Using RDODDA : Dump of skymap source point information



In this exercise RDODDA will be used to extract to the output file "Sky.dat" the time (UT), Zenith, Azimuth; Range (km), Frequency (MHz), Amplitude (dB), Most Probable Amplitude (MPA), Least squares fit RMS error, Doppler Frequency shift (Hz) and line of sight velocity (m/s) information for each source detected and stored in the skymap file drift0.sky.


Computer generated responses are given in Red, the required typed inputs are given in black, Comments are preceded by // and are in green. The <function> qualifier specifies keyboard function keys, e.g.




Refers to the enter or return key

Refers to the escape key

Refers to the F1 key … etc…..


Remember before starting the program, delete any Sky.dat file that exists, or rename it for archiving the data set. Otherwise RDODDA will not allow you to overwrite this file and report an error if this file exists.

In the DOS (VM) window, or from the command line enter the following;



rdodda <Enter> // Start program

Enter path and file name.

drift0.sky <Enter> // enter filename containing skymap data

Specify Skymap=1, DDA.Vel=2, Q.C.=3 or

GDDA.Vel=4 ??

1 <Enter>

# of sources = 1, edit skymap file = 0, ??

0 <Enter>

Select ADEP = 1 or F.R.Bin = 2

2 <Enter>

Select Range=3 or Freq. #=4 or Frequency=5,

DATE=6, Single point=7, Az,Zen = 8,

Doppler = 9, Dump Src. Spectra = 10 ??

10 <Enter>

Select Time, Day and Year

e.g. DAY,YR


10,97 <Enter> // in this example looking at 10 January 1997 data

Select frequency LIMITS in MHz

Specify the Lower & Upper limit inclusive.

0,30 <Enter> // taking all frequencies possible

Select Group Range LIMITS in km

Specify the Lower & Upper limit inclusive.

0,700 <Enter> // taking all ranges possible

Select Source RMS error upper limit.

100 <Enter> // taking all RMS error values

Select Cleaning factor CL.

0 <Enter> // taking all sources detected

Select Max = 1 Normal = 2

2 <Enter> // taking normal skymap output

Select Time/Az/Zen = 1

Select Time/Lat/Long = 2

Select Alt./Lat/Long = 3

1 <Enter> // First 3 columns contain time, Azimuth and zenith

Stop - Program terminated.

Result :

The file Sky.dat will be generated with the following format.

TIME Zenith Azimuth Range km Freq. MHz ..etc..

20.1000 0.0 0.0 0.0

20.1000 0.0 0.0 0.0

20.1000 90.0000 209.3272 90.0000 ..

20.1000 85.2873 209.7805 90.0000 ..

20.1000 74.7964 209.4871 90.0000 ..

20.1000 90.0000 209.5778 90.0000 ..





Refers to decimal Universal Time



Refers to zenith angle of single source detected.



Refers to Azimuth angle of single source.


Range (km)

Refers to the group range of single source detected.


Freq. (MHz)

Refers to zenith angle of single source detected.


Amp. dB

Refers to spectral line amplitude of single source detected.



Refers to the most probable amplitude (used as a threshold to remove noise) statistically determined from all data in the specific frequency-range-polarization bin.



Refers to least squares RMS error of single source detected.



Doppler line frequency shift in Hz


LOS Vel.

Line of sight velocity in m/s

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