SimTX API/Packets/EphemerisResponse

EphemerisResponse

Frame	ServerFrame, field 40
Member	ephemeris
Direction	Server → client
Session	Control
Roles	ROLE_CONTROL.
Permission	None
Answered by
Answers	EphemerisRequest
Defined in	control.proto

EphemerisResponse returns the satellite positions requested by an EphemerisRequest. Failures arrive as Error.

Definition

message EphemerisResponse {
  reserved 4;
  int64 request_id = 1;
  bytes station_id = 2;
  repeated EphemerisSample samples = 3;
}

Fields

#	Field	Type	Description
1	request_id	int64	The request this answers.
2	station_id	bytes	The satellite.
3	samples	repeated EphemerisSample	Samples from from_ms to to_ms every step_seconds.

Field number 4 is reserved; do not use it.

EphemerisSample

message EphemerisSample {
  int64 t_ms = 1;
  double latitude_deg = 2;
  double longitude_deg = 3;
  double altitude_meters = 4;
  double x = 5;                // ECEF metres (6371 km sphere)
  double y = 6;
  double z = 7;
}

#	Field	Type	Description
1	t_ms	int64	Sample time, Unix ms.
2	latitude_deg	double	Sub-satellite latitude, degrees.
3	longitude_deg	double	Sub-satellite longitude, degrees.
4	altitude_meters	double	Height above the 6,371 km sphere, metres.
5	x	double	Earth-fixed (ECEF) position, metres, on the 6,371 km sphere model.
6	y	double	ECEF y, metres.
7	z	double	ECEF z, metres.

Example

Complete frames, including the varint length prefix.

ephemeris_response (server to client, 152 bytes):

96 01                           frame length 150
C2 02 92 01                     ephemeris (EphemerisResponse), 146 bytes
  08 15                         request_id = 21
  12 10 99 99 99 99 …           station_id = 99999999-8888-4777-8666-555555555555
  1A 3D                         samples (EphemerisSample), 61 bytes
    08 80 94 83 B9 97 34        t_ms = 1793000000000
    11 00 00 00 00 00 00 24 40  latitude_deg = 10.0
    19 00 00 00 00 00 00 34 40  longitude_deg = 20.0
    21 00 00 00 00 E0 C8 20 41  altitude_meters = 550000.0
    29 00 00 00 00 70 8D 56 41  x = 5912000.0
    31 00 00 00 00 2C 69 40 41  y = 2151000.0
    39 00 00 00 00 50 57 32 41  z = 1202000.0
  1A 3D                         samples (EphemerisSample), 61 bytes
    08 B0 FE 84 B9 97 34        t_ms = 1793000030000
    11 9A 99 99 99 99 99 27 40  latitude_deg = 11.8
    19 66 66 66 66 66 66 34 40  longitude_deg = 20.4
    21 00 00 00 00 A8 C9 20 41  altitude_meters = 550100.0
    29 00 00 00 00 E4 50 56 41  x = 5850000.0
    31 00 00 00 00 C0 7A 40 41  y = 2160000.0
    39 00 00 00 00 A8 60 35 41  z = 1401000.0

See also

• EphemerisRequest
• SimTX API/Satellites