Full transcript
0:00today after going through some of the
0:03stuff because we're going to revisit it
0:05I'm sorry I'm gonna turn spice down so
0:12you know last weekend through a lot of
0:13material at you but today I want to
0:17finish up chapter four and then I wanna
0:19go back and revisit some of the stuff
0:20that we did last week as you remember
0:23the lab assignment dealt with both the
0:25mathematical part of it and then the
0:28conceptual part about it and a lot of
0:29people came to the conceptual part we're
0:32saying I'm really struggling with this
0:34part of the math yeah once it started to
0:36go you all eventually ended up fairly
0:39well but what you did kind of find out
0:41from doing that lab assignment was it's
0:43all interconnected right you mess up on
0:45one of those and everything else falls
0:48apart which means each and every one of
0:51those formulas will impact the other
0:54formulas and today I want to talk to you
0:56a little bit about how they interact
0:59with each other and to what magnitude
1:01because ultimately when you adjust a
1:04button on your machine every formula we
1:06discussed last week as a button on the
1:08machine they are all related to benefits
1:12deficits or trade-offs if you will when
1:15you touch or move one button if you
1:18increase or decrease in one button what
1:21are the other parameters that are
1:22affected by that that's what you learn
1:24from lab assignment last week was that
1:25when you start with one of these is off
1:28it messes up everything else in a row so
1:30your board exam wants to make certain
1:33that you're competent to know that if I
1:35change this button I understand what I'm
1:38benefiting from changing that button but
1:40I also understand the deficits that I'm
1:43now causing so I may increase my
1:45resolution but I may impact my ability
1:48to resolve time I may impact my exposure
1:52to my patient now I may give them more
1:54heat generated because now I'm exposing
1:57them more just by getting this one
1:58benefit so what we want you to is
2:01understand that everything has a trade
2:03off and hopefully after today you'll
2:05have a better understanding of when you
2:07change one thing how it impacts
2:09everything else in that line and I have
2:13one huge formula to share with you it's
2:16a modified formula that only came out
2:19ten years ago we came this familiar it's
2:22a movie Beautiful Mind where you just
2:24see things
2:25well we a group of students and I sat
2:28what a day after class and said well
2:31well if we understand how to read
2:32formulas and look at formulas we could
2:34actually create this modified formula or
2:36you could understand how everything
2:37interacts with each other if you
2:39understood one simple formula so I want
2:42to share that with you today after we
2:44finish up chapter four but before we
2:46finish up chapter four we have to talk
2:47about the concept of resolution well
2:49last week we talked primarily about
2:51pulsing the sound so we can listen to
2:54echoes coming back that's what your
2:55ultrasound system does we pulse a little
2:57bit of sound we listen for those echoes
2:59come back and based on how long it takes
3:01for him to come back we can locate where
3:04they are in the body right well it turns
3:07out that that pulse that we send out has
3:09a certain size to it the size of the
3:12pulse is what we call resolution so the
3:16smaller the pulse in its parameters both
3:19the length of the pulse which we
3:21described a spatial pulse length last
3:22week and the width of the pulse which is
3:25the beam width which we'll discuss a
3:27little bit more into Chapter five we've
3:30discussed a little bit today but beam
3:31with the width of the beam determines
3:33how wide that little tiny dot on your
3:36screen is going to be so what I like to
3:38do is I'm actually going to turn down
3:39the last one because I think okay so
3:43what I have is two pictures here one
3:45that has 19 1920 pixels one that has
3:513840 pixels what you'll notice is that
3:53this image is broken up into pixels here
3:58and even smaller pixel here if you blow
4:00this up you'll notice that the more
4:03pixels we have inside this box
4:06the smaller each pixel is right and
4:08therefore the smaller each pixel is the
4:11greater the detail we have so let's take
4:14this into understanding in altra sound
4:17so in ultrasound if we have a little
4:25tiny pixel
4:28the height of the box is determine on
4:31what we discussed last week which is the
4:33spatial pulse length as you remember is
4:35the number of cycles and that pulse
4:37multiplied by its wavelength right you
4:40remember that and then the width of this
4:43each individual pixel is related to beam
4:49width which is primarily determined by
4:53the size of the piezoelectric element
4:55which again we'll discuss much further
4:57into chapter 5 but ultimately each tiny
5:00box or pixel inside an ultrasound system
5:03it's related to beam length from side to
5:05side and the height spatial pulse length
5:08so what you would derive from that is
5:10the smaller the spatial pulse length or
5:12the smaller the beam width the better
5:14detail or the better resolution you have
5:16agreed okay so let's go through the
5:19definitions of axial and lateral
5:21resolution I know it's on your notes so
5:23if you have your notes you won't have to
5:24do anything if you don't have your notes
5:26they are as follows axial resolution is
5:30the ability to resolve a gauge how many
5:35people reading is the ability to resolve
5:38two objects as separate along the beams
5:45axis so here's what they're talking
5:48about we have a transducer we have two
5:52objects that is in the same direction in
5:54which the beam is heading which is the
5:56mat direction the ability resolved two
5:59objects is separate along the beams axis
6:02so if we have a wave that has a certain
6:05thickness and it's headed out towards
6:08these two objects when that wave hits
6:12the first object on our screen that
6:16object will equal the width of that
6:21pulse as well as the thickness or
6:23spatial pulse length of that pulse and
6:25that one tiny little dot will show up
6:27like that on our screen that pulse will
6:30continue to travel and resolve the space
6:32that exists between those two which
6:34means nothing's going to be there and
6:35then again it's going to hit these
6:37second object and again it
6:40will equal the width of the beam width
6:43as well as the thickness of the spatial
6:45pulse length so those tiny little two
6:47dots here look like this on your
6:51ultrasound machine anyway we could
6:54reduce the size of that pulse would we
6:58would increase our ability to resolve
7:01these two objects in smaller detail for
7:05example if oh I'm afraid I'm going to
7:09have to erase the whole thing yep
7:12yeah I somehow created a thinner pulse
7:15that was less wide and it's still going
7:19to hit these two dots now on our screen
7:22it won't be quite as big or quite as
7:24thick they now will be looking something
7:27like this still bigger than the
7:30originals but not nearly as big as the
7:33ones I just showed you because the
7:35spatial pulse length is smaller the beat
7:36with the smaller the level of detail
7:39that we're able to really resolve this
7:41better let's take this back to what
7:45happens when we increase our spatial
7:47pulse length and these two objects if we
7:50send out a pulse that is so big that it
7:56encompasses both of them that is it is
7:58too big to fit in between these two
8:01objects and resolve the space that lives
8:04between them that echo comes back this
8:07big and that wide now a person is on a
8:13very small level I mean obviously we
8:15don't have dots that are this big a
8:17trail ultrasound but you get an idea of
8:19the size of the pulse and the size of
8:22that wave sending out actually equals
8:25our ability to resolve things now this
8:27is axial resolution the ability to
8:29resolve two objects as separate along
8:31the beams axis it's also true lateral
8:35resolution by definition sounds very
8:39similar but it's slightly different
8:41final resolution is the ability to
8:43resolve two objects separate
8:44perpendicular to the beam you beat that
8:49are you good
