Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide
Appendix B: RF Specifications
Downloads: This chapterpdf (PDF - 404.0KB) The complete bookPDF (PDF - 12.42MB) | Feedback

RF Specifications

Table Of Contents

RF Specifications

DOCSIS 1.0 Transmission Characteristics

Downstream RF Channel Transmission Characteristics

Upstream RF Channel Transmission Characteristics

DOCSIS 1.1 Transmission Characteristics

Downstream RF Channel Transmission Characteristics

Upstream RF Channel Transmission Characteristics

EuroDOCSIS Transmission Characteristics

Downstream RF Channel Transmission Characteristics

Upstream RF Channel Transmission Characteristics

Electrical Input and Output


RF Specifications


Information in the following tables is from the DOCSIS and EuroDOCSIS Radio Frequency Interface Specification, and should be considered minimum recommended performance criteria for reliable data transmission on cable networks. The full specification may be found at the CableLabs website (http://www.cablemodem.com), and additional Euro-DOCSIS information may be found at tComLabs' Website.

NCTA—"NCTA Recommended Practices for Measurements on Cable Television Systems, 2nd Edition"- National Cable Television Association, Washington DC, revised October 1993

CableLabs1—"Two-Way Cable Television System Characterization" - Cable Television Laboratories, Inc., April 12, 1995

CableLabs2—Digital Transmission Characterization of Cable Television Systems, Cable Television Laboratories, Inc. November, 1999


Note Raw data rate in Table B-1 and Table B-2 includes nominal data throughput plus overhead.


Table B-1 Downstream Channel Data Rates

Modulation Format
Channel Bandwidth, MHz
Symbol Rate, Msym/sec
Raw Data Rate, Mbps
Nominal Data Rate, Mbps

QAM-64

6

5.056941

30.34

~27

QAM-256

6

5.360537

42.88

~38

QAM-64

8

6.952

41.71

~37

QAM-256

8

6.952

55.62

~50


Table B-2 Upstream Channel Data Rates 

Symbol Rate, ksym/sec
Channel Bandwidth, MHz
QPSK Raw Data Rate, Mbps
QPSK Nominal Data Rate, Mbps
QAM-16 Raw Data Rate, Mbps
QAM-16 Nominal Data Rate, Mbps

160

0.20

0.32

~0.3

0.64

~0.6

320

0.40

0.64

~0.6

1.28

~1.2

640

0.80

1.28

~1.2

2.56

~2.3

1280

1.60

2.56

~2.3

5.12

~4.6

2560

3.20

5.12

~4.6

10.24

~9.0


DOCSIS 1.0 Transmission Characteristics

The following tables provide information on the assumed downstream RF channel transmission characteristics for DOCSIS 1.0.

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 NCTA or CableLabs2 documentation.

Go to URL http://www.ncta.com/. Search on "transmission".
Go to URL
http://www.cablelabs.com/.

Table B-3 DOCSIS 1.0 Assumed Downstream RF Channel Transmission Characteristics 

Parameter
Value

Frequency range1

Cable system normal downstream operating range is from 50 MHz to as high as 860 MHz. However, the values in this table apply only at frequencies Š 88 MHz.

RF channel spacing (design bandwidth)

6 MHz

Transit delay from headend to most distant customer

ü£ 0.800 msec (typically much less)

Carrier-to-noise ratio in a 6-MHz band (analog video level)

Not less than 35 dB2

Carrier-to-interference ratio for total power (discrete and broadband ingress signals)

Not less than 35 dB within the design bandwidth

Composite triple beat distortion for analog modulated carriers

Not greater than -50 dBc within the design bandwidth

Composite second-order distortion for analog modulated carriers

Not greater than -50 dBc within the design bandwidth

Cross-modulation level

Not greater than -40 dBc within the design bandwidth

Amplitude ripple

0.5 dB within the design bandwidth

Group delay ripple in the spectrum occupied by the CMTS

75 ns within the design bandwidth

Micro-reflections bound for dominant echo

-10 dBc @ £ 0.5 microsecond
-15 dBc @ £ 1.0 microsecond
-20 dBc @ £ 1.5 microsecond
-30 dBc @ >1.5 microsecond

Carrier hum modulation3

Not greater than -26 dBc (5%)

Burst noise

Not longer than 25 msec at a 10-Hz average rate

Signal level slope, 50-750 MHz

16 dB

Seasonal and diurnal signal level variation

8 dB

Maximum analog video carrier level at the cable modem input, inclusive of above signal level variation

17 dBmV

Lowest analog video carrier level at the cable modem input, inclusive of above signal level variation

-5 dBmV

1 For measurements above the normal operating frequency band (except hum), impairments are referenced to the highest-frequency NTSC 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.

3 For hum measurements above the normal downstream operating frequency band, a continuous-wave carrier is sent at the test frequency at the same level as the highest-frequency NTSC carrier.


