North American cable television frequencies

In North American cable TV networks, the radio frequencies used to carry signals to the customer are allocated to standardarized channel numbers listed in the CEA

Consumer Electronics Association

The Consumer Electronics Association is a standards and trade organization for the consumer electronics industry in the United States. The Consumer Electronics Association is the preeminent trade association promoting growth in the $173 billion U.S...

standard 542. Cable channel frequencies are generally different from off-air broadcast frequencies. Since the cable network is a closed system, frequencies used for over-the-air services such as mobile radio, cellular telephone, or aircraft communications can be assigned to carry television programming. The assignment of channel frequencies must on the one hand reduce the effects of distortion and mutual intereference generated within the cable television distribution system, and on the other hand maintain compatibility with the customer's connected equipment.

Slight frequency offsets are applied in some systems so that any signal leakage out of the cable distribution plant is less likely to cause objectionable interference to over-the-air users of the same frequencies.

Harmonically-related carriers (HRC)

Harmonically-related carriers (HRC) is a system for assigning television channel numbers to bands of frequencies over a cable TV network. All vision carrier frequencies are on exact multiples of the channel bandwidth frequency (6 MHz in the case of System-M

Broadcast television system

Broadcast television systems are encoding or formatting standards for the transmission and reception of terrestrial television signals. There are three main analog television systems in current use around the world: NTSC, PAL, and SECAM...

used in most countries of the Americas, other TV systems worldwide use 7 MHz or 8 MHz). William Grant, in his book, Cable Television, 2nd edition, GWG Associates, Schoharie, NY, 1988, page 82, states:

"By harmonically-relating the carrier frequencies

Carrier wave

In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...

themselves it is ... possible to improve system performance. This does not reduce the beats

Beat (acoustics)

In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies....

produced, but positions them within the system transmission

Transmission (telecommunications)

Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

spectrum, such that they are more tolerable. In effect, all signal carriers are spaced precisely at 6 MHz

Transmission (telecommunications)

apart, and thus, all beats generated are at 6 MHz increments.

Since the television signals are vestigial sideband modulation

Single-sideband modulation

Single-sideband modulation or Single-sideband suppressed-carrier is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth....

, if the beat products can be manipulated to fall on or near the RF

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

carriers themselves, they are much less offensive."

Incrementally-related carriers (IRC)

Incrementally-related carriers (IRC) is a system for assigning television channel numbers to bands of frequencies over a cable TV network. The IRC plan attempts to minimize distortion products by deriving all video carrier signals from a common source. The IRC system assigns channel frequencies (for the North American NTSC-M system) spaced 6 MHz apart. In an IRC (Incrementally Related Carrier) system, the VHF channels are at their off-air frequencies except for channels 5 and 6, which will be 2 MHz higher than usual.

In North American cable television the IRC frequency plan would be:

Channel	NTSC-M standard	IRC
2	54-60 MHz
3	60-66 MHz
4	66-72 MHz
1	44-50 MHz¹	72-78 MHz (A-8)
5	76-82 MHz	78-84 MHz (A-7)
6	82-88 MHz	84-90 MHz (A-6)

North America cable television frequencies

These frequencies are used for both (NTSC

NTSC

NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

-based analog television) and (QAM

Quadrature amplitude modulation

Quadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...

-based digital television). Band plans for North American cable television systems are standardized in EIA

Electronic Industries Alliance

The Electronic Industries Alliance was a standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They developed standards to ensure the equipment of different manufacturers was compatible and interchangeable...

standard 542-B.

NOTE: Frequencies given are for luminance carriers. For channel center frequencies, add 1.75 MHz.

Channel	Video Carrier (MHz Hertz The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications.... )	QAM Carrier(MHz Hertz The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications.... )	Audio Carrier(MHz Hertz The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications.... )
Subband CATV "T" Channels
T-7	7.00
T-8	13.00
T-9	19.00
T-10	25.00
T-11	31.00
T-12	37.00
T-13	43.00
T-14	49.00