8:52so again we're heading in this direction
8:54perpendicular would be side to side all
8:58we have to do is have a beam width that
9:01fits in between these two dots of course
9:04if we shoot another beam over here we
9:07can resolve that one and another beam
9:09over here we can resolve that one and on
9:11our screen we could actually have two
9:14objects as separate however it all falls
9:21apart if these two objects and our beam
9:24width is wider than the those two
9:28together in that case we don't resolve
9:31them as separate and those two are
9:33reflected and equal to the beam width so
9:38the bigger our beam width the bigger our
9:41solution falls like the bigger the
9:42reflections that come back and therefore
9:45we can't resolve as well so anyway we
9:47can reduce the size of the spatial pulse
9:50length or the beam width will improve
9:53resolution and I want to talk a little
9:54bit about more that we talked a little
9:56bit last week about the parameters that
9:57would impact that the long talk it
10:00further about the other parameters that
10:01might do that right everybody with this
10:04so far actually a lot of resolution you
10:07understand the definitions and smaller
10:10is better in terms of detail reading all
10:13right good got the thumbs up all right
10:15so the next thing I want to talk about
10:18is ring time so as you remember spatial
10:22pulse length is equal the number of
10:23cycles in that pulse multiplied by its
10:25wavelength so last week we said we want
10:29to have short pulses and then listening
10:35time for the echoes to come back right
10:37we said that the spatial pulse length is
10:41the length in millimeters of one pulse
10:47all right so anyway we can reduce the
10:50size of this pulse we're going to
10:52improve our resolution we now understand
10:54that so according to the formula we can
10:57reduce it by two ways one reduce the
11:00number of cycles we have one two cycles
11:02in this pulse it's a two cycle Falls or
11:05two
11:06somehow decrease the wavelength the best
11:09way we know how to decrease the
11:10wavelength is to increase our operating
11:12frequency so what would that look like
11:16so here we go here's our first example
11:21here's my two cycle pause plus my
11:24listening time here's the new one one I
11:29can keep the frequency the same but
11:32simply reduce the number of cycles
11:34somehow shorten the pulse or ring time
11:37of that transducer that's one way the
11:40other way here is to increase the
11:46frequency oops I fell off the side there
11:51we go so but I still have a two cycle
11:54pulse here and here but you notice that
11:57the wavelength is much smaller therefore
11:59the frequency is higher so by reducing
12:02the number of cycles in the pulse and/or
12:05increase in the frequency and as we
12:08discussed in Chapter two frequency is
12:11relative to the size of your patient
12:12right because higher frequencies do not
12:15penetrate into deep each patient so
12:18whenever we have big patients we don't
12:20resolve things very well because higher
12:22frequencies while they do produce small
12:25spatial pulse lengths and beautiful
12:26resolution they simply can't penetrate
12:28into large patients so we have to find
12:30another way to reduce the size of our
12:33pulse and the way we do this is by
12:35something called dampening so dampening
12:40the best way to explain this dampening
12:45stops the crystal from ringing okay so
12:48let's let's get an idea here so here we
12:56go
12:56that's a bell can you tell see I told my
13:03mom that art school was not at least
13:06okay so we have a hammer we're gonna
13:10strike the spell and it will ring a
13:12specific frequency and when you ring a
13:14bell what happens it rings but then it
13:17decays out to the point read on here
13:19we call that an attenuation right so
13:22eventually the amplitude is very high
13:24and then it just fades off it has one
13:27particular frequency and it would look
13:31something like this a consistent
13:32frequency that eventually just fades
13:34often nothing happens right okay so
13:37another scenario so that's not going to
13:40be good for diagnostic ultrasound if we
13:42rein the crystals inside of our
13:44transducer and had a spatial pulse
13:46length that holy smokes
13:47was this big that poor lady's eye would
13:50look as they would go to her waist
13:52because it would take forever for those
13:54echoes to get back right so it would be
13:56huge so we can't have spatial pulse
13:59lengths this big and again we want to
14:00reduce the amount of ring time so the
14:03analogy was the next thing we do is we
14:06take that same Bell see I'm getting
14:10better at well this is even better I'm
14:14gonna put a wet damp towel over it and
14:16then I'm gonna strike it with that same
14:18hammer what are you gonna hear she's
14:24gonna Clank right but it won't ring off
14:27you won't hear it for a very long time
14:29in an essence we have created a
14:32shortened pulse length that we not
14:36dampening in the early age days of
14:39ultrasound was performed by literally a
14:41piece of insulation like you would put
14:44in their walls and they literally would
14:45place it on the back of the of the
14:47crystal inside the transducer today
14:49we're much more sophisticated in that
14:51because we send pulses of reverse
14:55polarity positive and negative to either
14:58sides of the piezoelectric element and
15:00that sends sound we then reverse the
15:02polarity and send it again and it stops
15:04it from ringing fairly quickly we can
15:06control the ring time of our transducer
15:08inside this for the main purpose of
15:12stopping it from ringing and doing that
15:15produces better
15:17axial resolution because we've shortened
15:19the spatial pulse like so small that now
15:22we can do it at a whim we literally can
15:24say I want a spatial pulse like this
15:25long computers control electronics
15:28stimulate and then unstimulating and
15:30quickly we have a shortened spatial
15:32pulse length the
15:33problem is as you just described is
15:35you're gonna get a claim not a clear
15:38ringing frequency so here's what
15:41happened when we did this every time
15:44whether we do it electronically or by
15:45the old piece of insulation on the back
15:48of the crystal we create a Clank and the
15:50Clank creates overtones of different
15:54frequencies so how many of you had DMS
15:57108 but if you actually all of you
16:00perfect so you know that when your DMS
16:02108 and you are choosing to scan a
16:05person you choose a frequency right and
16:08do you remember the names of the
16:10transducers do you remember the names of
16:12that you commonly use do you remember
16:14what they were or the names of there was
16:22an owl and were there numbers yes what
16:27would some numbers okay so the compounds
16:34we have in our lab here are an L 12 3
16:37nice clothes and c-51 ok L and C are not
16:42really important for this lecture look
16:44at that some later time but the 12 3 and
16:47the 5 1 means something specifically so
16:50here's what happened when we dynamically
16:53dampened that crystal we created not a
16:56single operating frequency but the claim
16:59produced multiple frequencies so here's
17:03what happened we have a trans
17:32we're still live okay good now let me
17:36Kym's there Lenny's there okay so we
17:39just do a couple things real quick sorry
17:42presentation and all okay Kim are you
17:50still there or do they kick her out -
17:54there's nobody over there we're still
18:02recording and still a continuation so it
18:04might take a minute for her to join us
18:06back okay oh she stupid okay
18:11all right sorry I had I meant that I
18:13made that mistake again of going too far
18:16one way and it kicked me out so sorry
18:18about that alright so if we were to
18:21graph the frequencies that are created
18:24from a particular transducer if this was
18:28your one megahertz and let's say this is
18:3310 megahertz and let's say we designed a
18:36transducer to ring at exactly five
18:39megahertz and we were to graph the
18:41results we will find that the
18:43frequencies emitted from that particular
18:45transducer would only be admitted at
18:49five megahertz if it is an undamped and
18:52crystal allowed to ring and decay
