Pioneer 10 Doppler tracking data Data Directories: Compiled and processed by Slava Turyshev, John Anderson, and Craig Watkins. The Pioneer 10 and Pioneer 11 Doppler data sets provided here are in ASCII text format, derived from NAVIO format. See Both data sets provide a substantial number of 60 second interval Doppler data. An example record is provided below, coupled with basic guidance on what the key parameters are: RECORD NUMBER =967245 TIMETAG = 5-OCT-1990 11:41:30.0000 DTYPE = 13 DNLINK= 1 NET = 1 TRANS = 14 RCVR1 = 43 RCVR2 = 0 SC = 24 QUASAR= 0 LOCOMP= 0 HICOMP= 0 CAMERA= 0 UPLINK= 1 CHANEL= 0 WBMODE= 0 MODFLG= 0 SOBJSG= 0 SOBJID= 0 VALID = 0 PICTUR= 0 UPRCVR= 1 RERAMP= 0 VLBIFG= 0 RFQTYP= 1 DPLCNL= 0 ODFMT = 4 TIMTAG=-2.916011100000000E+08 OBSVBL= 5.964832813833340E+05 FREQCY= 2.111177280000000E+09 CMPTIM= 6.000000000000000E+01 MOD = 0.0 TA4RNG= 0.0 TB4RNG= 0.0 DDELAY= 0.0 TRAXAZ= 0.0 UDELAY= 0.0 Depending on the approach/coding language used to read this data, the lack of whitespace between the equals sign and parameters, such where negative parameters are present, or for the larger record numbers, may cause difficulty in parsing the records. A recommended approach is a pre-processing step of search and replace to insert an extra white-space character. DTYPE is the Doppler type, with 13 being “3 way” Doppler, or that sent and received by different DSN stations, and 12 being two-way Doppler sent and received by the same DSN station. SC identifies the spacecraft. Spacecraft 23 is Pioneer 10, and spacecraft 24 is Pioneer 11. CMPTIM is the “compression” time, or the integration interval for the Doppler data. In the above example the data point represents 60 seconds of data capture. ++++ Apparent Ku band data Both the Pioneer 10 and Pioneer 11 data sets include significant data captures with a reference frequency that appears to be within the Ku band at approximately 15 GHz. This enigma is able to be unwrapped due to the existence within the Pioneer 10 data set of multiple overlapping data sets, some with the peculiar, apparently Ku band, reference frequency, and some with the regular S band reference frequency recorded. (The “reference frequency” is labelled FREQCY within the text file data records, as per the above record example.) Although it is not clear what rationale was used for the alternative recording of reference frequency, the apparently Ku band values can be directly converted to the correct S band frequency via: Reference_Frequency = (Recorded_Frequency + 7 GHz)*96/1000 ++++ Other Reference Frequency Peculiarities In some instances a single reference frequency value is clearly out-of-line with those immediately preceding or following, and can be identified and corrected with high reliability. A similar approach can be applied where there is a contiguous string of such incorrectly recorded reference frequencies. ++++ Incorrect recording of transmit station In some instances the incorrect recording of the transmit station is able to be determined with ease. In a minority of cases two Deep Space Network (DSN) receiving stations have overlapping Doppler data records, while displaying varied capture of the DSN transmit stations within the records. In other instances, the indicated transmit DSN station will not align with the station transmitting one round-trip light time prior, and using the presumed corrected transmitting station within an orbit determination will obtain a solid enough fit to provide confidence in the correction to the transmitting station. ++++ Values where Doppler counts have been misplaced A number of errors exist where Doppler counts have been added to the wrong data point, and are absent from the preceding or following data point. As the Doppler rate varies over time, it is not possible to accurately identify the contribution that would need to be subtracted from one data point and added to the other to correct. However, two treatments are possible short of discarding such data points entirely. One is combining the two points to form a single data point covering twice the time interval. The second is more complex, but potentially of interest to some investigations. The time intervals and central data point recording time can be adjusted. This is possible due to the fact that we can relatively safely assume that Doppler counts missed from one data point and appearing in another data point all appear as a contiguous group of counts at the 0.1 second primary count interval, and lie on the boundary between the two data points. Determining the (usually small) number of 0.1 second intervals to adjust by is a simple calculation based on the magnitude of the deviation seen. Other isolated errors are unlikely to be recoverable in any way, and must necessarily lead to elimination of the data point. ++++ Values where Doppler counts are in error by exactly 500,000 A small number of Doppler counts are higher or lower than they potentially should be by a fixed amount of exactly 500,000. These errors are easily identified and corrected. ++++ Mixing of spin calibrated and non-spin calibrated data It appears that some data within at least the large Pioneer 10 data set is spin-adjusted, while other data is not. The spin calibration offset value of approximately 0.16 Hz in the Pioneer 10 case, is theoretically detectable and hence correctable, even with diurnal fluctuation concerns. ++++ Incorrect capture of Observable high part A peculiarity occurs across both Pioneer 10 and 11 Doppler data sets, with some recorded data showing errors of multiples of 1000 Hz. This problem is particularly prevalent in early parts of the Pioneer 10 data set. It is often clear from the lower frequency component that a good data capture has been present when the signal was received by the relevant DSN station. However, at some point data has been corrupted. Lower percentages of corrupted data may be recoverable by reference to the predominant data, but the same approach is unlikely to succeed where the corruption is extensive. Please acknowledge the NASA Space Physics Data Facility for data usage.