Stupid Question

[goaliebob99]

Ok Stupid question.

What is the difference in Lband, KU band, Cband and DBS in relations to Lband.

Meaning I know what the differences between KU / KA / Cband are, but how does L band tie into all of this!

 

[Mr Tony]

Bob there are no stupid questions

L Band from what I remember is just another band in the frequency spectrum. I thought the military used the L Band

 

[qwert1515]

The frequency ranges vary depending on where you look (Frequency ranges were taken from WIKI).

L Band: 1 to 2 GHz
C band: 4 to 8 GHz
Ku band: 12 to 18 GHz
K band: 18 to 26.5 GHz
Ka band: 26.5 to 40 GHz

The C, Ku and Ka bands are at "Ultra" high frequencies and are hard to work with over a coaxial cable because of high signal loss per a foot of cable. So the LNB using a LO down converts the satellite frequency band to the L-Band (in our case 950 - 2150 MHz) where there is less loss per foot over a coaxial line.

The general conversions are:

Conversion for C-Band to L-Band:
(LO) - Frequency = L-Band Frequency

Conversion for Ku-Band to L-Band:
Frequency - (LO) = L-Band Frequency

 

[Mr Tony]

dang...I always called that the IF frequency....didnt know it was the L Band

 

[qwert1515]

Well, it kind of is the IF frequency, depending how you want to call it....

From WIKI:
Intermediate frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception.

In this case the IF frequency is in the L-Band portion of the spectrum.

An analogy using analog TV is that you have a cable receiver or satellite receiver (We are at SatelliteGuys )
that picks up a channel at a high frequency and the receiver brings it down and outputs the video on channel 3 or 4 to the analog TV.

 

[goaliebob99]

Ok so basically, the LNB converts the KA/KU/C band signal and transforms it into an L band signal so it can go across the cable at a much futher distance without the loss in quality. Very good now I understand. Im trying to go back to the basics of satellite engineering, in preparation for plunking down alot of change on sling path training. I just want to make sure I have everything down before going that route Especially since I'm paying out of pocket for it!

 

[Mr Tony]

actually bob the L band is what you start with (950-2150)...also called the IF frequency

its the LNB that converts it depending on the correct LNB LO. If you've ever had a Pansat receiver when you blind scan it shows the IF frequency in the corner as it scans.

The receiver deals with the IF (L Band) frequency regardless. That is why if you have the wrong LNB LO you can still pick up channels (just at the "wrong" frequencies)

 

[goaliebob99]

Ok that explains it, so when the pansat is doing its blind scan, its scanning in the Lband frequency and then converts the frequency based on the LNB LO, that gives it the proper band frequency (ka, KU ect) So, you can say that all satellite transmissions are in the Lband or in their retrospective bands.

 

[Mr Tony]

Ok that explains it, so when the pansat is doing its blind scan, its scanning in the Lband frequency and then converts the frequency based on the LNB LO, that gives it the proper band frequency (ka, KU ect) .

correct. It scans the L-Band (as shown in the top of the pic below) and then shows the converted frequency

I bet all receivers do it that way but most don't show the IF frequency. I know when I blind scan on the Geosatpro you set the IF limits (950-1450 for KU). Also on the Coolsat 4/5/6000 models when you scan C-Band it starts at 4200 and works its way down (4200 is 5150-950)

It scan 950-2150 regardless of band. Most receivers know to limit it with standard LNB's in the software to stop at around 1500 (Pansat's go to 1600).

 

[Anole]

Since all (modern) satellite receivers tune the L band for their first IF frequency...
They can operate on C-band, Ku-band or Ka-band (new DirecTV) by using the appropriate LNBF and local oscillator frequency.
They just have to know and believe the LO frequency you give them, to calculate the actual received frequency.

So, a Ku LNB with 10750, 10600, or some of the non-USA frequencies like 10100 or 10300 will receive their intended band and display it properly... if the receiver will accept your strange frequency as truth.

Here is a discussion with calculations pertaining to bandstacked LO frequencies on Ku.

But the most important thing I've read here, is that many commercial receivers require you to put in the L-band or IF frequency to tune, and do NOT do the calculation themselves.

 

[Mr Tony]

But the most important thing I've read here, is that many commercial receivers require you to put in the L-band or IF frequency to tune, and do NOT do the calculation themselves.

thats true. Or some like the SA9234 (the one used for Armed Forces TV) can input either IF or "normal" frequency

 

[McGuyver]

The frequency ranges vary depending on where you look (Frequency ranges were taken from WIKI).

L Band: 1 to 2 GHz
C band: 4 to 8 GHz
Ku band: 12 to 18 GHz
K band: 18 to 26.5 GHz
Ka band: 26.5 to 40 GHz

The C, Ku and Ka bands are at "Ultra" high frequencies and are hard to work with over a coaxial cable because of high signal loss per a foot of cable. So the LNB using a LO down converts the satellite frequency band to the L-Band (in our case 950 - 2150 MHz) where there is less loss per foot over a coaxial line.

The general conversions are:

Conversion for C-Band to L-Band:
(LO) - Frequency = L-Band Frequency

Conversion for Ku-Band to L-Band:
Frequency - (LO) = L-Band Frequency

I thought that the L-band freq's were converted to C & Ku band freq's.
L-band is received then converted.

L-band freq's are converted to C & Ku band so that they can be handled through coax, I think you have it backwards or I am completely misunderstanding your post so please forgive me if I am. Maybe I'm completely misunderstanding the conversion process so please educate me

Quote: "The C, Ku and Ka bands are at "Ultra" high frequencies" , I believe it's just the opposite, the higher numbers are low freq's, the lower numbers are high freq's as in wifi 2.4 GHz are ultra high. 5.150 GHZ is low.

