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10 Cards in this Set
- Front
- Back
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What does PSTN stand for?
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Public Switched Telephone Network.
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What are the three main components of an analog electrical signal?
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Frequency (how many times the signal repeats itself in a second). Amplitude (how strong the signal is). Phase (where the signal is at a point in time, at the top, going up, going down, etc).
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What is the original standard for converting voice to digital signals?
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Pulse Code Modulation (PCM). It defines that an incoming analog voice sample should be sampled 8000 times per second.
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What is a codec?
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Encoder/decoder responsible for translating analog voice to digital. For each sample, the codec measures the frequency, amplitude, and phase. Then it looks those values up in a table and finds the appropriate binary representation (an 8 bit code).
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What are some of the ways that modems can encode binary data in an electrical signal?
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Amplitude modulation, frequency modulation, and phase modulation.
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What does baud mean?
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By combining different kinds of modulation, modems can encode multiple data points in a single sample. Baud refers to one of these samples that contains more than 1 bit of information. So a 28,000 bps modem using a modulation scheme that sends two bits per sample, is running at 14,000 baud per second.
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What are the main modem standards?
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V.22 (1200 bps, 600 baud). V.22bis (2400 bps, 600 baud). V.32 (4800/9600 bps, 2400 baud). V.32bis (14.4 kbps, 2400 baud). V.34 (28.8 kbps). V.42 (28.8 kbps). V.90 (56 kbps down, 33 kbps up). V.92 (56 kbps down, 33 up, or 48 kbps for each).
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What does ISDN stand for?
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Integrated Services Digital Network.
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What is the name of the ISDN device that connects a router or PC to the Telco?
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An ISDN Terminal Adapter (TA) provides connectivity to the ISDN switch at the Telco.
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What two kinds of lines are included in an ISDN connection?
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Basic Rate Interface (BRI) and Primary Rate Interface (PRI). Each includes 1 D channel for setting up and breaking down calls, and multiple B channels for transmitting data. BRI's offer 2 B channels and 1 D channel. In the US, most PRI's offer 23 B channels and 1 D channel.
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