Lowband
2	55.25	57.00	59.75
3	61.25	63.00	65.75
4	67.25	69.00	71.75
1	73.25 (A-8)	75.00	77.75 (A-8)
5	77.25 or 79.25 (A-7)	79.00 or 81.00 (A-7)	81.75 or 83.75 (A-7)
6	83.25 or 85.25 (A-6)	85.00 or 87.00 (A-6)	87.75 or 89.75 (A-6)
Midband
95	91.25 (A-5)	93.00	95.75
96	97.25 (A-4)	99.00	101.75
97	103.25 (A-3)	105.00	107.75
98	109.25 (A-2)	111.00	113.75
99	115.25 (A-1)	117.00	119.75
Midband
14	121.25	123.00	125.75
15	127.25	129.00	131.75
16	133.25	135.00	137.75
17	139.25	141.00	143.75
18	145.25	147.00	149.75
19	151.25	153.00	155.75
20	157.25	159.00	161.75
21	163.25	165.00	167.75
22	169.25	171.00	173.75
Highband
7	175.25	177.00	179.75
8	181.25	183.00	185.75
9	187.25	189.00	191.75
10	193.25	195.00	197.75
11	199.25	201.00	203.75
12	205.25	207.00	209.75
13	211.25	213.00	215.75
Superband
23	217.25	219.00	221.75
24	223.25	225.00	227.75
25	229.25	231.00	233.75
26	235.25	237.00	239.75
27	241.25	243.00	245.75
28	247.25	249.00	251.75
29	253.25	255.00	257.75
30	259.25	261.00	263.75
31	265.25	267.00	269.75
32	271.25	273.00	275.75
33	277.25	279.00	281.75
34	283.25	285.00	287.75
35	289.25	291.00	293.75
36	295.25	297.00	299.75
Hyperband
37	301.25	303.00	305.75
38	307.25	309.00	311.75
39	313.25	315.00	317.75
40	319.25	321.00	323.75
41	325.25	327.00	329.75
42	331.25	333.00	335.75
43	337.25	339.00	341.75
44	343.25	345.00	347.75
45	349.25	351.00	353.75
46	355.25	357.00	359.75
47	361.25	363.00	365.75
48	367.25	369.00	371.75
49	373.25	375.00	377.75
50	379.25	381.00	383.75
51	385.25	387.00	389.75
52	391.25	393.00	395.75
53	397.25	399.00	401.75
54	403.25	405.00	407.75
55	409.25	411.00	413.75
56	415.25	417.00	419.75
57	421.25	423.00	425.75
58	427.25	429.00	431.75
59	433.25	435.00	437.75
60	439.25	441.00	443.75
61	445.25	447.00	449.75
62	451.25	453.00	455.75
63	457.25	459.00	461.75
64	463.25	465.00	467.75
Ultraband
65	469.25	471.00	473.75
66	475.25	477.00	479.75
67	481.25	483.00	485.75
68	487.25	489.00	491.75
69	493.25	495.00	497.75
70	499.25	501.00	503.75
71	505.25	507.00	509.75
72	511.25	513.00	515.75
73	517.25	519.00	521.75
74	523.25	525.00	527.75
75	529.25	531.00	533.75
76	535.25	537.00	539.75
77	541.25	543.00	545.75
78	547.25	549.00	551.75
79	553.25	555.00	557.75
80	559.25	561.00	563.75
81	565.25	567.00	569.75
82	571.25	573.00	575.75
83	577.25	579.00	581.75
84	583.25	585.00	587.75
85	589.25	591.00	593.75
86	595.25	597.00	599.75
87	601.25	603.00	605.75
88	607.25	609.00	611.75
89	613.25	615.00	617.75
90	619.25	621.00	623.75
91	625.25	627.00	629.75
92	631.25	633.00	635.75
93	637.25	639.00	641.75
94	643.25	645.00	647.75
Jumboband
100	649.25	651.00	653.75
101	655.25	657.00	659.75
102	661.25	663.00	665.75
103	667.25	669.00	671.75
104	673.25	675.00	677.75
105	679.25	681.00	683.75
106	685.25	687.00	689.75
107	691.25	693.00	695.75
108	697.25	699.00	701.75
109	703.25	705.00	707.75
110	709.25	711.00	713.75
111	715.25	717.00	719.75
112	721.25	723.00	725.75
113	727.25	729.00	731.75
114	733.25	735.00	737.75
115	739.25	741.00	743.75
116	745.25	747.00	749.75
117	751.25	753.00	755.75
118	757.25	759.00	761.75
119	763.25	765.00	767.75
120	769.25	771.00	773.75
121	775.25	777.00	779.75
122	781.25	783.00	785.75
123	787.25	789.00	791.75
124	793.25	795.00	797.75
125	799.25	801.00	803.75
126	805.25	807.00	809.75
127	811.25	813.00	815.75
128	817.25	819.00	821.75
129	823.25	825.00	827.75
130	829.25	831.00	833.75
131	835.25	837.00	839.75
132	841.25	843.00	845.75
133	847.25	849.00	851.75
134	853.25	855.00	857.75
135	859.25	861.00	863.75
136	865.25	867.00	869.75
137	871.25	873.00	875.75
138	877.25	879.00	881.75
139	883.25	885.00	887.75
140	889.25	891.00	893.75
141	895.25	897.00	899.75
142	901.25	903.00	905.75
143	907.25	909.00	911.75
144	913.25	915.00	917.75
145	919.25	921.00	923.75
146	925.25	927.00	929.75
147	931.25	933.00	935.75
148	937.25	939.00	941.75
149	943.25	945.00	947.75
150	949.25	951.00	953.75
151	955.25	957.00	959.75
152	961.25	963.00	965.75
153	967.25	969.00	971.75
154	973.25	975.00	977.75
155	979.25	981.00	983.75
156	985.25	987.00	989.75
157	991.25	993.00	995.75
158	997.25	999.00	1001.75

Channel usage

Channels T-7 through T-14 are sub-band channels and are not used for normal television channel distribution. These channels are used for sending video back to the cable television headend

Cable television headend

A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. The headend facility is normally unstaffed and surrounded by some type of security fencing and is typically a building or large shed housing electronic...

, such as by Public, educational, and government access

Public, educational, and government access

Public, educational, and government access television, refers to three different cable television specialty channels...

