![]() ![]() There is no separate control channel, and no fixed voice channels so the tower could theoretically handle an unlimited number of cellphones and an unlimited number of calls up until the channel is completely saturated, if it wasn't for the noise.Ī CMDA signal sounds like noise but the receivers still have to filter out actual noise. The cellphones (and the towers) use a complex algorithm (explained on wikipedia) to extract the Individual data streams out of the noise. All the signals overlap with each other and the resulting channel just sounds like noise. While the number of phones that each tower can support was greatly increased and there is still a separate control channel that the phones can always access, each tower can still handle a fixed number of calls at once.Ī more complex method is CDMA (used by CDMA networks, and 3g GSM networks), where essentially each phone transmits onto the same channel (which is much wider than a normal channel) at the same time. This was used in the old TDMA networks (Time Deviation Multiple Access) and GSM networks (in 2g mode). The simpler method is dividing the channels up into time slots and letting each phone have exclusive access to the channel for a fraction of a second, and rapidly cycling through the different phones. The most obvious solution would be to divide the frequency range into even smaller channels, but you get interference problems between channels, so I don't think anyone ever used that method. When the 2g networks were developed, one of the primary motivations was to service more cellphones in the same frequency range (A digitally compressed voice signal is way smaller than a analog signal). If there were no free channels when you went to make the call, your phone would show a 'network busy' signal. When a phone isn't making a call it only listened to the shared control channel, only receiving the rights to 2 voice channels when the call was connected. In first generation cellphone networks, this frequency range was split into a number of channels, each wide enough to support a single analog voice signal. Go wireless.Ĭell phone towers have a fixed frequency range that they can use. Other subreddits The BIG list of related subreddits Pro Tip: Computers can get viruses. Message the moderators, and we will look at it. If your submission does not appear in the new tab - it may have been caught by the spam filter. Moderation Policy We use the reddit FAQ guidelines for spam when removing spam posts. Exact copies are never allowed, as are copies that are just slightly rewritten versions of original articles. Avoid blogs/websites that rehost content without giving credit. However we highly recommend you also look at the list of related subreddits since you are more likely to find an answer in a specialized subreddit. If you need advice about a gadget you should ask in the advice superthread. Comments should be on-topic and contribute to the conversation. ![]() No sensationalized, misleading or non-descriptive titles.Īrticles must about a single gadget, listicles are not allowed.
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