3
rd
Generation Rack-
Mount RDMS™
35
Quasonix, Inc.
•
16-bit sync pattern (0xFAC4)
MSB first: 1111101011000100
•
16-bit ID word (format TBD)
•
16-bit DQM = min(round(-log10(LR) / 12 *
(2^16)), 2^16 -1)
16-bit unsigned integer, ranges from 0 to 65,535
Likelihood Ratio (LR) = BEP / (1-BEP)
Easily reversed:
LR = 10^(-12 * DQM / 2^16)
BEP = LR / (1 + LR)
Q is defined as the
“User’s DQM”:
Q = 12 * DQM / 65536
Represents the exponent of 10 in the LR,
which approximates the BEP
Examples:
Q = 3 BEP = 1E-3
Q = 7 BEP = 1E-7
BEP
LR
DQM
Q
0.5
1.00
0
0.00
1E-01 1.11111E-01
5211
0.95
1E-02 1.01010E-02 10899
2.00
1E-03 1.00100E-03 16382
3.00
1E-04 1.00010E-04 21845
4.00
1E-05 1.00001E-05 27307
5.00
1E-06 1.00000E-06 32768
6.00
1E-07 1.00000E-07 38229
7.00
1E-08 1.00000E-08 43691
8.00
1E-09 1.00000E-09 49152
9.00
1E-10 1.00000E-10 54613 10.00
1E-11 1.00000E-11 60075 11.00
1E-12 1.00000E-12 65535 12.00
Figure 39: DQE Format
Payload data is a user selectable length with a default of 4096 bits, unless block decoding is in use. In STC mode,
the default is 3200 bits. In SOQPSK/LDPC or STC/LDPC mode, the default is the selected LDPC block size. When
Reed-Solomon decoding is enabled, the default is 1024 bits.
With a payload data length of 4096 bits, the network bandwidth expansion is ~1%.
DQM accuracy is verified under various channel impairments including AWGN-static level, AWGN-dynamic level
(step response), dropouts, in-band and adjacent channel interference, phase noise, timing jitter, static multipath, and
dynamic multipath (similar to break frequency).
To change the DQE, press the Enter key on the front panel keypad when the parameter is highlighted on the Main
Menu. The parameter options are Enable or Disable. Toggle between options to select the desired state. The default
is Disabled.
Note:
When DQE is enabled, normal bit error rate measurements cannot be made on the output data stream.
