L band refers to four different bands of the electromagnetic spectrum: 40 and 60 GHz (NATO), 1 to 2 GHz (IEEE), 1565 nm to 1625 nm (optical), and around 3.5 microns (infrared astronomy).

[edit] NATO L band

The NATO L band is defined as the frequency band between 40 and 60 GHz (5–7.5 mm).

[edit] IEEE L band

The IEEE L band (20-cm radar long-band) is a portion of the microwave band of the electromagnetic spectrum ranging roughly from 1 to 2 GHz.^[1][2] It is used by some communications satellites, and for some terrestrial Eureka 147 digital audio broadcasting (DAB). The amateur radio service also has an allocation between 1240 and 1300 MHz (23-centimeter band). The L band refers to the frequency range of 950 MHz to 1450 MHz. It is the result of the downconversion of the received downlink satellite signals (C, Ku or Ka) by the LNB (Low-noise block converter).

[edit] Military use

In the United States and overseas territories, the L band is held by the military for telemetry, thereby forcing digital radio to in-band on-channel (IBOC) solutions. DAB is typically done in the 1452–1492-MHz range as in most of the world, but other countries also use VHF and UHF bands.

[edit] GNSS

The Global Positioning System carriers are in the L band, centered at 1176.45 MHz (L5), 1227.60 MHz (L2), 1381.05 MHz (L3), and 1575.42 MHz (L1) frequencies.

• The Galileo Navigation System uses the L-band similarly to GPS.
• The GLONASS System uses the L-band similarly to GPS.

[edit] Telecommunications use

GSM mobile phones operate at 800–900 and 1800–1900 MHz. Iridium Satellite LLC phones use frequencies between 1616 and 1626.5MHz^[3] to communicate with the satellites

[edit] Digital Audio Broadcasting (Earth Orbital)

WorldSpace satellite radio broadcasts in the 1467–1492 MHz L sub-band.

[edit] DAB L band usage

The following blocks are used for T-DAB (terrestrial) broadcasts:

The following blocks are used for S-DAB (satellite) broadcasts:

Note: Canada uses slightly different central frequencies for L-band DAB while in many European countries DAB is limited part of Band III due to television and mobile two way radio using the rest.

[edit] Physics issues relating to band use

The band also contains the hyperfine transition of neutral hydrogen (the hydrogen line), which is of great astronomical interest as a means of imaging the normally invisible neutral atomic hydrogen in interstellar space. Consequently parts of the L-band are protected radio astronomy allocations world-wide.

[edit] Optical communications L band

L band is also used in optical communications to refer to the wavelength range 1565 nm to 1625 nm.

[edit] Infrared astronomy

Atmospheric windows in the infrared. The L band is the transmission window centred on 3.5 microns

In infrared astronomy, the L band refers to an atmospheric transmission window centred on 3.5 microns (in the mid-infrared).

[edit] Other Microwave bands

The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1 GHz to 100 GHz in frequency, but older usage includes lower frequencies. Most common applications are within the 1 to 40 GHz range. Microwave frequency bands, as defined by the Radio Society of Great Britain (RSGB), are shown in the table below:

Footnote: P band is sometimes incorrectly used for Ku Band. "P" for "previous" was a radar band used in the UK ranging from 250 to 500 MHz and now obsolete per IEEE Std 521, see[1] and [2]. For other definitions see Letter Designations of Microwave Bands

[edit] References

1. ^ "The Electromagnetic Spectrum and the Color Light Spectrum". http://emandpplabs.nscee.edu/cool/temporary/doors/electrospectrum/spectrum.htm. 
2. ^ McBride, Donald (2006-03-01). "Electromagnetic Frequency Spectrum". http://www.oocities.com/dtmcbride/tech/em-spectrum.html. 
3. ^ http://www.fcc.gov/Bureaus/International/Orders/1995/da950131.txt

[edit] See also

• Earth observation satellites transmission frequencies