Digital Communications with Phase 3D: Table 2


Phase 3D Downlink Margin

Downlink, 9600 baud FSK

Frequency, MHz                     436

Spacecraft

Transmitter power, dBm              43
Line Losses, dB                    0.7
Antenna Gain, dBic                  13

Path

Sat. Altitude, km                43800
Max. distance, km                49765
Polarization Loss, dB                0
Atmospheric Loss, dB               0.3

Ground Station

Isotropic Signal at Ground, dBm -134.1

Antenna Gain, dBic                  13
Sky Temperature, K                  50
Feedline Loss, dB                    1
Receiver NF, dB                    0.5
Bandwidth, kHz                      15
Data Rate, symbols/sec            9600
Receiver Noise Temperature, K    169.6
Receiver Noise Power, dBm       -134.5

User S/N, dB                      13.4

Link Margin                        9.9

The spacecraft antenna gain at 146 MHz is 10 dBic, at 2400 MHz it is 18 dBic.


Phase 3D Uplink Margin

Uplink, 9600 baud FSK

Frequency, MHz                          146   1270

Ground Station

Transmitter power, dBm                   40     40
Line Losses, dB                           1      1
Antenna Gain, dBic                       12     24

Path

Sat. Altitude, km                     43800  43800
Max. distance, km                     49765  49765
Polarization Loss, dB                     0      0
Atmospheric Loss, dB                      1    0.3

Spacecraft

Isotropic Signal at Spacecraft, dBm  -119.6 -125.7
Antenna Gain, dBic                       10     15
Sky Temperature, K                      300    300
Feedline Loss, dB                       0.7    0.7
Receiver NF, dB                           1      1
Bandwidth, kHz                           15     15
Data Rate, symbols/sec                 9600   9600
Receiver Noise Temperature, K         438.9  438.9
Receiver Noise Power, dBm            -130.4 -130.4

User S/N, dB                           20.8   19.7

Link Margin                             7.3    6.2

The 1270 ground antenna gain is for a 1 meter dish.


Data from Lyle Johnson, WA7GXD. Original article by Harold E. Price, NK6K (nk6k@amsat.org), published in QEX, The ARRL Experimenter's Exchange, February 1995. Hypertext conversion by and feedback to KB5MU.

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