Data files should be uploaded onto one of two KNMI EMADDC SFTP servers into a given sub-directory provided by the EMADDC team. For test data (DTA) services the data should be uploaded to ftppro.knmi.nl while operational data should be uploaded to ftpservice.knmi.nl using one of the methods described here.
Upon request, an SFTP account will be provided by the EMADDC team to upload and / or to download data.
Upload of data
Files should be uploaded using unique filenames that start with a static prefix defining the source (country /location) and contains the date and time in the filename in UTC:
where the first time (YMD_HM) indicates the start of the expected time window of observations in the uploaded file and the second (YMD_HM) contains the end time of the window. In case of a 5 minute time window, this should indicate for example country_organization_site_20220401_1200_20220401_1204.ext. The next file should start at country_organization_site_20220401_1205_20220401_1209.ext. It is also preferred that observations in this file fall exactly in this window and no observations from a previous window are included to reduce transmission delays. EMADDC cannot guarantee that observations from an older time window will be present in the EMADDC output products. This depends on the length of the window and transmission delay. If for any reason no observations are present in a time window, EMADDC expects to receive empty files with the expected time window in the filename for data monitoring. Thus, for a 5 minute time window, EMADDC expects to receive 12x24=288 files per day.
For country use the ISO 3166-1 classification and a logical and short abbreviation for your organisation. This will be used to code and identify the source in the EMADDC data output.
The <site> key could be an abbreviation for the site of the receiver/radar or could be "MUL" in case a file contains data from MULtiple sources (preferred). The file extension, <dataType/extension>, could be ‘raw’ or ‘ avr’ in case of local Mode-S / ADS-B receiver data, 'txt' for EMADDC ASCII and 'cat48' or 'cat62' for ASTERIX data and data could be compressed using gzip.
Also note that it is important to upload the file with a temporary extension (*.tmp). After uploading has finished the uploaded file shall be renamed to the final filename and extension to signal a successful and completed file upload. This method assures that EMADDC only processes fully uploaded files. Uploading without temporary extension would result in corrupted or duplicate data input and discarding of the data by the EMADDC system. Also assure that you upload the file only once.
The EMADDC team also appreciates to be informed about the upload interval (e.g., 5, 10 or 15 minute batches). Also note that EMADDC requests to receive files as soon as they are available to reduce delays.
For local Mode-S / ADS-B receiver data (see here) only messages containing 112 bits contain usefull information and shorter messages shall be omitted.
Finally, do not use rsync and assure files are uploaded only once. Protections are in place to resolve issues but this consumes resources unnecessarily.