(PEG) stations on a cable TV system. They are also used by cable modem

Cable modem

A cable modem is a type of network bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high...

s for sending upstream data to the headend's CMTS

Cable modem termination system

A cable modem termination system or CMTS is a piece of equipment typically located in a cable company's headend or hubsite, and used to provide high speed data services, such as cable Internet or voice over Internet Protocol, to cable subscribers...

.

Channel 1 frequency assignments, where provided, are non-standard. If a Channel 1 were inserted (A-8) between Channels 4 and 5, Channel 5 would need to move 2 MHz off-frequency, thereby pushing Channel 6 into spectrum needed for FM stereo radio by the same 2Mhz. Any assignment placing Channel 1 in its historical location before VHF Channel 2 would also be problematic, as the last cable reverse channel (T-14) now occupies frequencies from the defunct terrestrial Channel 1. Most systems that provide a (named) "Channel 1" will therefore either alias "1" to some higher converter channel (such as 101) or to a digital virtual channel

Virtual channel

In telecommunications, a logical channel number , also known as virtual channel, is a channel designation which differs from that of the actual radio channel on which the signal travels....

.

Cable channels 2 through 13 operate on the same frequencies as broadcast television (the VHF

Very high frequency

Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...

band). They were assigned by the FCC. The other channels were assigned by cable television operators.

Cable channels 65 through 94 and 100 through 125 operate on approximately the same frequencies as broadcast television (the UHF

Ultra high frequency

Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

band). Ultraband 65 and up will appear to be UHF TV 14 and up on most non-cable-ready analog television receivers; as each ultraband channel is exactly 2 MHz below a standard UHF TV channel, a slight fine-tuning of mechanical UHF tuners is all that is required to shift this block squarely onto the UHF dial.

Cable channels 57-60 fall over frequencies assigned for ham radio

Amateur radio frequency allocations

Amateur radio frequency allocation is done by national telecommunications authorities. Globally, the International Telecommunication Union oversees how much radio spectrum is set aside for amateur radio transmissions...

; this overlap is utilized for amateur television

Amateur television

Amateur television is the transmission of Broadcast quality video and audio over the wide range of frequencies of allocated for Radio amateur use. ATV is used for non-commercial experimentation, pleasure and public service events...

.

Cable channels 95 through 97 (90 - 108 MHz) operate on the same frequencies as FM radio, so cable companies offering FM radio will not show TV programming on these channels.

Cable channels 98 and 99 (A2 and A1, 108-120 MHz), if used, have appeared as channel 00 and 01 respectively on some converter boxes

Many cable providers currently don't distribute any video content above channel 139, or about 900Mhz. As of 2009, it is common for TVs in North America with built in tuners to not search analog or digital channels above channel 139. Most TVs made before 2005 do not include a QAM tuner

QAM tuner

QAM stands for quadrature amplitude modulation, the format by which digital cable channels are encoded and transmitted via cable television providers...

, and only have an analog cable tuner which often cannot tune beyond channel 125. With the addition of services such as premium HD content, cable providers such as Cox Communications

Cox Communications

Cox Communications is a privately owned subsidiary of Cox Enterprises providing digital cable television, telecommunications and wireless services in the United States...

and Insight Communications

Insight Communications

Insight Communications is the 13th largest multiple system operator in the United States with approximately 692,000 customers in the three contiguous states of Kentucky, Indiana and Ohio...

have begun to roll out digital cable services which use frequencies up to 1Ghz (analog channel 158), while also dropping the analog channel formats.

Digital cable channels

Digital television

Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...

receivers with integrated QAM tuner

QAM tuner

QAM stands for quadrature amplitude modulation, the format by which digital cable channels are encoded and transmitted via cable television providers...

s use ATSC conventions for numbering channels; unlabelled channels would appear as a main channel number, separated by a dot or dash, then a digital subchannel

Digital subchannel

In broadcasting, digital subchannels are a means to transmit more than one independent program at the same time from the same digital radio or digital television station on the same radio frequency channel. This is done by using data compression techniques to reduce the size of each individual...

number. For instance, this may display as a physical converter channel number, a dot or dash, then a virtual channel

Virtual channel

In telecommunications, a logical channel number , also known as virtual channel, is a channel designation which differs from that of the actual radio channel on which the signal travels....

number as it appeared on a digital cable set-top box. As there is no requirement that any specific convention be used to number digital or virtual channels, numbering is at the discretion of the cable operator. Digital cable channels are often numbered starting at 100 or 200, but these are virtual channel

Virtual channel

In telecommunications, a logical channel number , also known as virtual channel, is a channel designation which differs from that of the actual radio channel on which the signal travels....

numbers and do not correspond to used frequencies.

External links

http://www.jneuhaus.com/fccindex/cablech.html#hrc
ARRL - TV Channel, CATV and FM Broadcast Frequencies by Kevin K. Custer (W3KKC)
U.S. cable television channel frequencies
TVTower.com - Commercial Television Frequencies

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Harmonically-related carriers (HRC)

Incrementally-related carriers (IRC)

North America cable television frequencies

Channel usage

Digital cable channels

See also

External links