VisualGPS, LLC

Products

VisualGPSView

A free tool to monitor GPS output

NMEATIme2

An advanced PC GPS time synchronization

VisualGPS (Legacy)

Legacy VisualGPS application

NMEATIme (Legacy)

A PC GPS time synchronization tool

VisualGPS XP (Legacy)

Legacy VisualGPS application

Clock Maze Screen Saver

A Free screen saver that sloves a maze and shows the time

VisualGPSView

VisualGPSView (Freeware) incorporates many advanced features that show the status of the GPS receiver via the NMEA 0183 protocol. Its sole purpose is to display graphically specific NMEA 0183 sentences for GPS and position analysis.

Features:

  • NMEA/GLONASS - Supports GPS NMEA and GLONASS NMEA
  • Azimuth and Elevation Plot - View all satellites that are in view. Each satellite identifies its pseudo random number (PRN) and its azimuth and elevation.
  • Scatter Plot - The scatter plot shows individual position samples referenced to several type of reference types, next sample, average or user defined.
  • Signal Quality/SNR Window - Monitor satellite signal to noise ratios and see them graphically on the screen. The signal quality window will grow or shrink to accommodate number of satellites in view
  • Position Plot - Monitor latitude, longitude and altitude averages.
  • NMEA Command Monitor - View NMEA sentences as they are received
  • NMEA Recording and Playback - Record NMEA directly to a file or read NMEA from a file. NMEA files consists of standard NMEA sentences in text ASCII characters.

Requirements:

  • GPS Receiver connected to a RS-232 port or USB with NMEA 0183 output
  • Windows 7 to Window 10
  • VisualGPS decodes the following NMEA 0183 sentences:
    • GPGGA and GLGGA
    • GPGSA and GLGSA
    • GPGSV and GLGSV

Screen Shots

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NMEATime2

The price for NMEATime2 is $20.48USD If you purchase NMEATime2, we will send you a registration key via email within 48 hours.

NMEATime2 is very different from the original. It’s set up as a system service where the PC clock is disciplined to the NMEA string from the GPS. The control loop uses the same techniques in disciplining OCXO oscillators and atomic Rubidium clocks. By charactering the arrival of NMEA messages, NMEATime2 uses advanced digital filters to minimize communication jitter and achieve the best reference to train the PC clock to.

Because of this, there are some requirements that need to be met. Specifically, the rate output of NMEA message GPGGA and GPRMC.

It’s getting more difficult to find a PC with a native RS-232 serial communication port, most GPS receivers that interface to a PC use a USB. The majority of the USB GPS receivers will look to the PC as if it is a serial port. However, the modern USB GPS looks to the PC as a USB to Serial driver that emulates the serial port. In the USB world, it’s referred as a CDC (communication device class) device.

NMEATime2 will use the NMEA string (GPGGA) transmitted from the GPS, time tag the first character of the that command and use this as a timing reference. As you would expect, there are delays between the 1PPS epoch and the RS-232 causing software jitter. The delay can be calibrated out. NMEATime2 will use digital filtering (the red line you see in the Time Difference Plot - see below) and discipline the PC clock to this reference.

Requirements

The minimum NMEA sentence requirements matter. The most important is that the GPGGA and GPRMC message output once per secnd.

  • GPGGA - must be at least once/second
  • GPRMC - must be at least once/second
  • GPGSA - every two seconds
  • GPGSV - every two sconds

Please note to access NMEATime control panel, simply right click on the tray bar icon and select show panel

GPS Receiver Notes

The following are GPS receivers have been tested and the notes at accompany them. If you find that another receiver is working well, please let us know and we can list it here.

  • BU-353-S4 - USGlobalsat - This USB SiRF Star IV based receiver seems to work well and has no issues.
  • Navibe GM 720 - USB SiRF Star III based GPS works with no issues
  • Holux M-215+ - This USB receiver will function, however it causes Windows 10 to BSOD when connecting/disconnecting the USB physically from the computer. Not recommended.
  • Generic USB GPS from Amazon (link) - This USB receiver seems to work well. No issues.

GPS Performance

The above plot is showing the GPS receiver under a startup condition, cold start. Consumer GPS receivers will not indicate cold start, however it will still navigate and produce time when tracking satellites. The problem is when in this mode, the GPS may not have a full almanac (all the data from the satellites) and the time may be referenced to GPS time or something close. When the timing portion of the almanac is received, you may notice a jump in timing as depicted above. This jump usually happens within 13 minutes from the time the GPS starts tracking satellites. This is the approximate time it takes to download an almanac from the satellites. The plot shows the GPS jumping two seconds taking just a less than five minutes to occur from the start of tracking satellites.

It’s recommended to wait for at least 15 minutes before using the PC for any critical timing application when first powering up the GPS.

The test setup was using a GlobalSat BU-353-S4 USB GPS with the PC referenced to a NTP server. The data was taken using NMEATime2 with the control loop turned off and the control loop logging enabled. You can perform the same test with your GPS receiver. The control loop log will produce a comma separated value file (CSV) where you can perform analysis. The value to use is the Raw Time Difference.

Screen Shots




VisualGPS (Legacy)

If you like VisualGPS and would like to support more products like these, please donate. Suggest donation $5 USD

Currently VisualGPS is over 10 years old! NMEA support is only limited to GPS NMEA strings (Not GLONASS or Galileo). We recommend that you download VisualGPSView.