Upstream RF Channel Transmission Characteristics

Transmission is from the cable modem output at the customer location to the headend. Measurement methods are defined in NCTA or CableLabs2 documentation.

Table B-4 DOCSIS 1.0 Assumed Upstream RF Channel Transmission Characteristics

Parameter
Value

Frequency range

5 to 42 MHz edge to edge

Transit delay from the most distant cable modem to the nearest cable modem 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 dB1

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%)

Burst noise

Not longer than 10 msec at a 1-kHz average rate for most cases2 , 3

Amplitude ripple

5 to 42 MHz: 0.5 dB/MHz

Group delay ripple

5 to 42 MHz: 200 ns/MHz

Micro-reflections—single echo

-10 dBc @ £ 0.5 microsecond
-20 dBc @ £ 1.0 microsecond
-30 dBc @ > 1.0 microsecond

Seasonal and diurnal signal level variation

Not greater than 8 dB min to max

1 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)

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

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


DOCSIS 1.1 Transmission Characteristics

The following tables provide information on the assumed downstream RF channel transmission characteristics for DOCSIS 1.1.

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 NCTA or CableLabs2 documentation.

Go to URL http://www.ncta.com/. Search on "transmission".
Go to URL
http://www.cablelabs.com/.

Table B-5 DOCSIS 1.1 Assumed Downstream RF Channel Transmission Characteristics

Parameter
Value

Frequency range

Cable system normal downstream operating range is from 50 MHz to as high as 860 MHz. However, the values in this table apply only at frequencies Š 88 MHz.

RF channel spacing (design bandwidth)

6 MHz

Transit delay from headend to most distant customer

£ 0.800 msec (typically much less)

Carrier-to-noise ratio in a 6-MHz band

Not less than 35 dB1

Carrier-to-composite triple beat distortion ratio

Not less than 41 dB1

Carrier-to-composite second order distortion ratio

Not less than 41 dB1

Carrier-to-cross-modulation ratio

Not less than 41 dB1

Carrier-to-any other discrete interference (ingress)

Not less than 41 dB1

Amplitude ripple

3 dB within the design bandwidth

Group delay ripple in the spectrum occupied by the CMTS

75 ns within the design bandwidth

Micro-reflections bound for dominant echo

-10 dBc @ £ 0.5 microsecond
-15 dBc @ £ 1.0 microsecond
-20 dBc @ £ 1.5 microsecond
-30 dBc @ >1.5 microsecond

Carrier hum modulation

Not greater than -26 dBc (5%)

Burst noise

Not longer than 25microseconds at a 10-Hz average rate

Maximum analog video carrier level at the cable modem input

17 dBmV

Maximum number of analog carriers

121

1 Measured relative to a QAM signal that is equal to the nominal video level in the plant.


Upstream RF Channel Transmission Characteristics

Transmission is from the cable modem output at the customer location to the headend. Measurement methods are defined in NCTA or CableLabs2 documentation.

Table B-6 DOCSIS 1.1 Assumed Upstream RF Channel Transmission Characteristics

Parameter
Value

Frequency range

5 to 42 MHz edge to edge

Transit delay from the most distant cable modem to the nearest cable modem or CMTS

£ 0.800 msec (typically much less)

Carrier-to-interference plus ingress (the sum of noise, distortion, common-path distortion, and cross-modulation and the sum of discrete and broadband ingress signals, impulse noise excluded) ratio

Not less than 25 dB1

Carrier hum modulation

Not greater than -23 dBc (7%)

Burst noise

Not longer than 10 microseconds at a 1-kHz average rate for most cases2 , 3

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 microsecond
-20 dBc @ £ 1.0 microsecond
-30 dBc @ > 1.0 microsecond

Seasonal and diurnal reverse gain (loss) variation

Not greater than 14 dB min to max

1 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 10 dBc. Ratios are guaranteed only within the digital carrier channels.

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

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


EuroDOCSIS Transmission Characteristics

The following tables provide information on the assumed RF channel transmission characteristics for EuroDOCSIS.

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
Value

Frequency range1

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.

RF channel spacing (design bandwidth)

7/8 MHz, 8 MHz channels are used for data communication

Transit delay from headend to most distant customer

£ 0.800 msec (typically much less)

Carrier-to-noise ratio in a 8-MHz band (analog video level)

Not less than 44 dB2

Carrier-to-interference ratio for total power (discrete and broadband ingress signals)

Not less than 52 dB within the design bandwidth

Composite triple beat distortion for analog modulated carriers

PAL—Not greater than -57 dBc within the design bandwidth

SECAM—Not greater than -52 dBc within the design bandwidth.

Composite second order distortion for analog modulated carriers

PAL—Not greater than -57 dBc within the design bandwidth.

SECAM—Not greater than -52 dBc within the design bandwidth.

