Uderstanding 09750 and 10600
- Thread starter coghurst
- Start date
SimonE
Regular Member
- My Satellite Setup
- 1.2m CM dish with elevation jack, Supermount 1224 H-H rotator, Octagon SX88+, DR.HD D15, GT Media Combo, Ku PLL LNB, C Band: Titanium C1W-PLL, Ka Band: XMW R9216AF with FD9000 feedhorn, Inverto Saorsat LNB and Inverto Ka/Ku LNB . Zone 2 dish pointing at 28E with Octagon SF8008.
- My Location
- Gloucestershire, UK
Those two frequencies in mhz are the frequencies of the two local oscillators in a Universal LNB.
weakbit
Member
- My Satellite Setup
- T90 Wavefrontier 5°;0,8°W-4,8°7°;9°;10°;13°;16°;19,2°;21,5°;23,6°;26°;31,5°;33;39°;42°
- My Location
- Vienna Austria
To understanding this why it is necessary to know the history. In 1987 as I start to receive my first signals from the space there are only single Band LNCs on the market and this have e.g. 10700 - 11700MHz input frequency on the dish side and 950 - 1950MHz I.F. (1st Intermediate Frequency) output this mean that the LO(Local Oscillator for down mixing the input signal) 10700MHz(input) - 9750MHz(LO) = 950MHz(IF) or 11700MHz(input) - 9750MHz(LO) = 1950MHz(IF). The IF is then in the Input of the Tuner and this mix it down to a deeper 2nd I.F. and so on till the end of the tuner and there we have fix frequency that will come into the demodulation form the signal. In modern LNCs you have now 2 Band Low/High and the Loser LO is for the lower Band to downmix and the Higher LO is for the upper Band 11700 - 12750MHz to down mix. (9750 low/10700 high LO) Best Regards weakbit
Terryl
Specialist Contributor
- My Satellite Setup
- OpenBox X5 on a 1 meter motorized dish.
And now a 10 foot "C" band dish.
Custom built PC
- My Location
- Deep in the Boonies in the central Sierra Nevada mountains of California.
Another reason is that the down link transponder frequency's from the satellites are way too high for a standard coax to handle. (10 to 12.7 GHz.)
If you tried to directly send this transponder frequency down to a receiver you would need some very expensive wave guide to do this.
So the LNB uses a LO frequency to down convert it to a lower frequency, this is called an IF, its this IF signal that can be transmitted down a coax cable to a satellite receiver. (coax should be rated to 2.5 GHz or swept to 3 GHz)
If you tried to directly send this transponder frequency down to a receiver you would need some very expensive wave guide to do this.
So the LNB uses a LO frequency to down convert it to a lower frequency, this is called an IF, its this IF signal that can be transmitted down a coax cable to a satellite receiver. (coax should be rated to 2.5 GHz or swept to 3 GHz)
weakbit
Member
- My Satellite Setup
- T90 Wavefrontier 5°;0,8°W-4,8°7°;9°;10°;13°;16°;19,2°;21,5°;23,6°;26°;31,5°;33;39°;42°
- My Location
- Vienna Austria
Or you use a Wave-Guide for the Microwave to transport it from the receiving Feedhorn to your Converter Mixer. In the picture to see the self build Wave-Guide for 10-12.75GHz and on the back side of the dish is the LNC for converting the very high frequency. And well the L.O. Local Oscillators are for the downmix the to receiving frequency for example 10.7GHz(receive) - 9.75GHz(LO) = 950MHz as I write in my first example this is for the Low Band from 10.7 - 11.7GHz you can mix also 11.7GHz(receive) - 9.75GHz(LO) = 1950MHz for the Low-Band top. 2nd the high Band is from 11.7-12.75GHZ and this need the higher Oscillator 10.6GHz(LO). 11.7GHz(receive) - 10.6GHz(LO) = 1100MHz bottom high band and 12.75GHz(receive) - 10.6GHz(LO) = 2150MHz top high band. This very high Microwave frequency can't be in a coax cable in case of the very high loss inside the coax-cable. I hope so this is more understanable too. And wellcome to our hobby it is very interst what happended inside the signal and how to. Best Regards weakbit
