BKG Ntrip Client (BNC) Version 1
Contents
1. x Caster hast we BUTE net Caster port 2101 User hr Password pocatcsacacsa E P Help Shilt F panel ok Fig 8 Add Mountpoints options 3 9 2 Broadcaster Host and Port required Enter the NTRIP broadcaster host IP and port number see Fig 8 http www rtcm ntrip org home provides information about known NTRIP broadcaster installations Note that EUREF and IGS operate NTRIP broadcasters at http www euref ip net home and http www igs ip net home 3 9 3 Broadcaster User and Password required for protected streams Some streams on NTRIP broadcasters may be restricted Enter a valid User ID and Password for access to protected streams Accounts are usually provided per NTRIP broadcaster through a registration procedure Register through http Aigs bkg bund de index_ntrip_reg htm for access to protected streams on www euref ip net and www igs ip net 3 9 4 Get Table Use the Get Table button to download the source table from the NTRIP broadcaster Pay attention to data fields format and format details Keep in mind that BNC can only decode and convert streams that come in RTCM Version 2 x RTCM Version 3 x or RTIGS format RTCM Version 2 x streams must contain message types 18 and 19 while RTCM Version 3 x streams must contain GPS or SBAS message types 1002 or 1004 and may contain GLONASS message types 1010 or 1012 see data field format details for available message types and their repet2. F 1 Fig 1 BNC v1 5 options 3 1 File The File button see Fig 1 lets you e select an appropriate font Use smaller font size if the BNC main window exceeds the size of your screen e save selected options Note that on Windows systems options are saved in register BKG_NTRIP_Client On Unix Linux systems options are saved in file HOME config B KG BKG_NTRIP_Client conf e quit the BNC program 3 2 Help The Help button see Fig 2 provides access to e help contents You may keep the Help Contents window open while configuring BNC e general information about BNC Close the About BNC window to continue working with BNC BNC comes with a help system providing online information about its functionality and usage Short descriptions are available for any widget Focus to the relevant widget and press Shift F1 to request help information A help text appears immediately it disappears as soon as the user does something else The dialogs on some operating systems may provide a button that users can click they then click the relevant widget to pop up the help text 3 3 Proxy for usage in a protected LAN BEG Strip Client BNC ersion 1 5 Oo x File Help Proxy General RINE Observations RINE Ephemeris Synchronized Observations Monitor Proxy host gate f Proxy port e00 Settings for the proxy in protected networks leave the boxes blank if none Fig 2 Proxy options If you are run
3. This is a known bug most likely resulting from an incompatibility of Qt libraries in the environment and in BNC Entering the command unset SESSION_MANAGER before running BNC may help as a work around e Currently BNC only handles GPS SBAS and GLONASS data Galileo is not yet supported e BNC currently will only handle C1 C2 Pl P2 L1 L2 S1 and S2 observations Which observables are available on a particular stream will depend on the setup of source receiver and the data format used RTCM Version 2 x streams do not carry signal to noise ratio S values while RTCM Version 3 x streams can only transport one code observable per frequency Note that signal to noise ratios S are also logged mapped to integer numbers to 9 e Using RTCM Version 2 x BNC will only handle message types 18 and 19 Using RTCM Version 3 x BNC will properly handle message types 1002 1004 1010 and 1012 Note that when handling message types 1001 1003 1009 and 1011 where the ambiguity field is not set the output will be no valid RINEX All values will be stored modulo 299792 458 speed of light e Streams coming in RTIGS format carry only GPS data e BNC s Get Table function only shows the STR records of a source table You can use an Internet browser to download the full source table contents of any NTRIP broadcaster by simply entering its URL in the form of http host port Data field number 8 in the NET records may provide information about where to
4. be edited The position must preferably be a point within the service area of the network RINEX files generated from these streams will contain an additional COMMENT line in the header beginning with NMEA showing the lat and long used Note that when running BNC in a Local Area Network LAN NMEA strings may be blocked by a proxy server firewall or virus scanner 3 10 Start Hit Start to start retrieving decoding and converting GNSS data streams in real time Note that Start generally forces BNC to begin with fresh RINEX which might overwrite existing files when necessary unless the option Append files is ticked 3 11 Stop Hit the Stop button in order to stop BNC 3 12 No Window optional On all systems BNC can be started in batch mode with the command line option nw BNC will then run in no window mode using options from the configuration file HOME config B KG BNC_NTRIP_Client conf Unix Linux see Config File example in the Annex or from the register BKG_NTRIP_Clhent Windows Note that the self explaining contents of the configuration file or the Windows register can easily be edited Terminate BNC using Windows Task Manager when running it in no window mode on Windows systems 4 Limitations e In Qt based desktop environments like KDE on Unix Linux platforms it may happen that you experience a crash of BNC at startup even when running the program in the background using the nw option
