North American broadcast television frequencies

From Academic Kids

In North America, terrestrial television is broadcast on designated channels numbered 2 through 69. Except for a few instances, consumer televisions and recorders come with these frequencies pre-programmed in, as opposed to what sometimes occurs in other places around the world. Traditionally, the frequencies are divided into two sections, the very high frequency (VHF) band and the ultra high frequency (UHF) band, but in reality, the VHF band is further subdivided into two more sections, VHF-Lo (band I) and VHF-Hi (band III). In between lies the FM band (band II) used for frequency-modulated radio transmissions and a VHF radio band typically used by civil service agencies and aircraft (often called the airband).

On many FM radios, the audio for channel 6 can often be picked up by turning the tuner dial all of the way toward the low end, at 87.75. Since there is no guard band, there is a slight overlap between that channel and the low FM band on most receivers. The volume is quite low as the deviation or modulation for TV audio is only 25kHz, versus 75kHz for FM. FM channel 200, centered at 87.9 (87.8 to 88.0), is only used for class D stations forced out of the rest of the FM band by a full-power station, and only if there is no nearby TV 6.

Channels 70 through 83 were removed from the bandplan to make way for AMPS cellular telephone service; these channels were mainly used in the U.S., and mainly for translators, some of which continued in operation if their frequencies were not in use for cellular. Channel 37 is allocated to radio astronomy and may not be used by any station.

Channels 14 through 19 are used for two-way radio in major cities, intended for use on a non-interference basis, although the transition to digital television (DTV) has caused problems in certain instances when a previously unused channel has begun to be used for DTV broadcasts. The same holds true for wireless microphones and medical telemetry devices in that band.

In many regions, the allocation of new digital TV channels is focused on channels 15 through 50, although some of the more crowded television markets use other channels as available. Through virtual channel numbering, many digital TV stations appear to be on the same channel they used previously. For example, a station that originally broadcast on channel 4 but now has a digital signal available on channel 32 will usually appear as 4-1 or 4.1 on a DTV receiver. Several subchannels can be multiplexed together, so 4-1 through 4-5 might be used by one station. The subchannel numbered as 0 (that is, 4-0) is designated for the analog broadcast.

Channels 52 through 69 will be removed from television service in the United States when the transition to DTV broadcasting is complete. Some of this radio spectrum has already been auctioned for use in other services, and may be used on a non-interference basis by those licensees. Almost no stations are being assigned to channel 6, although this has not officially been removed from the bandplan.

The VHF bandplan was modified multiple times up until 1948. The last change in that section was the deletion of channel 1, which had originally been intended to be a low-power (less than 1,000 watts) LPTV community channel. Channel 1 was removed early on for amateur radio, now called the six-meter band. Amateur television (ATV) is used on four UHF channels just below 14, especially for repeater output and direct communications. ATV repeater inputs may also be on other channels not near the broadcast bands.

The FM audio carrier is always 4.5MHz above the VSB video carrier, and the total channel bandwidth is 6MHz. The lower channel boundary is 1.25MHz lower than the video carrier's center frequency, the upper is 4.75MHz above. (See NTSC for more details.) Analog stations must be separated by at least one channel, except where a gap already exists (such as between channels 4/5, 6/7, and 13/14. Digital channels can operate adjacent channel to any station, which is the only reason so many channels could be removed from service for DTV.

VHF bands

VHF Lo-Band (Band I)
Channel Video carrier (MHz)
1* 49.25
2 55.25
3 61.25
4 67.25
5 77.25
6 83.25
VHF Hi-Band (Band III)
Channel Video carrier (MHz)
7 175.25
8 181.25
9 187.25
10 193.25
11 199.25
12 205.25
13 211.25

UHF band

UHF TV Band
Channel Video carrier (MHz)
14 471.25
15 477.25
16 483.25
17 489.25
18 495.25
19 501.25
20 507.25
21 513.25
22 519.25
23 525.25
24 531.25
25 537.25
26 543.25
27 549.25
28 555.25
29 561.25
30 567.25
31 573.25
32 579.25
33 585.25
34 591.25
35 597.25
36 603.25
37 609.25
38 615.25
39 621.25
40 627.25
41 633.25
42 639.25
43 645.25
44 651.25
45 657.25
46 663.25
47 669.25
48 675.25
49 681.25
50 687.25
51 693.25
52 699.25
53 705.25
54 711.25
55 717.25
56 723.25
57 729.25
58 735.25
59 741.25
60 747.25
61 753.25
62 759.25
63 765.25
64 771.25
65 777.25
66 783.25
67 789.25
68 795.25
69 801.25
70* 807.25
71* 813.25
72* 819.25
73* 825.25
74* 831.25
75* 837.25
76* 843.25
77* 849.25
78* 855.25
79* 861.25
80* 867.25
81* 873.25
82* 879.25
83* 885.25

* Channel no longer allocated to broadcast television

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