Ramacorp.org - Homebrew robotics and inventions, and other interesting things. http://www.ramacorp.org Tue, 05 Jul 2011 13:00:19 GMT I finally decided to take a moment and go back in time to my first cell phone. I think I bought my first cell phone in my second or third year in college. I started with a paltry 300 minutes which was fine most of the time. I did go on a vacation one time, and back then (late 1990's early 2000) when you go on roaming you may get jacked. And I did, I think I had a bill for $130 just for what seemed to be a handful of calls. Motorola v120c It was a Motorola v120c, and I thought it was particularly cool because of it looked like a walkie talkie (not a desired feature these days) and it had a long antenna. The LCD was monochromatic with a light green backlight. I was also particularly fond of the checkerboard pattern around the display. This was a time when cell phones looked weird and everyone had a different shaped phone. A few years later when my contract was up, I decided to get new phone. Still in college, I went for the free with contract phone. Kyocera QCP 3035 This phone also had an uber long antenna that is pulled out. The display was bigger than my previous phone by about 2 or 3 lines, which was important back then. I remember that this phone, even with the keypad locked, had a problem of pocket dialing people. Never figured that out... I remember at the time being jealous of another phone, the Kyocera QCP 6035, which was basically looked like a scientific calculator. One of the neat things about this phone was that it could store like 6000 contacts, which if you recall that during these days, you sometimes ran out of phonebook space and had to decide who you didn't really like or call much to make more room. Here's a pic of the QCP 3035 although I never owned it. The front face/dialpad flipped out to reveal a pda-style interface Nokia 5170 Time to get a new phone again. Seems like Nokia was doing very well at this time. I seemed to really like candybar phones, even though I should have learned my lesson with pocket dialing. Nevertheless, I decided to get Nokia candybar phone, with yes, a super-extendo antenna. It wasn't a bad phone, but not very cool either. This phone had an endless supply of different covers you can snap on that can make the buttons different shapes or so you can fly the American flag on your cell phone. I never really got into all of the mods, just kept it plain jane. LG VX6100 I finally decided to get a flip phone. This was also my first phone with a camera and a color LCD screen. The added bonus was an outside facing clock (Ooooh). The phone antenna could also be extended, but I rarely ever did so. The battery life on this thing was starting to fade after a year of use. So I went with an extended battery, which was big and bulgy and needed a bigger outside cover. This made the whole thing over 1" thick! Motorola KRZR K1m I think at this point i found that I liked flip phones. This phone came out after the RAZR was so popular. It was a little skinner and sleeker, and had touch buttons on the outside to listen to your music. When this phone was sold the carrier was also pushing for things like streaming