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The recommended settings listed in the following tables are based on an HFC network where the digital signal is carried 10 dB below the adjacent analog video channel. If the digital signal on your network is carried 6 dB below the adjacent analog video channel, add 4 dB to the recommended settings in Table B-3, Table B-4, and Table B-6.
| Upstream Bandwidth | QPSK Data Throughput | 16 QAM Data Throughput |
|---|---|---|
200 kHz | 0.3 Mbs | 0.6 Mbs |
400 kHz | 0.6 Mbs | 1.2 Mbs |
800 kHz | 1.2 Mbs | 2.3 Mbs |
1600 kHz | 2.3 Mbs | 4.5 Mbs |
3200 kHz | 4.6 Mbs | 9.0 Mbs |
| Downstream Bandwidth | 64 QAM Data Throughput | 256 QAM Data Throughput |
|---|---|---|
6 MHz | 27.0 Mbs | 38.0 Mbs |
8 MHz | 27.0 Mbs | 38.0 Mbs |
| Specification | DOCSIS Specifications1 | Minimum Settings2 | Your Headend Settings |
|---|---|---|---|
| System/Channel | |||
Frequency range | 5 to 42 MHz (North America) | 5 to 42 MHz (North America) |
|
Transit delay, CMTS to furthest customer | < 0.800 µsec | < 0.800 µsec |
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Carrier to noise ratio |
| ||
Carrier to ingress power ratio | > 25 dB | > 25 dB |
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Carrier to interference ratio |
| ||
Carrier hum modulation | < -23 dBc6 (7%) | < -23 dBc (7%) |
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Burst noise | < 10 µsec | < 10 µsec |
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Amplitude ripple | 0.5 dB/MHz | 0.5 dB/MHz |
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Group delay ripple | 200 ns/MHz | 200 ns/MHz |
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Micro reflections (single echo) | -10 dBc @ < 0.5 µsec | -10 dBc @ < 0.5 µsec |
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Seasonal/diurnal signal level variation | < 8 dB | < 8 dB |
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Carrier to second order | < -50 dBc | < -50 dBc |
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| Digital Signal Levels | |||
From cable modem (upstream) | +8 to +58 dBmV (QPSK) | +8 to +58 dBmV (QPSK) |
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Input amplitude to modem card (upstream) | -10 to +25 dBmV | -10 to +25 dBmV |
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Signal as relative to adjacent video signal | -6 to -10 dBc | -6 to -10 dBc |
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| 1DOCSIS specifications are baseline settings for a DOCSIS-compliant, two-way data-over-cable system. 2Minimum settings are slightly different than the DOCSIS settings to account for cable system variations over time and temperature. Using these settings should increase the reliability of DOCSIS-compliant, two-way data-over-cable systems. 3QPSK = Quadrature Phase-Shift Keying: a method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits. 4These settings are measured relative to the digital carrier. Add 6 or 10 dB, as determined by your company's policy and derived from the initial cable network setup, relative to the analog video signal. 5QAM = Quadrature Amplitude Modulation: a method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. 6dBc = decibels relative to carrier. |
| Specification | DOCSIS Specifications1 | Minimum Settings2 | Your Headend Settings |
|---|---|---|---|
| System/Channel | |||
RF channel spacing (bandwidth) | 6 MHz | 6 MHz |
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Transit delay3 | 0.800 µsec | 0.800 µsec |
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Carrier to noise ratio |
| ||
Carrier to ingress power ratio | > 35 dB | > 35 dB |
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Composite triple beat distortion | < -50 dBc6 | < -50 dBc |
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Carrier to second order | < -50 dBc | < -50 dBc |
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Cross-modulation level | < -40 dBc | < -40 dBc |
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Amplitude ripple | 0.5 dB in 6 MHz | 0.5 dB in 6 MHz |
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Group delay | 75 ns7 in 6 MHz | 75 ns in 6 MHz |
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Micro reflections bound for dominant echo | -10 dBc @ < 0.5 µsec | -10 dBc @ < 0.5 µsec |
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Carrier hum modulation | < -26 dBc (5%) | < -26 dBc (5%) |
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Burst noise | < 25 µsec | < 25 µsec |
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Seasonal/diurnal signal level variation | 8 dB | 8 dB |
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Signal level slope (50 to 750 MHz) | 16 dB | 16 dB |
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Maximum analog video carrier level | +17 dBmV | +17 dBmV |
