Amps Definition and 104 Threads

IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS), and a further development of the North American 1G mobile system Advanced Mobile Phone System (AMPS). It was once prevalent throughout the Americas, particularly in the United States and Canada since the first commercial network was deployed in 1993. D-AMPS is considered end-of-life, and existing networks have mostly been replaced by GSM/GPRS or CDMA2000 technologies.
This system is most often referred to as TDMA. That name is based on the abbreviation for time division multiple access, a common multiple access technique which is used in most 2G standards, including GSM, as well as in IS-54 and IS-136. D-AMPS competed against GSM and systems based on code division multiple access (CDMA).
D-AMPS uses existing AMPS channels and allows for smooth transition between digital and analog systems in the same area. Capacity was increased over the preceding analog design by dividing each 30 kHz channel pair into three time slots (hence time division) and digitally compressing the voice data, yielding three times the call capacity in a single cell. A digital system also made calls more secure in the beginning, as analogue scanners could not access digital signals. Calls were encrypted, using CMEA, which was later found to be weak.IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data (CSD), and an improved compression protocol. SMS and CSD were both available as part of the GSM protocol, and IS-136 implemented them in a nearly identical fashion.
Former large IS-136 networks, including AT&T in the United States, and Rogers Wireless in Canada, have upgraded their existing IS-136 networks to GSM/GPRS. Rogers Wireless removed all 1900 MHz IS-136 in 2003, and has done the same with its 800 MHz spectrum as the equipment failed. Rogers deactivated its IS-136 network (along with AMPS) on May 31, 2007. AT&T soon followed in February 2008, shutting down both TDMA and AMPS.
Alltel, who primarily uses CDMA2000 technology but acquired a TDMA network from Western Wireless, shut down its TDMA and AMPS networks in September 2008. US Cellular, which now also primarily uses CDMA2000 technology, shut down its TDMA network in February 2009.
IS-54 is the first mobile communication system which had provision for security, and the first to employ TDMA technology.

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  1. EagleOnePro

    High Volts Low Amps: Sustaining Power with Arduino & MOSFET

    Hello, I have a limited knowledge of electronic engineering, so please bear with me. I want to Have a device that I could have high volts with low amps and have the power be sustained. Then I could possibly use an Arduino with a silicon carbide MOSFET to do precise pause with modulation. The...
  2. T

    Why doesn't a light bulb draw 100 amps?

    I am asking this question in behalf of my father ( who does not have an account here to ask this question himself). My father said he does not understand why a simple light bulb in an AC circuit does not draw far more amps than a simple light bulb draws. He thinks that a typical light bulb...
  3. C

    How do rail-to-rail op amps get so close to the rail voltages?

    I'm just curious, I have looked for application notes and such but don't see a simple answer to this question. Given the band gap of semiconductors that are very obvious in devices like diodes and transistors and such, how do designers achieve 'rail-to-rail' performance in an op amp, and get...
  4. S

    Peak Amps of a heat pump based AC vs compressor based AC?

    In my city (USA) typical older houses have "100 Amp service" so their peak electric usage is limited to 100 Amps. In considering what sort of electric air conditioning system to install in such a house, peak usage is major consideration. Generally speaking, which type of residential unit...
  5. T

    Why do AC motors pull high amps when they go bad?

    I used to work in HVAC. There are three main types of alternating current (AC) motors in residential air-conditioners and heat pumps: outdoor fan motors, compressors, and indoor blower motors. All three types of AC motors have the maximum number of amps stated on the nameplates of the units...
  6. R

    Engineering Find Vout as a function of V1 and V2 (OP Amps)

    Here's the circuit in question: Solution: Now, when I try simulating in LTSpice, this is what I get: So, Vout appears to be around -13 V, which doesn't agree with the equation if V1=V2= 5 is plugged in. Does anyone see the mistake here? THanks.
  7. F

    What causes an AC motor to pull locked rotor amps?

    When an alternating current motor first turns on, what causes an alternating current motor to pull locked rotor amps for approximately one second after first turning on as opposed to just pulling the same amount of amps the entire time? What causes the amperage on an AC motor to drop after...
  8. Y

    Anyone in the SF Bay Area into audiophile and/or building amps etc.?