18:55naturally so as you imagine when we talk
18:59about a clink it's not allowing it to
19:02ring and decay naturally so what happens
19:05is we get let me draw this in color we
19:10get a range of frequencies around the
19:13operating frequency so this is how we
19:16end up with frequencies that say there
19:20are five one or twelve three in this
19:23case you'd probably say it's a tube -
19:26roughly seven so we would have a
19:28transducer that would it be a seven -
19:31that's what those numbers mean it's
19:33talking about all the different types of
19:35frequencies that are emitted by that
19:36particular transducer the wonderful
19:39thing about this is that as we learned
19:42from earlier chapters is that higher
19:44frequencies attenuate
19:45quickly lower frequencies penetrate deep
19:48higher frequencies produce better
19:50resolution while lower frequencies
19:52produce worse resolution if you have a
19:54transducer that has both low and high
19:57frequencies emitted at the same time you
20:00can penetrate at the depth of a 2
20:02megahertz I'll resolve at the frequency
20:05of a seven megahertz it is the best of
20:08both worlds except if you're an engineer
20:11because an engineer would call this low
20:15quality they also simply shorten and say
20:20this is a low Q transducer meaning this
20:27you decided that transducer to ring in a
20:30certain frequency and yet it doesn't
20:32ring not only at that frequency it wings
20:34it a bunch of frequencies other than
20:35that one that's pretty low quality but
20:38for diagnostic ultrasound it's an
20:41awesome transducer because we can
20:43penetrate deep into our patients as well
20:46as resolve at higher frequencies and if
20:49don't forget the whole reason why we
20:51stopped it from raining was to shorten
20:53the spatial pulse length to produce high
20:56resolution images so it seems
20:59counterintuitive but in diagnostic
21:02ultrasound we use low Q transducers low
21:06quality transducers by an engineering
21:08standpoint but it gives us the best
21:11benefits in terms of evaluating or
21:16imaging the patient we get penetration
21:18as well as resolution at the same time
21:20everybody okay with this so let's talk
21:23about how this impacts the rest of our
21:27ultrasound so we've said if we increase
21:32dampening we will decrease our ring time
21:40which is essentially our spatial pulse
21:41length correct right increased damping
21:46shortened cessation of all sync we need
21:47a Clank by doing this we in keep
21:51increase the band widths the bandwidth
21:53is the number of frequencies that are
21:55emitted from a particular transducer
22:01and when we shorten our space your pulse
22:05length we increase our axial resolution
22:10now is there anything on there that I
22:14said that is confusing or does that sum
22:19up what we just discussed about how
22:20dampening impacts our spatial pulse
22:23length in our resolution we good so far
22:28you know there's gonna be trick later I
22:30know we're gonna get to it but so far do
22:33you understand these concepts yes the
22:37q-value is like increasing is that SPL
22:42or is that completely different Q value
22:45controls your spatial pulse line so like
22:47should I just cuz like I'm the notes
22:49it's right here so should I just add if
22:53you wanted to I mean like this is that I
22:55think we're done today I don't think
22:57you'll need to look at that you'll have
22:59a pretty good idea of how everything's
23:02interconnected you would trust me on
23:06this so sweet all right everybody good
23:09with this we're simply talking about
23:11spatial false link how it impacts your
23:14axial resolution and how damping is a
23:16way of decreasing your reading time of
23:18your transducer the byproduct of that is
23:21it increases our bandwidth which
23:22actually turns out to be a good thing
23:24for us and we okay with that doing so
23:29good okay one other thing I want to talk
23:31about before I summarize all this
23:34together is frame rate I know that Miele
23:42talks about frame time that's an
23:45engineering thing frame timing as merely
23:49describes in your textbook he spends a
23:51great amount of time talking about frame
23:52time is the amount of time it takes to
23:55create one frame of information to be
23:57displayed on your ultrasound system it's
24:00not really something we are worried
24:02about nor do we actually pay a lot of
24:04attention to what we're worried about is
24:06frame rate how many frames per second
24:10and the reason being
24:12is because ultrasound is called real
24:15time ultrasound but let's think about
24:18how this actually happens in order for
24:21us to create one frame we have to send
24:25down each line of sight individually
24:28collecting data all the way across the
24:31entire transducer typical transducers
24:34have somewhere between 200 and 300 lines
24:38of sight it has to go down and back two
24:41to three hundred times before it creates
24:44one image on your screen and then it has
24:50to have roughly 30 images on your screen
24:54per second to be considered real-time
24:57think about that as to travel down the
25:00back inside the human body up to 300
25:03times and then do that 30 times a second
25:06to be considered real time ultrasound so
25:09as you can quite imagine while it looks
25:12near real-time model we're scanning it's
25:15not real-time it's close to real-time
25:18but it's not quite real time which is
25:20why frame rate is much more important to
25:23us as scenographer x' because we want to
25:26know how many frames per second are we
25:28actually imaging the patient is related
25:32to something called temporal resolution
25:34which has a much easier definition it is
25:37our ability to resolve time so we've
25:40discussed axial resolution we discussed
25:42lateral resolution and temporal
25:44resolution is simply the ability resolve
25:46time and it is related directly to
25:48something we discussed last week which
25:50is your pulse repetition frequency how
25:53frequently we pulse will determine how
25:56frequently we update our screen make
25:58sense okay so and if you remember last
26:02week we set the pulse repetition
26:04frequency is related to the depth set by
26:09you the operator the deeper you go the
26:12longer it's going to take to go all the
26:14way down gather that information and all
26:16the way back right so so pulse
26:19repetition frequency primarily
26:21controlled by depth is going to impact
26:23our frame rate and so much so
26:26let me show you a house how much force
26:28so frame rate the formula is velocity
26:31your constant 1540 meters per second
26:34divided by two times down and back your
26:38depth does that look familiar to you
26:41it looks exactly like ultra repetition
26:44frequency doesn't it except for we're
26:46going to now add an end to it not number
26:49of cycles in the pulse like you saw in
26:51spatial pulse length or pulse duration
26:53this end stands for lines of sight how
26:56many lines are we going to take to
26:58resolve this particular area inside your
27:02ear patient so as you can see there's an
27:05inverse relationship with the number of
27:06lines of sight you have to your frame
27:09rate and yet the number of lines of
27:12sight we have actually helps us reduce
27:14our beam winds let me show you what I
27:17mean
27:17so no I don't want to draw that I'm
27:23gonna draw one here I'm gonna draw one
27:25over here oh I almost picked myself out
27:28again let's say this one only has three
27:30elements in it and let's say this one
27:33has a bunch of elements in it okay as
27:36you can imagine as the way ultrasound
27:38works we fire one line of sight at a
27:40time it goes down and comes back once
27:41it's back we can fire the other one once
27:44it comes back then we can fire the other
27:46one this one has to do the same process
27:48can you imagine what's gonna happen to
27:50this one more elements means more time
27:53but the other thing you'll notice is
27:56that more elements you can sort of see
28:00it the width that's here compared to the
28:02width that's here is much bigger first
28:06I'm sorry smaller over over here bigger
28:08over there so the more elements you have
28:11the smaller your width of your beam
