IEEE Aerospace and Electronic Systems Magazine - July 2020 - 13
Davarian et al.
Figure 2.
Uplink data rate as a function of range.
A NOTE ON KA-BAND LINK PERFORMANCE
EMERGENCY MODE
In the above section, spacecraft-to-Earth Ka-band link
performance was evaluated at a low elevation angle of 20
that exaggerates atmospheric-related losses (X-band is
less susceptible to losses resulting from propagation
through the atmosphere than Ka-band). This assumption
coupled with other presumed losses, such as circuit,
antenna pointing, etc., may present a conservative picture
of Ka-band performance for mission planners who need to
decide between Ka- or X-band for their mission. Empirical
data based on the long-term observations of deep space
Ka-band links of Cassini and Kepler missions were analyzed to provide a performance estimate for mission planners and designers [1]. The resulting model not only
accounts for weather, it also includes other link losses that
are difficult to identify. Therefore, at the onset of mission
planning, it may be beneficial to apply the model provided
in [1] to evaluate the utility of Ka-band for the mission
of interest.
Emergency mode communications uses the X-band to avoid
weather-related losses, and assumes a low-gain antenna
onboard the spacecraft to prevent the need for accurate
pointing while in emergency. In this study, it is assumed that
the emergency mode rate is 10 b/s. Figure 3 shows the downlink margin in emergency mode as a function of range;
assumptions for the link are shown in Table 7. Similar to the
previous two figures, a number of targets have been shown
Table 6.
Assumptions for Figure 2
Spacecraft
CubeSat
MicroSat
Receive antenna gain
28.5 dBi
38.5
Noise figure
3 dB
3 dB
Elevation
20
20
DSN antenna
34 m
34 m
Weather
90%
90%
Command mod
index
1.5 rad
1.5 rad
Command data rate
Variable
Variable
Frequency
7150 MHz
7150 MHz
Modulation
BPSK
BPSK
Coding
Uncoded
Uncoded
Ground
UPLINK (EARTH TO SPACECRAFT)
Because the DSN antennas are very powerful transmitters,
the uplink scenario for SmallSats is more promising than
the downlink. Figure 2 illustrates uplink data rate values
of CubeSats and MicroSats as a function of distance;
assumptions for the link are shown in Table 6. It is
assumed that the uplink uses X-band to avoid weatherrelated losses associated with Ka-band. Color codes correspond to the same targets, as shown in Figure 1. SmallSats
can meet the requirement of 1 kb/s uplink data rate even
at Jovian distances. Therefore, the takeaway from this
chart is that SmallSats are not uplink limited.
JULY 2020
Link
IEEE A&E SYSTEMS MAGAZINE
13
IEEE Aerospace and Electronic Systems Magazine - July 2020
Table of Contents for the Digital Edition of IEEE Aerospace and Electronic Systems Magazine - July 2020
Contents
IEEE Aerospace and Electronic Systems Magazine - July 2020 - Cover1
IEEE Aerospace and Electronic Systems Magazine - July 2020 - Cover2
IEEE Aerospace and Electronic Systems Magazine - July 2020 - Contents
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 2
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 3
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 4
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 5
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 6
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 7
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 8
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 9
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 10
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 11
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 12
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 13
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 14
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 15
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 16
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 17
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 18
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 19
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 20
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 21
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 22
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 23
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 24
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 25
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 26
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 27
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 28
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 29
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 30
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 31
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 32
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 33
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 34
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 35
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 36
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 37
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 38
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 39
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 40
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 41
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 42
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 43
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 44
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 45
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 46
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 47
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 48
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 49
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 50
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 51
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 52
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 53
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 54
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 55
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 56
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 57
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 58
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 59
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 60
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 61
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 62
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 63
IEEE Aerospace and Electronic Systems Magazine - July 2020 - 64
IEEE Aerospace and Electronic Systems Magazine - July 2020 - Cover3
IEEE Aerospace and Electronic Systems Magazine - July 2020 - Cover4
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_july2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_june2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_april2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_february2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_january2023
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_july2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_june2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2022_tutorial
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_april2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_february2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_january2022
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_july2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_june2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_april2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2021_tutorials
https://www.nxtbook.com/nxtbooks/ieee/aerospace_february2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_january2021
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_july2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_june2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_april2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_february2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_january2020
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2019partII
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_july2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_june2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_april2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_may2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_march2019
https://www.nxtbook.com/nxtbooks/ieee/aerospace_december2018
https://www.nxtbook.com/nxtbooks/ieee/aerospace_august2018
https://www.nxtbook.com/nxtbooks/ieee/aerospace_october2018
https://www.nxtbook.com/nxtbooks/ieee/aerospace_september2018
https://www.nxtbook.com/nxtbooks/ieee/aerospace_november2018
https://www.nxtbookmedia.com