The term bandwidth as oppossed to frequency.

B

Beano

Guest
I understand the term 'Bandwidth' when used to refer to a range of
frequencies, eg Fmin to Fmax.
But I often hear the term used in place of 'frequency' and I wonder if
and when this should be done.
e.g. Should I refer to an oscilloscopes 'maximum frequency', or to
'it's bandwidth'.
So when should I use bandwidth and when should I use frequency?
 
When referring to oscilloscopes (and virtually all general test
equipment including sprectrum analyzers, logic anlyzers etc) the term
bandwidth has a very specific meaning and indeed is by far the most
commonly used term.
Although the manufacturer will state what it is, the most common
definition is where the gain response of the instrument is at -3dB.
Instrument bandwidth is used, but so is the term 'effective frequency
range' on some older equipment. Note this carefully - it means you
can't measure a 100MHz signal with a 100MHz (bandwidth of DC to 100MHz)
scope and expect accurate results (to say nothing of the fact you need
special probes at that frequency anyway).

I use the term 'frequency' (personally - there are many variants, and
it can start a holy war) for those occasions I have a specific
frequency or set of frequencies in mind. That said one might inquire as
to the frequency range of a signal or the (for instance) transmitted
bandwidth of some other signal. In such cases, the two terms are
interchangeable.

Other times I personally use the term frequency is when I have a known
set of discrete frequencies. In this case, I would refer to the set as
a set of frequencies spanning a range (or bandwidth).

Much of what you ask is down to personal choice, though. As you can
see, sometimes there is no difference, but generally the term bandwidth
is used for contiguous frequency ranges as it is a single word solution
to the opposing 'range of frequencies'.

Cheers

PeteS
 
OK, I'm going to attempt to answer my own question above.
Witout getting too finicky, 'frequency' should apply to a signal, and
'bandwidth' to a medium. Any better offers?
 

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