28:14meaning better resolution so you get
28:18better resolution yet you've slowed down
28:20your frame rate which seems to be the
28:22trade-off and almost everything we do in
28:24ultrasound if we improve resolution we
28:27somehow either don't penetrate our
28:31patient even off or we don't resolve
28:34things fast enough or we simply don't
28:39see
28:39so when we every time we touch one
28:43button to improve one parameter there is
28:45a trade-off usually negative of
28:47something else that happens so and they
28:53say the age-old problem that every
28:55scenographer has to figure out is a my
28:58penetrating my patient with enough
29:01penetrate my patient deep enough or am i
29:04resolving object well enough to see it
29:06it's a constant trade-off
29:08so resolution versus penetration is one
29:13of those age-old things that
29:14ultrasonographer just had to deal with
29:16and then ultimately now with this one
29:17frame rate are we resolving it fast
29:20enough and you would say yeah what the
29:22patient doesn't move all that much yeah
29:24you don't have to resolve that fast but
29:26what if you're talking about
29:27echocardiography where the heart is
29:28beating away at 80 90 minutes 80 90
29:32times a minute what about a fetus 120
29:36180 times a minute and you're trying to
29:38pick up small hard anomalies on a fetus
29:40and not only the heart is moving at 120
29:4280 beats per minute but baby's also
29:45doing somersaults at the same time this
29:48is why people really don't like doing OB
29:50on yourself because their heart is
29:54alright so looking at the form of frame
29:57rate velocity those two times that that
30:01x number of lines of sight looks very
30:05familiar to impalas repetition frequency
30:06as you remember from last week which was
30:08velocity divided by 2 D right so clearly
30:12pulse repetition frequency has an impact
30:15on frame rate so as Paul's reputation
30:18frequency increases your frame rate will
30:19increase because they are directly
30:21related because they are so similar
30:22their rate - they're related to the
30:24sample time or era temporal resolution
30:27so what I'd like to do is let's walk
30:30through a couple of frame rate problems
30:32and then I want to pull it all together
30:35in terms of what we discussed last week
30:37and talking about the trade-offs that we
30:40have with what we discussed in this
30:43chapter
30:44okay so let's attempt to frame rate make
30:48it this so tell me
30:50what is your frame rate in soft-tissue
30:58let's say your depth is equal to 10
31:03centimeters and we'll just keep it easy
31:09hundred lines of sight give that a shot
31:16so let's take a look at this one
31:18so again frame rate is our velocity
31:21divided by two de n so again because
31:25it's a soft tissue we have fifteen forty
31:27meters per second divided by two times
31:31the depth was ten centimeters multiplied
31:34by a hundred which is unitless right so
31:37putting this all together we have
31:40fifteen forty meters per second divided
31:44by two thousand centimeters right that's
31:51what y'all got right okay so did you
31:54convert meters per second into
31:56centimeters per second or two thousand
31:58centimeters into meters you mean the
32:02latter did any of you touch the velocity
32:05because you always hate touching
32:07velocities you left it alone okay so we
32:12end up with fifteen forty meters per
32:14second divided by 20 whoops
32:18meters that's that's um don't we're done
32:23we just have to divide this out right 20
32:25into 1 5 4 0 20 goes into 154 just seven
32:32times right forty we end up with 1/4
32:37again seven 77 meters will cancel out
32:42were left with 1 over seconds so 77 1
32:45over seconds or 77 Hertz how'd you do I
32:52know at least one person got that so
32:53good Kendra Morgan yeah yeah yeah Janey
32:59yeah broke I didn't get it right but I
33:02know what I did I forgot
33:04okay um Kira you got it right okay but
33:10you see where you went wrong and do we
33:12on do another one of these just as
33:15solidify it okay one more again what is
33:19the frame rate will go if we'll keep it
33:26in soft tissue this that's pretty much
33:28what you're gonna do we'll keep the
33:32depth at five centimeters and we'll go
33:38oh let's get something big
33:44let's go lines of sight is 300 lines of
33:52sight there we go some more realistic
33:53let's see what that frame rate adds up
34:39Hannah you Donna
34:42Kendra Brooke Morgan
34:48Kiera yeah everybody to this point
34:53alright looks like everybody knows I was
34:56walking around got this part so we got
34:57the correct formula we have a setup
34:59correctly the next step is simply
35:03simplifying that would be 2 times 5
35:09which is 10 times 300 which would be
35:113,000 centimeters I'm going to assume
35:15that we all tackled the bottom part I
35:17think the word into meters right right
35:27here we got to that point okay 30 into
35:38150 fours gotta go to 5 times great 54
35:44is left over 100 just goes in there once
35:49right so again meters cancel out one
35:53over seconds so 51 Hertz should be the
35:58answer everybody that look feeling
36:01better about this a little more
36:03confident yes I am going to we're going
36:12to talk about because framerate doesn't
36:14stand alone and that's kind of what I
36:15want to talk about for the second part
36:18of the lesson today is talk about how
36:19everything is interrelated I think this
36:21will really help especially when we got
36:23to like page 2 of the page 3 of our
36:26midterm remember as this increased how's
36:29that affect that and we were only
36:30talking about one formula from that
36:32whole page now those same types of
36:34questions are going to be asked of all
36:36the other formulas we discussed last
36:37week including frame rate so I want to
36:40talk to you about how to remember to
36:42keep them straight and hopefully not
36:45make any mistakes
36:47how things are in
36:48are we ready to discuss that or do you
36:51need a break let's go let's go do it
36:54yes all right because once I get this
36:56thing started it's a mess
36:58all right everybody pull out a blank
37:00piece of paper and we'll start with this
37:06last week we discussed duty factor right
37:11and we said that duty factor was the
37:14pulse duration divided by the pulse
37:17repetition period so we know that if I
37:30increase the pulse duration and we know
37:33how to how to read a formula what
37:35happens to our Duty factor what we're
37:36solving for does the increase decrease
37:38or remain the same he increases because
37:41whatever's in the numerator on top is
37:44directly proportional to whatever we're
37:46solving for always and forever if that
37:48number increases what we're solving as
37:50long as everything else remains the same
37:52what we're solving for will increase so
37:54as all station increases we know for a
37:57fact our duty factor will increase agree
38:03the opposite in the denominator if the
38:07pulse repetition period increased what
38:09happens to the duty factor heiwa
38:16decrease is inversely proportional right
38:19because it's in the denominator as that
38:21number gets bigger we're dividing a
38:22bigger number into the into whatever's
38:24on top which means what we're solving
38:26for is going to be smaller all right so
38:29it's inversely proportional all right
38:32let's carry this on last week we also
38:36said that the pulse duration was equal
38:38to the number of cycles and that pulse
38:40multiplied by its period right so either
38:46if either the number of cycles in the
38:49pulse increases or the period increases
38:52they are directly related to the pulse
38:54duration and therefore the duty factor
38:56right so here if I increase the number
39:02cycles in the pulse what happens to my
39:03boss and pulse duration and then if the
39:08pulse duration increases what happens in
39:09the duty factor so let's skip the middle
39:13part if the number of cycles and the
39:15pulse increases what happens to the duty
39:17factor right can we can we do can we
39:22quantify that amount if I said the
39:24number of cycles doubles what happens to
39:27the duty factor specifically does it
39:30increase two times three times four