video and watching tv and stuff. It had a slot in the back for a microSD card, so I threw a 1GB card in just to see how it plays music. It also made it easy to save pics to the card instead of trying to transfer it to the computer otherwise. The camera, if I recall, wasn't that bad. Samsung Omnia Smartphones were already very popular at this point. The iPhone was already out making headlines, and I believe you could still get a Palm Treo. When I got this phone, it actually seemed really fast ands mooth. Compared to devices out now, its actually rather sluggish. It ran Windows Mobile 6.1 The camera was very good for picture and video. And it was a very handy and small design. A neat aspect of this was the optical 'mouse,' which can be seen as the black square in the front. It was a must since Windows Mobile 6.1 and 6.5 were still designed to be used with a stylus, so being able to leave the stylus at home and still hit the teeny-tiny on screen buttons with a mouse using the optical pad was important. What's nice about the Omnia is all the stuff people started to do with it. I did run Android on it (1.6 from Andromnia ) and its amazing how smooth it runs on this device. The downside with the current port of Android for this phone is that you can't turn it off and it gets super hot! As a test I let Android run until thermal protection kicked in and shut off the phone. Pantech Jest The Omnia was the first phone with a data plan and I was at a point where I didn't like all of the add-on's with cell phones, cable, etc. I had cancelled my XM satellite service, reduced my cable to basic cable, and decided to get a new phone without the data plan, saving me just under $30/mo. $30/mo for 2 years is $720, so its pretty considerable. The Pantech was a phone you couldn't buy in the store, you had to purchase it online. It had a few first's for me like that it was a slider and it had a QWERTY keypad.The touchscreen keypad of the Omnia sucked, so I was looking forward to actual buttons to press. The Jest also had an 'optical' direction pad, which was under the 'OK' button. Most of the time it was fine but it would every now and then not respond, and either I'd have to wait a moment or hit back then go back in to what I was working on. The camera quality was really poor (still and video) and viewing pictures in the gallery was agonizingly slow (especially if it was stored on the microSD card). Memory was also low, and I would have to delete text message threads often because of this (I don't think there was an option to store texts onto external memory). Samsung Droid Charge Tired of the Pantech, missing access to the internet from my phone, and seeing how technology had improved, I decided to get back into smart phones. I had done a little research, but it was pretty much an impulsive action to stop into the store and buy a Droid Charg. It runs Android 2.2, exceptionally smooth, and I haven't had any complaints so far. The only challenge is the slight learning curve for using everything in Android efficiently (task switching, settings, etc). It's not hard, but considering I just moved from the Pantech, it was new to me. This is my current phone. Motorola EX112 This phone was purchased because it is a Quad-band GSM phone (850/900/1800/1900). 