Some editors will put articles on their lists to which they have merely made a small contribution. All the articles and images shown here and on the linked lists have been created by me from scratch, or at most from an insignificant stub.
An original drawing by Zobel of a band-pass filter used for impedance matching.
Otto Julius Zobel (October 20, 1887 – January 1970) was a design engineer who worked for the
American Telephone & Telegraph Company (AT&T) in the early part of the 20th century. Zobel's work on filter design was revolutionary and led, in conjunction with the work of
John R. Carson, to significant commercial advances for AT&T in the field of
frequency division multiplex (FDM) telephone transmissions.
Zobel invented the
m-derived filter and the
constant-resistance filter, which remains in use today. With Carson he helped to establish the nature of noise in electric circuits, concluding that—contrary to mainstream belief—it is not even theoretically possible to filter out noise entirely and that noise will always be a limiting factor in what it is possible to transmit. Thus, they anticipated the later work of
Claude Shannon, who showed how the theoretical information rate of a channel is related to the noise of the channel.
Analogue
filters are a basic building block of
signal processing much used in
electronics. Amongst their many applications are the separation of an audio signal before application to
bass,
mid-range and
tweeterloudspeakers; the combining and later separation of multiple telephone conversations onto a single channel; the selection of a chosen
radio station in a
radio receiver and rejection of others.
Analogue filters have played an important part in the development of electronics. Especially in the field of
telecommunications, filters have been of crucial importance in a number of technological breakthroughs and have been the source of enormous profits for telecommunications companies. It should come as no surprise, therefore, that the early development of filters was intimately connected with
transmission lines. Transmission line theory gave rise to filter theory, which initially took a very similar form, and the main application of filters was for use on telecommunication transmission lines. However, the arrival of
network synthesis techniques greatly enhanced the degree of control of the designer.
BBC engineers equalising audio landlines circa 1959 using adjustable Zobel networks
Zobel networks are a type of
filter section based on the
image impedance design principle. They are named after
Otto Zobel of
Bell Labs who published a much referenced paper on image filters in 1923. The distinguishing feature of Zobel networks is that the input impedance is fixed in the design independently of the transfer function. This characteristic is achieved at the expense of a much higher component count compared to other types of filter sections.
Zobel networks were formerly widely used in telecommunications to flatten and widen the frequency response of copper land lines, producing a higher quality line from one originally intended for ordinary telephone use. However, as analogue technology has given way to digital they are now little used.
Minimum orbit intersection distance, abbreviated MOID, is a measure used in
astronomy to assess collision risk between astronomical objects. It is defined as the distance between the closest points of the
osculating orbits of the two bodies in question. Of greatest interest is the risk of a collision with Earth; the MOID between an object and Earth is called Earth MOID. Earth MOID is often listed on
comet and
asteroid databases such as the
Jet Propulsion Laboratory's Small-body Database. However, MOID can be defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on.
An object is classified as a
Potentially Hazardous Object (PHO) – that is, posing a possible risk to Earth – if, among other conditions, its Earth MOID is less than 0.05
AU.
A mechanical filter using disc flexual resonators and magnetostrictive transducers.
A mechanical filter is a
signal processing filter that is used in place of an
electronic filter but for the same task, usually at
radio frequencies. At the input and output of the filter there are
transducers which convert the electrical signal into, and back from, a mechanical vibration.
The components of a mechanical filter are all directly analogous to the various elements of an electrical circuit. It is therefore possible use electrical network analysis and filter design techniques on mechanical filters which is a great convenience for electrical engineers in the design of these circuits. Any of the classic
frequency responses can be obtained with the right choice of component values.
A Murphy drip is a
rectal infusion apparatus to administer the medical procedure of
proctoclysis, also known as rectoclysis. During the procedure, an end of the Murphy drip is inserted into the
rectum and large quantities of liquid are infused into the rectum drop-by-drop. Prior to fluids or medicines being given
intravenously, the Murphy drip and
hypodermoclysis were the prime routes to administer fluids such as for
replacement when patients could not be fed by mouth.
Wisconsin surgeon
John Benjamin Murphy introduced the drip method of saline infusion per rectum in the treatment of peritonitis.
