Recommended Iridium SBD dataformats for buoys

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Recommended Iridium SBD dataformats for buoys By Pierre Blouch, Christophe Billon, Paul Poli, Météo-France Version 1.

1 Recommended Iridium SBD dataformats for buoys By Pierre Blouch, Christophe Billon, Paul Poli, Météo-France Version June 2018 The present document describes a list of dataformats which should be used to report buoy observations through Iridium SBD. These dataformats are the results of experiences got within the DBCP Iridium Pilot Project. Version 1.1: Addition of dataformats #021 (high resolution SVP-BS), #031 (new buoys fitted with a thermistor chain) and #032 (same but for sea ice). Version 1.2: Addition if dataformat #002 (sea ice SVP-B). Version 1.3: Addition of dataformat#033 and #034 (new SVP-BTC types). Removing of dataformats #001 and #030. Version 1.4: Addition of dataformat#022 (new SVP-BS reporting conductivity). Removing of dataformats #031 and #032. Update of table of section 3 (describing reported Iridium and GPS technical parameters). Version 1.5: Addition of dataformat#003 (SVP-B with internal physical parameters), #080 (temporary format for SIO SVP-B drifters => not standard) and #090 (draft for high sampled HRSST data). Version 1.6: Revision of dataformat#022 (SVP-BS reporting conductivity, renamed SVP-BSC) which had never been implemented, with increased accuracy for SST to K and SSS to psu. Version 1.7: Dataformat #091 (SVP with Barometer and Reference Sensor for Temperature) 1. Common characteristics Each dataformat starts with a 8-bit identifier which characterizes the type of the buoy: SVP-B drifter with or without GPS, SVP-BS drifter (salinity), SVP-BTC drifter (fitted with a thermistor chain), basic Ice buoy Another dataformat should be drawn for the SVP-BW drifter (Wind). The format identifier is followed by the observation timestamp (year, month, day, hour, minute), then by basic measurements carried out by SVP-B drifters (air pressure, SST, barometer tendency, submergence or strain gauge count, battery voltage). Then, two technical parameters are reported. Although the first should be the Iridium transmission duration in seconds, the second parameter is left in manufacturer s hands (see 3). Excepted for the SVP-B drifters which are not fitted with a GPS 1, the next block of all other dataformats contains the GPS position, its age (time delay) in minutes, as well as a couple of technical parameters which are left in manufacturer s hands (see 3). Important: 1 The Iridium position is used instead.

2 It is recommended to fill up the rooms of missing parameters with all bits to 1 excepted for the GPS position. In case a GPS fix is not available at the observation time, the previous position is reported with its time delay in minutes (reference is the time of observation for the other parameters). In case the most recent position is older than 4094 minutes, 4095 is reported in the message (i.e. all bits fitted to 1 ). In order to save energy on drifting buoys, GPS fixes may be get less frequently than other parameters (e.g. every thre hours instead of hourly). The GPS fix time delay is then different from zero. On ships, GPS fixes must be get at the same time than observed parameters. 2. List of dataformats Ident. Page Platform type SVP-B 001 SVP-B without GPS No longer suitable SVP-B (sea ice version) SVP-B with internal technical parameters Reserved for buoys SVP-BS (salinity drifter) Should no longer be used SVP-BS (high resolution salinity drifter) SVP-BSC (salinity drifter reporting conductivity) Reserved for buoys 030 SVP-BTC (thermistor chain) No longer used 031 SVP-BTC-v2 No longer used 032 SVP-BTC-v2 (sea ice version) No longer used SVP-BTC-v SVP-BTC-v3 (sea ice version) Reserved for buoys Basic Ice Buoy Reserved for buoys 050 SVP-BW (WOTAN buoy to be designed) Reserved for buoys SVP-B made by SIO (temporary format waiting for #003) Reserved for buoys (temporary dataformats) EUMETSAT SVP-B with two SST and one hydrostatic pressure buoys plus optional high frequency data (draft) SVP-BRST (SVP with Barometer and Reference Sensor for Temperature) Reserved for buoys (high frequency measurements) Reserved (see Iridium dataformats for ships) Reserved

3 Format #000 - SVP-B (20 bytes) Format identifier Forced to 0 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* Submergence/gauge count Subm. (%) = n * Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 3

4 Format #002 - SVP-B with GPS (sea ice version) (20 bytes) Format identifier Forced to 2 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* Submergence/gauge count Subm. (%) = n * Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 4

5 Format #003 - SVP-B with internal technical parameters Draft - (23 bytes) Should become the new standard for SVP and SBP-B drifters Format identifier Forced to 3 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Strain gauge count SGC (%) = n * Battery voltage Vbat (V) = n* Iridium transm. duration SBDT (s) = n*5 Iridium retries SBDR = n GPS time delay (since last fix) Delay (min) = n GPS Latitude (deg. N) Lat (deg) = n* GPS Longitude (deg. E) Lon (deg) = n* GPS Horiz. Dilution of Precision HDOP = n*0.1 GPS #sat Nsat = n GPS Time To First Fix (TTFF) TTFF (s) = n Hull Humidity Hum (%) = n*0.5 Hull Pressure Press (hpa) = n* Hull Temperature Temp ( C) = n*

