IQDat files
IQDat files are a level-zero type data product that reflect the ADC voltages sampled at the radar site.
Naming Convention
The community standard for naming IQDAT files is:
YYYYMMDD.HH.mm.ss.<3-letter radar code>.[a-d].iqdat
The field [a-d] is used when the data have been separated into multiple files based on a particular operating parameter (e.g. frequency, beam pattern, control program). This field may not be used if all the available data are provided in a single file.
Fields
IQDat files are composed of records that contain 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. |
| origin.time | None | string | ASCII representation of when the data was generated. |
| origin.command | None | string | The command line or control program used to generate the data. |
| 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 | Second. |
| time.us | μs | short | Microseconds |
| txpow | kW | short | Transmitted power |
| nave | None | short | Number of pulse sequences transmitted. |
| atten | None | short | Attenuation level. |
| lagfr | μs | short | Lag to first range |
| smsep | μs | 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 across 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 frequency bands scan-to-scan |
| bmnum | None | short | Beam number, zero based indexing |
| bmazm | degrees | float | Beam azimuth |
| scan | None | short | Scan flag. |
| offset | None | short | Offset between channels for a stereo radar (zero for all others). |
| rxrise | μs | short | Receiver rise time. |
| intt.sc | s | short | Whole number of seconds of integration time. |
| intt.us | μs | short | Fractional number of microseconds of integration time. |
| txpl | μs | short | Transmit pulse length. |
| mpinc | μs | short | Multi-pulse increment. |
| mppul | None | short | Number of pulses in sequence. |
| mplgs | None | short | Number of lags in sequence. |
| mplgexs | None | short | Number of lags used for tauscan. This field is stored for fit-level processing. |
| 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 ranges. |
| frang | km | short | Distance to first range. |
| rsep | rsep | short | Range separation. |
| xcf | *None | short | XCF flag. |
| tfreq | kHz | short | Transmitted frequency. |
| mxpwr | dB | int | Maximum power. |
| lvmax | None | int | Maximum noise level allowed. |
| iqdata.revision.major | None | int | Major version number of the iqdata library. |
| iqdata.revision.minor | None | int | Minor version number of the iqdata library. |
| combf | None | string | Comment buffer. |
| seqnum | None | int | Number of pulse sequences transmitted. |
| chnnum | None | int | Number of channels sampled (both I and Q quadrature samples). |
| smpnum | None | int | Number of samples taken per sequence. |
| skpnum | None | int | Number of samples to skip before the first valid sample. |
Arrays
| Field name | Units | Dimensionality | Data Type | Description |
|---|---|---|---|---|
| ptab | None | [mppul] | short | Pulse table. |
| ltab | None | [2,mplgs] | short | Lag table. |
| tsc | s | [seqnum] | int | Seconds component of time past epoch of pulse sequence. |
| tus | μs | [seqnum] | int | Microsecond component of time past epoch of pulse sequence. |
| tatten | None | [seqnum] | short | Attenuator setting for each pulse sequence. |
| tnoise | None | [seqnum] | float | Noise value for each pulse sequence. |
| toff | None | [seqnum] | int | Offset into the sample buffer for each pulse sequence. |
| tsze | None | [seqnum] | int | Number of words stored for this pulse sequence. |
| tbadtr | None | [seqnum] | int | |
| badtr | None | [2*mppul*seqnum] | int | |
| data | None | [totnum] | int | Array of raw I and Q samples. |
The extent of each dimension is determined by the radar operating parameters. For example a value of mppul of 7 would result in the array ptab[7].
The raw sample data is arranged in multiplexed I and Q sample order; so the first smpnum*2 samples are the interleaved I and Q values for the first pulse sequence. If more than one channel is samples, the next smpnum*2 samples represent the next channel. The total number of samples, totnum, is equal to 2*seqnum*chnnum*smpnum.