5. interpreted by BNC as a personal RINEX header skeleton file for the corresponding stream Examples for personal skeleton file name convention RINEX Observation files for mountpoints WETTZELL FRANKFURT and FRANCE same 4Char Station ID BRUSO from www euref ip net and BRUSO from www igs ip net same 4Char Station ID identical mountpoint stings would accept personal skeleton files named WETT skl FRAN KFURT skl FRAN CE skl BRUS 0 skl BRUS 1 skl if RINEX Skeleton extension is set to skl Note the following regulations regarding personal RINEX header skeleton files e If sucha file exists in the RINEX directory the corresponding public RINEX header skeleton file is ignored The RINEX header is generated solely from the contents of the personal skeleton e Personal skeletons should contain a complete first header record of type RINEX VERSION 7 TYPE e They should then contain an empty header record of type POM RUN BY DATE BNC will complete this line and include it in the actual RINEX file header e They should further contain complete header records of type MARKER NAME OBSERVER AGENCY REC TYPE VERS ANE ag YE APPROX POSLTION XYZ ANTENNA DELTA H E N WAVELENGTH FACT L1 2 e They may contain any other optional complete header record as defined in the RINEX documentation e They should then contain empty header records of type TYPES OF OBSERV TIME OF ELRSP OBS BNC will include the
6. log mn Network monitoring outages handling of corrupted streams latencies statistics Fig 7 Monitor options At various times the incoming stream might become unavailable or corrupted In such cases it is important that the BNC operator and or the stream providers become aware of the situation so that necessary measures can be taken to restore the stream Furthermore continuous attempts to decode corrupted stream s can generate unnecessary workload for BNC Outages and corruptions are handled by BNC as follows Stream outages BNC considers a connection to be broken when there are no incoming data detected for more than 20 seconds When this occurs BNC will attempt to reconnect at a decreasing rate It will first try to reconnect with second delay and again in 2 seconds if the previous attempt failed If the attempt is still unsuccessful it will try to reconnect within 4 seconds after the previous attempt and so on The wait time doubles each time with a maximum wait time of 256 seconds Stream corruption Not all bits chunk transfers to BNC s internal decoders return valid observations Sometimes several chunks might be needed before the next observation can be properly decoded BNC buffers all the outputs both valid and invalid from the decoder for a short time span size derived from the expected Observation rate and then determines whether a stream is valid or corrupted Outage and corruption events are report
7. once per second The header is 12 bytes long and the SOC data is 21 bytes per PRN So a typical RTIGSO_T message will be 390 bytes if 8 sats are being tracked e An ephemeris message is output when the ephemeris is decoded by the GPS receiver The time in the ephemeris header 1s the collected time Only one ephemeris can be bundled in a RTIGSE_T message A RTIGSE_T message contains one eph The message consists of 12 header bytes and 72 ephemeris bytes for a total of 84 bytes e The RTIGSM_T met message should be issued once every 15 minutes A basic met message consists of a 12 byte header and 3 longs temp press and relative humidity for a total of 24 bytes All records are related to a station configuration indicated by the Issue of Data Station IODS The IODS will enable the user to identify the equipment and software that was used to derive the observation data Each record header contains the GPS Time in seconds which flows continuously from 6 Jan 1980 onwards The data payload of each record consists of observations The structures indicate a pointer to data but in fact the broadcast messages do not contain the pointer only the data Users will have to manage the data and the pointer is shown in order to illustrate where the data is located in the message and one possible data management option All record data are in network byte order Big Endian 1 e A32 users have to swap bytes Visit http Agscb jpl nasa gov mail igs
8. time GNSS engine waiting for input epoch by epoch BNC drops whatever is received later than Wait for full epoch seconds A value of 3 to 5 seconds could be an appropriate choice for that depending on the latency of the incoming streams and the delay acceptable for your real time GNSS product Default value for Wait for full epoch is 5 seconds Note that Wait for full epoch does not effect the RINEX Observation file content Observations received later than Wait for full epoch seconds will still be included in the RINEX Observation files 3 7 3 File optional Specifies the full path to a File where synchronized observations are saved in plain ASCH format The default value is an empty option field meaning that no ASCII output file is created Beware that the size of this file can rapidly increase depending on the number of incoming streams This option is primarily meant for testing and evaluation 3 7 4 Sampling mandatory if File or Port is set Select the observation output sampling interval in seconds A value of zero 0 tells BNC to send store all received epochs This is the default value 3 8 Monitor BKG trip Client BNC ersion 1 5 Ioj x File Help Proxy General RINE Observations RINE Ephemers Synchronized Observations Monitor Observation rate MH Failure threshold 15min 4 Recover threshold Smin H Pause W Script full path home weber tinex mail operator 00 Performance
9. times are given in UTC The default value for Log full path is an empty option field meaning that BNC logs will not saved into a file 3 4 2 Append Files When BNC 1s started new files are created by default and any existing files with the same name will be overwritten However users might want to append existing files following a restart of BNC a system crash or when BNC crashed Tick Append files to continue with existing files and keep what has been recorded so far Note that option Append files affects all types of files created by BNC 3 5 RINEX Observations BEG Strip Client BNC Yersion 1 5 0 xl File Help Proxy General FINE Observations RINE Ephemeris Synchronized Observations Monitor Directory Biner Interval 15 rir Sampling E SEC Skeleton extension sk Script full path G tools upearchive Version 3 we Saving AINE observation files Fig 4 RINEX Observations options Observations will be converted to RINEX if they come in either RTCM Version 2 x RTCM Version 3 x or RTIGS format BNC s RINEX Observation files generally contain C1 C2 P1 P2 L1 L2 S1 and S2 observations In case an observation is unavailable its value is set to zero 0 000 Note that the RINEX TYPE field in the RINEX Observation file header is always set to M MIXED even if the file does not contain any GLONASS or SABAS data 3 5 1 RINEX File Names RINEX file names are derived by BNC