39:34times or decreased by half or quarter
39:37right if this number becomes bigger two
39:41times it goes directly across because a
39:44pulse duration will be two times bigger
39:45and now the duty factor will be two
39:47times bigger we can quantify how much
39:50bigger that is everybody okay with that
39:56we also said that all right
40:03spatial pulse length was directly
40:05proportional to pulse duration did we
40:07not remember that anytime the size of
40:10the pulse gets bigger it will take
40:13longer in a pulse duration for that
40:14occur right so it's the spatial pulse
40:17length gets figured the pulse duration
40:18also gets bigger which is why their
40:20formulas look so much alike the number
40:22of cycles in that pulse in this case
40:24multiplied by the wavelength so let's
40:30skip some steps yeah the wavelength
40:34increases what happens to my duty factor
40:37increase it does now let's try this
40:39again if I increase my wavelength I have
40:42to slice facial balls lines also
40:46increases if I increase my wavelength
40:47what happens to my pulse duration you
40:53just answered about six questions which
40:54you know could be and of course it
40:56doesn't always have to be increased I
40:57could say if wavelength decrease I would
40:59have impact all of these right okay
41:02let's continue on because there's more
41:05we also know that there's a formula
41:08website through that rather it mean to
41:13remember this from Chapter two that
41:17wavelength was equal to the velocity
41:18divided by frequency remember that one
41:21if you also remember the formula that
41:23said that the period is equal to the
41:25inverse of the frequency to remember
41:27that one
41:28so clearly stating that frequency is
41:30inversely proportional to both spatial
41:33pulse light and pulse duration agreed
41:35let's try this one out if I increase my
41:40frequency here what happens to my period
41:45remember frequencies in the denominator
41:47- the period so that means period would
41:51decrease if period decreases what
41:53happens to pulse duration it'll decrease
42:00and then what happens to duty factor
42:03there are you ago that was a long walk
42:06to get there what I'm telling you it
42:08gets even longer because you have to
42:11know how all of these are interrelated
42:14I'm not telling anything you don't
42:16already know I'm just showing you a
42:18different way to put it together
42:20alright so let's so let's try one more
42:22well let's go up above here frequency if
42:31I increase the frequency here what
42:32happens to my wavelength yes and if
42:36wavelength decreases we'll have to spy
42:38spatial pulse length yes and of spatial
42:41pulse lanky creases what happens to our
42:43pulse duration and then if my poster
42:47ation decreased swayam is my duty factor
42:50now let's skip all those steps in
42:53between if frequency increases what
42:55happens to Duty factor same thing we
43:04just did except I skipped all the
43:05in-between parts that walked us back to
43:07duty factor if you increase frequency
43:10here what happens to your new T factor I
43:14know you know the answer you see how we
43:17got there is there more to it there's
43:22more to it a lot more just like which
43:25definition of you know I'm so we're just
43:43getting the hang of this this is very
43:44early remember everything's hard until
43:46it becomes easy right
43:48you thought tying your shoes was
43:50difficult at one point in your life and
43:51now you don't even have to look while
43:53you're kind right so you just have to
43:56practice and what you will do I have
43:59done this with my senior students before
44:01and after mastering this formula you
44:05will know about 70% of what's going to
44:06be on your board examination to be able
44:08to tackle it with confidence weight 70%
44:11of my heart oh yeah because what we're
44:14going to do is each one of these
44:17formulas are related to a button on your
44:19machine and every time you tell when I
44:21tell you the name of that button on your
44:23machine you're gonna go oh when I touch
44:25that button that impacts this this does
44:27this and I'm doing this to my exposure
44:29I'm doing this to my resolution I'm
44:31doing this and that's exactly what your
44:33board wants you do to be competent to
44:36know how to operate the machines and you
44:37know the trade-offs of deficits of every
44:39button you push because they all have
44:41trade-offs this is it this is the big
44:45part of your board so it's important
44:47that we take time to learn how to do
44:48this and if you know how to read
44:50formulas and you know the formulas and
44:52how they're related to each button on
44:53your machine you do well on your board
44:56examination okay so let's continue on
44:58this process because you've got a little
45:00more a few more things to add to this
45:01but everybody okay with this so far am I
45:03going too fast right okay all right so
45:06let's walk this back this back to here
45:11okay so the the next thing we have to do
45:15is take a look at the bottom part of
45:18this formula let me go back to this and
45:22let me not kick us out so I'm gonna draw
45:25this way okay so the pulse repetition
45:27period as we know is inversely related
45:30to the pulse repetition frequency
45:31correct remember that right that was the
45:35form that I discussed last week so let's
45:37look at this one if we increase our ball
45:39repetition frequency how Sinopec impact
45:42our pulse repetition period remember
45:47it's in the denominator so it's
45:48inversely proportional
45:50so if PR F increases our PR P decreases
45:54right so remember PRP is in the
45:58denominator of solving for the duty
45:59factors so if the pulse repetition
46:01period decreases what happens to our
46:03duty factor I don't know if I heard both
46:09at the same time you both said decrease
46:11so palt repetition period decreases and
46:15it's inversely proportional to the duty
46:17factor that means our duty factor would
46:19increase right let's eat the sweet you
46:24can walk through it sorry I think it'd
46:26help if I imagined it like over one does
46:29that make sense it is over one well like
46:33what never okay let's try a little bit
46:39more here well let's take a step back I
46:45don't know why he chose orange I tried
46:46to hit red um a PRP increases what
46:50happens to duty factor yeah they're
46:53inversely proportional that's right
46:54we're there right so stepping it back
46:56one more time let's let's do the
46:58opposite of PRF decreased what happens
47:01to duty factor and then it would
47:12decrease it's like okay so PRF decrease
47:17what happens to PRP and then a PRP
47:22increase why does the duty factor so
47:25again the original question is of PRF
47:27decrease will have the duty factor good
47:33so far no sure we need no that's good
47:36we'll get there trust me
47:38we'll get there don't fret it we're
47:42gonna keep doing this until everybody's
47:43on board and then you go home and forget
47:45it but the beautiful thing is we're
47:47recording all of this so you can go home
47:50and watch it a hundred times and
47:51eventually it'll come true right
47:53all right I want to take it a step
47:57further because we got a little bit more
47:58to go so no all right pulse repetition
48:05frequency what's the formula we know oh
48:09don't
48:10velocity divided by two times the depth
48:14right oh yeah you had that thing okay
48:17here we go remember adapt that you know
48:20if you took DMS 108 you know that you
48:23control the button called depth right
48:26yeah so every time you touch this button
48:30I want to show you all the things you
48:32did that you didn't know all right so
48:36when you touch that button let's say we
48:38increased our depth how does this affect
48:42our pulse repetition frequency remember
48:47it's in the denominator okay RF so so it
48:52will increase the pulse repetition
48:53frequency so automatically increase a
48:56line through that backwards sorry it's
48:59inversely proportion so as you increase
49:01your depth you already reduced your
49:04pulse repetition frequency which is your
49:07sample rate which is your temporal
49:11resolution the ability to resolve time
49:12so you increase your down phenomena