VisualGPS (Freeware) incorporates many advanced features found in professional programs. Its sole purpose is to display graphically specific NMEA 0183 sentences and show the effects of selective availability (SA).

Features:

  • Azimuth and Elevation Graph - View all satellites that are in view. Each satellite identifies its pseudo random number (PRN) and its azimuth and elevation. Also plot and print the physical mask angle.
  • Survey - The survey window displays both position and xDOP (HDOP and VDOP) parameters. The ability for user selectable HDOP/VDOP color thresholds for position averaging make a great utility. Also monitor Standard Deviation and effects of Selective Availability. That's not all - print the results graphically. (Click here for example print output) (in PDF format - 157K)
  • Signal Quality/SNR Window - Monitor satellite signal to noise ratios and see them graphically on the screen. The signal quality window will grow or shrink to accommodate number of satellites in view
  • Navigation - Monitor latitude, longitude and altitude
  • NMEA Command Monitor - View NMEA sentences as they are received

Requirements:

  • GPS Receiver connected to a RS-232 port with NMEA 0183 output - NMEA demo file included for those who do not have a GPS receiver
  • Windows 2000 sp4, Windows XP, Vista or Windows 7
  • 486 100MHz or higher microprocessor
  • SVGA at least 1024X768 resolution
  • 16 megabytes of RAM
  • 6 megabytes of disk space
  • One available RS-232 port (or captured NMEA text file - included)
  • VisualGPS decodes the following NMEA 0183 sentences:
    • GPGGA
    • GPGSA
    • GPGSV

Download

Download a free copy of VisualGPS program. It is a 32 bit program written for both the Windows 2000, XP and Vista environments. This software is freeware and there is not charge for it.

Download
NMEATime (Legacy)

Purchase NMEATime for $15.00USD

Currently NMEATime is over 10 years old! It only supports GPS NMEA string (Not GLONASS or Galileo). We recommend that you download NMEATime2

NMEATime will automatically set your PC clock using a GPS receiver connected to the serial port of a PC or to  the National Institute of Standards and Technology (NIST) time servers over the Internet. Using network time or the time from a GPS receiver, NMEATime will keep your computer referenced to an atomic time standard.

Also included with NMEATime is a NASA type desktop clock configurable to show day of year, 24 hour time or local time, color and size.

Features

  • Digital desktop time code clock - like NASA has!
  • Analog desktop clock
  • Uses GPS Time to set your PC clock
  • NMEA 0183 v2.20 - 3.01 compatible
  • Software generated IRIG-B Output (requires sound card)
  • Two Network time Protocols - Daytime NIST ACTS compatible and SNTP compatible
  • Programmable time setting rate
  • Selectable GPS NMEA message for time reference
  • Random time server select mode from an editable server list
  • Accepts 1 Pulse Per Second (1PPS) input in to  RS-232 DSR or CTS port
  • BONUS SCREEN SAVER! (ClockMaze)
  • Transparent Clock! See what is behind the clock (XP and Win2000 only).

Requirments

  • For GPS time: GPS Receiver connected to a RS-232 port with NMEA 0183 output
  • For network time: Access to the internet
  • Windows 95/98, Win2000/XP, WinNT4.0 or higher with Internet Explorer 4.0 or higher
  • Pentium 166MHz or higher microprocessor
  • SVGA at least 800X600 resolution
  • 16 megabytes of RAM
  • 2 megabytes of disk space
  • One available RS-232 port (for GPS time)
  • Sound board for IRIG output

NMEA (GPS)

  • NMEATime decodes the following NMEA 0183 sentences:
    • GPGGA or GPRMC or GPZDA
    • GPGSA
    • GPGSV
  • Compatible with NMEA 0183 version 2.01 - 3.01
VisualGPS XP (Legacy)

Purchase VisualGPSXP for $9.95 USD

Welcome to the VisualGPSXP multipurpose GPS utility. Please note that VisualGPSXP uses specific NMEA sentences to display data graphically.

VisualGPSXP is a general purpose utility for monitoring the output of a GPS receiver. Using the NMEA data from the GPS receiver, VisualGPSXP will display various statuses graphically. Tools such as a survey utility average the position and shows accuracy of the GPS receiver in a static application. Other features such as analog gauges show altitude, speed, vertical speed and direction. One additional feature is the capability to connect and share a GPS receivers data over the Internet.

Features

  • User definable window sizes and positions
  • Multiple connection paths to a GPS receiver
    • Connect using an RS-232 port
    • Connect using the network/Internet
    • Connect or read data directly from a NMEA text file
  • Analog display instruments
    • Altimeter
    • Speedometer
    • Compass
    • Vertical Speed
  • Graphical GPS status
    • Signal quality
    • Azimuth/Elevation plot
  • GPS Analyses
    • Monitor NMEA data
    • Static position averaging and statistics
    • Antenna mask determination
    • NMEA 0813 Version 2.0 - 3.01 compatible
Clock and Maze Screen Saver

If you like our software, please donate! Suggested donation: $2USD

ClockMaze is a simple screen saver that creates a maze, solves it, and shows the current time. You can setup itemse such as solve color, maze color, and solve speed. It's free. Enjoy.

Features:
  • Multiple monitor support
  • Custom colors
  • Free

Screen Shots


Contact

VisualGPS is located in Anaheim California, USA. If you have any questions or comments or simply send us a email or twitter.

info @ visualgps.net.

Twitter @VisualGPS