10. 008 Antenna serial number e Type 1009 GLONASS L1 code and phase e Type 1010 GLONASS L1 code and phase and ambiguities and carrier to noise ratio e Type 1011 GLONASS L1 and L2 code and phase e Type 1012 GLONASS L1 and L2 code and phase and ambiguities and carrier to noise ratio e Type 1013 Modified julian date leap second configured message types and interval e Type 1014 and 1017 Network RTK MAK messages under development e Type 1019 GPS ephemeris e Type 1020 GLONASS ephemeris e Type 4088 and 4095 Proprietary messages under development A 3 RTIGS RTIGS stands for a data format and transport protocol for GPS observations It was defined by the Real Time IGS Working Group RTIGS WG Its definition is based on the SOC format Every RTIGS record has one of the following numbers Station record number 100 Observation record O_T number 200 Ephemeris record E_T number 300 Meteorological record M_T number 400 Every station has one of the following unique numbers 1 99 reserved for JPL 100 199 reserved for NRCan 200 299 reserved for NGS 300 399 reserved for ESOC 400 499 reserved for GFZ 500 599 reserved for BKG 600 699 reserved for GEOSCIENCE AUS 700 799 others etc The number of bytes in each real time message includes the header as well as the data content but NOT the pointer For example e A station message is output once per hour and is 20 bytes e An observation message is output
11. 6 to activate this function The default is an empty option field meaning that no binary output is generated The binary output is a continuous stream in the following order begEpoch begObs Observation begObs Observation begObs Observation endEpoch begEpoch with the corresponding structures defined as follow const char begEpoch A const char begObs B const char endEpoch C struct Observation INC flags char Stati bp 2Ush 377 Stacion ID char satSys Satellite System G or R LNE satNum Satellite Number PRN for GPS NAVSTAR int slot Slot Number for Glonass PAC GPSWeek Week of GPS Time double GPSWeeks Second of Week GPS Time double Cis CA code pseudorange meters double C23 CA code pseudorange meters double Pl Pl code pseudorange meters double P2 P2 code pseudorange meters double Liy Ll carrier phase cycles double L2 L2 carrier phase cycles double S1 L1 signal to noise ratio double S2 L2 signal to noise ratio ERE SNR1 L1 signal to noise ratio mapped to integer TRL SNR2 L2 signal to noise ratio mapped to integer jeg The source code for BNC comes with an example program called test_bnc_qt cpp that allows you to read BNC s binary observation output from the IP port hard coded to 1968 and save the observations in file obs txt 3 7 2 Wait for Full Epoch mandatory if File or Port is set When feeding a real
12. INEX files are uploaded to an archive using script up2archive General adviseFail 15 adviseReco 5 adviseScript binSamp1l 0 casterHost www euref ip net casterPassword pass casterPort 80 Ccasverluser user ephintr 1 day ephPath home user rinex ephv3 2 logFile home user log txt makePause 0 mountPoints user pass www euref ip net 2101 ACORO RTCM 2 3 43 36 351 60 No 7 USer pass twwwegs 1p nets2 101 EEMd3 RICM 3 0 41 56 1240 no obsRate outEphPort 2102 outFile home user ascii outPort 2101 perfintr proxyHost proxyhost proxyPort 8001 rnxAppend 2 Pax I ner LS min rnxPath home weber rinex rnxSamp1 0 rnxScript home weber upZarchive rnxSkel SKL rnxV3 2 waitTime 5 A 5 Links NTRIP http Ags bkg bund de index_ntrip htm EUREF IP NTRIP broadcaster http www euref ip net home IGS IP NTRIP broadcaster http www igs ip net home NTRIP broadcaster overview http www rtcm ntrip org home EUREF IP Project http www epncb oma be _dataproducts data_access real_time Real time IGS Pilot Project http www rtigs net pilot Radio Technical Commission for Maritime Services http www rtcm org
13. Note that it is only effective if an Observation rate is specified Do not tick Pause if you want to prevent BNC from making any decoding pause Be aware that this may incur an unnecessary workload 3 8 5 Advisory Script optional As mentioned previously BNC can trigger a shell script or a batch file to be executed when one of the events described are reported This script can be used to email an advisory note to network operator or stream providers To enable this feature specify the full path to the script or batch file in the Script field The affected mountpoint and type of event reported Begin _Outage End_Outage Begin_Corrupted or End_Corrupted will then be passed on to the script as command line parameters 1 and 2 on Windows systems or 1 and 2 on Unix Linux systems together with date and time information Leave the Script field empty if you do not wish to use this option An invalid path will also disable this option Examples for command line parameter strings passed on to the advisory Script are FEMJU Begin Outage O30221 UITATI FEMJO End Outage US 02 2 LL OTOZ Began was Vos0Z920 O9 2a Sample script for Unix Linux systems bin bash sleep 60 RANDOM 32767 cat mail s NABU 1 email address lt lt Advisory Note to BNC User Please note the following advisory received from BNC Stream S Regards BNC Note the sleep command in this script which causes the system t
