LRO Mini-RF PDS4 Bistatic Raw Data (BSEDR4)

BSEDR4 – PDS4 Bistatic Raw Data

PDS3 Data Set ID: LRO-L-MRFLRO-2/3/5-BISTATIC-V3.0DOI: 10.17189/1520653Citations of DOI: 10.17189/1520653

PDS4 Bundle:urn:nasa:pds:lro_minirf_bistaticDOI: 10.17189/c3ym-tk17

For more information about Bistatic raw data products, see the Mini-RF SAR Bistatic PDS Data Product Software Interface Specification.

The Mini-RF (MRFLRO) Bistatic Raw data collection (BSEDR4) contains the raw data products. These include the internal calibrations, the unencoded 12-bit burst engineering data, and the housekeeping raw data. There are six different types of raw data. A sequence of four, short internal calibrations are executed, then two normal monostatic-like collections are acquired with 12-bit samples (no BAQ encoding), followed by the 3-bit BAQ encoded receive only science collection, and lastly a repeat of the four internal calibrations. W hen flight constraints are a challenge to work around, the two normal monostatic-like engineering collections may not be acquired to shorten the observation. The last burst of each collection is rarely a complete set of pulses as specified by the pulses per b urst element of the commanded waveform. This has to do with how the data is packaged by the instrument and communicated to the spacecraft systems. The final package of data formed in the instrument is incomplete and thus dropped.

Receive Only Science Data - sciraw data

This is the standard science data that is processed into images and the higher-level products. In this mode the receiver is open and collecting data. The data are organized into a single burst of pulses or blocks of 8192 samples that are then encoded to fewer than the native 12-bits using the BAQ algorithm. Collects are typically long enough that the 16-bit unsigned pulse counter will roll over multiple times.

Normal 12-bit Engineering Data - eng data

This data is 12-bit, no BAQ encoding applied, data that is collected primarily to monitor the impact of the encoder on the collected signals. Typically, several minutes of this data is acquired just prior to the receive only science collection. While the instrument is operating in a normal monostatic like configuration, the transmitter is not radiating a signal in the transmit pulse windows.

There is no synchronization of the Mini-RF internal clock with that of the ground station. The pulses collected here are a drifting mix of noise, direct path, forward and back scatter signals from the surface.

Internal Calibration Data - caln, calc, calt, bitl data

There are four types of internal calibration data acquired just after activation and just prior to deactivation. These short, usually sub-second collections, are acquired using the aforementioned normal 12-bit engineering collection waveform parameters. The timing is slightly different because the transmitter is looped back into the receiver to monitor instrument performance. While the transmitter failed back in 2010, the signal generated by the electronics is still functional and valid for this purpose.

Chirp calibration data product (calc) captures the data from internal calibration modes where the transmitted chirp is looped back directly into the receiver. If the commanded waveform calls for noise pulses at the end of each burst, then the transmitted chirp is omitted for these pulses and noise is captured instead. In the bistatic configuration there are typically two noise pulses captured at the end of e very burst.

Tone calibration data product (calt) captures the data from another of the internal calibration modes where a transmitted tone is looped back directly into the receiver. This tone’s frequency is offset from the center frequency which is transferred to baseband. As with the other internal calibrations, if the waveform calls for noise pulses, then the transmitter is off for these last requested pulses within a burst. In the bistatic configuration this is typically the last two pulses at the end of a burst. The

Noise calibration data product (caln) collects noise both from a source and just from the receiver. Pulses are interleaved, starting with an injected signal from a Gaussian noise source followed by no source. Unlike the other internal calibration modes, if the waveform calls for noise pulses, they are collected in this mode; but the alternating sequence of noise source and no source is preserved.

Transmitter Bit Leak data peoduct (bitl) is designed to test leakage from the transmitter, and disables the RF inputs to the system. However, it is part of the standard concept of operations, so the data are included for completeness. If the waveform calls for noise pulses, the transmitter is disabled for those pulses. A s is typical with the bistatic waveforms used, two noise pulses are called for and included in the data.

The sciraw, eng, and the four internal calibration products described previously all use the same common raw data format. This format consists of a fixed-width binary table where each record contains information at a given burst and pulse within that burst. Metadata parameters defining the characteristics of the raw data collection are stored in mission dictionary keywords in the PDS4 label. Note that while the same binary format is used by the raw data products, the number of samples N per pulse will vary between products, therefore the number of fields in the binary table will vary between products. The number of samples per pulse is also stored in a keyword in the PDS4 label (lro:samples_per_pulse).

MRFLRO BSEDR4 products have the following file names:

Mini-RF Bistatic science data products

lfm_yyyydoyhhmmss_<type>{c}_ppdqqq_Vv.ext (with detached PDS label)

Mini-RF Bistatic calibration and engineering data

lfm_yyyydoyhhmmss_<type>{C}_vV.ext (with detached PDS label)

where:

l = LRO

f= Frequency band

S = S-band

X = X-band

m = operational mode(T=bistatic, ground-based transmitter)

yyyydoyhhmmss = Time of data file start in UTC

yyyy = year

doy = day of year

hh = two digit hour of day

mm = two digit minutes of hour

ss = two digit seconds of minute

<type> = type of data file

For science data products

caln = internal noise calibration

calt = internal tone calibration

calc = internal chirp calibration

bitl = internal transmitter bit leak calibration

eng = 12-bit, unencoded, engineering collection

hskraw = raw, DN-valued housekeeping status telemetry

hskcal = calibrated to engineering units housekeeping status telemetry

For calibration and engineering data

sciraw = unprocessed receiver time series data (raw)

scip = receiver processed into an image (calibrated)

s1 - s4: derived Stokes parameters (derived)

cpr = circular polarization ratio (derived)

ddr= derived geometry and timing data formatted as image backplanes (derived)

{C} = Receiver channel

For science data products This is only for sciraw and scip data types (raw and calibrated science data)

For calibration and engineering dataThis is for all products other than hskraw and hskcal (housekeeping data is not attributed to a specific receiver channel)

h = H-channel

v = V-channel

pp = reference latitude of the map projection to the nearest whole degree. range: 00-90

d = hemisphere of reference latitude. "n" northern hemisphere, "s" southern hemisphere

qqq = reference longitude of the map projection to the nearest whole degree. range: 000-359

v = hardcoded character

V = integer indicating the version of the PDS4 data product. Initial versions start at 1. Version is incremented by 1 for previously delivered products that are redelivered to PDS.

ext = the file extension

dat = binary table files

xml = PDS4 XML labels

img = binary image files

In ODE, BSEDR4 products have the following product ID:

LFM_YYYYDOYHHMMSS_<type>{C}_PPDQQQ_vV for science data products

LFM_YYYYDOYHHMMSS_<type>{C}_vV for calibration and engineering data