GPSBOX Keyboard Video Overlay Units From airborne surveys in Amazonia to fishery observation in Australia, there are a number of applications where it is useful to display the information from a GPS receiver as a video text overlay. The GPSBOXKBD units are designed to meet the needs of those who require a flexible text interface combined with a GPS video text overlay. Four lines of GPS data can be displayed combined with four lines of text which can be edited from a PS/2 keyboard and positioned as a block on the screen. Two models are available. The GPSBOXKBD+ has an internal GPS receiver to provide the data for the overlay and an external antenna. It is available in versions with a 5Hz and 1Hz update rate. The GPSBOXKBD model is designed to be compatible with any GPS receiver which sends data using the NMEA 0183 standard. The GPSBOXKBD-D version displays depth instead of altitude for use with combined GPS receiver / depth transducer units. GPSBOXKBD+5HZ Order GPSBOXKBD Order GPSBOXKBD+1HZ Order GPSBOXKBD-D Order No keyboard is included. Order the FLEXKYBD item for use with these units. The GPSBOXKBD unit can be used with any GPS receiver with NMEA 0183 RS232 serial output. 4800 baud 8N1. The units are housed in an aluminum enclosure with phono connectors for video in / out, a 2.1mm DC power socket and a power switch. Keyboard connection is via a 6-pin mini DIN socket for a PS/2 keyboard. These units will only work with standard PS/2 keyboards and USB keyboards which implement PS/2 functionality. They will not work with USB only keyboards which require PC operating system support. The external GPS receiver's PC connection cable goes into the GPSBOXKBD's upper male DB9 connector. The GPS receiver's RS232 NMEA serial data output is available from the lower female DB9 connector. This allows the output of the receiver to be used with data logging or satellite navigation software. Please note that the update rate of the GPSBOXKBD+ units is fixed and cannot be changed by the user. The performance of the 1Hz and 5Hz units is similar. The essential difference between the 1Hz and 5Hz is the data update rate. The 1Hz version provides a position update once per second and the serial data is output at 4800 baud. This is the NMEA standard and so will interface with any other NMEA standard navigation or logging equipment. The 5Hz version provides a position update 5 times per second and the serial data is output at 38400 baud. This is non-standard and therefore if you intend to use the unit with any navigation or logging software you should ensure it is capable of receiving this baud rate. The higher baud rate is useful in any vehicle mounted application as the update rate is closer to real time, although there is still a lag just under half a second. For an illustration please see the FAQ on this subject. Video Clip showing screen display modes The GPS data can be displayed in four default configurations as shown below. The data position on each line is fixed, but each line can be moved to any line location on the screen or hidden dependent on the user requirement. The speed over ground display can be switched between knots, kilometres per hour or miles per hour. The character background can be toggled on and off. The altititude display can be shown in feet or metres. The date can be shown in either the standard DD/MM/YY format or the North American MM/DD/YY format. The time is displayed according to a user selected +/- 12 hour timezone offset from the GPS UTC time. The character size cannot be changed by the user, although some customisation of the character set is possible. Please contact us before you make your order for details of customisation. The gps data display configuration cannot be changed. The table below summarises the data types and user selectable options displayed by the unit, with the NMEA data sentence each is derived from. If you are unfamiliar with the serial output of the GPS receiver you intend to use with the GPSBOXKBD unit you should connect it to a PC and use hyperterminal to check that the GPRMC, GPGGA and GPVTG data sentences are transmitted. If they are not refer to the documentation from your receiver's manufacturer for the method required to enable NMEA output. Data type Data sentence Latitude $GPRMC Longitude $GPRMC Time ( User selected timezone offset ) $GPRMC Date ( DD/MM/YY or MM/DD/YY format ) $GPRMC Heading ( Track made good, degrees true ) $GPRMC Speed over ground ( in knots, kph or mph* ) $GPRMC, $GPVTG Altitude ( in metres or feet* above / below mean-sea-level (geoid) ) $GPGGA *Calculated by the unit. Accurate to +/- 1. GPSBOXKBD video overlay unit documentation Depth Data Sentences The GPSKBDBOX-D unit may be used to display depth, instead of altitude, for marine applications. The GPSBOXKBD-D unit can be used with devices that generate NMEA depth data combined with GPS data. It cannot be used with a GPS receiver and separate depth sensor, for this order GPSBOXKBD-XDT. The unit can be programmed to read one of three different NMEA depth data sentences, however you must specify which sentence you require when you make your order. The data sentences which can be read are XXDBS, XXDBT or XXDPT. Some devices will transmit all three, but many will only have one or two. Please check the manual for your device, and if possible, confirm its serial output using hyperterminal to see which sentence(s) are available in your case. Each of the data sentences reports the depth in a slightly different way. The table below summarises the NMEA sentences which can be read and the data from each that will be displayed by GPSBOXKBD-D. Please note that the XXDPT sentence reports the depth as two figures, a combination of the depth measured and an offset, either positive or negative, that you may be able to enter into the receiver or sensor. This allows adjustment of the measured depth to either the keel or waterline as required. The GPSBOXKBD-D unit ignores this offset. The depth reported in feet and fathoms is also ignored. As with the altitude described above, the depth can be displayed in feet, but this value is calculated by the unit and is accurate to +/- 1. Although GPSBOXKBD-D can be used to display GPS data alone, it cannot display the depth data without the GPS data. If you require a unit to only display depth please contact us. Depth data sentence Depth displayed as: $XXDBS,35.4,f,10.8,M,5.9,F Depth below surface in metres. ( feet and fathoms ignored ) $XXDBT,25.5,f,7.8,M,4.2,F Depth below transducer in metres. ( feet and fathoms ignored ) $XXDPT,7.8,3.0 Depth below transducer in metres. ( offset in metres ignored ) Suitability   The GPSBOXKBD+ units are suitable for a wide range of visual survey tasks. However it should be understood that the standard 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 GPSBOXKBD+ unit determines that it is in fact stationary based on pre-defined velocity and distance values which cannot be changed. When the units’s 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 GPSBOXKBD+ velocity threshold you should use GPSBOXKBD with an appropriate external GPS receiver. For low speed maritime surveys select the GPSBOXKBDPLUS-XDT unit. 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 *.kml track files. Please ensure you are aware of the limitations of the GPS system before ordering. GPSBOXKBD GPSBOXKBD-D Four lines of 26 characters, font and character size fixed UK English or US / International English keyboard mapping available* Compatible with colour and mono composite video signals. 1Vp-p. PAL or NTSC Dimensions 110 x 110 x 45mm LxWxH Power supply required 9 - 12V DC Power consumption 50mA (without keyboard) Operating Temp. 0° - 85°C *All units are shipped with US / International English keyboard mapping unless ordered from the UK. GPSBOXKBD+5HZ GPS Receiver with external Antenna* GPSBOXKBD+1HZ GPS Receiver with external Antenna* High performance 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 BOXMOUNT Order Mounting Brackets for GPSBOXKBD units. BNC CONNECTORS All the GPSBOX units can be supplied with BNC connectors on request. Please email us prior to ordering. Home Back Order © The BlackBoxCameraTM Company Limited 2010