6 Format #020 - SVP-BS (salinity) (24 bytes) Format identifier Forced to 20 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* CT temperature CT_temp ( C) = n* Salinity SSS (psu) = n* CT sensor error Err = n Submergence/gauge count Subm. (%) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 Spare (unused) All bits forced to «1» 2 Sea temperature measured by the conductivity sensor 6

7 Format #021 - High resolution SVP-BS (salinity) (24 bytes) Format identifier Forced to 21 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* CT temperature CT_temp ( C) = n* Salinity SSS (psu) = n* CT sensor error Err = n Submergence/gauge count Subm. (%) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 3 Sea temperature measured by the conductivity sensor 7

8 Format #022 - SVP-BSC (salinity/conductivity) (26 bytes) Format identifier Forced to 22 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendency dp (hpa) = n* CT temperature CT_temp ( C) = n* CT conductivity CT_cond (ms/cm) = n*0.001 Salinity SSS (psu) = n* CT sensor error Err = n Submergence/gauge count Subm. (%) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 Spare (unused) All bits forced to «1» 4 Sea temperature measured by the conductivity sensor 8

9 Format #033 - SVP-BTC (version 3) (variable length) Format identifier Forced to 33 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* Air temperature AT ( C) = n* Submergence/gauge count Subm. (%) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 Number of temp. probes NbT = n Depth indicator Di = n Depth of temp. probe T DT1 (m) = n*0.5 Temp. of probe T T1 ( C) = n* Depth of temp. probe T DT2 (m) = n*0.5 Temp. of probe T T2 ( C) = n* Number of press. probes NbP = n Pressure of probe P P1 (dbar) = n*0.01 Differences with regards to dataformat #031 are: - an offset of 900 hpa instead of 850 hpa for air pressure; - the addition of a room for air temperature; - the addition of one-bit parameter to tell if the depths are computed (0) or nominal (1); - an increase of the resolution for subsurface sensors and depths. The length of the message is equal to: ( bytes + NbT * bytes + NbP * byte) 5 Subsurface pressure values are reported in decibar here (1 dbar = 10 4 Pa). The atmospheric pressure must be removed to compute the depths of hydrostatic pressure probes. One decibar corresponds on one metre depth, approximately. 9

10 where NbT is the number of temperature probes and NbP is the number of pressure probes. For instance: - the length of the message for a buoy having 17 temperature probes and three pressure sensors will be 73 bytes; - the length of the message for a buoy having 11 temperature probes and one pressure sensor will be 54 bytes; By default, the depth of each temperature probe is provided by the buoy (indicator = 0). In case this is not possible, its nominal position (distance from the buoy) is given instead (indicator = 1). 10

11 Format #034 - SVP-BTC (version 3 - Sea ice version) (variable length) Format identifier Forced to 34 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* Air temperature AT ( C) = n* Submergence/gauge count Subm. (%) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 Number of temp. probes NbT = n Depth indicator Di = n Depth of temp. probe T DT1 (m) = n*0.5 Temp. of probe T T1 ( C) = n* Depth of temp. probe T DT2 (m) = n*0.5 Temp. of probe T T2 ( C) = n* Number of press. probes NbP = n Pressure of probe P P1 (dbar) = n*0.01 The difference with regards to dataformat #033 is a lower range for sea temperatures. The length of the message - which is variable -, is the same. 11

12 Format #040 - Basic Ice Buoy (21 bytes) Format identifier Forced to 40 in present version Air pressure AP (hpa) = n* Hull temperature HT ( C) = n* Pressure tendency dp (hpa) = n* Air Temperature AT ( C) = n* Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 Spare (unused) All bits forced to «1» 12

13 Parameter Format #080 - SIO SVP-B drifters (temporary, not standard) (23 bytes) Bit s Pos Offset Max Formula Format identifier Forced to 80 in present version Air pressure AP (hpa) = n* SST SST ( C) = n* Pressure tendancy dp (hpa) = n* Strain gauge count SGC (%) = n * Battery voltage Vbat (V) = n* Iridium transmit duration SBTD (s) = n*5 Iridium retries SBTR = n Hull internal humidity IHum (%) = n* Hull internal pressure IPress (hpa) = n* GPS fix time delay TTFF (s) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* GPS HDOP HDOP = n*0.1 Nb of GPS satellites Nsat = n Hull internal temperature ITemp ( C) = n* GPS Time To First Fix (TTFF) TTFF (s) = n 6 HDOP : Horizontal Dilution Of Precision 13