14. Proxy General RINE Observations RINES Ephemeris Synchronized Observations Monitor Directory Gines Interval 2 mir Port 1968 Version 3 a Saving AINEs ephemeris files and ephemeris output through IP port Fig 5 RINEX Ephemeris options Broadcast ephemeris can be saved as RINEX Navigation files when received via RTCM Version 3 x as message types 1019 GPS and 1020 GLONASS or via RTIGS records type 300 The file name convention follows the details given in section RINEX File Names except that the first four characters are BRDC and the last character is e N or G for GPS or GLONASS ephemeris in two separate RINEX Version 2 11 Navigation files or e P for GPS plus GLONASS ephemeris saved together in one RINEX Version 3 Navigation file 3 6 1 Directory optional Specify the path for saving broadcast ephemeris data as RINEX Navigation files see Fig 5 If the specified directory does not exist BNC will not create RINEX Navigation files Default value for Ephemeris Directory is an empty option field meaning that no RINEX Navigation files will be created 3 6 2 Interval mandatory if Ephemeris Directory is set Select the length of the RINEX Navigation file generated The default value is 1 day 3 6 3 Port optional BNC can output broadcast ephemeris in RINEX ASCII format on your local host IP 127 0 0 1 through an IP port Specify an IP port number to activate this function The default is a
15. The BKG Ntrip Client BNC by Georg Weber Federal Agency for Cartography and Geodesy BKG Frankfurt Germany Leos Mervart Czech Technical University Prague Department of Geodesy Introduction The BKG Ntrip Client BNC is a program for simultaneously retrieving decoding and converting real time GNSS data streams from NTRIP broadcasters like http www euref ip net home or http www igs ip net home BNC has been developed for the Federal Agency for Cartography and Geodesy BKG within the framework of EUREF s Real time GNSS Project EUREF IP IP for Internet Protocol and the Real Time IGS Pilot Project RTIGS BNC has been written under GNU General Public License GPL Binaries for BNC are available for Windows 32 bit Linux 64 bit Linux compiled using option m32 Solaris and Mac systems from http igs bkg bund de index_ntrip_down htm We used the MinGW Version 5 3 1 compiler to create the Windows binary It is likely that BNC can be compiled on other systems where a GNU compiler and Qt Version 4 3 2 are installed BNC s Qt Graphic User Interface GUI has been developed for the Federal Agency for Cartography and Geodesy BKG by Leos Mervart Czech Technical University Prague Department of Geodesy It includes the following GNU GPL software components e RTCM 2 x decoder written by Oliver Montenbruck German Space Operations Center DLR Oberpfaffenhofen e RTCM 3 x decoder written for BKG by Dirk Stoecker Alberding G
16. as is BNC allows users to by pass its decoders and directly save the input in daily log files To do this specify the decoder string see Fig 1 as ZERO The generated file names are created from the characters of the mountpoints plus two digit numbers each for year month and day Example Setting the decoder string for mountpoint WTZZO to ZERO and running BNC on March 29 2007 would save the raw data in a file named WTZZ0_070329 e BNC can also retrieve streams from virtual reference stations VRS To initiate these streams an approximate rover position needs to be sent in NMEA format to the NTRIP broadcaster In return a user specific data stream is generated typically by a Network RTK software This stream is customized to the exact latitude and longitude as shown in the lat and long columns under Mountpoints These VRS streams are indicated by a yes in the nmea column under Mountpoints as well as in the source table The default lat and long values are taken from the source table however in most cases you would probably want to change this according to your requirement Double click on lat and long fields see Fig 1 enter the values you wish to send and then hit Enter The format is in positive north latitude degrees e g for northern hemisphere 52 436 for southern hemisphere 24 567 and eastern longitude degrees example 358 872 or 1 128 Only mountpoints with a yes in its nmea column can
17. e for Directory is an empty option field meaning that no RINEX Observation files will be written 3 5 3 Interval mandatory if Directory is set Select the length of the RINEX Observation file generated The default value is 15 minutes 3 5 4 Sampling mandatory if Directory is set Select the RINEX Observation sampling interval in seconds A value of zero 0 tells BNC to store all received epochs into RINEX This is the default value 3 5 5 Skeleton Extension optional Whenever BNC starts generating RINEX Observation files and then once every day at midnight it first tries to retrieve information needed for RINEX headers from so called public RINEX header skeleton files which are derived from sitelogs A HTTP link toa directory containing these skeleton files may be available through data field number 7 of the affected NET record in the source table See http www epncb oma be 80 stations log skl brus skl for an example of a public RINEX header skeleton file for the Brussels EPN station However sometimes public RINEX header skeleton files are not available its contents is not up to date or you need to put additional optional records in the RINEX header For that BNC allows using personal skeleton files that contain the header records you would like to include You can derive a personal RINEX header skeleton file from the information given in an up to date sitelog A file in the RINEX Directory with a Skeleton extension is
18. e satellites You need to make sure that the connection can sustain the required bandwidth Note that running BNC requires the clock of the host computer to be properly synchronized BNC has the capacity to retrieve hundreds of GNSS data streams simultaneously Please be aware that such usage may incur a heavy load on the NTRIP broadcaster side depending on the number of streams requested We recommend limiting the number of streams where possible to avoid unnecessary workload 3 Options BKG Mtrip Client BNC ersion 1 5 Oo x File Help Provy General RINE Observations RINE Ephemeris Synchronized Observations Monitor Logfile full path G rinew bne_log Append files wt General settings for logfile and fle handling Ie a a WW elrel ip net 101 BELFO AT Ch 3 1 p4 ad 5 55 no 11 055 kb ww eurel ip net 2101 OU FO ATCM 23 46 56 12 97 no 29 226 kb wew 1gs ip net 2101 4ALBHO ATIGS 46 39 236 51 ro OF6 kb 05 04 17 12 33 13 s s Start BNC U6 04 7 7 12 33 13 Get Data BELFO in ATEM 3 format 08 04 17 12 33 13 Get Data 2OUFO in ATEM 2 format 08 04 17 12 33 13 Get Data ALBHO in ATIGS format 08 04 17 12 33 46 OUFO Mean latency 1 2 sec min 0 52 max 1 57 32 epochs 08 04 17 12 33 46 BELFO Mean latency 1 417 sec min 0 75 mas 3 64 33 epochs 08 04 17 12 33 48 ALBHO Mean latency 2 78 sec min 2 mas 3 02 32 epochs 4ddMountpoints Delete Mountpoints Star Stop Help Shitt
