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General Purpose GPS Video Overlay Unit

The GPSBOX-GP video overlay unit provides a simple method for displaying the speed, time and position information from a GPS receiver over the picture from a standard definition composite video camera. The unit has an integral 66 channel GPS receiver which provides the data for the overlay. The display is updated 10 times per second (10Hz). The unit is supplied with an external antenna suitable for vehicle mounting. In addition the unit has a three axis accelerometer for vehicle applications. With additional equipment the unit may also be used as part of a lap / interval timing system. There are three versions of the unit with different video interfaces. Each version is housed in an aluminum enclosure.

All GPSBOX-GP versions have been discontinued

Statement on GPS week number rollover

Display Layout
The GPSBOX-GP unit can display 7 data types described below. Each can be individually selected / deselected for display during the setup process described in the documentation.
1 Speed over ground selected for display in miles per hour, kilometres per hour or knots
2 Altitude above / below mean-sea-level selected for display in feet or metres
3 Heading in degrees
4 Acceleration in 2 or 3 axes with ±2g, ±4g or ±8g ranges. Accurate to ±0.1g
5 Lap timer, current, last and best lap ( Requires optional external equipment )
6 Latitude and Longitude
7 Time and Date. User selected timezone offset, DD/MM/YY or MM/DD/YY format


GPSBOX-GP video overlay unit documentation

The GPSBOX-GP version connects via standard RCA phono connectors to a camera and monitor / recorder


The GPSBOX-GP-25 version is designed to be used with either the KL509 or MiniDVRIII mini dvr units which use a 2.5mm jack plug connector between the camera cable and the DVR unit. The video in / out connectors on the GPSBOX-GP-25 are 2.5mm jack sockets and a 2.5mm jack plug to plug cable is supplied with the unit.

Mini DVR units compatible with the GPSBOX-GP-25

The DVR camera is connected to the 2.5mm video input of the GPSBOX-GP-25 and the supplied cable is connected between the video output and the AVin socket of the DVR unit. Always ensure that the 2.5mm jack plugs are fully inserted into the unit. Never remove or replace any cables when either the DVR or the overlay unit are powered as damage to the units will result.

DVR unit AVin connectors

The DVR camera cable is inserted into the overlay unit and overlay unit cable into the DVR unit

The video overlay unit will not pass the video signal from the camera when it is switched off. Therefore when powering up the system always switch the overlay unit on first or at the same time as the DVR. If the DVR is turned on first it will report no video signal. If the camera is not attached to the video overlay unit it will generate its own video signal displaying the data over a blank black background.


The GPSBOX-GP-35 is designed to be used with a range of personal media players (PMP) and other equipment that connect to external video equipment via a 3.5mm jack plug. The video in / out connectors on the GPSBOX-GP-35 are 3.5mm jack sockets and a 3.5mm jack plug to plug cable is supplied with the unit.

Example of AVin connections of JXD PMP

The PMP unit shown as an example is a JXD 990. Like similar units it is provided with an AVin cable for recording from televisions or other video sources. This cable normally connects to a 3.5mm socket marked Avin on the PMP.

Camera set up with PMP and GPSBOX-GP-35

To connect the PMP to the GPSBOX-GP-35 unit first remove the AVin cable from the PMP AVin socket and then insert it into the 3.5mm socket marked video in on the front panel of the GPSBOX-GP-35. Next insert the video out cable from the GPSBOX-GP-35 into the AVin socket of the PMP. Switch on the overlay unit before you turn on the PMP as it will not pass video while switched off.

The GPSBOX-GP units are suitable for a wide range of applications. However it should be understood that the units may not provide a continuously stationary display when the unit is stationary. Even when a GPS receiver is stationary each calculated position can be different from the last due to the sources of error in the GPS system. These errors can give the appearance of random motion of the GPS receiver even when stationary or occasional jumps in speed when stopped, particularly among high buildings which can produce multipath errors. The GPSBOX-GP unit determines that it is in fact stationary based on pre-defined velocity and distance values which cannot be changed. When the unitsís velocity drops below a threshold value, shown below, then the position and heading are pinned to the last computed value. The position and heading will remain at these values until the receiver detects that the velocity has increased above a slightly higher threshold. If you intend operating at speeds below the velocity threshold these units are not suitable for your application.

Approximate velocity threshold values
2.3 mph
3.7 kph
2.0 knot
1.0 m/s

The accuracy of the GPS position in practice can be judged from the NMEA track files. Please ensure you are aware of the limitations of the GPS system before ordering.
Speed is accurate to ±1 mph.
The lap or interval time is accurate to ±0.4 seconds over one hour.
The accelerometer readings are accurate to ±0.1g. The accelerometer will only give an accurate indication of vehicle motion if the unit is securely mounted to a non-vibrating part of the vehicle structure.

The gps data and accelerometer readings displayed are not precisely synchronised with each other or with the frames of the video. The gps data lags the accelerometer data by approximately 400ms. The accelerometer is only accurate to ±0.1g and may not be precisely aligned with the axes of the GPSBOX-GP case. As the values displayed are discrete samples made at 100ms intervals, any event between the sample points may be seen on the video, but not completely reflected in the data display. Due to this lag the display will not accurately represent periods of sharp acceleration or deceleration less than half a second in duration. The GPSBOX-GP units are therefore not suitable for high performance professional motor sport testing applications as an alternative to systems such as those from racelogic. The unit is most suited to applications where speeds will be maintained for more than a second in a relatively straight line. A detailed scientific explanation of the way GPS receivers derive speed can be read here.


GPSBOX-GP video overlay unit documentation

GPSBOX-GP Example Videos

Display Set Up Example Video

Gyrocopter Trial Flight Example Video

Compatible with colour and mono composite video signals. 1Vp-p. PAL or NTSC
Dimensions 95 x 65 x 30mm LxWxH (without connectors)
Weight 160g
Power supply required 9 - 12V DC
Power consumption 150mA with antenna
Operating Temp. 0° - 85°C
The GPSBOX-GP-25 and GPSBOX-GP-35 do not draw power from the DVR or PMP they are connected to.
GPS Receiver with external Antenna*
High performance 66 Channel MTK GPS chipset
Very high sensitivity (Tracking Sensitivity: -165 dBm)
Rapid Time To First Fix at low signal level, Cold start average 41 seconds, Hot start average 1 second
WAAS & ENGOS supported
Position Accuracy 10 meters 2D RMS, 5 meters 2D RMS WAAS enabled
Datum WGS-84
* GPS antenna specification
3 axes
Choice of three ranges ±2g, ±4g or ±8g
Accurate to ±0.1g

Mounting Brackets for GPSBOX-GP units.

Velcro mount for GPSBOX-GP units.




© The BlackBoxCameraTM Company Limited 2019