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A relational DBM uses related data fields (columns) to correlate information between tables. [5] For example, two tables, transaction_user and transaction_amount, would both contain the column "key", and keys between tables would match, making it easy to find both the user and the amount of a specific transaction if the key is known.
In model checking, a field of computer science, a difference bound matrix (DBM) is a data structure used to represent some convex polytopes called zones.This structure can be used to efficiently implement some geometrical operations over zones, such as testing emptyness, inclusion, equality, and computing the intersection and the sum of two zones.
The dBm is also dimensionless, [1] [2] but since it compares to a fixed reference value, the dBm rating is an absolute one. The dBm is not a part of the International System of Units (SI) and therefore is discouraged from use in documents or systems that adhere to SI units.
7 dBm tech: laser in a CD-ROM drive 5–10 × 10 −3: 7 dBm to 10 dBm tech: laser in a DVD player: 10 −2: centi-(cW) 7 × 10 −2: 18 dBm tech: antenna power in a typical consumer wireless router: 10 −1: deci-(dW) 1.2 × 10 −1: 21 dBm astro: total proton decay power of Earth, assuming the half life of protons to take on the value 10 35 ...
sdbm ("small dbm"), a public domain rewrite of dbm. It is a part of the standard distribution for Perl and is available as an external library for Ruby. [6] [7] qdbm ("Quick Database Manager"), a higher-performance dbm employing many of the same techniques as Tokyo/Kyoto Cabinet. Written by the same author before they moved on to the cabinets.
Examples. 100 dBμ or 100 mV/m: blanketing interference may occur on some receivers; 60 dBμ or 1.0 mV/m: frequently considered the edge of a radio station's protected area in North America; 40 dBμ or 0.1 mV/m: the minimum strength at which a station can be received with acceptable quality on most receivers
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A power level of 0 dBm corresponds to one milliwatt, and 1 dBm is one decibel greater (about 1.259 mW). In professional audio specifications, a popular unit is the dBu . This is relative to the root mean square voltage which delivers 1 mW (0 dBm) into a 600-ohm resistor, or √ 1 mW × 600 Ω ≈ 0.775 V RMS .