    Hi I live in the Santa Clara bay area in the Silicon Valley, I want to see anyone here that are living close by that are into high end audiophile stuffs particular designing and building audio electronics. It's hard to find anyone that is into this, it would be nice to find people to share this...
  9. kolleamm

    High current power supply for servos? 40+ amps

    So I've basically built a robot that has a lot of servo motors. 14 of them can draw up to 3 amps each(max)(usually 1 amp average) at 4.8 to 7 volts. What's my best option to power it? The power source doesn't need to be connected to the robot, so weight shouldn't be an issue. My best guess is...
  10. K

    Electric Circuts (Voltage, Ohms, Amps)

    I made a chart and this is my attempt. I am not sure that I am doing the calculations right thou
  11. F

    What causes locked rotor amps on a motor?

    When an electric motor first starts running, the motor will draw approximately 5X the normal amp draw of the motor for approximately the first half second that the motor runs. The amps that an electric motor draws for about half a second that are about 5X the normal amp draw of the motor are...
  12. T

    How does mechanical torque affect generator volts and amps?

    Hello! today I have a question regarding the most efficient way to generate electricity by moving a magnet across a coil. The theoretical magnet would be moving in a circular motion fixed to the outer circumference of a driver wheel like in many simple generators, how does the physical torque...
  13. S

    How to calculate power using amps drawn?

    Is there a formula that I can use to calculate the HP a motor is actually making if all I have is amp draw? I am trying to size a gearbox, but the customer has no idea what torque is needed. All they know is the motor is drawing 5 amps when it spikes and 3.5 amps when it is running. I am...
  14. O

    What does a lightbulb prefer? Volts or Amps?

    Lightbulbs are rated in watts. Watts = energy/time = volts*current Does it matter if you have a very low voltage source with a very high current or a very high voltage with a very low current? If the voltage and current multiplied meets the power rating, what should it matter what proportion...
  15. R

    Looking for a quad rail-to-rail op amp similar to TL074 in DIP14 package?

    Hello. I'm looking for a quad op amp similar to TL074 but rail to rail (mainly for input) in DIP14 (I found a lot in SMD) and supporting +12V / -12V as power supply.
  16. T

    How to determine how many watts / amps for lifting a weight

    Is there a way to determine how many amps / watts is required from an electric motor in order to move (lift, push or pull) an object weighing a specific amount? Conversely, is there a way to determine the maximum amount of weight an electric motor can move (lift, push or pull) based on its...
  17. J

    Limiting amps and volts from a battery

    I have a project that involves a small motor, and the battery powering it would blow the motor in an instant without proper use of resistors. The battery I'm using is rated at 9.6 volts and 1600ma. The motor however, is rated at 3 volts and 0.3 Amps. I would like to go just under these ratings...
  18. VFEmitter

    What really is "energy" -- is it the amps or the wattage?

    If volts is only an "electro motive force", that is, it only pushes, and resistance is what tries to hold everything back, and "amperage", that is, current, is the actual electricity ( or not, that is my question ) and watts is the calculation of everything together and the total output, is it...
  19. yavorh

    BLDC: Required voltage to get set rpm at given amps

    Hey guys! So I'm trying to do this pretty wide diameter in-runner engine, where the rotor is hollow (essentially trying to make a short tube within a short tube :D). After checking out the details between the different types of electric motors (and realizing that I can barely find any...
  20. T

    Batteries connected in parallel - Amps won´t add up?

    Batteries are connected in parallel. Multimeter shows: 1,5V AND... "0.12A" regardless of battery number. Volts stay the same but should not Amps add up in parallel? "0.12A" with 4, 5 or 6 batteries... Details: Amps measured correctly by closing the circuit with multimeter probes (bulb lights...
  21. D

    12V charging circuit between two batteries limiting max amps

    Hello, I was reading a previous thread that is now closed. What I'm curious about is a simple wiring schematic. I want to charge a battery on my trailer while it's hooked to the truck from the trailer 7 pin rv connection. The rv connection has a 12v hot all the time wire that I could use to...
  22. K

    Inverting a signal up to 100mV using op amps

    Greetings, I'd like to invert a signal I get from a photodetector (the signals are up to 100 mV). I decided to use an inverting op amp circuit for that, however, when looking online through the op amp catalogs - the minimum input voltage in the descriptions is a few volts while my input would...
  23. B

    Input and output voltages and amps on my laptop's charger

    The wire on the charger that came with my laptop eventually frayed, and I had to buy a new charger for my laptop. Both the new and old chargers for my laptop plug into a standard wall outlet. On the new charger, it says the following: " Input: 100-240V ~ 1.5A 50-60Hz Output: 19V --3.42A 65W...
  24. Sam19KY

    Increase of Amps form 1 to 2 means what?

