|
|
|
|
GPS Speed Video Overlay Unit with 5Hz update
|
|
|
| Helmet cameras are widely used to capture performance in extreme sports, motor sports and just about any activity
that requires a helmet, and some that don't. These compact cameras can already capture your outdoor sport thrills
and spills. Now you can add speed to your video footage. The GPSSPD-E-5HZ video overlay unit is designed to generate
a display of speed from a GPS receiver over the video from a helmet or vehicle mounted camera. The compact, pocket
sized unit can be used for a variety of applications. The speed data for the overlay is provided by the unit's
integral 32 channel GPS receiver. The five times per second update rate gives a near real-time display. |
|
|
|
|
|
|
|
| Video Overlay unit with integral GPS receiver and external antenna. |
|
| The GPSSPD-E-5HZ unit is housed in an ABS enclosure with phono connectors for video in / out, a 2.1mm DC power
socket and a connector for the external antenna. Display options and the ID string are selected by two push buttons
mounted inside the unit. These also control the WAAS setting described below. The speed over ground display can
be toggled between miles per hour, kilometres per hour or knots. In addition a 9 character ID string can be displayed
to identify the video footage alongside the speed if required. The time can be displayed according to a user selected
timezone offset from the GPS UTC time. The date can be shown in either the standard DD/MM/YY format or the North
American MM/DD/YY format. The altititude display can be toggled between feet and metres. You can select whether
to display the data on either line 1 only, lines 1 & 2 only, lines 1,2, & 3 only, all four lines or have
the screen clear. The solid black character background can be toggled on and off. You cannot display any other
combination of lines, change on which line each data type is displayed or change the position of the display on
the screen. The character size cannot be changed. Once set, the user options remain stored in the unit until they
are changed again. The unit has no other user controls. If you require a rearrangement of the standard data positions,
please contact us before you make your order. |
WAAS/EGNOS settings |
| Even when a GPS receiver is stationary each calculated position will be different from the last due to the sources of error in the GPS system. These errors will give the appearance of random motion
of the GPS receiver even when stationary or occasional jumps in position when stopped, particularly among high
buildings with severe multipath. WAAS
is a system of ground stations and satellites which transmits corrections to GPS signals in North America. The
EGNOS system performs the same
function for Europe. Both systems correct for GPS signal errors caused by ionospheric disturbances, timing, satellite
orbit errors and provide integrity information regarding the health of each GPS satellite. When a GPS receiver
is stationary the WAAS corrections can result in the appearance of continuous random fluctuations of the speed
reported. To avoid this the receiver in the GPSSPD-E-5HZ unit can be set to ignore the WAAS corrections. |
|
|
Suitability |
The GPSSPD-E-5HZ unit can be used for a wide range applications where a display of speed over video is required.
The overlay is updated five times per second. As the GPS receiver must calculate the speed and then transmit it
for display, the displayed data lags the actual motion by less than half a second. This is seen clearly when a
vehicle starts or stops. Due to this lag the display will not accurately represent periods of sharp acceleration
or deceleration less than half a second in duration. The GPSSPD-E-5HZ units are therefore not suitable
for professional motor sport 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.
There are many different combinations of equipment which can be used to create a helmet camera or other video camera
system. The most common type of system combines a small, light, waterproof camera worn on the helmet, with a video
recording device. Examples of this type of system are shown below. The recorder can be either a camcorder with
analogue video in or a digital PVR. |
|
|
The GPSSPD-E-5HZ video overlay unit is compatible with any combination of camera and recording device that generate
and record a standard composite video signal. The unit simply needs to be placed inline between the camera and
the recorder as in the example below. The GPS overlay will then be recorded with the video from the camera on the
recorder. |
|
|
GPSSPD-E-5HZ |
 |
Compatible with colour and mono composite video signals. 1Vp-p. PAL and NTSC |
|
GPSSPD-E-5HZ dimensions 110 x 70 x 28mm LxWxH |
|
Power supply required regulated 9 - 12V DC |
|
Power consumption 150mA maximum with antenna |
|
Operating Temp. 0° - 85°C |
|
GPS receiver specification |
|
MTK-3301 high performance GPS Chip Set 32 channel all-in-view tracking |
|
Very high sensitivity ( Tracking Sensitivity: -158dbm ) |
|
Rapid Time To First Fix at low signal level, Cold start typically <41 seconds, Hot start typically 1 second |
|
WAAS & ENGOS supported |
|
Position Accuracy 3.3 m CEP, 2.6 m WAAS enabled |
|
Datum WGS-84 |
|
| GPS antenna specification |
|
|
|
|
|
|
© The BlackBoxCameraTM Company Limited 2008
|
|
