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Quasonix, Inc.
1.2.2.5
Telemetry Over IP
–
IP
The Telemetry Over IP (TMoIP) capability packages PCM payload data into IP packets at the receiver. The receiver
provides simultaneous PCM and network outputs with separate RJ-45 connectors for network control and data
output. UDP and TCP protocols are available.
A web based graphical user interface (GUI) provides end-to-end TMoIP configuration, control, and status. Network
Auto-Tune capability performs automatic measurement and compensation for uncertain or varying network delay
and jitter. PCM serial input channels support automatic bit rate detection and IP packet size auto-configuration.
Fully configurable network parameters include DSCP/DiffServ Quality of Service, IPv4/IPv6, MTU, link speed, etc.
Security features include integrated firewall with port blocking, password-authentication and user permissions,
encrypted management interface, audit logging, and support for IPv6.
Detailed operating instructions are located in section 14, Appendix H of this manual.
1.2.2.6
Viterbi Decoder (for Legacy PSK Only)
–
K7
The K7 option enables Viterbi decoding of a convolutionally encoded data stream, which converts it back to the
original (uncoded) source data stream.
Convolutional encoding is a form of legacy forward error correction. Like LDPC, it adds redundant information at
the transmitting end of a telemetry link and then uses that redundancy to detect and correct errors at the receiving
end of the link. Use of convolutional encoding requires a matching Viterbi decoder in the receiver to extract the
source data. The decoded data rate is half the encoded data rate. The receiver has two independent decoders, one for
in-
phase (“I”) data and one for quadrature (“Q”) data. For BPSK, only a single decoder is used. Each decoder is
compatible with the convolutional encoding described in the “Consultative Committee for Space Data Systems,
Recommendation for Space Data System Standards, TM Synchronization and Channel Coding, CCSDS 131.0-B-2,
Section 3.”
Viterbi decoding is used to decode constraint-length (K) 7, rate I 1/2, G2-inverted convolutional-encoded data.
The purpose and benefits of convolutional encoding are similar to LDPC. However, convolutional encoding requires
more bandwidth than all but the lowest-rate LDPC codes, and its error-correcting performance is inferior to LDPC.
Therefore, LDPC is the preferred forward error correction if possible.
The Viterbi Decoder control requires the K7 option, and the RDMS must be set to one of the following PSK modes:
BPSK, QPSK, AQPSK, AUQPSK, OQPSK, or UQPSK.
Viterbi decoding and Reed-Solomon decoding can be used together or separately.
