RAWACF files

RAWACF files are raw files produced at radar sites.

Sometimes they are post-processed from IQDAT files or converted from the older-format dat files (see dattorawacf).

Naming Conventions

Currently the common naming convention for RAWACF files is:

YYYYMMDD.HH.mm.ss.<3-letter abbreviation>.rawacf

SuperDARN radars routinely change operating frequency. Some operating modes use multiple frequencies, either at the same time, or by alternating between frequencies. As a result, some files from some radars include all records for all frequencies in the same file and other radars separate out the individual frequencies into separate files, designated by a channel letter in the file name:

YYYYMMDD.HH.mm.ss.<3-letter abbreviation>.[a-d].rawacf

For example, on 2019-02-01 the King Salmon radar (KSR) was operating simultaneously on two channels as seen from the file names 20190201.0401.00.ksr.a.rawacf and 20190201.0401.00.ksr.b.rawacf. Each file contains data from a different frequency channel.

Note

Sometimes modes like twofsound will write data into a single file. In this case the two frequencies are marked as two separate channels, denoted using the channel parameter. However, it is important to note that some SuperDARN radars have stereo capability (transmitting and receiving on 2 frequencies simultaneously), which was the original intended usage of the channel parameter.

Fields

RAWACF files contain a record that contains scalar and vector fields.

Scalars

Field name Units Data Type Description
radar.revision.major None char Major version number of the radar operating system
radar.revision.minor None char Minor version number of the radar operating system
origin.code None char Code indicating origin of the data (0 if generated at the radar)
origin.time None string Text indicating when the file was generated
origin.command None string Command line routine used to generate the file
cp None short Control program identifier
stid None short Station identifier
time.yr None short Year
time.mo None short Month number (not padded)
time.dy None short Day (not padded)
time.hr hrs short Hour
time.mt min short Minute
time.sc s short Seconds
time.us us int Micro-seconds
txpow kW short Transmitted power
nave None short Number of pulse sequences transmitted
atten None short Attenuation level
lagfr us short Lag to first range
smsep us short Sample separation
ercod None short Error Code
stat.agc None short Automatic gain control status word
stat.lopwr None short Low power status word
noise.search None float Calculated noise from clear frequency search
noise.mean None float Average noise from clear frequency band
channel None short Channel number, used to denote different Tx/Rx channels on Stereo radars, and to denote changes in radar operating parameters between scans, e.g. alternating between 2 frequencies scan-to-scan
bmnum None short Beam number, zero based indexing
bmazm degrees float Beam azimuth
scan None short Scan flag, switches between 0 to +/-1. For some radars, the sign indicates scan direction.
offset us short Offset between channels for a stereo radar
rxrise us short Receiver rise time
intt.sc s short Number of seconds of integration time
intt.us us int Number of microseconds of integration time
txpl us short Transmitted pulse length
mpinc us short Multi-pulse increment (lag separation)
mppul None short Number of pulses in the sequence
mplgs None short Number of lags in the lag table
mplgexs None short Number of lags used for tauscan. This field originates from fitex algorithm and is not used in RAWACF file format.
ifmode None short A flag indicating that the receiver voltage samples were obtained by digitizing the signal at an intermediate frequency (and then digitally mixed to baseband) instead of directly sampling the RF signals (ifmode=0).
nrang None short Number of range gates
frang km short Distance to the first range gate
rsep km short Range separation
xcf None short XCF flag, indicating whether the power, velocity, spectral width and phi0 parameters fitted from the cross-correlation function are available (xcf=1) or not available (xcf=0)
tfreq kHz short Transmitted frequency
mxpwr dB int Maximum power
lvmax None int Maximum noise level allowed
combf None string Comment buffer, usually contains the control program name
rawacf.revision.major None int Major version number of the RAWACF algorithm
rawacf.revision.minor None int Minor version number of the RAWACF algorithm
thr None float Threshold factor

Vectors

Note

slist contains the range gates that obtained data points during the integration period of the beam.

Field name Units Dimensionality Data Type Description
ptab None [mppul] short Pulse table, showing when pulses are transmitted as integer multiples of mpinc/smsep
ltab None [mplgs+1][2] short Lag table, showing which pulses to use to estimate each lag
pwr0 None [nrang] float Lag zero power, estimated from voltage samples (not fitted)
slist None [0-nrang] short List of range gates with ACF/XCF data available
acfd None [2][mplgs][0-nrang] float Calculated ACFs
xcfd None [2][mplgs][0-nrang] float Calculated XCFs

File structure

RAWACF files contain typically 2 hours of data. Individual records in the RAWACF file contain the raw data for a single integration period (usually 3s or 7s, but depends on operating mode of the radar). In the standard operational mode (common mode) where each beam is scanned sequentially, the beam number bmnum will increase or decrease by 1 after each integration period. Other control programs may involve different beam sequences, including sampling the beams in a different order, or sampling a subset of the available beams. A "scan" is a beam sequence which gets repeated. In the common mode (normal scan), one scan is completed when each beam has been sampled sequentially from 0 to bmnum-1 (or bmnum-1 to 0). Radars with more than 16 beams may sample a subset of beams rather than their full field of view in order to maintain a 1min scan time. Scans usually begin on whole-minute boundaries and last for either 1min or 2min. Custom control programs which define different scan lengths may also exist. The scan flag is used to indicate the beginning of each scan pattern. A value of 1 or -1 indicates the beginning of the scan, and then the value changes to 0 for the rest of the scan. When the scan value changes from 0 back to 1 this indicates the end of the scan.

Note

Different control programs in general have different beam patterns; cp will indicate the control program numerical value, and combf sometimes contains the control program's command/name.