19. ed in the Log file section They can also be passed on as parameters to a shell script or batch file to generate an advisory note to BNC operator or affected stream providers This functionality lets users utilise BNC as a real time performance monitor and alarm system for a network of GNSS reference stations 3 8 1 Observation Rate mandatory if Failure threshold Recovery threshold Pause and Advisory Script is set BNC can collect all returns success or failure coming from a decoder within a certain short time span to then decide whether a stream has an outage or its content is corrupted This procedure needs a rough a priory estimate of the expected observation rate of the incoming streams see Fig 7 An empty option field default means that you don t want an explicit information from BNC about stream outages and incoming streams that can not be decoded and that the special procedure for handling of corrupted streams is by passed decoding attempt will never get paused 3 8 2 Failure Threshold optional Event Begin_Failure will be reported if no data is received continuously for longer than the Failure threshold time Similarly event Begin_Corrupted will be reported when corrupted data is detected by the decoder continuously for longer than this Failure threshold time The default value is set to 15 minutes and is recommended so not to innundate user with too many event reports Note that specifying a
20. from the first 4 characters of the corresponding mountpoint 4Char Station ID For example data from mountpoints FRANKFURT and WETTZELL will have hourly RINEX Observation files named FRAN ddd h yy 0 WETT ddd h yy 0O where ddd is the day of year h is a letter which corresponds to an hour long UTC time block and yy is the year If there are more than one stream with identical 4Char Station ID same first 4 characters for their mountpoints the mountpoint strings are split into two sub strings and both become part of the RINEX file name For example when simultaneously retrieving data from mountpoints FRANKFURT and FRANCE their hourly RINEX Observation files are named as FRAN ddd h KFURT yy 0 FRAN ddd h CE yy 0 If several streams show exactly the same mountpoint name example BRUSO from www euref ip net and BRUSO from www igs ip net BNC adds an integer number to the file name leading 1 e to hourly RINEX Observation files like BRUS ddd h 0 yy 0 BRUS ddd h 1 yy o Note that RINEX file names for all intervals less than 1 hour follow the file name convention for 15 minutes RINEX Observation files 1 e FRAN ddd h mm yy 0O where mm is the starting minute within the hour 3 5 2 Directory optional Here you can specify the path to where the RINEX Observation files will be stored see Fig 4 If the specified directory does not exist BNC will not create RINEX Observation files Default valu
21. is function or select the empty option field if you do not want BNC to log latencies and statistical information 3 9 Mountpoints Each stream on an NTRIP broadcaster is defined using a unique source ID called mountpoint An NTRIP client like BNC access the desired data stream by referring to its mountpoint Information about mountpoints is available through the source table maintained by the NTRIP broadcaster Note that mountpoints could show up in BNC more than once when retrieving streams from several NTRIP broadcasters Streams selected for retrieval are listed under the Mountpoints section on BNC s main window see Fig 1 The list provides the following information extracted from source table s produced by the NTRIP broadcasters NTRIP broadcaster URL port and mountpoint decoder Type of decoder used to handle the incoming stream content according to its format editable Approximate latitude of reference station in degrees north editable if nmea yes yes nmea Indicates whether or not streaming needs to be initiated by BNC through sending NMEA GGA message carrying position coordinates in lat and long Number of bytes retrieved Approximate longitude of reference station in degrees east editable if nmea 3 9 1 Add Mountpoints Button Add Mountpoints see Fig 1 opens a window that allows user to select data streams from an NTRIP broadcaster according to their mountpoints Add Mountpoints
22. ition rates in brackets Note that in order to produce RINEX Navigation files RTCM Version 3 x streams containing message types 1019 GPS and 1020 GLONASS are required Select your streams line by line use Shift and Ctrl when necessary The contents of data field nmea tells you whether a stream retrieval needs to be initiated by BNC through sending an NMEA GGA message carrying position coordinates virtual reference station Hit OK to return to the main window If you wish you can click on Add Mountpoints and repeat the process again to retrieve mountpoints from different casters 3 9 5 Delete Mountpoints To remove a stream from the Mountpoints list in the main window highlight it by clicking on it and hit the Delete Mountpoints button You can also remove multiple mountpoints simultaneously by highlighting them using Shift and Ctrl 3 9 6 Edit Mountpoints e BNC automatically allocates one of its internal decoders to a stream based on the stream s format and format details as given in the source table However there might be cases where you need to override the automatic selection due to incorrect source table for example BNC allows users to manually select the required decoder by editing the decoder string Double click on the decoder field see Fig 1 enter your preferred decoder and then hit Enter The accepted decoder strings are RTCM_2 x RTCM_3 x and RTIGS e Incase you need to log the raw data