49:14you're already slowing down your frame
49:15rate okay so you decrease your pulse
49:18repetition frequency how does this
49:19impact your pulse repetition period it's
49:24inversely proportional so it increased
49:26your pulse repetition period and how
49:28does that affect your duty factor in
49:36verse eight degrees these in the
49:37denominator it will do the opposite so
49:42by increasing your depth you have
49:43reduced your temporal resolution because
49:47you're pulsing less time because it's
49:49taking longer to go out and back and
49:51then finally compulsive games so you
49:53reduced your ability to resolve time in
49:55your patient but the good by-product is
49:59that you have reduced your exposure to
50:02your patient and reduce the likelihood
50:03of causing any of Bayeux effects
50:06associated with heat but you didn't know
50:10that you were just changing your depth
50:12or Jeff nice alright um take this back
50:24there's more what do we know D to be
50:27associated is there a formula that
50:28calculates depth for us chapter one echo
50:33ranging what is it say that again
50:42what did you say velocity times time
50:49right yeah we refer to as echo time
50:55remember the act the amount of time for
50:57the echo to go out and back so let's
50:59let's tackle this one um here's my
51:02question I want to know how the echo
51:04time impacts duty factor so I'm gonna
51:07start here I'm gonna have you work it
51:10all the way back to duty factor nobody
51:11say a word and then also I'll tell the
51:14answer at the same time so as echo time
51:16increased what happened to our duty
51:17factor exposure to our patient
51:46you're gonna hate what we do next but
51:49are you serious
51:51alright can I can I ask a question I
51:54think you probably know what's coming I
51:56do my two are the two D in the C e
51:59proportional no the to the to D and are
52:09you making jokes on my writing again no
52:11it's a 2d in the see they are all
52:16directly proportionate are ya none of
52:18them are in the denominator they're all
52:20essentially over ones I will I'll get
52:27you this far if the echo time increases
52:29your debt increases so where do you go
52:32from there all the way back to duty
52:36factor does everybody Hannah you got the
52:38answer you look pretty confident over
52:39there or you're tired of doing this
52:41whole thing you didn't want to go is to
52:46remains the same zero double zero on the
52:49roulette wheel remains the same it's
52:56like zero double zero on the roulette
52:58wheel yeah it wouldn't suggesting
53:05gambling advice now okay here I got an
53:08answer whether it's right or wrong I
53:09don't care whether it's right or wrong
53:10but you have an answer you walked it
53:11back the best you understand it all
53:13together now what is the answer what
53:15happens to duty factor does everybody
53:19agree that it's decrease Hannah you look
53:22like you're smiling like you're trying
53:23to be kind is that not the answer you
53:25have okay anybody else has increased
53:33them and here's the thing I don't know
53:42what the answer is because I haven't
53:43walked it back myself
53:44so how confident are you that you're
53:49right on your answer let's find out
53:52okay so time does impact death in the
53:56same way
53:57so it is directly proportional however
53:58depth is impersonally proportional to
54:00altar petition frequency pulse
54:03repetition frequency if that decreases
54:05that means our PRP is going to increase
54:07and if our PRP increases that means our
54:09duty fact will in fact decrease as you
54:12all promised me it would are you feeling
54:15about this okay so far I have some
54:19nuances to add well I mean not so good
54:23the ones that will help beautiful we
54:25recently just talked about remains the
54:27same right so let's talk about where
54:30those come in first of all velocity
54:34you'd only be taken to this point it
54:39cannot go back to duty factor because
54:41you feel if you'll notice velocity shows
54:43up in both the numerator of this mess
54:45as well as the denominator in this mess
54:47so if velocity increases for one
54:49increases for both therefore you can't
54:51say what happens to duty factor if the
54:53velocity somehow increases it stops
54:56there however you can take velocity back
54:58to this level which includes the spatial
55:01pulse length of ulceration or pulse
55:03repetition period so I can say as
55:06velocity increases how's that impact
55:08your spatial pulse length can you walk
55:10that one back if let me go the
55:16checkmarks off if velocity increases
55:18here how's that in effect your spatial
55:20pulse length no it's not yes or no
55:30increase your eighth grades so
55:33philosophy increases how's that effect
55:34your wavelength let's start there it
55:40does increase
55:41so if wavelength increases how does it
55:42affect your spatial bosley there you go
55:45boom boom boom you can stop there but
55:49you could not go to duty factor because
55:51then velocity would be involved both in
55:53the numerator and denominator and they
55:55wouldn't be able to figure it out
55:58because it would increase
55:59proportionately
56:00that makes sense okay so all the things
56:04that we know the impacts velocity which
56:06was also on your midterm do you remember
56:09them the for me
56:10characteristics of impact velocity vault
56:12modulus density stiffness which is bulk
56:17modulus what else we have no
56:21compressibility one more elastin stain
56:26remember oh yeah look at her right so
56:31remember ball modulus and stiffness are
56:33the same the higher the ball magis the
56:35higher the stiffness the higher your
56:37velocity dense these the opposite
56:39density is heavy right those heavy
56:42particles don't move so they reduce your
56:44velocity those are the two most
56:46important ones then when it comes to
56:48compressibility more compressible is the
56:51more water balloons you have so the more
56:53compressible the slower it is it is the
56:56opposite of stiffness and then of course
56:57elasticity it really get bounced back
56:59originally think of bean bags and tennis
57:02balls so bean bags are just look and
57:04tennis balls would go they would produce
57:06higher velocity right so let's look at
57:10that so if I go increased stiffness how
57:20will that impact my pulse duration one
57:27step at a time find velocity how is it
57:32related to pulse duration
57:45got it that's okay Jamie it's okay
57:59okay we ready you got an answer okay
58:04stiffness increased stiffness actually
58:06produces high velocity so here's our
58:09velocity here we've increased our
58:11velocity and what happens to wavelength
58:15also increases what happens to spatial
58:17pulse length and if spatial pulse length
58:20increases what happens to pulse duration
58:28same thing I want to know what happens
58:35if we increase density though what
58:41happens to fall stray sure the density
58:43increases what happens to all station
58:47doesn't that sound like a question that
58:49can be off next week's test next week
58:51yeah
59:02increase density what happens to fall
59:03straight you're there already good Jamie
59:10can we write this on the board during
59:12the test so clearly it doesn't work all
59:33right
59:33increased density what happens to
59:35velocity velocity decreases what happens
59:39wavelength spatial pulse length and
59:42pulse duration duty factor doesn't
59:48matter indeterminate or that or remains
59:52the same right okay so we got a good
59:55idea handle on this correct everybody
59:57okay with us so I show you another
1:00:00nuance and this one confuses a few
1:00:04students for a few minutes
1:00:06few readings
1:00:10oh no don't go go back away everything
1:00:17on top has nothing to do with everything
1:00:20on the bottom spatial pulse length does
1:00:26not impact pulse repetition frequency
1:00:28pulse duration doesn't impact pulse
1:00:30repetition period the doubts doesn't
1:00:34impact frequency the echo time does not
1:00:38impact wavelength everything that's on
1:00:41top that you see has nothing to do with
1:00:43what's on ah and here's where it gets
1:00:46confusing the frequency has nothing to
1:00:48do with the pulse repetition frequency
1:00:50and the period has nothing to do with
