Dynamic Data Exchange (DDE) Specifications for Nova for Windows

Nova for Windows can act as a DDE server. The program can supply satellite
tracking and range-rate data to any standard DDE client application; this
information may be used to implement customized interfaces for antenna tracking
or radio tuning.

Following are general specification for DDE as implemented in NfW. Note that all
names and strings are case sensitive.

DDE Server name : NFW_SERVER
DDE conversation : NFW_DATA

DDE is activated when the server (NfW) receives the string 'TUNE ON'.

The AutoTracking Status Box must be displayed in NfW although autotracking does
not have to be activated. The status box is displayed if any interface is
selected from Setup/Antenna rotator.

When DDE has been activated, a single string containing the following data is
"transmitted" 2-10 times per second (depending on CPU speed and loading) via

SatName AZ:Azimuth EL:Elevation RR:RangeRate AH:x

SatName = the current autotracking satellite name as derived from the NfW
database, maximum 12 characters;
Azimuth = current satellite azimuth, 0.1 degree precision, no sign;
Elevation = current satellite elevation, 0.1 degree precision, signed;
RangeRate = satellite rate of change of distance from the observer
expressed as a signed floating point number in units of
1/the speed of light.
AH = indicates whether the satellite is above the horizon.
Possible values are Y and N. NOTE: This indication is in
reference to the horizon table associated with the AutoTracking
Observer. See AutoTracking/AutoTracking Observer from the Main
Menu to fill in the horizon table. If the horizon table is not
filled in, a horizon of 0 degrees is assumed.

One space separates each field; no space after (:) labels. Make no assumptions
about field lengths or total string length. Values are referred to the current
AutoTracking Observer in NfW at the current UTC time and date.

Sample DDE string:
Mir AZ:116.4 EL:-21.0 RR:-1.4396996895 AH:N

To find Doppler shift from Range Rate,
DopplerHz = -FreqHz * RR * (1.0/299792.458)

Additions 4-10-01

Autotracking in Nova for Windows can be controlled from a DDE client. Forcing
the DDE string by the client (in Delphi, this is with the command "PokeData")
affects Nova in the following way:

TUNE ON turns DDE output on
TUNE OFF turns DDE output off
TRACK ON turns autotracking on
TRACK OFF turns autotracking off
SAT=* sets the AutoTracking satellite.
*=the desired satellite catalog number
ANTAZ=xxx.xx tell Nova the current antenna Az/El

Diagnostic displays of incoming and outgoing DDE strings are available by
pressing the F1(outgoing) or F3(incoming) keys.

M.R. Owen
Northern Lights Software Associates