Channel spacing

With channel spacing, the difference between the center frequencies of two adjacent transmission channels is referred to in a frequency band in radio technology. The required bandwidth of the transmission channels may be smaller, equal or greater than the channel spacing. If the channel spacing smaller than the channel bandwidth, one speaks of overlapping channels.

Long and medium - and short-wave broadcasting

In Europe, Asia, Africa and Australia is in the long and medium wave broadcast bands the tuning step from 9 kHz, the channel center frequency in kHz without remainder divisible by 9. An exception to the two originally coordinated for 180 kHz transmitter Felsberg ( Europe program 1) and Zehlendorf ( Germany Kultur ), which are shifted to reduce mutual interference by 3 kHz up or down. In the Americas, the channel spacing is 10 kHz, the channel center frequency in kHz is divisible by 10 without remainder. In the short wavelength range is a 5 - kHz step inside the world broadcast bands used ( channel mid-frequency in kHz without remainder divisible by 5 ).

Ultrakurzwelle Volume II

In broadcasting, Volume II ( FM radio) used a channel spacing of 100 kHz. In some countries and in the broadband cable a channel spacing of 50 kHz is used sporadically. The receiver equipment to the 1960s, often on the frequency scale channels in 300 kHz steps shown starting with channel 2 ( corresponds to 87.6 MHz) have long had no practical significance.

Television broadcasting

In Germany and Western Europe, the channels lie in bands VHF Band I ( channel 2 to 4, a distance is 7 MHz ) and Band III ( conduit 5 to 12, a distance is 7 MHz ) and UHF band IV and V ( passage 21 to 69, distance 8 MHz). See frequencies of TV channels

Aeronautical radio

Until the early 1970s, the channel spacing was in flight radio ( VHF) 50 kHz and was then reduced to 25 kHz. This meant a doubling of usable channels.

For the VHF air band in the range of 117.975 MHz to 137.000 MHz by the International Telecommunication Union ( ITU) is defined in the Radio Regulations. Are possible frequencies from 118.000 MHz to 136.975 MHz for aeronautical applications. With the 25 - kHz channel spacing there are thus 720 possible VHF frequencies.

Between 118.300 MHz and 118.400 MHz in the following possible VHF frequencies result in 25- kHz steps

These frequencies are published on the aerodrome charts and flight cards, applications for frequency assignment for a ground station can be found at the Federal Network Agency, through the competent state authorities in Germany.

The increase in air traffic capacity required an increase in air traffic management. In order to multiply the resources available for the aviation radio frequencies, the 8.33 - kHz channel spacing has been since 1999 in European airspace in the airspace above flight level 245 ( 24,500 feet = about 7.5 miles) introduced mandatory from 2007 FL 195 In lower airspace remains first in the conventional 25 - kHz channel spacing.

Operating radio

In the German radio operating the channel spacing is 20 kHz. One speaks of the odd grid, because the frequencies of all end with 10, 30, 50, 70 or 90 kHz. For example, 150.250 MHz; 150.270 MHz; 150.290 MHz.

BOS radio

In BOS radio there is no uniform channel spacing. Thus, the 8 m band has a straight 20 - kHz steps. The frequencies are thus eg 34.360 MHz; 34.380 MHz; 34,400 MHz. In the 4- meter band, there is the odd 20 - kHz channel spacing with 5 series ending. For example, 74.215 MHz; 74.235 MHz; 74.255 MHz. In the 2- m band, there are both the odd and the even 20 - kHz steps. Eg 165.210 MHz; 165.230 MHz; 165.250 MHz 167.560 MHz as well; 167.580 MHz; 167.600 MHz. In the 70 cm band, the 12.5 kHz channel spacing, ie 443.6000 MHz applies; 443.6125 MHz; 443.6250 MHz, etc.

Marine Radio

Also in the VHF receiver there is no uniform grid, the channel spacing is 50 kHz, although always between two consecutive channel numbers, but in some cases two different channels are located on adjacent frequencies even at a distance of only 25 kHz.

Example:

• Channel 60: 156.025 MHz
• Channel 1: 156.050 MHz
• Channel 61: 156.075 MHz
• Channel 2: 156.100 MHz

This chopped channel allocation is historical, as the higher channels were allocated later and were simply interposed between the existing ones.

Amateur radio

In amateur radio, there is no uniform - if present - channel spacing. Due to the narrow-band modes such as CW and SSB on short wave and usually continuous tunable radios, there is no need to introduce a channel grid. It simply looks for a vacancy as possible in the middle between two adjacent stations to send. Due to the bandwidth occupied by a modulation, we speak in this sense of channel, if one thinks the used frequency range. In CW are some 100 Hz, at about 2.7 kHz SSB. On higher bands where you work also with wider modulation types, a recommendation has enforced, hold on to a " channel spacing ", which is dictated by the bandwidth of the modulation. Thus, the channel spacing in the FM area of ​​the 10-meter band is typically 10 kHz. In the FM band, where PLL -tuned devices are the rule, the channel spacing is dictated by the increment of the vote. In the 2- meter band and the 70 -centimeter band 25 kHz were thus traditionally defined as the channel grid. Due to a better utilization of the frequencies and the device capabilities of newer the grid was cut in half in a 2- m band at 12.5 kHz - which, however, often pose problems, because the bandwidth of most devices, and the hub are adapted to the small channel spacings. In the United States and other countries, the channel spacing in the 2- m and 70 - cm band is 20 kHz. For tapes that are not yet being used for so long by radio amateurs as the 6 meter band, trying to 20 kHz ( instead of 25 kHz) introduce for frequency modulation and channel spacing as narrow-band mode 10 kHz (instead of 12.5 kHz ), corresponding to as at 25/12, 5 with 5 and 2.5 kHz deviation.

Freenet

In the area of ​​Freenet radio ( semi-professional radio without registration and for free with 500 mW) only six frequencies are allocated with a channel spacing of 12.5 kHz. The frequencies are thus: 149.0250 MHz; 149.0375 MHz; 149.0500 MHz; 149.0875 MHz; 149.100 MHz; 149.1125 MHz.