DRAFT RECOMMENDATIONS FOR SPACE
DATA SYSTEM STANDARDS
RADIO FREQUENCY AND
MODULATION SYSTEMS—
PART 1
EARTH STATIONS AND SPACECRAFT
CCSDS 401.0-BP
BLUE BOOKPINK SHEETS
April 2002
DRAFT CCSDS RECOMMENDATIONS FOR RADIO FREQUENCY AND MODULATION SYSTEMS
Earth Stations and Spacecraft
CCSDS 401 (2.4.3) B-1P-1.1
Page 2.4.3-1
January 1987April 2002
2.4.3
SUBCARRIERS IN LOW BIT RATE RESIDUAL CARRIER TELEMETRY
SYSTEMS
The CCSDS,
considering
(a)
that at low bit rates, interaction between data sidebands and the residual RF carrier causes a
performance degradation;
(b)
that subcarrier modulation schemes eliminate interaction between data sidebands and the residual
RF carrier but are bandwidth-inefficient;
(c)
that some space agencies presently utilize ranging systems whose minor tones are below 20 kHz
and whose major tone is 100 kHz, while others are planning to do so in the near future;
(c)
that PSK modulation is a very efficient type of digital modulation because of its bit error
performance;
(d)
that simultaneous ranging and telemetry operation should be possible;
(d)
that for Category A missions, it is more important to limit the occupied bandwidth while for
Category B missions, it is more important to minimize the susceptibility to in-band interference.
recommends
(1)
that CCSDS agencies use subcarriers with their residual carrier systems when transmitting low
bit rates;
(2)
that the subcarrier be placed between the 20 kHz and 100 kHz ranging tones, or above the
100 kHz tone.
(1)
that CCSDS agencies limit the use of subcarriers to cases justified by technical reasons, i.e., low
bit rate transmissions or radio science;
(2)
that CCSDS agencies use PSK modulation for these subcarriers;
(3)
that for Category A missions telemetry transmission, CCSDS agencies use sine wave
subcarriers;
(4)
that for Category B missions telemetry transmission, CCSDS agencies use square wave
subcarriers.
DRAFT CCS