850/1900 is used in the Americas, and 900/1800 is used everywhere else. Because I am a man of international travel (not really) I wanted a phone that I could use everywhere instead of getting a local phone or figuring out other clever ways of communicating back with the family at home. I believe the EX112 is actually sold for the South American market (not US). Similar there is an EX115 that I think is sold for the Indian market. I just tested it out and its video/photo capability is not bad. It's also very thin and light. It's a very basic interface, but when travelling I don't think it will matter. http://www.ramacorp.org/my_past_cell_phones.php http://www.ramacorp.org/my_past_cell_phones.php Consider an Ackerman steered vehicle. If we were to control the speed of each wheel (as in a 4-wheel drive electric car with a hub motor for each wheel) then the wheel speeds change as our steer angle increases. This even accounts for large steer angles. Consider making a sharp left turn where our steer angle (δ) is 90 degrees. The rear-left wheel would go backwards. R is the radius from the turning center to the center of the rear axle. This is not always the case even in neutral-steer vehicles with perfect Ackerman steered vehicle – the body would experience some vehicle slip angle. The relationship between radius, steering angle, vehicle rotational rate and vehicle dimensions are shown below: wb is wheelbase, tb is trackbase. Positive steer angle δ means a left hand turn, positive turning radius R means a left hand turn. We notice that if the steer angle is zero, our turning radius would be infinite, essentially so large we're going straight. As we round a corner at some desired velocity, regardless of the velocity of each wheel, the entire vehicle and thus the radii of from the turning center to each wheel all share the same rotational velocity, ω. The radii from the turning center to each wheel can be computed as follows: Going back to basics the relationship between velocity, rotational speed, and turning radius is: Using the above formula to derive the velocity of each wheel, and substituting the equation for finding R, we start with the front-left wheel: Bringing tan(δ) into the square root, we remove the sgn(δ) function since it "balances" the sign of tan(δ) . We find: Repeating this for the front-right wheel, we get: Doing the same for the rear-left wheel: And repeated for the rear-right wheel: Showing the velocities of all four wheels, with our steering angle δ and Vdes as variable inputs: http://www.ramacorp.org/4wd_vehicle_with_independent_wheel_speed_control.php http://www.ramacorp.org/4wd_vehicle_with_independent_wheel_speed_control.php So somehow I was stupid enough to get a virus on my computer. I started noticing weird performance when my browser (firefox and ie) wouldn't do anything when I typed in an address, followed a link, etc -- I'd get a blank page. I found in my event viewer a TCP/IP warning "TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts." I checked how many connections I had using netstat -a in the command prompt and found that I was connected to 100's of yahoo mail accounts, and