ASKA DSS SATELLITE INSTALLATION GUIDELINES. LINKS TO INSTALLATION DIAGRAMS AT BOTTOM OF PAGE

I. SIGNAL LOSSES

In MDU installations, there are many factors to create the RF Signal losses which come from the following devices:

a) Coax Cable Losses

b) Splitter Losses (Input to Output)

c) Dip!exer Losses (Input to Output)

d) Tapoff Losses (Input to Output)

e) Tapoff Isolation Losses (Input to Tap)

f) Multi-Switch Loss (Input to Output)

a.). Cable and Cable Losses.

It is recommended to use RG-6U coax cable, which has been sweep tested to the maximum frequency in use. RG-59U coax cable should not be used for the. down lead cable due to higher cable loss. With longer cable runs it is recommended that RG- 11 U coax cable be used for minimum cable loss and less voltage drop. Please refer to the typical cable loss for RG-59U, RG-6U and RG-11U.

CABLE TYPE

Loss in dB per 100 teet Length

             100MHz   200MHZ   500MHZ    900MHZ      1450MHZ    1750MHz     2050MHz

RG59U   2.6dB      4.0dB         6.5dB         9.0 dB          11.9 dB       13.6dB        15.3dB

RG6U     2.1 dB     3.1 dB        5.0 dB        6.9 dB          9.1 dB         10.4 dB       11.7dB

RG11U   1.5dB      2.2dB         3.7dB         5.2 dB          6.9 dB         7.9 dB         8.9 dB

b.) Splitters

Uses transformers to maintain impedance matching and to divide the signal equally to each port.

c.) Tapoffs

Tapoff is a special splitters that do not divide the signal equally. They provide High Isolation of the Tapoff ports to prevent devices on the port from interfering with the main signal through input to output The value   of each port of the tap is calculated by subtracting the Tapoff isolation value from the input signal.

d.) Other Devices Loss

Insertion loss of Feed-through losses are created by any device, whether active or passive, placed in the  signal line. This signal loss, from input to output, is due to the internal losses of the device. Such devices   are Diplexers Multi-switches, Power Inserters, Voltage Blocks, Combiners, Tapofl, etc.

2. SIGNAL LOSS CALCULATION

Following is the basic method of Loss Calculation for Satellite MDU Installation System MDU-l per Fig 2. Each signal loss and signal gain are described in the chart of Aska product specifications on   page 21. Here is the example of loss calculation of output of MST2-17 cascadeable Multi-switch No.3 to Receiver Input:

Point       Loss        Description

a.          -35dBm    - LNB output level (Typical level per transponder)

b.          -4.5dB     - Coax Cable Loss (50 Ft.) from LNB to Amplifier Input (SHA-16)

c.           +16dB     - Gain from SHA- 16 Headend Amplifier

d            -1.8dB     - 20Ft. Cable loss from SHA-16 Amplifier Output to MST2-17

e             -3.5dB    - Loss from Input to Output of No.1 MST2-17 Multi-switch

f.             -1.8dB     - 20ft. Cable loss from No.1 MST2-17 Output to No.2 MST2-17 input

g.             -3.5dB    - Loss from Input to Output of No.2 MST2-l 7 Multi-switch

h.             -1.8dB     - 20Ft. Cable loss from No.2 MST2-17 to No.3 MST2-17 input

               -35.9dB - Total Loss up to Input of No.3 MST2-17 Multi-switch

i              -17dB - Tap Isolation Loss of No.3 MST2-17 Multi-switch

               -52.9dB - Output Level of No.3 Tap Output of MST2-17 Multi-switch

3. POWER LOSS THROUGH CABLE

In addition to DC resistance loss, coaxial cable experiences power losses due to 11Skin Effect" which is due to the tendency of higher frequency RF signals to travel on the thinner skin layer of the conductor. Dielectric losses occur due to the dielectric materials used in the cable construction. Length of cable becomes a resistor and will attenuate the voltage that is being applied. This resistance is referred to as "Loop Resistance". This resistance becomes a critical measurement that must be addressed in the inherent power loss through the cable, when the LNB and powering source are separated. Loop resistance on each coax cable are:

RG-59U Cable 60 Ohms per l,000ft. or 0.06 Oohms per ft.

