http://en.wikipedia.org/wiki/L_band
From Wikipedia, the free encyclopedia
| ||||||||
|
L band refers to four long different bands of the electromagnetic spectrum: 40 to 60 GHz (NATO), 1 to 2 GHz (IEEE), 1565 nm to 1625 nm (optical), and around 3.5micrometres (infrared astronomy).
Contents[hide] |
NATO L band[edit]
IEEE L band[edit]
Military use[edit]
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. Digital Audio Broadcasting (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.
GNSS[edit]
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.
Telecommunications use[edit]
GSM mobile phones operate at 800–900 and 1800–1900 MHz. Iridium Satellite LLC phones use frequencies between 1616 and 1626.5 MHz[1] to communicate with the satellites. Inmarsat and LightSquared terminals use frequencies between 1525 and 1646.5 MHz to communicate with the satellites. Thuraya satellite phones use frequencies between 1525 and 1661 MHz to communicate with the satellites.
Amateur radio[edit]
The Radio Regulations of the International Telecommunication Union allow amateur radio operations in the frequency range 1,240 to 1,300 MHz, and amateur satellite up-links are allowed in the range 1,260 to 1,270 MHz. This is known as the 23-centimeter band by radio amateurs and the L-band by AMSAT.
Digital Audio Broadcasting (Earth Orbital)[edit]
WorldSpace satellite radio broadcasts in the 1467–1492 MHz L sub-band.
DAB L band usage[edit]
The following blocks are used for T-DAB (terrestrial) broadcasts:
| Block | Center Frequency |
|---|---|
| LA | 1452.960 MHz |
| LB | 1454.672 MHz |
| LC | 1456.384 MHz |
| LD | 1458.096 MHz |
| LE | 1459.808 MHz |
| LF | 1461.520 MHz |
| LG | 1463.232 MHz |
| LH | 1464.944 MHz |
| LI | 1466.656 MHz |
| LJ | 1468.368 MHz |
| LK | 1470.080 MHz |
| LL | 1471.792 MHz |
| LM | 1473.504 MHz |
| LN | 1475.216 MHz |
| LO | 1476.928 MHz |
| LP | 1478.640 MHz |
The following blocks are used for S-DAB (satellite) broadcasts:
| Block | Center Frequency |
|---|---|
| LQ | 1480.352 MHz |
| LR | 1482.064 MHz |
| LS | 1483.776 MHz |
| LT | 1485.488 MHz |
| LU | 1487.200 MHz |
| LV | 1488.912 MHz |
| LW | 1490.624 MHz |
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.
Physics issues relating to band use[edit]
The band also contains the hyperfine transition of neutral hydrogen (the hydrogen line, 1420 MHz), 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 worldwide.
Optical communications L band[edit]
L band is also used in optical communications to refer to the wavelength range 1565 nm to 1625 nm.
Infrared astronomy[edit]
In infrared astronomy, the L band refers to an atmospheric transmission window centred on 3.5 micrometres (in the mid-infrared).
Other microwave bands[edit]
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:
| L band | 1 to 2 GHz |
| S band | 2 to 4 GHz |
| C band | 4 to 8 GHz |
| X band | 8 to 12 GHz |
| Ku band | 12 to 18 GHz |
| K band | 18 to 26.5 GHz |
| Ka band | 26.5 to 40 GHz |
| Q band | 30 to 50 GHz |
| U band | 40 to 60 GHz |
| V band | 50 to 75 GHz |
| E band | 60 to 90 GHz |
| W band | 75 to 110 GHz |
| F band | 90 to 140 GHz |
| D band | 110 to 170 GHz |
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
Inga kommentarer:
Skicka en kommentar