others that whizzed past the screen that I couldn't make out. After some research, I found that I had an unusual process called csrss.exe running. Usually csrss.exe runs from c:/windows/system32 but it seems that I now also had another copy at c:/windows (the same applied to winlogon.exe which should be under the system32 folder). Ad-Aware found this: Many sites seems to recognize that csrss.exe is a windows process and is safe, but that's not always the case. You should see something odd in the Task Manager if you do have this, two instances of csrss.exe running, one from username SYSTEM, and one under your username. You may not be able to kill this process, you may need to go to safe mode. This website also discusses csrss.exe to a short extent. http://www.ramacorp.org/csrss_exe_virus_mass_mailer.php http://www.ramacorp.org/csrss_exe_virus_mass_mailer.php I'm new to linux and have found that there are several apps that make an annoying system beep, even if the audio is muted. Here is one way to stop the beeps for Firefox and Emacs: In firefox, to stop the beep when trying to find a search string, type in about:config in the search bar and under the value accessibility.typeahead.enablesound change the value to false . In emacs, to stop the beep when scrolling to the top or bottom, create/edit a file named .emacs in your home folder and add a line that says (setq visible-bell 1) . This will turn the annoying beep into a flashing bar at the top and bottom if you scrolled passed the limits. http://www.ramacorp.org/stop_annoying_beeps_in_linux.php http://www.ramacorp.org/stop_annoying_beeps_in_linux.php Don't you hate it when you don't have the Matlab toolbox to design a lowpass butterworth filter? I do. So I printed them all out so I can use it later. %Long list of butterworth (lowpass) filter designs % %For example: data was sampled at 100Hz. Building a butterworth filter %with cutoff of 20 Hz would have Wn = 0.4 for 20 Hz %(Wn = 1 corresponds to 50Hz, half the sample rate) % %Apply filter using fil = filter(b,a,raw); % % for i=1:1:10 % for j=0.1:0.1:0.9 % [b,a] = butter(i,j); % % cmd = ['%[b, a] = butter(' num2str(i) ', ' num2str(j) ')']; % disp(cmd); % disp(['b = [' num2str(b) '];']); % disp(['a = [' num2str(a) '];']); % disp(' '); % end % end %[b, a] = butter(1, 0.1) b = [0.13673 0.13673]; a = [1 -0.72654]; %[b, a] = butter(1, 0.2) b = [0.24524 0.24524]; a = [1 -0.50953]; %[b, a] = butter(1, 0.3) b = [0.33754 0.33754]; a = [1 -0.32492]; %[b, a] = butter(1, 0.4) b = [0.42081 0.42081]; a = [1 -0.15838]; %[b, a] = butter(1, 0.5) b = [0.5 0.5]; a = [1 -5.5511e-017]; %[b, a] = butter(1, 0.6) b = [0.57919 0.57919]; a = [1 0.15838]; %[b, a] = butter(1, 0.7) b = [0.66246 0.66246]; a = [1 0.32492]; %[b, a] = butter(1, 0.8) b = [0.75476 0.75476]; a = [1 0.50953]; %[b, a] = butter(1, 0.9) b = [0.86327 0.86327]; a = [1 0.72654]; %[b, a] = butter(2, 0.1) b = [0.020083 0.040167 0.020083]; a = [1 -1.561 0.64135]; %[b, a] = butter(2, 0.2) b = [0.067455 0.13491 0.067455]; a = [1 -1.143 0.4128]; %[b, a] = butter(2, 0.3) b = [0.13111 0.26221 0.13111]; a = [1 -0.74779 0.27221]; %[b, a] = butter(2, 0.4) b = [0.20657 0.41314 0.20657]; a = [1 -0.36953 0.19582]; %[b, a] = butter(2, 