Computer Science – Performance
Scientific paper
Nov 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991sct..conf...75p&link_type=abstract
In NASA. Lewis Research Center, Space Communications Technology Conference: Onboard Processing and Switching p 75-81 (SEE N92-14
Computer Science
Performance
Bandwidth, Binary Data, Coding, Data Transmission, Phase Shift Keying, Viterbi Decoders, Bit Error Rate, Hubble Space Telescope, Modulation, Rates (Per Time), Signal Encoding, Transponders
Scientific paper
As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.
Costello Daniel J. Jr.
Pietrobon Steven S.
No associations
LandOfFree
A bandwidth efficient coding scheme for the Hubble Space Telescope does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A bandwidth efficient coding scheme for the Hubble Space Telescope, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A bandwidth efficient coding scheme for the Hubble Space Telescope will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1719252