Cross-modulation level

Under consideration

Amplitude ripple

2.5 dB in 8 MHz

Group delay ripple in the spectrum occupied by the CMTS

100 ns over frequency range 0.5 - 4.43 MHz

Micro-reflections bound for dominant echo

-10 dBc @ £ 0.5 microsecond
-15 dBc @ £ 1.0 microsecond
-20 dBc @ £ 1.5 microsecond
-30 dBc @ > 1.5 microsecond

Carrier hum modulation3

Not greater than -46 dBc (5%)

Burst noise

Not longer than 25 microseconds at a 10-Hz average rate

Signal level slope, 85-862 MHz

12 dB

Seasonal and diurnal signal level variation

8 dB

Maximum analog video carrier level at the system outlet, inclusive of above signal level variation

PAL: 77 dBmicroV

SECAM: 74 dBmicroV

Lowest analog video carrier level at the system outlet, inclusive of above signal level variation

PAL: 60 dBmicroV

SECAM: 57 dBmicroV

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.

3 For hum measurements above the normal downstream operating frequency band, a continuous-wave carrier is sent to the test frequency at the same level as the highest-frequency PAL/SECAM carrier.


Upstream RF Channel Transmission Characteristics

Transmission is from the cable modem output at the customer location to the headend.

Table B-8 EuroDOCSIS Assumed Upstream RF Channel Transmission Characteristics

Parameter
Value

Frequency range

5 up to 65 MHz to edge

Transit delay from the most distant cable modem to the nearest cable modem or cable modem termination system

£ 0.800 msec (typically much less)

Carrier-to-noise ratio in active channel

Not less than 22 dB

Carrier-to-ingress power (the sum of discrete and broadband ingress signals) ratio in active channel

Not less than 22 dB1

Carrier-to-interference (the sum of noise, distortion, common-path distortion, and cross-modulation) ratio in active channel

Not less than 22 dB

Carrier hum modulation

Not greater than -23 dBc (7%)

Burst noise

Not longer than 10 microsecond at a 1 kHz average rate for most cases2 , 3

Amplitude ripple

5 to 65 MHz: 2.5 dB in 2 MHz

Group delay ripple

5 to 65 MHz: 300 ns in 2 MHz

Micro-reflections—single echo

-10 dBc @ £ 0.5 microsecond
-20 dBc @ £ 1.0 microsecond
-30 dBc @ > 1.0 microsecond

Seasonal and diurnal signal level variation

Not greater than 12 dB min to max

1 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.

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

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


Electrical Input and Output

The information in Table B-9 and Table B-10 relates to both DOCSIS and EuroDOCSIS specifications.

Table B-9 Electrical Input to the Cable Modem 

Parameter
Value

Center frequency

DOCSIS: 91 to 857 MHz ±30 kHz

EuroDOCSIS: 112 to 858 MHz ±30 kHz

Level range (one channel)

DOCSIS: -15 dBmV to +15 dBmV

EuroDOCSIS: 43 to 73 dBmicroV for QAM-64
47 to 77 dBmicroV for QAM-256

Modulation type

QAM-64 and QAM-256

Symbol rate (nominal)

DOCSIS: 5.056941 Msym/sec (QAM-64) and 5.360537 Msym/sec (QAM-256)

EuroDOCSIS: 6.952 Msym/sec for QAM-64 and QAM-256

Bandwidth

DOCSIS: 6 MHz

18% square root raised cosine shaping for QAM-64

12% square root raised cosine shaping for QAM-256

EuroDOCSIS: 8 MHz

15% square root raised cosine shaping for both QAM-64 and QAM-256

Total input power (40 - 900 MHz)

< 30 dBmV (90 dBmicroV)

Input (load) impedance

75 ohms

Input return loss

DOCSIS: > 6 dB (88-860 MHz)

EuroDOCSIS: > 6 dB (85-862 MHz)

Connector

F connector per ISO-169-24 (common with the output)


Table B-10 Upstream Electrical Output from the Cable Modem 

Parameters
Value

Frequency

DOCSIS: 5 to 42 MHz edge to edge

EuroDOCSIS: 5 to 65 MHz edge to edge

Level range (one channel)

QAM-16: +8 to +55 dBmV (+68 to +115 dBmicroV)

QPSK: +8 to +58 dBmV (+68 to +118 dBmicroV)

Modulation type

QPSK and QAM-16

Symbol rate (nominal)

160 ksym/sec
320 ksym/sec
640 ksym/sec
1280 ksym/sec
2560 ksym/sec

Bandwidth

200 kHz
400 kHz
800 kHz
1600 kHz
3200 kHz

Output impedance

75 ohms

Output return loss

DOCSIS: >6 dB (5-42 MHz)

EuroDOCSIS: >6 dB (5-65 MHz)

Connector

F connector per ISO-169-24 (common with the input)