0.5) b = [0.29289 0.58579 0.29289]; a = [1 -2.6368e-016 0.17157]; %[b, a] = butter(2, 0.6) b = [0.39134 0.78267 0.39134]; a = [1 0.36953 0.19582]; %[b, a] = butter(2, 0.7) b = [0.505 1.01 0.505]; a = [1 0.74779 0.27221]; %[b, a] = butter(2, 0.8) b = [0.63895 1.2779 0.63895]; a = [1 1.143 0.4128]; %[b, a] = butter(2, 0.9) b = [0.80059 1.6012 0.80059]; a = [1 1.561 0.64135]; %[b, a] = butter(3, 0.1) b = [0.0028982 0.0086946 0.0086946 0.0028982]; a = [1 -2.3741 1.9294 -0.53208]; %[b, a] = butter(3, 0.2) b = [0.018099 0.054297 0.054297 0.018099]; a = [1 -1.76 1.1829 -0.27806]; %[b, a] = butter(3, 0.3) b = [0.049533 0.1486 0.1486 0.049533]; a = [1 -1.1619 0.69594 -0.13776]; %[b, a] = butter(3, 0.4) b = [0.098531 0.29559 0.29559 0.098531]; a = [1 -0.57724 0.42179 -0.056297]; %[b, a] = butter(3, 0.5) b = [0.16667 0.5 0.5 0.16667]; a = [1 -3.3307e-016 0.33333 -1.8504e-017]; %[b, a] = butter(3, 0.6) b = [0.25692 0.77075 0.77075 0.25692]; a = [1 0.57724 0.42179 0.056297]; %[b, a] = butter(3, 0.7) b = [0.37445 1.1234 1.1234 0.37445]; a = [1 1.1619 0.69594 0.13776]; %[b, a] = butter(3, 0.8) b = [0.52762 1.5829 1.5829 0.52762]; a = [1 1.76 1.1829 0.27806]; %[b, a] = butter(3, 0.9) b = [0.72944 2.1883 2.1883 0.72944]; a = [1 2.3741 1.9294 0.53208]; %[b, a] = butter(4, 0.1) b = [0.0004166 0.0016664 0.0024996 0.0016664 0.0004166]; a = [1 -3.1806 3.8612 -2.1122 0.43827]; %[b, a] = butter(4, 0.2) b = [0.0048243 0.019297 0.028946 0.019297 0.0048243]; a = [1 -2.3695 2.314 -1.0547 0.18738]; %[b, a] = butter(4, 0.3) b = [0.018563 0.074252 0.11138 0.074252 0.018563]; a = [1 -1.5704 1.2756 -0.4844 0.076197]; %[b, a] = butter(4, 0.4) b = [0.046583 0.18633 0.2795 0.18633 0.046583]; a = [1 -0.7821 0.67998 -0.18268 0.030119]; %[b, a] = butter(4, 0.5) b = [0.093981 0.37592 0.56389 0.37592 0.093981]; a = [1 -2.2551e-016 0.48603 -4.6876e-018 0.017665]; %[b, a] = butter(4, 0.6) b = [0.16718 0.66872 1.0031 0.66872 0.16718]; a = [1 0.7821 0.67998 0.18268 0.030119]; %[b, a] = butter(4, 0.7) b = [0.27541 1.1017 1.6525 1.1017 0.27541]; a = [1 1.5704 1.2756 0.4844 0.076197]; %[b, a] = butter(4, 0.8) b = [0.43285 1.7314 2.5971 1.7314 0.43285]; a = [1 2.3695 2.314 1.0547 0.18738]; %[b, a] = butter(4, 0.9) b = [0.66202 2.6481 3.9721 2.6481 0.66202]; a = [1 3.1806 3.8612 2.1122 0.43827]; %[b, a] = butter(5, 0.1) b = [5.9796e-005 0.00029898 0.00059796 0.00059796 0.00029898 5.9796e-005]; a = [1 -3.9845 6.4349 -5.2536 2.1651 -0.35993]; %[b, a] = butter(5, 0.2) b = [0.0012826 0.0064129 0.012826 0.012826 0.0064129 0.0012826]; a = [1 -2.9754 3.806 -2.5453 0.88113 -0.12543]; %[b, a] = butter(5, 0.3) b = [0.0069332 0.034666 0.069332 0.069332 0.034666 0.0069332]; a = [1 -1.9759 2.0135 -1.1026 0.32762 -0.040709]; %[b, a] = butter(5, 0.4) b = [0.02194 0.1097 0.2194 0.2194 0.1097 0.02194]; a = [1 -0.98533 0.97385 -0.38636 0.11116 -0.011264]; %[b, a] = butter(5, 0.5) b = [0.052786 0.26393 0.52786 0.52786 0.26393 0.052786]; a = [1 -4.6491e-016 0.63344 -2.0438e-016 0.055728 -3.0935e-018]; %[b, a] = butter(5, 0.6) b = [0.10837 0.54187 1.0837 1.0837 0.54187 0.10837]; a = [1 0.98533 0.97385 0.38636 0.11116 0.011264]; %[b, a] = butter(5, 0.7) b = [0.20189 1.0094 2.0189 2.0189 1.0094 0.20189]; a = [1 1.9759 2.0135 1.1026 