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السؤال 2 ADSL modem assigns more bits to channels with low SNR and less bits to channels with high SNR صواب
Consider a signal of 3 KHz bandwidth The SSB modulated signal is resulted by using a carrier frequency of 66 kHz La La 3 KHI 66 KHE Spectrum of Spectrum of a modulated signal The following figure represents a spectrum of a composite 4 SSB-FDM modulated signals (81, 82, 83, and :54) with 1 kHz gap between any two SSB signals Lower sideband Band Lower Sideband 1 kHz Guard Band Lower Sidebandan 1 kHz Guard Band Lower sideband. kHz Guard Band Li ? 7 Subcarrier 4 66 ? Subcarrier 1 Subcarrier 2 Subcarrier 3 Spectrum of composite signal using multiple subcarriers ..) The subcarrier 2 frequency of sz(t) signal is kHz)
السؤال 4 .The Asymmetric DSL (ADSL) is characterized that it has more downstream rate than upstream صواب خطا السؤال 5 TDM scheme to multiplex the 10 voice signals, each with a maximum frequency Fmax =5000 Hz. These voice signals are sampled at 10,000 samples/sec, quantized, and encoded into 6-bit PCM words using PCM. Next, the PCM digital signals are multiplexed using TDM Each TDM frame contains one PCM sample of 6-bit for each of the 10 voice signals. In addition, 1 framing bit is added to the frame to provide synchronization at the receiver Frame Channel 1 - Channel 2 - Channel 10 1 2 3 ... 6 123 ...6123 ... 6 Framing One PCM Bit Sample Then, the data rate of this channel is bps
السؤال 6 TDM scheme to multiplex the 10 voice signals, each with a maximum frequency Fmax =5000 Hz. These voice signals are sampled at 10,000 samples/sec, quantized, and encoded into 6-bit PCM words using PCM. Next, the PCM digital signals are multiplexed using TDM Each TOM frame contains one PCM sample of 6-bit for each of the 10 voice signals. In addition, 1 framing bit is added to the frame to provide synchronization at the receiver Frame Channel 1 - Channel 2 - Channel 10 123 -. 6 1 2 3 ... 6. |1||16 1|2|3 - 6 Framing Bit One PCM Sample The total number of bits per frame including the framing bit is bits
.Consider a signal of 3 KHz bandwidth The SSB modulated signal is resulted by using a carrier frequency of 66 kHz sile 0 3 KHI Spectrum of anal 66 ΚΗΣ Spectrum of a modulated signal The following figure represents a spectrum of a composite 4 SSB-FDM modulated signals (81, 82, 83, and :54) with 1 kHz gap between any two SSB signals Lower sideband, 530) Lower Sideband Lower Sideband Band Lower sideband, sin 1 kHz Guard Band 1 kHz Guard Band 1 kHz Guard Band ? ? ? Subcarrier 4 66 ? Subcarrier1 Subcarrier 2 Subcarrier 3 Spectrum of composite signal using multiple subcarriers ..) The subcarrier 4 frequency of s4(6) signal is kHz)
Consider the following block diagram for TDM PCM system that will accommodates three analog inputs and four synchronous digital inputs. Assume the following The maximum frequency of the analog inputs are: 1000 Hz, 2000 Hz, and 1000 Hz The bit rate of each synchronous digital input is 1200 bps- The analog samples will be encoded into 5-bit PCM words The data rate of the TDM PCM output signal is 45 kbps. The frame size of 900 bits - TDS PAM signal Agregate TOM PAM Sampling Rate? 5-bit A/D TDM PCM signal TDPCM Bit Rate? From Sourcel 1000 Hz, Analog From Source2 2000 Hz, Analog From Source 1000 Hz, Analog From Source4 1200 bps, Digital From Sources 1200 bps, Digital Pale Stuffing? Pulse stuffing Pulse stuffing Scan operation TDM PCM output signal 45 kbps Pulse stuſling From Source 1200 bps, Digital From Source 7 1200 bps, Digital Pulse stuffing The TDM PCM bit rate is bos
السؤال 9 The ADSL signal is divided into a total of 224 subchannels صواب السؤال 10 Subscriber line is a link between your home and the network صواب خطأ
السؤال 12 Considering 15 signals each of 6 KHz with 2 KHz guard band, the minimum total channel bandwidth (B) is kHz Signal 1 (Lower Band) Signal 2 (Lower Band) Signal 10 (Lower Band) Guard hund Guard band Frequency 000 Ві В. Gead bund os B. Total Channel Bandwidth (B)
Consider a signal of of 4 KHz The DSBTC modulated signal is resulted by using a carrier of 64 kHz Diper Sideband Lower sideband La 0 4 64 Spectrum of a signal a KHZ KHZ Spectrum of a modulated signal The following figure represents a spectrum of a composite DSBTC-FDM modulated signals (1.52 and (53 side Lw w imuno Lu 64 KHZ Subcarrier 2 Subcarrier 3 Spectrum of composite signal using multiple subcarriers The subcarrier 3 frequency of $3() signal is kHz
السوال 15 In ADSL, the lowest 25kHz of the bandwidth is reserved to carry multiple voices, each of 4 kHz صواب