© Microhard Systems Inc.
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6.0 Configuration
Values
S158
FEC (Forward Error Correction) Mode
0 No FEC
1 Hamming (7,4)
2 Hamming (15,11)
3 Hamming (31,24)
5 Binary BCH (47,36)
6 Golay (23,12,7)
7 Reed-Solomon (15,11)
A number of FEC schemes are available with different coding rates.
FEC consumes some bandwidth: depending on which coding rate is chosen, a
number of coding bits are transmitted along with the ‘data’ bits.
In ‘noisy’ or long-range communications environments, FEC may effectively increase
throughput by decreasing the amount of packet retransmissions which would
otherwise be required.
Communications range may also be extended with the use of FEC: at a certain
distance where data would otherwise be unacceptably corrupted, employing FEC
may be all that is required to maintain the integrity of that data at that distance.
Types of FEC available within the Nano:
Hamming (7,4)
:
Information rate 0.5,
corrects 1 out of 7 bits
Hamming (15,11)
:
Information rate 0.66,
corrects 1 out of 15 bits
Hamming (31,24)
:
Information rate 0.75,
corrects 1 out of 31 bits
Binary BCH (47,36)
:
Information rate 0.75,
corrects 2 bits
Golay (23, 12, 7)
:
Information rate 0.5,
corrects 3 bits
Reed-Solomon (15,11) :
Information rate 0.687,
corrects 2 nibbles
If throughput is not of primary
concern and there is an
emphasis on providing the
most
robust
data
communications, FEC should
be considered.