0.32762 0.040709]; %[b, a] = butter(5, 0.8) b = [0.35416 1.7708 3.5416 3.5416 1.7708 0.35416]; a = [1 2.9754 3.806 2.5453 0.88113 0.12543]; %[b, a] = butter(5, 0.9) b = [0.59994 2.9997 5.9994 5.9994 2.9997 0.59994]; a = [1 3.9845 6.4349 5.2536 2.1651 0.35993]; %[b, a] = butter(6, 0.1) b = [8.5766e-006 5.1459e-005 0.00012865 0.00017153 0.00012865 5.1459e-005 8.5766e-006]; a = [1 -4.78714 9.64952 -10.4691 6.44111 -2.12904 0.295172]; %[b, a] = butter(6, 0.2) b = [0.00034054 0.0020432 0.0051081 0.0068108 0.0051081 0.0020432 0.00034054]; a = [1 -3.5794 5.6587 -4.9654 2.5295 -0.70527 0.083756]; %[b, a] = butter(6, 0.3) b = [0.0025851 0.01551 0.038776 0.051701 0.038776 0.01551 0.0025851]; a = [1 -2.3797 2.9104 -2.0551 0.87792 -0.20987 0.021832]; %[b, a] = butter(6, 0.4) b = [0.010313 0.061877 0.15469 0.20626 0.15469 0.061877 0.010313]; a = [1 -1.1876 1.3052 -0.67433 0.26347 -0.051753 0.0050225]; %[b, a] = butter(6, 0.5) b = [0.029588 0.17753 0.44382 0.59176 0.44382 0.17753 0.029588]; a = [1 -1.164e-015 0.7777 -5.2358e-016 0.1142 -7.0192e-017 0.0017509]; %[b, a] = butter(6, 0.6) b = [0.070115 0.42069 1.0517 1.4023 1.0517 0.42069 0.070115]; a = [1 1.1876 1.3052 0.67433 0.26347 0.051753 0.0050225]; %[b, a] = butter(6, 0.7) b = [0.14773 0.88639 2.216 2.9546 2.216 0.88639 0.14773]; a = [1 2.3797 2.9104 2.0551 0.87792 0.20987 0.021832]; %[b, a] = butter(6, 0.8) b = [0.28941 1.7364 4.3411 5.7881 4.3411 1.7364 0.28941]; a = [1 3.5794 5.6587 4.9654 2.5295 0.70527 0.083756]; %[b, a] = butter(6, 0.9) b = [0.543298 3.25979 8.14947 10.866 8.14947 3.25979 0.543298]; a = [1 4.78714 9.64952 10.4691 6.44111 2.12904 0.295172]; %[b, a] = butter(7, 0.1) b = [1.2296e-006 8.6075e-006 2.5823e-005 4.3038e-005 4.3038e-005 2.5823e-005 8.6075e-006 1.2296e-006]; a = [1 -5.58898 13.5047 -18.2709 14.9365 -7.3738 2.0344 -0.241873]; %[b, a] = butter(7, 0.2) b = [9.0349e-005 0.00063244 0.0018973 0.0031622 0.0031622 0.0018973 0.00063244 9.0349e-005]; a = [1 -4.1823 7.8717 -8.5309 5.7099 -2.3492 0.54826 -0.055845]; %[b, a] = butter(7, 0.3) b = [0.00096289 0.0067403 0.020221 0.033701 0.033701 0.020221 0.0067403 0.00096289]; a = [1 -2.7825 3.9668 -3.4052 1.8759 -0.65095 0.13085 -0.011663]; %[b, a] = butter(7, 0.4) b = [0.0048421 0.033895 0.10168 0.16947 0.16947 0.10168 0.033895 0.0048421]; a = [1 -1.3893 1.675 -1.0539 0.50855 -0.14483 0.026252 -0.0020297]; %[b, a] = butter(7, 0.5) b = [0.016565 0.11596 0.34787 0.57979 0.57979 0.34787 0.11596 0.016565]; a = [1 -4.8572e-017 0.91997 4.9692e-017 0.1927 1.1289e-017 0.0076835 -4.2652e-019]; %[b, a] = butter(7, 0.6) b = [0.045311 0.31718 0.95154 1.5859 1.5859 0.95154 0.31718 0.045311]; a = [1 1.3893 1.675 1.0539 0.50855 0.14483 0.026252 0.0020297]; %[b, a] = butter(7, 0.7) b = [0.108 0.75599 2.268 3.7799 3.7799 2.268 0.75599 0.108]; a = [1 2.7825 3.9668 3.4052 1.8759 0.65095 0.13085 0.011663]; %[b, a] = butter(7, 0.8) b = [0.23631 1.6542 4.9626 8.271 8.271 4.9626 1.6542 0.23631]; a = [1 4.1823 7.8717 8.5309 5.7099 2.3492 0.54826 0.055845]; %[b, a] = butter(7, 0.9) b = [0.491806 3.44264 10.3279 17.2132 17.2132 10.3279 3.44264 0.491806]; a = [1 5.58898 13.5047 18.2709 14.9365 7.3738 2.0344 0.241873]; %[b, a] = butter(8, 0.1) b = [1.7626e-007 1.41e-006 4.9352e-006 