UNIT 17 in GEODYN IIS is used as input for the simulated data capability where observations are to be created not from real data replacement with computed observations but from generation of simulated tracking data according to the users instructions. These instructions are to be supplied in UNIT 17 as a set of input cards containing information about measurement types, station/satellite configuration, times and various other limitations. The same information may be specified on UNIT 05 instead, right after the ARC OPTION SIMDAT card. Information on UNIT 05 overrides information on UNIT 17. Data created using this capability after being checked for visibility will be output on UNIT 20 in the internal GEODYN II format and therefore they can be reintroduced later into GEODYN IIS as if they were real data.
The simulated data generation capability is introduced by including a SIMDAT card in the ARC section of UNIT 05. The ARC OPTION SIMDAT card must have a 1 on column 8, otherwise simulated data will be generated by replacing real observations with the computed ones.
The input cards in UNIT 17 (or UNIT 05) must begin with a SIMDAT card. This card is NOT the same as the ARC OPTION SIMDAT card. Its presence requests simulated data generation according to the specifications that follow. The cards which can be included on UNIT 17 are the following:
SIMDAT
SIMLIM
SIMSAT .
SIMSTA . These cards are called the simulated
SIMTYP . data configuration group.
SIMTIM .
ENDCON .
ENDSIM
The sequence of the input cards is as given above. The SIMDAT card is mandatory. The SIMLIM card introduces certain limitations for the blocks of data to be generated.
The simulated data configuration group describes in five cards elements and scheduling information for the simulation. These cards are described individually in the next chapter. The last card in this group is the ENDCON card and denotes the end of this particular configuration.
The user may include as many simulated data configuration groups as desired. Finally the ENDSIM card denotes the end of the simulated data generation input.
A detailed description of all the cards on UNIT 17 is given in Section 2.6 right after the SIMDAT arc option card and right before the SOLRAD arc option card.