Thread: Stupid Question

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!

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

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

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

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.

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!

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)

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.

Originally Posted by 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) .

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).