23. mbH Schoenefeld e RTIGS decoder written by Ken MacLeod Natural Resources Canada The following is a complete description of BNC comprising its purpose user resources options and limitations Background information concerning NTRIP RTCM RTIGS and configuration files is provided as an annex The paper is written in a way that it can serve as a BNC user manual 1 Purpose The purpose of BNC is to e retrieve real time GNSS data streams available through NTRIP transport protocol e generate high rate RINEX Observation and Navigation files to support near real time GNSS post processing applications and or e generate ephemeris and synchronized observations epoch by epoch through an IP port to support real time GNSS engines and or e monitor the performance of a network of real time GNSS reference stations to generate advisory notes BNC supports the following GNSS data formats e RTCM Version 2 x containing message types 18 and 19 GPS and GLONASS e RTCM Version 3 x containing message types 1002 GPS SBAS or 1004 GPS 1010 or 1012 GLONASS 1019 or 1020 broadcast ephemeris e RTIGS containing GPS record types 200 observations and 300 ephemeris BNC allows to by pass its decoding and conversion algorithms leave whatever is received untouched and save it in files 2 Resources BNC requires access to the Internet with a minimum of about 2 to 6 kbits sec per stream depending on the stream format and the number of visibl
24. measurements and pseudo range corrections used in RTK e Type 23 message provides the information on the antenna type used on the reference station e Type 24 message carries the coordinates of the installed antenna s ARP in the GNSS coordinate system coordinates A 2 2 RTCM Version 3 x RTCM Version 3 x has been developed as a more efficient alternative to RTCM Version 2 x Service providers and vendors have asked for a standard that would be more efficient easy to use and more easily adaptable to new situations The main complaint was that the Version 2 parity scheme was wasteful of bandwidth Another complaint was that the parity is not independent from word to word Still another was that even with so many bits devoted to parity the actual integrity of the message was not as high as it should be Plus 30 bit words are awkward to handle The Version 3 x standard is intended to correct these weaknesses RTCM Version 3 x defines a number of message types Messages that may be of interest here are e Type 1001 GPS L1 code and phase e Type 1002 GPS L1 code and phase and ambiguities and carrier to noise ratio e Type 1003 GPS L1 and L2 code and phase e Type 1004 GPS L1 and L2 code and phase and ambiguities and carrier to noise ratio e Type 1005 Station coordinates XZY for antenna reference point e Type 1006 Station coordinates XYZ for antenna reference point and antenna height e Type 1007 Antenna descriptor and ID e Type 1
25. n empty option field meaning that no ASCII ephemeris output via IP port is generated The source code for BNC comes with an example perl script called test_bnc_eph pl that allows you to read BNC s ASCII ephemeris output from the IP port 3 6 4 Version optional Default format for RINEX Navigation files containing broadcast ephemeris is RINEX Version 2 11 Select Version 3 if you want to save the ephemeris in RINEX Version 3 format 3 7 Synchronized Observations BKG Strip Client BNC ersion 1 5 e oO x File Help Proxy General RINES Observations RAINES Ephemeris Synchronized Observations Monitor Fort C Walt for full epoch B H File full path GAdatatabs t Sampling isc H Output synchronized observations epoch by epoch Fig 6 Synchronized Observations options BNC can generate synchronized epoch by epoch observations from all stations and satellites The output can be in either a plain ASCII format and or a binary format It comprises the following observations where available StatID SVPRN GPSWeek GPS Weeks C1 C2 P1 P2 L1 L2 S1 S2 SNR1 SNR2 Note that SNR stands for the signal to noise ratio S mapped to integer numbers 1 to 9 In case an observation is not available its value is set to zero 0 000 3 7 1 Port optional BNC can produce synchronized observations in binary format on your local host IP 127 0 0 1 through an IP Port Specify an IP port number here see Fig
26. ning BNC within a protected Local Area Network LAN you might need to use a proxy server to access the Internet Enter your proxy server IP and port number see Fig 2 in case one is operated in front of BNC If you don t know the IP and port of your proxy server check the proxy server settings in your Internet browser or ask your network administrator Note that IP streaming is often not allowed in a LAN In this case you need to ask your network administrator for an appropriate modification of the local security policy or for the installation of a TCP relay to the NTRIP broadcasters If these are not possible you might need to run BNC outside your LAN on a host that has unobstructed connection to the Internet 3 4 General BKG trip Client BNC Yersion 1 5 oj x File Help Proxy General RINE Observations RINE E phemeris Synchronized Observations Monitor Logfile full path G rinex bne_log Append files cl General settings for logfile and file handling Fig 3 General options 3 4 1 Logfile optional Records of BNC s activities are shown in the Log section on the bottom of the main window These logs can be saved into a file when a valid path is specified in the Log full path field see Fig 3 The message log covers the communication status between BNC and the NTRIP broadcaster as well as problems that may occur in the communication link stream availability stream delay stream conversion etc All