9.8703e-006 1.2338e-005 9.8703e-006 4.9352e-006 1.41e-006 1.7626e-007]; a = [1 -6.39036 18.0003 -29.1711 29.7314 -19.5056 8.041 -1.90367 0.1981]; %[b, a] = butter(8, 0.2) b = [2.396e-005 0.00019168 0.00067087 0.0013417 0.0016772 0.0013417 0.00067087 0.00019168 2.396e-005]; a = [1 -4.78451 10.445 -13.4577 11.1293 -6.02526 2.07927 -0.417217 0.0372001]; %[b, a] = butter(8, 0.3) b = [0.00035844 0.0028675 0.010036 0.020073 0.025091 0.020073 0.010036 0.0028675 0.00035844]; a = [1 -3.1846 5.1829 -5.2162 3.4955 -1.573 0.46074 -0.07978 0.0062257]; %[b, a] = butter(8, 0.4) b = [0.0022718 0.018175 0.063612 0.12722 0.15903 0.12722 0.063612 0.018175 0.0022718]; a = [1 -1.5906 2.0838 -1.5326 0.86944 -0.31918 0.08209 -0.012247 0.00086137]; %[b, a] = butter(8, 0.5) b = [0.0092673 0.074138 0.25948 0.51897 0.64871 0.51897 0.25948 0.074138 0.0092673]; a = [1 -2.145e-015 1.0609 -1.8348e-015 0.29089 -4.8597e-016 0.02043 -5.0603e-017 0.00017177]; %[b, a] = butter(8, 0.6) b = [0.029261 0.23409 0.81931 1.6386 2.0483 1.6386 0.81931 0.23409 0.029261]; a = [1 1.5906 2.0838 1.5326 0.86944 0.31918 0.08209 0.012247 0.00086137]; %[b, a] = butter(8, 0.7) b = [0.078902 0.63122 2.2093 4.4185 5.5231 4.4185 2.2093 0.63122 0.078902]; a = [1 3.1846 5.1829 5.2162 3.4955 1.573 0.46074 0.07978 0.0062257]; %[b, a] = butter(8, 0.8) b = [0.192873 1.54299 5.40045 10.8009 13.5011 10.8009 5.40045 1.54299 0.192873]; a = [1 4.78451 10.445 13.4577 11.1293 6.02526 2.07927 0.417217 0.0372001]; %[b, a] = butter(8, 0.9) b = [0.445084 3.56067 12.4624 24.9247 31.1559 24.9247 12.4624 3.56067 0.445084]; a = [1 6.39036 18.0003 29.1711 29.7314 19.5056 8.041 1.90367 0.1981]; %[b, a] = butter(9, 0.1) b = [2.526e-008 2.2734e-007 9.0936e-007 2.1218e-006 3.1828e-006 3.1828e-006 2.1218e-006 9.0936e-007 2.2734e-007 2.526e-008]; a = [1 -7.19144 23.1362 -43.6819 53.3153 -43.6086 23.8956 -8.45602 1.7531 -0.162195]; %[b, a] = butter(9, 0.2) b = [6.3519e-006 5.7167e-005 0.00022867 0.00053356 0.00080034 0.00080034 0.00053356 0.00022867 5.7167e-005 6.3519e-006]; a = [1 -5.38622 13.3786 -19.9617 19.624 -13.137 5.97321 -1.77518 0.312381 -0.024765]; %[b, a] = butter(9, 0.3) b = [0.00013337 0.0012004 0.0048015 0.011203 0.016805 0.016805 0.011203 0.0048015 0.0012004 0.00013337]; a = [1 -3.5863 6.5587 -7.552 5.9363 -3.2606 1.2421 -0.31458 0.047856 -0.0033201]; %[b, a] = butter(9, 0.4) b = [0.0010654 0.0095886 0.038354 0.089493 0.13424 0.13424 0.089493 0.038354 0.0095886 0.0010654]; a = [1 -1.7916 2.5319 -2.1182 1.3708 -0.60904 0.19933 -0.043105 0.0058043 -0.00035558]; %[b, a] = butter(9, 0.5) b = [0.0051819 0.046637 0.18655 0.43528 0.65292 0.65292 0.43528 0.18655 0.046637 0.0051819]; a = [1 -6.5356e-016 1.201 -4.804e-016 0.4085 -1.1608e-016 0.042661 -8.4317e-018 0.00096666 -5.3661e-020]; %[b, a] = butter(9, 0.6) b = [0.018887 0.16998 0.67993 1.5865 2.3798 2.3798 1.5865 0.67993 0.16998 0.018887]; a = [1 1.7916 2.5319 2.1182 1.3708 0.60904 0.19933 0.043105 0.0058043 0.00035558]; %[b, a] = butter(9, 0.7) b = [0.057621 0.51859 2.0743 4.8401 7.2602 7.2602 4.8401 2.0743 0.51859 0.057621]; a = [1 3.5863 6.5587 7.552 5.9363 3.2606 1.2421 0.31458 0.047856 0.0033201]; %[b, a] = butter(9, 0.8) b = [0.157369 1.41632 5.66529 13.219 19.8285 19.8285 13.219 