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Minimum analog video carrier level | -5 dBmV | -5 dBmV |
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| Digital Signal Levels | |||
From headend | -15 to +15 dBmV | -15 to +15 dBmV |
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Signal as relative to adjacent video signal | -6 or -10 dBc | -6 or -10 dBc |
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| 1DOCSIS specifications are baseline settings for an DOCSIS-compliant, two-way data-over-cable system. 2Minimum settings are slightly different than the DOCSIS settings to account for cable system variations over time and temperature. Using these settings should increase the reliability of DOCSIS-compliant, two-way data-over-cable systems. 3Transit delay is defined as the "round trip" from the cable headend to the furthest customer and back. 4QAM = Quadrature Amplitude Modulation: a method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. 5These settings are measured relative to the digital carrier. Add 6 or 10 dB, as determined by your company's policy and derived from the initial cable network setup, relative to the analog video signal. 6dBc = decibels relative to carrier. 7ns = nanoseconds. |
| Specification | DOCSIS Specifications1 | Minimum Settings2 | Your Headend Settings |
|---|---|---|---|
| System/Channel | |||
Frequency range | 5 to 65 MHz | 5 to 65 MHz |
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Transit delay, CMTS to furthest customer | < 0.800 µsec | < 0.800 µsec |
|
Carrier to noise ratio |
| ||
Carrier to ingress power ratio | > 25 dB | > 25 dB |
|
Carrier to interference ratio |
| ||
Carrier hum modulation | < -23 dBc6 (7%) | < -23 dBc (7%) |
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Burst noise | < 10 µsec | < 10 µsec |
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Amplitude ripple | 0.5 dB/MHz | 0.5 dB/MHz |
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Group delay ripple | 200 ns/MHz | 200 ns/MHz |
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Micro reflections (single echo) | -10 dBc @ < 0.5 µsec | -10 dBc @ < 0.5 µsec |
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Seasonal/diurnal signal level variation | < 8 dB | < 8 dB |
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Carrier to second order | < -50 dBc | < -50 dBc |
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| Digital Signal Levels | |||
From cable modem (upstream) | +8 to +58 dBmV (QPSK) | +8 to +58 dBmV (QPSK) |
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Input amplitude to modem card (upstream) | -10 to +25 dBmV | -10 to +25 dBmV |
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Signal as relative to adjacent video signal | -6 to -10 dBc | -6 to -10 dBc |
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| Specification | DOCSIS Specifications1 | Minimum Settings2 | Your Headend Settings |
|---|---|---|---|
| System/Channel | |||
RF channel spacing (bandwidth) | 8 MHz | 8 MHz |
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Transit delay3 | 0.800 µsec | 0.800 µsec |
|
Carrier to noise ratio |
| ||
Carrier to ingress power ratio | > 35 dB | > 35 dB |
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Composite triple beat distortion | < -50 dBc6 | < -50 dBc |
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Carrier to second order | < -50 dBc | < -50 dBc |
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Cross-modulation level | < -40 dBc | < -40 dBc |
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Amplitude ripple | 0.5 dB in 8 MHz | 0.5 dB in 8 MHz |
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Group delay | 75 ns7 in 8 MHz | 75 ns in 8 MHz |
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Micro reflections bound for dominant echo | -10 dBc @ < 0.5 µsec | -10 dBc @ < 0.5 µsec |
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Carrier hum modulation | < -26 dBc (5%) | < -26 dBc (5%) |
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Burst noise | < 25 µsec | < 25 µsec |
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Seasonal/diurnal signal level variation | 8 dB | 8 dB |
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Signal level slope (50 to 750 MHz) | 16 dB | 16 dB |
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Maximum analog video carrier level | +17 dBmV | +17 dBmV |
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Minimum analog video carrier level | -5 dBmV | -5 dBmV |
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| Digital Signal Levels | |||
From headend | -15 to +15 dBmV | -15 to +15 dBmV |
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Signal as relative to adjacent video signal | -6 or -10 dBc | -6 or -10 dBc |
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Posted: Tue Mar 28 08:52:18 PST 2000
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