27. o wait for a random period of up to 60 seconds before sending the email This should avoids overloading your mail server in case of a simultaneous failure of many streams 3 8 6 Performance Log optional Latency Latency is defined in BNC by the following equation UTC time provided by BNC s host GPS time of currently processed epoch Leap seconds between UTC and GPS time hard coded to 14 Latency BNC can average the latencies per stream over a certain period of GPS time the Performance log interval Mean latencies are calculated from the individual latencies of at most one first incoming observation per second Note that computing correct latencies requires the clock of the host computer to be properly synchronized Statistics BNC counts the number of GPS seconds covered by at least one observation It also estimates an observation rate independent from the a priory specified Observation rate from all observations received throughout the first full Performance log interval Based on this rate BNC estimates the number of data gaps when appearing in subsequent intervals Latencies and statistical information can be recorded in the Log file section at the end of each Performance log interval A typical output from a 1 hour Performance log interval would be O9 03 17 15759247 BRUSOY Mean datvency 1 047 Sec min 0 266 dmax 30024 3 585 epochs 15 gaps Select a Performance log interval to activate th
28. register for an NTRIP broadcaster account e EUREF as well as IGS adhere to an open data policy Streams are made available through NTRIP broadcasters at www euref ip net and www igs ip net free of charge to anyone for any purpose There is no indication up until now how many users will need to be supported simultaneously The given situation may develop in such a way that it might become difficult to serve all registered users at the same times In cases where limited resources on the NTRIP broadcaster side software restrictions bandwidth limitation etc dictates first priority in stream provision will be given to stream providers followed by re broadcasting activities and real time analysis centers while access to others might be temporarily denied e We experienced a limitation of the Standard Version of Microsoft Windows related to socket communication where sockets are not always handled properly Since BNC makes intensive use of communication through sockets we recommend to use the Server Version of Microsoft Windows when running BNC continuously for extended on a Windows platform e The source code provided by NRCan for decoding RTIGS streams is 32 bit dependent Hence the BNC executable generated for 64 bit Linux systems would only run when compiled using the m32 compiler option e Once BNC has been started its configuration can not be changed as long as it is stopped A reconfiguration on the fly is not implemented Acknowledgement
29. rtwg 2004 msg00001 html for further details A 3 1 SOC The SOC format has been designed in July 1999 by the Jet Propulsion Laboratory JPL and the California Institute of Technology CalTech to transport 1Hz GPS data with minimal bandwidth over the open Internet SOC follows the little endian byte order meaning that the low order byte of a number is stored in memory at the lowest address and the high order byte at the highest address Because the transport layer is UDP the format does not include sync bits a checksum or cyclic redundancy checksum CRC SOC allows to transport the GPS observable CA P1 P2 L1 and L2 efficiently compressed down to 14 bytes with 1 mm range resolution and 0 02 mm phase resolution SOC contains epochs for cycle slips a stand alone time tag per epoch a minimum representation of the receiver s clock solution 3 SNR numbers a unique site id a modulo 12 hour sequence number and flags for receiver type and GPS health SOC s simple structure comprises an 8 byte header a 9 byte overhead for timetag number of gps etc plus 21 data bytes per gps Visit http gipsy jpl nasa gov igdg papers SOC_FORMAT ppt for further details A 4 Configuration File The following is an example for the contents of a Unix Linux configuration file HOME config B KG BKG_NTRIP_Client conf It enables the retrieval of stream ACORO form www euref ip net and FFMJ3 from www igs ip net for the generation of 15 min RINEX files R
30. s BNC s Help Contents has been proofread by Thomas Yan University of New South Wales Australia Scott Glazier OmniSTAR Australia included the decoding of broadcast ephemeris from RTIGS streams and has been helpful in finding BNC s bugs James Perlt BKG helped fixing bugs and redesigned BNC s main window Andre Hauschild German Space Operations Center DLR revised the RTCMv 2 decoder Annex A 1 NTRIP Networked Transport of RTCM via Internet Protocol Version 1 0 NTRIP stands for an application level protocol streaming Global Navigation Satellite System GNSS data over the Internet NTRIP is a generic stateless protocol based on the Hypertext Transfer Protocol HTTP 1 1 The HTTP objects are enhanced to GNSS data streams NTRIP Version 1 0 is an RTCM standard designed for disseminating differential correction data e g in the RTCM 104 format or other kinds of GNSS streaming data to stationary or mobile users over the Internet allowing simultaneous PC Laptop PDA or receiver connections to a broadcasting host NTRIP supports wireless Internet access through Mobile IP Networks like GSM GPRS EDGE or UMTS NTRIP is implemented in three system software components NTRIP clients NTRIP servers and NTRIP broadcasters The NTRIP broadcaster is the actual HTTP server program whereas NTRIP client and NTRIP server are acting as HTTP clients NTRIP is an open none proprietary protocol Major characteristics of NTRIP s dissemination
31. sage in code phase differential positioning DGPS It is computed in the base receiver by computing the error in the range measurement for each tracked SV e Type 2 message is automatically generated when a new set of satellite ephemeris is downloaded to the base receiver It is the computed difference between the old ephemeris and the new ephemeris Type 2 messages are used when the base station is transmitting Type 1 messages e Type 3 and 22 messages are the base station position and the antenna offset Type 3 and 22 are used in RTK processing to perform antenna reduction e Type 6 message is a null frame filler message that is provided for data links that require continuous transmission of data even if there are no corrections to send As many Type 6 messages are sent as required to fill in the gap between two correction messages type 1 Message 6 is not sent in burst mode e Type 9 message serves the same purpose as Type 1 but does not require a complete satellite set As a result Type 9 messages require a more stable clock than a station transmitting Type 1 s because the satellite corrections have different time references e Type 16 message is simply a text message entered by the user that is transmitted from the base station to the rover It is used with code phase differential e Type 18 and 20 messages are RTK uncorrected carrier phase data and carrier phase corrections e Type 19 and 21 messages are the uncorrected pseudo range