5.66529 1.41632 0.157369]; a = [1 5.38622 13.3786 19.9617 19.624 13.137 5.97321 1.77518 0.312381 0.024765]; %[b, a] = butter(9, 0.9) b = [0.402735 3.62461 14.4985 33.8297 50.7446 50.7446 33.8297 14.4985 3.62461 0.402735]; a = [1 7.19144 23.1362 43.6819 53.3153 43.6086 23.8956 8.45602 1.7531 0.162195]; %[b, a] = butter(10, 0.1) b = [3.6197e-009 3.6197e-008 1.6289e-007 4.3436e-007 7.6014e-007 9.1216e-007 7.6014e-007 4.3436e-007 1.6289e-007 3.6197e-008 3.6197e-009]; a = [1 -7.9923 28.9122 -62.3154 88.5877 -86.7671 59.281 -27.8903 8.64568 -1.59424 0.132768]; %[b, a] = butter(10, 0.2) b = [1.6836e-006 1.6836e-005 7.5761e-005 0.00020203 0.00035355 0.00042426 0.00035355 0.00020203 7.5761e-005 1.6836e-005 1.6836e-006]; a = [1 -5.98759 16.6722 -28.2588 32.1598 -25.6017 14.4057 -5.64707 1.47373 -0.230919 0.0164796]; %[b, a] = butter(10, 0.3) b = [4.9614e-005 0.00049614 0.0022326 0.0059536 0.010419 0.012503 0.010419 0.0059536 0.0022326 0.00049614 4.9614e-005]; a = [1 -3.98765 8.09441 -10.4763 9.42334 -6.08421 2.83526 -0.936403 0.208912 -0.0283359 0.00176963]; %[b, a] = butter(10, 0.4) b = [0.00049945 0.0049945 0.022475 0.059934 0.10489 0.12586 0.10489 0.059934 0.022475 0.0049945 0.00049945]; a = [1 -1.9924 3.0195 -2.8185 2.0387 -1.0545 0.41445 -0.11572 0.022499 -0.0026689 0.00014876]; %[b, a] = butter(10, 0.5) b = [0.0028964 0.028964 0.13034 0.34757 0.60825 0.7299 0.60825 0.34757 0.13034 0.028964 0.0028964]; a = [1 -8.7289e-016 1.3404 -1.0058e-015 0.54535 -3.0468e-016 0.077041 -8.9291e-017 0.0031655 -3.6529e-018 1.6779e-005]; %[b, a] = butter(10, 0.6) b = [0.012187 0.12187 0.5484 1.4624 2.5592 3.071 2.5592 1.4624 0.5484 0.12187 0.012187]; a = [1 1.9924 3.0195 2.8185 2.0387 1.0545 0.41445 0.11572 0.022499 0.0026689 0.00014876]; %[b, a] = butter(10, 0.7) b = [0.042067 0.42067 1.89301 5.04804 8.83406 10.6009 8.83406 5.04804 1.89301 0.42067 0.042067]; a = [1 3.98765 8.09441 10.4763 9.42334 6.08421 2.83526 0.936403 0.208912 0.0283359 0.00176963]; %[b, a] = butter(10, 0.8) b = [0.128373 1.28373 5.77679 15.4048 26.9583 32.35 26.9583 15.4048 5.77679 1.28373 0.128373]; a = [1 5.98759 16.6722 28.2588 32.1598 25.6017 14.4057 5.64707 1.47373 0.230919 0.0164796]; %[b, a] = butter(10, 0.9) b = [0.364374 3.64374 16.3968 43.7248 76.5184 91.8221 76.5184 43.7248 16.3968 3.64374 0.364374]; a = [1 7.9923 28.9122 62.3154 88.5877 86.7671 59.281 27.8903 8.64568 1.59424 0.132768]; http://www.ramacorp.org/list_of_computed_butterworth_filter_coefficients.php http://www.ramacorp.org/list_of_computed_butterworth_filter_coefficients.php If you find yourself bored at home (or at work...) and would like to help out the astronomy community, you can spend an hour helping classify galaxies. The kicker for them is that with all of our technology, they still don't have classification software reliable enough to correctly classify galaxies into 1 of 6 bins: spiral (clockwise from our view), spiral (counterclockwise from our view) spiral (edge-on), elliptical, merging galaxies, or unsure. They maintain robustness in having us classify their galaxies just by the reliability in shear number of users. Their website is http://www.galaxyzoo.org http://www.ramacorp.org/galaxy_zoo.php http://www.ramacorp.org/galaxy_zoo.php