similar in function to the Z3801A, but has some physical differences. The Z3816A command sequence is different from the Z3801A. Satstat will still work, but certain initialization commands must be sent to to the Z3816A. A Windows™ utility named gps.exe Ver 1.4 will take care of this, and will automatically find the Z3816A on your PC serial port. Satstat may then be run normally.

This utility was written by John MacConnell, and is available for download from this site with his specific permission. The file includes information on making the null modem required for the Z3816A to PC serial connection. Details on the program initialization as provided by John:
When you first turn on the Z3816A GPS receiver, it is always continuously sending time. There are two commands you need to use: one to put it into the SCPI> command mode, the other to switch it back to sending time. The two commands are:

To go to the SCPI mode:
ptim:tcod:cont 0

To go to the continuous time mode:
ptim:tcod:cont 1

The screen photo of gps.exe shows it attempting to communicate with a Z3816A receiver. It will NOT communicate with a Z3801A.

Z3816A DOS utility

John MacConnell has also provided another utility program named GPS-dos2.exe. This DOS program for the Z3816A looks very much like the one above, and performs the same functions.
It also:

  • sets your computer's clock to GPS time

  • displays GPS time on your computer in a large font
  • will find "lost" gps receivers. It is possible for a receiver to get into an unknown serial communications mode. The only way to get it back is to go through all the possible combinations of baud rate, parity, etc. until you regain communications with the gps. This will go through and do that for you and set the GPS back to the factory default settings of 9600,8,N,1.

Download John MacConnell's Z3816A GPS-dos2.exe program in Zip format (50K)