TIMTER™ Multi-mode Digital Telemetry Transmitter
82
Quasonix, Inc.
6.7 Modulated RF Power Spectrum
The transmitter’s modulated spectrum complies with the IRIG-106 PSD mask:
M (dBc) = Max ( {K
– 100 log |f – f
c
| + 90 log (R)}, {-(55 + 10 log (P))} ), |f
– f
c
|
≥ R/m where
M
=
power relative to unmodulated carrier (i.e., units of dBc) at frequency f (MHz)
f
=
frequency in MHz
f
c
=
the carrier frequency in MHz
R
=
the bit rate in Mb/s
P
=
the rated power output of the UUT, in Watts
and the values of K and m are as tabulated in Table 19.
Table 19: K and m Values per Waveform
K
m
PCM/FM, Tier 0
-28
2
SOQPSK TG, Tier I
-61
4
MULTI-h CPM, Tier II
-73
4
As noted in the equation above, the mask has a floor at –(55 + 10 log(P)) dBc, and the mask imposes no limit on the
spectrum for frequency offsets less than R/m. Representative examples of the transmitted spectrum, with the
appropriate mask, are shown in Figure 24, Figure 25, and Figure 26.