Some editors will put articles on their lists to which they have merely made a small contribution. All the articles and images shown here and on the linked lists have been created by me from scratch, or at most from an insignificant stub.
An original drawing by Zobel of a band-pass filter used for impedance matching.
Otto Julius Zobel (October 20, 1887 – January 1970) was a design engineer who worked for the
American Telephone & Telegraph Company (AT&T) in the early part of the 20th century. Zobel's work on filter design was revolutionary and led, in conjunction with the work of
John R. Carson, to significant commercial advances for AT&T in the field of
frequency division multiplex (FDM) telephone transmissions.
Zobel invented the
m-derived filter and the
constant-resistance filter, which remains in use today. With Carson he helped to establish the nature of noise in electric circuits, concluding that—contrary to mainstream belief—it is not even theoretically possible to filter out noise entirely and that noise will always be a limiting factor in what it is possible to transmit. Thus, they anticipated the later work of
Claude Shannon, who showed how the theoretical information rate of a channel is related to the noise of the channel.
Analogue
filters are a basic building block of
signal processing much used in
electronics. Amongst their many applications are the separation of an audio signal before application to
bass,
mid-range and
tweeterloudspeakers; the combining and later separation of multiple telephone conversations onto a single channel; the selection of a chosen
radio station in a
radio receiver and rejection of others.
Analogue filters have played an important part in the development of electronics. Especially in the field of
telecommunications, filters have been of crucial importance in a number of technological breakthroughs and have been the source of enormous profits for telecommunications companies. It should come as no surprise, therefore, that the early development of filters was intimately connected with
transmission lines. Transmission line theory gave rise to filter theory, which initially took a very similar form, and the main application of filters was for use on telecommunication transmission lines. However, the arrival of
network synthesis techniques greatly enhanced the degree of control of the designer.
BBC engineers equalising audio landlines circa 1959 using adjustable Zobel networks
Zobel networks are a type of
filter section based on the
image impedance design principle. They are named after
Otto Zobel of
Bell Labs who published a much referenced paper on image filters in 1923. The distinguishing feature of Zobel networks is that the input impedance is fixed in the design independently of the transfer function. This characteristic is achieved at the expense of a much higher component count compared to other types of filter sections.
Zobel networks were formerly widely used in telecommunications to flatten and widen the frequency response of copper land lines, producing a higher quality line from one originally intended for ordinary telephone use. However, as analogue technology has given way to digital they are now little used.
Minimum orbit intersection distance, abbreviated MOID, is a measure used in
astronomy to assess collision risk between astronomical objects. It is defined as the distance between the closest points of the
osculating orbits of the two bodies in question. Of greatest interest is the risk of a collision with Earth; the MOID between an object and Earth is called Earth MOID. Earth MOID is often listed on
comet and
asteroid databases such as the
Jet Propulsion Laboratory's Small-body Database. However, MOID can be defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on.
An object is classified as a
Potentially Hazardous Object (PHO) – that is, posing a possible risk to Earth – if, among other conditions, its Earth MOID is less than 0.05
AU.
A mechanical filter using disc flexual resonators and magnetostrictive transducers.
A mechanical filter is a
signal processing filter that is used in place of an
electronic filter but for the same task, usually at
radio frequencies. At the input and output of the filter there are
transducers which convert the electrical signal into, and back from, a mechanical vibration.
The components of a mechanical filter are all directly analogous to the various elements of an electrical circuit. It is therefore possible use electrical network analysis and filter design techniques on mechanical filters which is a great convenience for electrical engineers in the design of these circuits. Any of the classic
frequency responses can be obtained with the right choice of component values.
A Murphy drip is a
rectal infusion apparatus to administer the medical procedure of
proctoclysis, also known as rectoclysis. During the procedure, an end of the Murphy drip is inserted into the
rectum and large quantities of liquid are infused into the rectum drop-by-drop. Prior to fluids or medicines being given
intravenously, the Murphy drip and
hypodermoclysis were the prime routes to administer fluids such as for
replacement when patients could not be fed by mouth.
Wisconsin surgeon
John Benjamin Murphy introduced the drip method of saline infusion per rectum in the treatment of peritonitis.