    Does that mean that the electrons are moving faster or what ?
  25. G

    Energy Calculations: P=VxIxt - Why Watts & not Joules?

    The question: Calculate the energy used by the lamp in 6 hours of use. The answer: P=V.I.t P= 240v X 0.2A X 6hrs X 3600s P= 1036800W!? I thought energy was Joules? Why has the answer been given in watts? Please help!
  26. C

    Understanding Inputs and Outputs for Specific Project

    << Mentor Note -- Please read to the end of this thread -- important information about AC Mains connected projects is discussed >> Hello everyone, I am an electrical engineering student (though in the very beginner stage of it), and I could really use some help with understanding inputs and...
  27. B

    Energy to lift a mass, voltage, amps, time, distance confuse

    Homework Statement A student investigates the efficiency of a small electric motor. He uses a motor to lift it a mass through a constant distance of 1 m. He times how long it takes to lift the masses and makes a record of the potential difference and the current of the motor. In the book that...
  28. 1

    OP Amp Comparators: V+ > V- for +16V Output

    Homework Statement https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/73/73750-4bf3d2aa03a724fcf0b13a6b1111902f.jpg The Attempt at a Solution V+ > V- for Vout to be +16V V+ < V- for Vout to be -16V V+ = -8x(in) V- = (-15x18)/30 + (15x12)/30 = -3 My attempt on it was that...
  29. ptownbro

    Is it possible to increase the amps within/along a circuit?

    Let's say you have a basic series circuit with a battery power source that has 12 volts. You also have a load of some sort with 3 ohms of resistance. Therefore you'll have 4 amps of current throughout the circuit. Is it possible to add some item within or along the circuit (and before the load)...
  30. B

    Amp vs. USB: Understanding the Truth About Voltage and Resistance

    What am I missing here? I know USBs don't kill you so I know I've got something wrong. Google tells me that around 0.1A has a really good chance of killing you; and everything I read says it's the amps that kill you not the volts. So I know van der grafs and static shocks won't kill you. My...
  31. Abir

    What power supply (amps) would run this plasma globe?

    my 3inch plasma globe needs 5V 300mA dc supply... Can I use an adapter with 4.5V and 50mA output rating? If can't then what will happen if I still do use it?
  32. Superposed_Cat

    Cheapest way to amplify 40ma to 2 amps

    Hey all, working on a pet project where I need a microcontroller with a 40ma pin output to be amplified to 2A, op-amps can't do the job, and H bridge motor drivers will be too expensive i think considering the amount of motors I need. What is the cheapest and smallest way to do this? Any help...
  33. H

    What Wattage Rating Is Needed for a 33Ohm Resistor in a 9V, 1A Circuit?

    Hello, I am new to any type of engineering and just have been working with Arduinos and other microcontroller lately for fun. I am creating a prototype for a project that requires me to use a 9V power supply with 1Amp to power the Arduino(note, the arduino only needs around 300mA to run). I...
  34. B

    Electricity Question Amps & volts confusion

    Homework Statement [/B] A) If a laptop computer charger is designed for use in a country where mains voltage is 230V. Will the user still be able to charge the laptop computer in a country where the mains supply is 110V? B) Also what happens if a 110V charger is used in a country where the...
  35. R

    Fixed Gain Op Amps | Pre-Set Resistance for Voltage Boost

    Are there any readily available op amps with built in resistors that give a fixed gain, say 5, 10, 50, 100 etc. A lot of times I need to boost a sensor output and I'm too lazy to find/solder resistors do it. I'd rather buy a bunch of pre-set amplifiers that are ready to be plugged in and...
  36. A

    Sinusoidal Current of .5 Amps (rms) & 5 kHz

    This is just a quick question: A problem I'm working on says "a sinusoidal current of .5 amps (rms) and 5 kHz." Later, in the problem solution, I(t) is written as .5 \sqrt{2} \cos{(10^4 \pi t)}. I think I'm simply misunderstanding something about the construction of a current function when...
  37. perplexabot

    IF amps for a superhet AM receiver

    Hey all. So I am now trying to work on IF amps for a superhet AM receiver (medium wave) and found the following figure in the ARRL handbook: I have a couple of questions regarding these schematics. First and most importantly, do these work for IF signals (of 455KHz with BW of 18KHz)...
  38. T

    Can Increasing Amperage Generate Arbitrarily Large Power with a Hand Generator?