RG-6U Cable 40 Ohms per 1,000 ft. or 0.04 Oohms per ft.

RG-11 U Cable 20 Ohms per l,000 ft. or 0.02 Ohms per ft.

0.500 Cable (Half inch) 2 Ohms per l,000 ft. or 0.002 Ohms per ft.

Voltage Drop Calculation Formula is: E=I x R

E= Voltage loss through cable run

I= Current being drawn through cable in amperes

R= Loop Resistance X cable length in feet

Example of calculation are as follows:

LNB uses 300 mA of current -0.3 Amp

Inline Amps uses 30 rnA of current - .03 Amp

Cable run from LNB to Power - 300 Feet of RG-6U cable

a.) Without using Inline Amp

I = 0.3 Amp (300mA)

R=0.04 Ohms x300ft.

E = 0.30 x (0.04 X 300)

E=3.6Volts

b) Using in lineAmp

I = 0.3 + 0.03 (300mA + 30mA)

R = 0.04 Ohms x 300 ft.

E=0.33 x (0,04X300)

E-3.96Volts

Since LNB requires 13V on right polarity and 18V on left polarity, the RG-6U cable will deliver:

9.4Volts (13 3.6) to the right polarity and   14.4Volts (18 - 3.6) to the left polarity

The LNB usually requires voltage between II to 14 Volts on the right polarity (RHCP or Vertical Polarity) and 15.5 to 21 Volts for the left polarity( LHCP or Horizontal polarity). The voltage loss shown above is below the operating window and will not operate this system properly.

Longer runs of cable should be avoided. The manufacturer recommends that the powering source be located no farther than 125 ft. from the Dish and that RG-6U cable should be the minimum cable size used.

If longer cable runs can not be avoided, you will be required to use either RG-l IU or .500 Hard line coax cable depending on the calculation and loop resistance specifications. Another solution would be to add an extra power supply in the long cable run to supply extra power to the LNB. When mapping out all possible IRD locations, plot the longest runs first, keeping in mind to avoid extremely long cable runs whenever possible. Two (2) 125 ft. runs would be normally better than one 250 ft. run. Decide how many branches will be required and calculate the loss for the longest one first.

In case of adding more power to compensate for the power loss to activate the inline amplifier, Aska model LA-917 single Inline Amp or LA9520D dual inline amp , the PS-2D Dual Power Inserter should be placed at the end of system or where extra power is required. Typical example is shown per MDU installation diagrams MDU- 1 through MDU-6.

4. FREQUENCY RANGE USED IN L-BAND SATELLITE AS WELL AS IN UHF/VHF SYSTEM

a.) Transmitting signal from Satellite to Earth in DBS band is 12.2 to 12.7 GHz

b.) Transponder frequency are as per chart on page 22. Transponder which consist of receiver, amplifier and transmitter on satellite which receives signal   from earth and then transmits and also downlink microwave to earth.

c) L-band IF frequencies are 950 - 2050 MHz. They are usually 950 - 1450MHz in U.S.A. and 950-1750MHz in Latin America.

d.) UHF/VHF frequency (Off-Air broadcasting) arranged between 54 - 806MHz.