Maybe I'm wrong, I may stand corrected... ugh!

 

[Wescopc]

McGuyver,
The "C", "K", "KU", "Ka" frequencies are to high for coax cable so they must be converted down to 2 GHz (2,000 MHz) or less for transmission on coax. If you look at the specs of coax cable you will see how the transmission losses increase dramatically as you get up to 2 GHz, look at the chart on the bottom of this page:
Coax Cable Frequency Loss, DC Resistance, Flooded, Plenum RG-6, RG-11

Hope this helps - rather than confuses.
Bob

 

[classicsat]

The frequency stays the same. The maths in the reciever let you tune the original RF frequency the satellite transmitter, and it calculates the L-band/IF frequncy it should tune, or more accurately its LO frequency based on its internal IF frquency. Just think of your receiver as an L-band tuner, which you could tune direct with L-band frequency, or the LNBF RF frequency, by adding the LO frequency to the L-band frequency in the tuner software. I do have one of those security cameras that operates at 1.2 Ghz, and can be tuned on an analog satellite receiver. You might be confusing frequency with wavelength, which as frequency goes up, wavelength gets smaller. FWIW, DBS is just a part of Ku band, technically. It just uses a different LO to land on the standard L-band IF, and circular polarization.

 

[AcWxRadar]

Just some C&P from WikiPedia regarding L-Band (and others) for fun and interesting reading.

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).

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.

Physics issues relating to band use

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 world-wide.


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

Radio Spectrum:

subHertz
subHz 0 < 3 Hz
> 100,000 km
Natural and man-made electromagnetic waves (millihertz, microhertz, nanohertz) from earth, ionosphere, sun, planets, etc[citation needed]

Extremely low frequency
ELF 1 3–30 Hz
100,000 km – 10,000 km Communication with submarines

Super low frequency
SLF 2 30–300 Hz
10,000 km – 1000 km Communication with submarines

Ultra low frequency
ULF 3 300–3000 Hz
1000 km – 100 km Communication within mines

Very low frequency
VLF 4 3–30 kHz
100 km – 10 km Submarine communication, avalanche beacons, wireless heart rate monitors, geophysics

Low frequency
LF 5 30–300 kHz
10 km – 1 km Navigation, time signals, AM longwave broadcasting, RFID

Medium frequency
MF 6 300–3000 kHz
1 km – 100 m
AM (medium-wave) broadcasts

High frequency
HF 7 3–30 MHz
100 m – 10 m Shortwave broadcasts, amateur radio and over-the-horizon aviation communications, RFID

Very high frequency
VHF 8 30–300 MHz
10 m – 1 m FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications

Ultra high frequency
UHF 9 300–3000 MHz
1 m – 100 mm
Television broadcasts, microwave ovens, mobile phones, wireless LAN, Bluetooth, GPS and two-way radios such as Land Mobile, FRS and GMRS radios

Super high frequency
SHF 10 3–30 GHz
100 mm – 10 mm Microwave devices, wireless LAN, most modern radars

Extremely high frequency
EHF 11 30–300 GHz
10 mm – 1 mm Radio astronomy, high-frequency microwave radio relay

Terahertz
THz 12 300–3,000 GHz
1 mm – 100 ?m Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications

RADAR: Radar - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Radar_antenna.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/9/90/Radar_antenna.jpg/220px-Radar_antenna.jpg"@@AMEPARAM@@commons/thumb/9/90/Radar_antenna.jpg/220px-Radar_antenna.jpg

 

[AcWxRadar]

Ok Stupid question.

What is the difference in Lband, KU band, Cband and DBS in relations to Lband.

Meaning I know what the differences between KU / KA / Cband are, but how does L band tie into all of this!

As you witness the replies, you can see that there are NO stupid questions here!

RADAR

 

[rgk]

Intermediate frequency refers to a frequency shift made to a signal by any receiver (TV, Satellite, Radio, etc). This is to allow more efficient amplification of the signal.

 

[AcWxRadar]

I think that what most people don't really consider, is that with all TVs, the L.O. and the mixer stage is within the TV itself and within its own tuner.

When you incorportate a satellite antenna, you have an additional circuit that performs the same function as the front end of the TV tuner, which is not located within the TV (or the STB) itself. It is located externally and within the LNB out on the dish (it has to be this way because you cannot take the received signal over a wire or cable into the house to the TV due to its frequency and power leve). It has to be converted to a lower frequency and amplified first.

Basically, the LNBF is just another part of your tuner, but it is remotely located. The frequency that it (the LNBF) produces to send to the next stage of the tuner is the L-Band signal.

I think that many people think that what happens out on the dish and within the LNBF is "magic". Well, it is magic, but it isn't any different magic then what goes on within the tuner of a 1968 Sylvania B&W TV. It is only slightly different as the LNBF has to perform part of the job of the antenna as well as part of the job of the tuner.

It's really cool what we can do with electronics, magnetism and frequencies and some gadgets made from silicon or germanium, etc. Doped up with boron, arsenic, phosphorus or gallium! Just neat stuff all around!

RADAR

 

[warnerwlf98]

It's really cool what we can do with electronics, magnetism and frequencies and some gadgets made from silicon or germanium, etc. Doped up with boron, arsenic, phosphorus or gallium! Just neat stuff all around!

RADAR

This coolness made me become an electrical engineer. But after spending 6 years and countless hours swearing in completing my PhD, unforunately hate has replaced some of the coolness.