SP-RFI-I03-980202 datasheet(21/200 Pages) ETC

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Radio Frequency Interface Specification

SP-RFI-I03-980202

2.3.2

Transmission Upstream

The RF channel transmission characteristics of the cable network in the upstream direction assumed for the

purposes of minimal operating capability are described in Table 2-2. All conditions are present concurrently.

Table 2-2. Assumed Upstream RF Channel Transmission Characteristics

Notes to Table 2-2.

Transmission is from the CM output at the customer location to the headend.

Ingress avoidance or tolerance techniques MAY be used to ensure operation in the presence of time-varying discrete

ingress signals that could be as high as 0 dBc [CableLabs1].

Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.

CableLabs report containing distribution of return-path burst noise measurements and measurement method is

forthcoming.

Impulse noise levels more prevalent at lower frequencies (< 15 MHz).

2.3.2.1 Availability

Typical cable network availability is considerably greater than 99 %.

2.4 Transmission Levels

The nominal power level of the downstream CMTS 64QAM signal(s) within a 6-MHz channel is targeted to be

in the range -10 dBc to -6 dBc relative to analog video carrier level and will normally not exceed analog video

carrier level. The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the

required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed

in setting upstream signal levels, with specific levels established by the cable network operator to achieve the

required carrier-to-noise and carrier-to-interference ratios.

Parameter

Value

Frequency range

5 to 42 MHz edge to edge

Transit delay from the most distant CM to the nearest

CM or CMTS

<= 0.800 msec (typically much less)

Carrier-to-noise ratio

Not less than 25 dB

Carrier-to-ingress power (the sum of discrete and

broadband ingress signals) ratio

Not less than 25 dB (Note 2)

Carrier- to-interference (the sum of noise, distortion,

common-path distortion and cross-modulation) ratio

Not less than 25 dB

Carrier hum modulation

Not greater than -23 dBc (7.0 %)

Burst noise

Not longer than 10

µsec at a 1 kHz average rate for

most cases (Notes 3, 4 and 5)

Amplitude ripple

5-42 MHz: 0.5 dB/MHz

Group delay ripple

5-42 MHz: 200 ns/MHz

Micro-reflections -- single echo

-10 dBc @ <= 0.5 µsec

-20 dBc @ <= 1.0 µsec

-30 dBc @ > 1.0 µsec

Seasonal and diurnal signal level variation

Not greater than 8 dB min to max

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