The Committee on Radio Astronomy Frequencies (CRAF) is a committee of
the European Science Foundation (ESF).
The format of the input file for the CRAF database was defined by the 18th CRAF meeting and revised in the 23rd CRAF meeting. This revised format is as follows:
| Field | Field-Name | Format | Field Width | Field description |
| 1 | DATE | Character | 8 bytes | date of interference event as yy-mm-dd: yy = year - 1900 for year before 2000 and yy = year - 2000 for year after 1999. mm = number of month. dd = day number in month |
| 2 | STATION | Character | 10 bytes | name of radio astronomy station: up to the first 10 leading characters of the station name (first 10 leading characters of station name) |
| 3 | START | Character | 5 bytes | start time of interference event in hh:mm (UT): hh = hour; mm = minute. Note that the minimum time resolution is 15 minutes. |
| 4 | END | Character | 5 bytes | end time of interference event in hh:mm (UT): hh = hour; mm = minute. Note that the minimum time resolution is 15 minutes. |
| 5 | ANTENNA | Character | 4 bytes | identification of antenna with which event was observed according to the following coding: for EMI database: according to coding: '[diameter in meters]m '; for Spectrum Occupancy Database: 'MON '. Note that the 4th character is usually blank (except for 100m telescope at Effelsberg). |
| 6 | RFIFREQ | Character | 10 bytes | EMI centre frequency in MHz (accuracy 0.001 MHz) - format is ffffff.fff. Note that the minimum frequency resolution is 1 kHz. |
| 7 | BANDWIDTH | Character | 10 bytes | EMI bandwidth in MHz (accuracy 0.001 MHz) (if known) - format is ffffff.fff. Note that the minimum frequency resolution is 1 kHz. |
| 8 | REP_INTERVAL | Character | 4 bytes | Repetition interval of pulses (for radars): seconds NOTE: REP_INTERVAL = -1.0 if no repetition is observed |
| 9 | INTENSITY | Character | 6 bytes | Intensity of interference (decimals are allowed): if the intensity exceeds 999999, the number 999999 should be specified. |
| 10 | INT_UNIT | Character | 2 bytes | Intensity unit: KE = Kelvin, JY = Jansky Note: the intensity is uncalibrated: it can only be calibrated if it is known where in the antenna pattern the interfering transmission is received and the antenna pattern is known. |
| 11 | RFI_AZ | Character | 3 bytes | Azimuth of EMI source in degrees (if available); 'AAA' if azimuth is not defined. |
| 12 | RFI_EL | Character | 2 bytes | Elevation of EMI source in degrees (if available); 'EE' if elevation is not defined. |
| 13 | TYPE | Character | 2 bytes | kind of observation: BR = broadband; SP = spectral |
| 14 | ANT_AZ | Character | 3 bytes | Azimuth of observation (in degrees); 'AAA' if azimuth is not defined |
| 15 | ANT_EL | Character | 2 bytes | Elevation of observation (in degrees); 'EE' if elevation is not defined. |
| 16 | DEG | Character | 3 bytes | degree of degradation of observation in percent. For spectrum occupancy data: '000'. |
| 20 | EOR | bytes | 1 byte | specify '=' to identify end-of-record |
** Total ** 80 bytes
The input to the database file is an ASCII file with a record-length of 80 characters, which is written into the database itself at the CRAF clearing house. Usually the underlined fields in this format form can be filled in automatically by using a simple tool as experience at Westerbork Radio Observatory showed. The others need to be filled in manually by the radio observatory (e.g. by an operator checking the observation).
This format applies to both the CRAF EMI database and to the Spectrum Occupancy database.
On the basis of practice with Westerbork database input it is considered useful a radio observatory sends each month the ASCII file by email to the CRAF clearing house. This process can also easily be automated via the CRAF ftp-server (for info: contact CRAF clearing house).