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# db() - Signal Processing

### Syntax

### Example

### Output / Return Value

### Limitations

### Alternatives / See Also

### Reference

dboutput = db(X) converts the elements of the vector or matrix X to decibels (dB). The elements of X are voltage measurements across a resistance of 1 ohm.dboutput = db(X,SignalType) specifies the signal type represented by the elements of X as 'voltage' or 'power'. The entries are not case sensitive. The default value is 'voltage'. For voltage measurements, the resistance defaults to 1 ohm. If you specify SignalType as 'power', the elements of X must be nonnegative.dboutput = db(X,R) specifies the resistance R for voltage measurements. You can specify a resistance only when the signal measurements are voltages.dboutput = db(X,'voltage',R) specifies the resistance R for voltage measurements. This syntax is equivalent to db(X,R).

dboutput = db(X)dboutput = db(X,SignalType)dboutput = db(X,R)dboutput = db(X,'voltage',R)

Decibels from Voltage and PowerOpen This Example Convert voltage to decibels. Assume that the resistance is 2 ohms. Compare the answer to the definition, . V = 1; R = 2; dboutput = db(V,2); compvoltage = [dboutput 10*log10(1/2)] compvoltage = -3.0103 -3.0103 Convert a vector of power measurements to decibels. Compare the answer to the result of using the definition.rng default X = abs(rand(10,1)); dboutput = db(X,'power'); comppower = [dboutput 10*log10(X)] comppower = -0.8899 -0.8899 -0.4297 -0.4297 -8.9624 -8.9624 -0.3935 -0.3935 -1.9904 -1.9904 -10.1082 -10.1082 -5.5518 -5.5518 -2.6211 -2.6211 -0.1886 -0.1886 -0.1552 -0.1552