Comtech EF Data MIDAS Version 4.X NMS Configuration User Manual
Page 142
MIDAS 4.X NMS Configuration, Rev. 6
A-10 Frequency
Translations
C
C
-
-
B
B
a
a
n
n
d
d
F
F
r
r
e
e
q
q
u
u
e
e
n
n
c
c
y
y
C
C
o
o
n
n
v
v
e
e
r
r
s
s
i
i
o
o
n
n
F
F
o
o
r
r
m
m
u
u
l
l
a
a
s
s
C-Band (with High Side Injection) follows similar frequency conversions as Ku- Band,
except for the following; the effect of the High Side Injection will invert the L-Band
spectrum in relation to the RF and IF spectrums. This means that the beginning of a
transponder will have a lower frequency than the end of the transponder at RF and IF,
but the opposite will be true at L-Band; the beginning will be a higher frequency than
the end of the transponder. The relationship between C-Band and L-Band frequencies is:
Downlink Factor -
Transponder RX
Center = L-band
5.150 GHz – 3.720 GHz = 1430 MHz
In order to convert an IF frequency to L-Band, the conversion factor is:
Conversion Factor =
Downlink Factor - Transponder RX Center + IF
(5150 MHz – 3720 MHz + 70 MHz)
Conversion Factor =
1500 MHz
To convert from L-band to IF, the formula is:
IF Freq =
Conversion Factor - L-band Freq
(1500 MHz –1430 MHz)
IF Freq =
70 MHz
A
A
n
n
E
E
x
x
a
a
m
m
p
p
l
l
e
e
C
C
-
-
B
B
a
a
n
n
d
d
C
C
a
a
r
r
r
r
i
i
e
e
r
r
The translation formulas above show the RX center frequencies of a 36 MHz transponder
at C-Band, L-band and IF. This establishes the reference points need when determining
how to set up the MIDAS system to manage the bandwidth that occupies a portion of a
transponder.
System Setup
For example, suppose you have 1.2 MHz on this transponder and that your C-Band RX
center frequency is 3.7285 GHz (
± 0.6 MHz). This example will use a 5.150 GHz C-Band
to L-Band LO (High Side Injection), 1.4 x symbol rate carrier spacing, and a 70 MHz IF.
Select System Administrator. Configure the Satellite and Transponder in the System Ad-