    Hi, I am a bit confused about what exactly is being produced when someone uses a hand generator. I know P=R(I^2). Does this mean that if I have a hand crank that can produce 1 amp I can use a 200 ohm resistor and produce 200 watts of power. If this is the case it seems as though producing any...
  39. A

    Can differential op amps operate without any supply?

    Just want to amplify the difference of inputs.
  40. C

    Coversion - how many amps in 310 kW?

    Coversion -- how many amps in 310 kW? Hello all, I am engineering handicap, can someone help me figure out how many amps in 310 kW.
  41. A

    How Do I Maximize Amps from AA Batteries?

    What's the maximum amps that can i get from an aa battery without damaging it and how fast that should happen? Also if i had 2 aa batteries and i want to get maximum amps, how it is better to connect them (series or paralel) and how much does it take them to discharge? (sorry for my poor...
  42. T

    Question about bistable multivibrator op amps

    Homework Statement So for one of my labs, I had to make a bistable multivibrator and observe the transfer characteristics. The circuit is setup as follows: http://i.imgur.com/1G4M7DE.jpg (Image is too big to be inserted in this forum) This resulted in the following hysteresis loop...
  43. R

    Adjusting Op Amps for LED Lighting: Understanding Comparator Behavior

    Edit: I solved it, and found that it should be 30v because that causes a 24v drop across 40kohm resistor which is 6v, which is equal to the voltage at the non inverting terminal, meaning Vout will be +VSat, but I don't understand why this is correct, because my notes say that if the voltage at...
  44. T

    Question about bistable multivibrator op amps

    Homework Statement Here is the problem: So this is a bistable multivibrator. Homework Equations KVL and KCL lawsThe Attempt at a Solution I don't entirely understand bistable multivibrators. I get what the solution is, the input voltage caps at 0.1V and the output caps at 0.7V and hysteresis...
  45. S

    Heating water with amps ohms and time

    so if i have 89.6g water at 304K and a constant p=1.00bar and i heat it by running 1.75A through 24.7 for 105 seconds what will the final temp be? im thinking i can take q=mC(Tf-Ti) and q=IT and I=R/V to say that Tf= (Rt/vCm)+Ti i can't rember that much about physics and this stuff...
  46. A

    Can you boost RF signal power with a generic op amp?

    Sorry if this seems like a simple question, but I am new to RF systems. Is there a difference between an RF amplifer and a single rail operational amplifer? Or can you boost the power of an RF signal with a generic op amp? Also, when dealing with an RF signal, are coax cables and SMA...
  47. K

    What power supply (amps) would run this plasma globe optimally?

    It says DC in 12volts but I'm not sure how many amps this thing can handle... I don't want to plasma myself so I was looking for helpful answers, thanks guys pic of globe (paid $8 not bad) http://postimg.org/image/462gwlj5v/
  48. B

    Amps through Christmas tree lights

    I always wanted to know how this worked? I know AMPs is how many Electrons move past one point in a SEC. I know that Voltage is the Force that drives the AMPs. I know that a House Outlet will supply 120 Volts at 15 Amps. Now take Christmass Tree Lights and to keep this easy let's...
  49. K

    Op amps, negative feedback or not?

    Homework Statement What is the exact definition of negative feedback? the instructor told us that negative exists if the output is connected back to the inverting input through a passive element. But what exactly is precise the definition ? (say parallel connect, same two nodes, I want the...
  50. P

    Does volts and amps get at half while charging multiple batteries?

    Hi guys (and gals) Say, i have a solar panel rated at 100w 12v with the following specs: Short circult current(Isc): 6.01A Open circuit voltage(Voc): 21.5V Optimum operating current: (Imp) 5.52A Optimum operating voltage: (Vmp) 17.78v Maximum power: (Pmax) 100W And I decide to...
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