14 Format #090 - SVP-B with two SST probes and one hydrostatic pressure sensors (Eumetsat), plus optional high frequency data Draft - (26.5 to about 1490 bytes) Format identifier Forced to 90 in present version Air pressure AP (hpa) = n* Air pressure tendancy dp (hpa) = n* Analog SST SST ( C) = n* Digital SST (mean) SST ( C) = n* Hydrostatic press. (mean) phydr (dbar) = n*0.005 Digital SST (sd) SST Sd ( C) = n*0.001 Hydrostatic pressure (sd) phydr Sd (dbar) = n*0.005 Submergence/gauge count Subm. (%) = n * Battery voltage Vbat (V) = n* st Tech. parameter (Iridium) See 3 2 nd Tech. parameter See 3 GPS fix time delay Delay (min) = n GPS Latitude Lat (deg) = n* GPS Longitude Lon (deg) = n* rd Tech. parameter (GPS) See 3 4 th Tech. parameter (GPS) See 3 High Frequency bloc presence indicator Nb. of samples NbS = n Digital SST obs SST ( C) = n* Hydrostatic pressure obs phydr (dbar) = n*0.005 Air pressure obs AP (hpa) = n* Digital SST obs SST ( C) = n* Hydrostatic pressure obs phydr (dbar) = n*0.005 Air pressure obs AP (hpa) = n* The length of the message is equal to ( bytes + NbS * bytes). For 60 samples at 1 Hz, the message will be bytes long (i.e. equivalent to eleven 30-byte invoiced blocks). For a five-minute sample, the data can be sent through 5 consecutive SBD messages, or sent in one single message with appropriate Iridium transceiver allowing up to 1960 bytes SBD message size. Important remark: note this dataformat has not been yet adopted. Modifications has still to be made before implementation. 14

15 Format #091 - SVP-BRST (SVP with Barometer and Reference Sensor for Temperature) (30 bytes) Parameter Bits Pos Offset Slope Max Formula Format identifier Forced to 91 Year Year = n Month Month = n Day Day = n Hour Hour = n Minute Minute = n Air pressure AP (hpa) = n* Analog SST SST ( C) = n* Digital SST (mean) HRSST Mean ( C) = n* Digital SST 10th percentile HRSST ( C) P10 = n* Digital SST 10th to 30th percentiles range HRSST ( C) P30-P10 = n*0.01 Digital SST 30th to 50th percentiles range HRSST ( C) P50-P30 = n*0.01 Digital SST 50th to 70th percentiles range HRSST ( C) P70-P50 = n*0.01 Digital SST 70th to 90th percentiles range HRSST ( C) P90-P70 = n*0.01 Hydrostatic pressure (mean) offset from phydr (dbar) = n* dbar Hydrostatic pressure standard deviation phydr Sd (dbar) = n*0.005 Submergence/gauge count Subm. (%) = n * Battery voltage Vbat (V) = n* Iridium SBD transmission duration SBTD (s) = n*5 Iridium retries SBDR = n GNSS delay since last fix Delay (min) = n GNSS Latitude (deg N) Lat (deg) = n* GNSS Longitude (deg E) Lon (deg) = n* GNSS number of satellites Nsat = n GNSS Time To First Fix TTFF (s) =n GNSS error radius max one-sigma ERR (km) = n*0.015 Optional 1-Hz message indicator if additional 1-Hz messages are to be sent by the buoy, 0 otherwise 15

16 3. Manufacturer s technical parameters (updated on March 1 st, 2017) Manufacturer 1 st parameter (Iridium - 8 bits) 2 nd parameter (8 bits) 3 rd parameter (GPS - 7 bits) 4 th parameter (GPS - 4 bits) DBi Iridium SBTD Iridium RSSI GPS TTFF Nb of satellites Marlin Iridium SBTD Iridium SBTR GPS TTFF Nb of satellites Metocean Iridium SBTD Iridium CSQ GPS TTFF GPS S/N ratio Pacific Gyre Iridium SBTD Iridium SBTR GPS TTFF GPS Quality Flag NKE Iridium SBTD Iridium SBTR GPS TTFF (TTTF(s) = n) Examples of manufacturer s technical parameters Nb of satellites CSQ: Iridium SBD Signal Quality CSQ = n GPS quality flag Flag = n GPS S/N ratio GPS S/N (db) = n*4 RSSI: Iridium Received Signal Strength Indication SBTD: Iridium SBD Transmission Duration SBDT (s) = n SBTR: Number of Iridium SBD Transmission Retries SBTR = n TTFF: Time to First GPS fix TTFF (s) = n*2 16

Analysis of Argos 3 Technology on Buoy Platforms. By L. Braasch, L. Centurioni, C. McCall Scripps Institution of Oceanography, La Jolla, California

Analysis of Argos 3 Technology on Buoy Platforms By L. Braasch, L. Centurioni, C. McCall Scripps Institution of Oceanography, La Jolla, California Purpose of Study Controlled tests with same host controller