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Technology Stocks : Qualcomm Incorporated (QCOM) -- Ignore unavailable to you. Want to Upgrade?

To: JMD who wrote (4980)	10/24/1997 6:01:00 PM
From: Ramsey Su	Read Replies (1) \| Respond to of 152472

Mike, do you have to post in such big long paragraphs that challenge my attention span? QCOM puts out a bunch of little brochures about CDMA, WLL etc etc. I have many misc articles on QCOM so I can't remember where these came from. If you call investor relations, I think they will provide. They do a very good job in explaining the technology. Ramsey

To: JMD who wrote (4980)	10/24/1997 9:12:00 PM
From: Asterisk	Read Replies (2) \| Respond to of 152472

Cellular telephony 101 is in session, everyone take your seats: Here is how a cell phone works (or pretty close). From your question I think that you wanted to know how the signals from your phone get routed to someone elses phone. If you want to know the physics of how your voice gets translated from voice to electrical impulses we can do that too but this is about radio waves. A simple experiment to demonstrate the basics of how a radio wave is transmitted and recieved: Go to your bathtub with 2 sticks. One of these sticks has to have a washer or something on it. Place the 2 sticks some distance apart (it doesn't matter how far). Move that washer up and down on the stick. See how it generates waves on the water? Now imagine that the water is air, the same thing happens. When you are transmitting you are basically moving air particles like the washer moved the air, and the waves are propigating (moving) through the air like the waves moved through the water. With an ideal antenna you get circular waves, like you got in the bathtub, that theoretically go on forever. In reality there is some resistance (loss of energy because the air does not automatically move) in the air and the signal attenuates (gets smaller) as you move farther and farther away from the source. That is basically how a transmitter transmits, it sets up waves of energy (like the waves of water) in specific patterns in something. For reception: We're back in the bathtub with the washer moving up and down. Look at the stick that does not have the washer. See how the waves go up and down the stick? Imagine that there is a float (a fishing bobber) on the stick that can follow the height of the wave up and down the stick. Tie a pen to that bobber and let the pen draw on a piece of paper. See how the wave the pen drew on the paper is an exact replica of the wave that you created with the washer (with time delay)? That is how an antenna works. As the antenna sits still and the waves of energy that you set off from the phone move up and down the antenna it induces (creates) a voltage in the antenna that varies as the waves wash over it. If you watched the voltage you would see an exact replica of the voltage that caused the waves in the first place. Thus you have just transmitted waves from one antenna to another. As the cellular antenna recieves the signal it basically just connects it onto the public telephone network. Once it is on the network it uses the telephone number that you dialed to set up a series of switches that route the call to the person that you want it to go to. Imagine an old fashioned movie where when you place a call you get an operator. Madge (our operator) sees a light on her board light up that tells her that you picked up your phone and want her attention. She takes one of her wires and plugs it into the hole on the board that corresponds to you. You are now talking to Madge. You tell madge that you want a connection to 555-0123 (the arbitrary (random) number that has been assigned to Ramsey Su in this case). She pulls out another wire and puts it into the hole that corresponds to 555-0123. Then she pushes a button that rings Ramseys phone. Ramsey picks up and yells "What? It's two in the morning, what do you want?". You now have a connection with Ramsey through the old telephone network. The new network works the same way, only the switching is all done automatically with computers instead of Madges. You pick up the phone, and get a dial tone, at that point you tell the computer where you want to place a call to (by dialing a number) and it throws the appropriate switches in the blink of an eye and you are connected. The way that the Cellular network knows where you are is as follows: Whenever you have your phone on you are registered with the nearest phone tower. So the phone tower knows who is in its area, and tells a central computer. When a call comes into the central computer that needs to be completed the central computer looks on its list of phones that are in its area and sees if the number corresponds to one that it has. If it is then it switches the switches (like Madge) to send the call to the nearest tower to the phone that it needs to make a connection with. Then we go back to the bathtub and receive and transmit again. Hope this helps, if it doesn't then ask more questions: Mike P.S. At no point does the signal get transmuted from electrical pulses to anything else, so it is irrelevant what you send. You could send data or nothing and the phone network will never know the difference (or care).