32. se lines in the final RINEX file header together with an additional COMMENT line describing the source of the stream e They should finally contain an empty header record of type END OF HEADER last record If neither a public nor a personal RINEX header skeleton file is available for BNC a default header will be used 3 5 6 Script optional Whenever a RINEX Observation file is saved you might want to compress copy or upload it immediately via FTP BNC allows you to execute a script batch file to carry out these operations To do that specify the full path of the script batch file here BNC will pass the RINEX Observation file path to the script as a command line parameter 1 on Windows systems 1 on Unix Linux systems The triggering event for calling the script or batch file is the end of a RINEX Observation file Interval If that is overridden by a stream outage the triggering event is the stream reconnection As an alternative to initiating file uploads through BNC you may like to call an upload script or batch file through your crontable or Task Scheduler independent from BNC once every 2 or 3 minutes after the end of each RINEX file Interval 3 5 7 Version optional The default format for RINEX Observation files is RINEX Version 2 11 Select Version 3 if you would like to save observations in RINEX Version 3 format 3 6 Ephemeris BEG Ntrip Client BNC ersion 1 5 E iol x File Help
33. technique are e Based on the popular HTTP streaming standard comparatively easy to implement when having limited client and server platform resources available e Application not limited to one particular plain or coded stream content ability to distribute any kind of GNSS data e Potential to support mass usage disseminating hundreds of streams simultaneously for thousands of users possible when applying modified Internet Radio broadcasting software e Considering security needs stream providers and users don t necessarily get into contact streams often not blocked by firewalls or proxy servers protecting Local Area Networks e Enables streaming over mobile IP networks because of using TCP IP A 1 1 Source table The NTRIP broadcaster maintains a source table containing information on available NTRIP streams networks of NTRIP streams and NTRIP broadcasters The source table is sent to an NTRIP client on request Source table records are dedicated to one of the following Data Streams record type STR Casters record type CAS or Networks of streams record type NET Source table records of type STR contain the following data fields mountpoint identifier format format details carrier nav system network country latitude longitude nmea solution generator compr encryp authentication fee bitrate misc Source table records of t
34. value of zero 0 for the Failure threshold will force BNC to report any stream failure immediately Note also that for using this function you need to specify the Observation rate 3 8 3 Recovery Threshold optional Once a Begin_Failure or Begin_Corrupted event has been reported BNC will check for when the stream again becomes available or uncorrupted Event End_Failure or End_Corrupted will be reported as soon as valid observations are again detected continuously throughout the Recovery threshold time span The default value is set to 5 minutes and is recommended so not to innundate users with too many event reports Note that specifying a value of zero 0 for the Recovery threshold will force BNC to report any stream recovery immediately Note also that for using this function you need to specify the Observation rate 3 8 4 Pause optional In case of a corrupted stream the decoding process can be paused and decodings are then attempted again at decreasing rate BNC will first attempt to decode again after a 30 second lag and if unsuccessful make another attempt within 60 seconds after the previous attempt If itis still unsuccessful it will make another attempt to decode within 120 seconds after the previous attempt and so on Each decoding attempt doubles the wait time since the previous attempt The maximum wait time between attempts is limited to 960 seconds Tick Pause to activate this function
35. ype NET contain the following data fields 1dentifiey operator authentication fee web net web str web reg misc Source table records of type CAS contain the following data fields host port identifier operator nmea country latitude longitude misc A 2 RTCM The Radio Technical Commission for Maritime Services RTCM is an international non profit scientific professional and educational organization Special Committees provide a forum in which governmental and non governmental members work together to develop technical standards and consensus recommendations in regard to issues of particular concern RTCM is engaged in the development of international standards for maritime radionavigation and radiocommunication systems The output documents and reports prepared by RTCM Committees are published as RTCM Recommended Standards Topics concerning Differential Global Navigation Satellite Systems DGNSS are handled by the Special Committee SC 104 Personal copies of RTCM Recommended Standards can be ordered through http www rtcm org orderinfo php A 2 1 RTCM Version 2 x Transmitting GNSS carrier phase data can be done through RTCM Version 2 x messages Please note that only RTCM Version 2 2 and 2 3 streams may include GLONASS data Messages that may be of some interest here are e Type message is the range correction message and is the primary mes
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