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EuroDOCSIS Transmission Characteristics
Downstream RF Channel Transmission Characteristics
Transmission is from the headend combiner to the cable modem input at the customer location.
Measurement methods are defined in CENELEC 50083-7 documentation.
Table B-7
EuroDOCSIS Assumed Downstream RF Channel Transmission Characteristics for Analog TV and Sound
Signals
Parameter
1
Frequency range
RF channel spacing (design bandwidth)
Transit delay from headend to most distant customer
Carrier-to-noise ratio in a 8-MHz band (analog video level)
Carrier-to-interference ratio for total power (discrete and
broadband ingress signals)
Composite triple beat distortion for analog modulated carriers PAL—Not greater than –57 dBc within the design bandwidth
Composite second order distortion for analog modulated
carriers
Cross-modulation level
Amplitude ripple
Group delay ripple in the spectrum occupied by the CMTS
Micro-reflections bound for dominant echo
3
Carrier hum modulation
Burst noise
Signal level slope, 85–862 MHz
Seasonal and diurnal signal level variation
Maximum analog video carrier level at the system outlet,
inclusive of above signal level variation
Lowest analog video carrier level at the system outlet,
inclusive of above signal level variation
1. For measurements shown, the normal downstream operating frequency band (except hum), impairments are referenced to the highest-frequency
PAL/SECAM carrier level.
2. This presumes that the digital carrier is operated at analog peak carrier level. When the digital carrier is operated below the analog peak carrier level, the
carrier-to-noise ratio may be less.
Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
B-6
Value
Cable system normal downstream operating range is from
47 MHz to as high as 862 MHz. However, the operating range
for data communication is from 108 to 862 MHz. The use of
frequencies between 108 and 136 MHz may be forbidden due
to national regulation with regard to interference with
aeronautical navigation frequencies.
7/8 MHz, 8 MHz channels are used for data communication
≤ 0.800 msec (typically much less)
2
Not less than 44 dB
Not less than 52 dB within the design bandwidth
SECAM—Not greater than –52 dBc within the design
bandwidth.
PAL—Not greater than –57 dBc within the design bandwidth.
SECAM—Not greater than –52 dBc within the design
bandwidth.
Under consideration
2.5 dB in 8 MHz
100 ns over frequency range 0.5 to 4.43 MHz
–10 dBc @ ≤ 0.5 microseconds
–15 dBc @ ≤ 1.0 microseconds
–20 dBc @ ≤ 1.5 microseconds
–30 dBc @ > 1.5 microseconds
Not greater than –46 dBc (5%)
Not longer than 25 microseconds at a 10-Hz average rate
12 dB
8 dB
PAL: 77 dBmicroV
SECAM: 74 dBmicroV
PAL: 60 dBmicroV
SECAM: 57 dBmicroV
Appendix B
RF Specifications
OL-17309-01
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