1:00:54the pulse repetition period are you okay
1:00:57with what I just said yeah
1:00:59yes everything on top it's nothing to do
1:01:02with everything on the bottom what
1:01:04confuses students most is that frequency
1:01:07has no impact on pulse repetition
1:01:09frequency and period has no impact on
1:01:12pulse repetition period all right I have
1:01:51two pulse sequence the first one has a
1:01:54whole sequence of two Hertz second has a
1:01:57pulse sequence of four Hertz this is
1:01:59related to your p RF how many pulses
1:02:02occur per second did our pulse
1:02:04repetition frequency change yes how
1:02:08about our frequency their wavelengths
1:02:11look roughly the same and mind you I'm
1:02:13trying to draw it to scale I tried to
1:02:14draw out whether frequencies are
1:02:16identical so it doesn't matter what the
1:02:20frequency is when it comes to the
1:02:22pulsing characteristics
1:02:23that frequency okay so if this is
1:02:33frequency one and this is frequency two
1:02:37in a frequency one equals frequency -
1:02:41meaning they are the same frequencies
1:02:44you with me there do they have the same
1:02:47pulse repetition frequency 's no so this
1:02:51frequency here this wavelength here is
1:02:54equal to this wavelength here but that
1:02:56has nothing to do with how many times it
1:02:58has been pulsed right that is it doesn't
1:03:01matter how big or small those
1:03:04frequencies are it all it's related to
1:03:06how often it is pulsed
1:03:08bract yes you with me there so it turns
1:03:16out that the pulse repetition frequency
1:03:17and the pulse repetition period change
1:03:20but the frequency did not which means
1:03:24the period did not which means the
1:03:27frequency has nothing to do with the
1:03:28pulse repetition frequency in the period
1:03:31has nothing to do with the pulse
1:03:32repetition period he got means now yeah
1:03:36okay so going back to what I said
1:03:38everything on top has nothing to do with
1:03:40everything in about the size of the
1:03:43pulse has nothing to do with how often
1:03:45we pulse it that makes sense so if I ask
1:03:51you as pulse repetition frequency
1:03:53increases how does this impact your
1:03:55pulse duration it doesn't or it remains
1:04:00the same right if your period increases
1:04:04how does this impact your pulse
1:04:05repetition period it doesn't it remains
1:04:10the same your wavelength how does this
1:04:13impact your death it doesn't has nothing
1:04:17to do with it if you increase your down
1:04:21how's this affect your spatial balls
1:04:22length has no impact you follow me on
1:04:27this yeah hey will we be asked questions
1:04:31like this I'll tell you exactly the
1:04:33questions because I went through back
1:04:35here labs mid
1:04:37term in your next test and pull every
1:04:39question that said is something
1:04:42increased what happened to something
1:04:44else and put it down on a piece of paper
1:04:47Tori oh and I'm going to let you work
1:04:50through it right now is this our lab
1:04:54this is not our laughs booth this is
1:04:57part of class so think of this as
1:04:58another test remember we had tests early
1:05:01on and for the online group I think I
1:05:04have it here show it's also available
1:05:07for download Kim let me know if this is
1:05:11too small and I change the scale of it
1:05:14there we go that's probably way too
1:05:15small yeah it's too small okay so I'm
1:05:19gonna do that and I'll probably only
1:05:22have to show a little bit of it at a
1:05:23time but it's also available for
1:05:25download for the online students so what
1:05:26I'm gonna do is pause the recording now
1:05:29and we'll let them work through it then
1:05:30when we go through all the answers in
1:05:32about 30 minutes or so and then
1:05:35hopefully they'll have all that
1:05:36available for the test and probably what
1:05:39will be on their final exam too so I'm
1:05:43gonna pause this for a little while good
1:05:47all right here we go starting at the top
1:05:50if I get all these right so I'm gonna
1:06:01write down the answers and then you
1:06:04raise your hand when you don't you see
1:06:12mama up there I'm trying to break and
1:06:14read them that way you can see them all
1:06:18right starting with number one
1:06:20I have whoops supposed to write they
1:06:23have increased all right number two I
1:06:27have decreased number three I have
1:06:30decreased number four I have increased
1:06:35number five I have decreased number six
1:06:40I have decreased number seven
1:06:43I have decreased number eight I also
1:06:47have decreased number nine
1:06:50I have increased let's stop there
1:06:53because that's where the page is at does
1:06:54anybody have any questions about the
1:06:55first not just a number yeah so
1:07:04remembering the formula this PRF equals
1:07:07C over to D and ask if depth increases
1:07:14what happens to PRF because depth is in
1:07:17the denominator if this increases in the
1:07:19Dominator it's inversely reports
1:07:21proportionately PRF so it would decrease
1:07:25any other questions the first nine
1:07:29number six if the frequency increases
1:07:32okay so I'm gonna go to the second page
1:07:35so frequency increases what happens to
1:07:38false duration so going here and here if
1:07:47frequency increases that means period
1:07:51will decrease which means pulse duration
1:07:53will decrease okay hold on you know undo
1:07:59oh sorry go you had a question Morgan no
1:08:02you decrease oh yeah decrease is the
1:08:07answer okay okay okay
1:08:11all right now let's go back to the
1:08:13original page and Henry had a question
1:08:15about I feel like I know this - okay -
1:08:20goes back to echo ranging so it
1:08:22specifically asks what happens to time
1:08:25the only formula we have that calculates
1:08:28time is distance over velocity and it
1:08:32says if compressibility of the medium
1:08:34decreases and the distance remains
1:08:37unchanged what happens to time so
1:08:40compressibility is related to velocity
1:08:42so if compressibility a medium decreases
1:08:45that means the stiffness increases which
1:08:48means the velocity increases velocities
1:08:51in the denominator so if the velocity
1:08:53and the denominator increases that means
1:08:55what we're solving for will decrease or
1:08:58time decreases all right yeah all right
1:09:02any other questions
1:09:03one through nine for Dan said okay this
1:09:11is another one like what happens to the
1:09:12echo ranging formula I'm gonna switch
1:09:14over to black because there's too much
1:09:17red so if the density increases and all
1:09:20that other factors remain saying what
1:09:22happens to velocity this is simply as
1:09:24density decreases what happens to
1:09:27acoustic propagation speed as remember
1:09:29density is how heavy the particles are
1:09:32so if the density decreases that means
1:09:35these particles become light and airy
1:09:37which means sound should propagate
1:09:39through them well which means velocity
1:09:41should increase all right other
1:09:45questions on one through nine okay let's
1:09:51move on from ten to as far as we can see
1:09:56twenty questions on ten through twenty
1:09:59oh I got to give you answers first so
1:10:01let me go back to red here we go
1:10:05ten I had a decrease he 11 I have
1:10:10increase 12
1:10:12I have decreased 13 I have decreased 14
1:10:18decreased 15 is increased
1:10:2416 is increase 17 increase 18 increased
1:10:3219 decreased and 20 increased do you
1:10:38need me to go over any of those yup guys
1:10:43liked it which one 15:15 frame rate and
1:10:47pulse repetition frequency PRF equals
1:10:52velocity over 2d frame rate equals
1:10:55velocity over 2d n if we pulse faster we
1:11:01will have higher frame rates so there's
1:11:04a direct correlation between pulse
1:11:06repetition frequency and frame rate if
1:11:08your frame rate is faster we must have
1:11:11somehow pulsed faster so they are
1:11:14directly proportional so
1:11:16if frame rate increases also repetition
1:11:20frequency must also have increased what
1:11:23makes the 2d is that to DN yeah and four
1:11:27lines of sight okay there are questions
1:11:32on 10 through 20 did you find 10 3 20 a
1:11:37little bit easier because we covered
