# [amsat-bb] Doppler and direction calculation?

n3wwn@futuretek.cx n3wwn at futuretek.cx
Tue Jan 9 15:10:35 PST 2007

```Hi!

I've been trying to find the answer to this question using Google, but
can't seem to find a complete answer.

How can I calculate the doppler shift and direction of travel of a
satellite accurately?

I have the following information based on the observation point:

Longitude
Latitude
Azimuth
Elevation
Range
Altitude
Velocity
Phase
Eclipse Depth
Squint Angle

For example (AO-27 - it's the first sat in my test keps):

Sat Lon = 82.58 W
Sat Lat = 27.10 S
Sat Az = 182.93
Sat El = -28.64
Sat Range = 7516.62 km
Sat Altitude = 799.74 km
Sat Velocity = 7.46 km/s
Sat Orbit Num = 69288
Sat Visibility = D
Sat Phase = 317.61
Sat Eclipse Depth = -62.93
Sat Squint = 360.00

I'd like to be be able to calculate the doppler for any satellite and any
frequency.

I'd also like to find out the direction of travel, relative to the
lat/lon coordinate system (90 if travelling east, 180 if south, 270 if
west, etc).

Can anyone help me out here with some equations or point me in the right
direction?!

Thanks!

73 de Rich N3WWN (FN00fh)

```