Partial Response Maximum Likelihood


Also found in: Acronyms.

Partial Response Maximum Likelihood

(storage)
(PRML) A method for converting the weak analog signal from the head of a magnetic disk drive into a digital signal. PRML attempts to correctly interpret even small changes in the analog signal, whereas peak detection relies on fixed thresholds. Because PRML can correctly decode a weaker signal it allows higher density recording.

For example, PRML would read the magnetic flux density pattern 70, 60, 55, 60, 70 as binary "101", and the same for 45, 40, 30, 40, 45. A peak detector would decode everything above, say, 50 as high, and below 50 as low, so the first pattern would read "111" and the second as "000".
References in periodicals archive ?
9384 4-Channel 1GHz DSO; 4 GS/s Max, with 400k Memory $19,490 9384M 4-Channel 1GHz DSO; 4 GS/s Max, with 2M Memory $22,490 9384TM 4-Channel 1GHz DSO; 4 GS/s Max, with 2M Memory $24,990 9384L 4-Channel 1GHz DSO; 4 GS/s Max, with 4M Memory $28,990 93XX-WP01 Waveform Math Option $1,250* 93XX-WP02 FFT Processing Option $1,250* 93XX-WP03 Statistical Analysis Package $1,250 93XX-DDM Disk Drive Measurement Package $3,000 93XX-PRML Partial Response Maximum Likelihood Analysis $1,250 93XX-ORM Optical Recording Measurements $2,250 93XX-HD01 Hard Disk Adapter $590 93XX-HD02 PCMCIA Hard Disk 170MByte $499 93XX-HDD Hard Disk Adapter and 170 Mbyte Drive $990 93XX-MC01/04 Memory Card and Reader Option $500 93XX-FD01 3.
These include Pivoting Optical Servo (POS) that eliminates the need for pre-formatted tape; Magneto-Resistive Cluster heads (MRC) and new high-efficiency Partial Response Maximum Likelihood (PRML) channel that deliver higher data-transfer rates and capacity; Advanced Metal Powder (AMP) media for extremely high data densities; and Positive Engagement, a robust tape-leader-buckling mechanism for high-duty-cycle automated environments.
Marvell's 88E3061 Hex and 88E3081 Octal Fast Ethernet transceivers leverage technology developed through Marvell's first generation Physical Layer (PHY) transceivers as well as through its family of Alaska Gigabit Ethernet transceiver products and four generations of Partial Response Maximum Likelihood (PRML) read channels designed for the data storage market.
The EIM houses another key feature: the Advanced Partial Response Maximum Likelihood (PRML) channel.
This is accomplished by achieving rate efficiency of greater than 99 percent, making it one of the most efficient Partial Response Maximum Likelihood (PRML) implementations ever developed.

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