1:11:40that today the first 4 questions of 1
1:11:44through 9 which was literally half of
1:11:46what we covered were the old echo
1:11:48ranging DT equals C times T which is
1:11:50what you are familiar with off of your
1:11:52midterm so remember the same application
1:11:54can go for D equal C times T is just
1:11:57manipulating the formula figuring out
1:11:59whether it's in the whether it's
1:12:01directly or impersonally proportional by
1:12:02whether it's in the numerator or
1:12:04denominator so it's can be applied to
1:12:05other formulas as well all right let's
1:12:08move on I think there's only two more
1:12:10questions on this page 21 and 22 which
1:12:15is frequency increases what happens to
1:12:18axial resolution it will either improve
1:12:24or increase and if the beam length
1:12:27increases gets bigger what happens a lot
1:12:29of resolution it will degrade or
1:12:31decrease all related to the size of the
1:12:35pulse so frequency increases it creates
1:12:38smaller space it creates smaller
1:12:40wavelengths and therefore smaller
1:12:42spatial pulse links and therefore better
1:12:44axial resolution can I interrupt you yes
1:12:49okay so and for my students I'm pretty
1:12:56picky on that terminology yes like you
1:12:59said when the actual measurement of the
1:13:02resolution decreases it means it
1:13:05improves so I just want to make sure
1:13:08that there were of that yeah okay so
1:13:14sorry I wrote this wrong already
1:13:17and I now erased everything that's great
1:13:20spatial pulse length no I did it wrong
1:13:24again
1:13:25it's axial resolution equals the spatial
1:13:29pulse
1:13:30length in millimeters divided by 2 so
1:13:35what this is written what Kim's talking
1:13:37about is the numerical value of axial
1:13:40resolution the numerical value of axial
1:13:43resolution actually gives you a size in
1:13:45millimeters of how small of an object we
1:13:49can resolve so if you look at this
1:13:52formula and if you increase the spatial
1:13:55pulse length you would say that you
1:13:57increase axial resolution which is the
1:13:59opposite of what I just said
1:14:01I said smaller spatial calls lengths
1:14:03produce better axial resolution the
1:14:07numerical value of this would indicate
1:14:11that a spatial pulse length if it
1:14:14increased in size when that were there
1:14:16for increased axial resolution in terms
1:14:19of a numerical value in measurement but
1:14:22as the numerical value in measurement in
1:14:24millimeters gets bigger our ability to
1:14:28resolve small objects actually gets
1:14:29worse that makes sense
1:14:32so what Kim's talking about is the the
1:14:36apparent opposite of understanding is
1:14:39that the axial that's your resolution as
1:14:42the numerical value in size gets bigger
1:14:46axial resolution actually degrades think
1:14:49of it this way as the pixel gets bigger
1:14:51on the screen it actually looks uglier
1:14:54because the resolution is worse right we
1:14:57saw that earlier as the pixels got
1:15:00smaller
1:15:00we actually improved our rows axial
1:15:03resolution so think of the numerical
1:15:06value of axial resolution as the size of
1:15:08the pixel as it gets bigger the
1:15:10numerical value of x 0 solution gets
1:15:13bigger
1:15:13it means our axial resolution actually
1:15:16degrades or gets worse so the only way
1:15:19that you would be able to tell that on a
1:15:20test is if I actually said axiom
1:15:24resolution measured in millimeters or
1:15:26the numerical value of axial resolution
1:15:28is directly proportional to your spatial
1:15:31pulse length axial resolution the
1:15:34ability resolve small detail actually
1:15:36improves as your spatial pulse length
1:15:38gets smaller does that make sense
1:15:42alright moving to page to them all I
1:15:46start were there any other questions 21
1:15:48and 22
1:15:50just those two questions okay let's go
1:15:55over 23 through 39 the last one
1:15:59so 23 color red here 23 and I have
1:16:06decreased 24 I have increased 25 I have
1:16:12increased 26 I have increased 27
1:16:18I have decreased 28
1:16:21I have decreased 29 is increased 30 is
1:16:29increased 31 decreased 3 whoa
1:16:35oh wait 32 there it is
1:16:39I'm sorry I skipped over that that is
1:16:42decreased and 33 is increased 34 is
1:16:51increase 35 as decrease 36 is decreased
1:16:5637 decreased 38 increased and lastly 39
1:17:05is decreased you me get over there go
1:17:08over any of those 31 as frequency
1:17:14increases what happens to wavelength so
1:17:17again we know the formula wavelength
1:17:18equals velocity divided by frequency
1:17:20right so it's frequency in the
1:17:23denominator increases wavelength would
1:17:27decrease in person a proportional 13 for
1:17:33velocity decreases and the distance
1:17:36remains unchanged what happens to time
1:17:38again going back to the formula T equals
1:17:40D over C from chapter one if time whoops
1:17:47which one was that again time Oh
1:17:52velocity its velocity decreases which is
1:17:54in the denominator
1:17:55what happens to time inversely
1:17:57proportional time should increase 35
1:18:05velocity equals distance over time and
1:18:11it says time increases and distance
1:18:16remains unchanged what happens velocity
1:18:18again because it's in the denominator as
1:18:20it increases what we're solving for will
1:18:22be inversely proportional or decrease
1:18:26any other questions 23 so it's already
1:18:29done
1:18:29can I see 27 yes 27 as density of the
1:18:36medium increases propagation speed this
1:18:38is remembering from acoustic variables
1:18:41to remember density is inversely
1:18:43proportional to propagation speed so as
1:18:45density increases propagation speed
1:18:48should decrease
1:18:49I'm pretty proud of myself only got a
1:18:51couple wrong good which means this works
1:18:54right yes card it's not that bad to
1:19:03memorize because a lot of stuff follows
1:19:05patterns high spatial pulse length the
1:19:07entire formula is books is here so that
1:19:12part you know you also know the formula
1:19:16for wavelength it follows a pattern
1:19:17pulse duration that whole formulas there
1:19:20the period formulas here again you know
1:19:24that P rpm PRF are inversely
1:19:26proportional you know the formula for PR
1:19:28F and you know the echo ranging formula
1:19:32they all follow patterns and then lastly
1:19:34the pulse duration over the PRP is known
1:19:37as duty factors so you know all these
1:19:39patterns you just have to put it
1:19:41together and the process of learning how
1:19:44to write this formula will help you
1:19:47understand how you can see that they're
1:19:48all related so I would suggest getting a
1:19:52blank piece of paper turning it over and
1:19:54trying to write it from memory then look
1:19:56again see if you got a right turn over
1:19:59another blank piece of paper
1:20:00try it again keep doing it until you can
1:20:03do it without even trying
1:20:07in tariffs he's always opposite oh yes
1:20:11yeah and remember everything on top has
1:20:14nothing to do with what's on the bottom
1:20:16all right they don't relate to each
1:20:19other it's a lot to cover in one day but
1:20:25hopefully you feel a little bit better
1:20:26about how they're interconnected and how
1:20:28you can relate to them Venus right could
1:20:32you just answer 39 questions about it
1:20:34and I would agree other than a momentary
1:20:39lapse of judgment
1:20:40you probably got most of them right if
1:20:42you look at the formula if you tried to
1:20:45do it without looking at the program you
1:20:47probably messed up Hey
1:20:50all right that being said are there any
1:20:53other questions about chapter 4 or this
1:20:56formula and please remember when you go
1:20:59to take your test next week when I can
1:21:00to test out the first thing you should
1:21:02do is write this formula right at the
1:21:03top so that nerves don't get in your way
1:21:07of remembering how the formula works
1:21:09okay and then from there you can
1:21:13reference that the entire test long I've
1:21:17also given you a practice test to take
1:21:21home and the next thing we're going to
1:21:23lab are there any questions about
1:21:25chapter 4 before we sign off once twice
1:21:33Kim you got anything nope we're good
1:21:36here