5. SIGNAL LEVELS.

NOTE: Although the DBS signal information is in digital form (that is, all information is relayed by the computer language of  1's and 0's), the Microwave signals still are analog based. It also must be understood that until the LNB signal reaches the IRD, it is still an analog signal that can be distorted by the same interference and other degradation that analog RF signals may be.

a.) Output signal level from LNB is USA is normally -40dBm.

dBm (Power Level) is used for L-Band satellite signal level. It runs between -30 dBm to -40dBm depending on accuracy of dish alignment or weather condition and location of site of footprint of   the satellite dish antenna.

b.) Most satellite receivers are designed to operate with input signal level between -30dBm to 40dBm.   It is recommended that IF distribution systems to be designed to give -55dBm or more per Channel.

c.) IRD (Satellite Receiver) Output level is +5dBmV (+65dBuV or -43.75 dBm). dBmV (Voltage Level) is used for UHF/VHF Off-Air signal level. *Acceptable signal level is 0dBmV or 100uV to input of Headend Amplifier.

The recommended minimum level for UHF/VHF for ASKA products are:

* 25dBmV at the input of Aska model no. LNC-34, LNC-38A and LNC-16 Multi-switches.

* 6dBmV at the input of Aska model no. LNC-34, LNC-34A and LNC-38B.

NOTE: Various terms in the industry are taken to mean the same thing although they may not look identical. We must be certa!n to compare like terms especially in signal level appucations. OdBmV is equal to +60dBuV and also equal to -48.75 dBm in 75 Ohm applications. While the signal level is not one-for-one interchangeable, signal levels are expressed in Power (dBrn) or Voltage (dBmV), as the dB level goes down so does the signal level.

A SIGNAL LOSS WILL ALWAYS SUBTRACT FROM THE ORIGINAL LEVEL WHILE SIGNAL AMPLIFICATION WILL ALWAYS ADD.

6. WHEN TO ADD AMPLIFIERS.

A good rule of thumb when applying amplification is to amplify the signal based on the circuit losses at the point of amplification. It is not a good idea to amplify before distribution losses occur to prevent degradation of the signal. Since we normally use -35dBm of signal as the nominal output level of the LNB, we will assume a system begins with that level. If the combination of splitters, taps, switchers, connectors and cable has made the system losses of 15dB, then a 15dB gain amplifier should be placed at that point to bring the signal level back up to the nominal -35dBm or closer. lf at another point, we have lost 24dB and amplifier having close to 24dB gain should be placed in the system.

NOTE: Some consideration should be made in Front-End design of MDU Systems as follows:

a.) Amplifiers accept -20dBm before overload occurs and amplify signal down to -65dBm. Amplifiers may add noise so each amplifier must be taken into consideration when designing the system.

b.) The Composite Triple Beat (CTB) and Cross Modulation (XMOD) are caused by non-linearity in the amplifiers and overdriven amplifiers. Specifically CTB is the unwanted 3rd Order Beat and XMOD is any unwanted channel crossing into a wanted channel on a analog TV

c.) Too much signal level causes clipping of signal distorting the carrier. Too little signal will not allow the carrier to be retrieved from the noise floor.

d.) Amplify the Off-Air and DSS signals separately, then combine. This will enable the use of presently available amplifiers, reduces distortion and increase the amplifier's output capabilities.

e.) Amplifiers should operate at 5dBm below the rated input levels to reduce CTB, HUM and XMOD distortions. For example; if an input is spec'd at -30dBm/Channel Max., operate at 35dBm/Channel.

f.) It is recommended that distribution systems be designed for no more than four active units in any one cascade line from the headend to the customer outlet. to prevent degradation of signal due to noise factors such as CTB, Second Order Distortion, XMOD and HUM Double for every doubling of amplifiers.

Remember that operating amplifiers at less than the maximum rated output will reduce overall system CTB, XMOD and HUM. The active units are headend amp, inline amp, and active multiswitch.

7. TERMINATING DEVICES

Unused outputs of any devices must be terminated to achieve optimum flatness, return loss and isolation of each devices and system. Aska Model AFS9TB DC blocked and AF59T Not-DC blocked terminators are recommended.

8. EXAMPLE OF TYPICAL HOME,  HOME -RUN AND MDU INSTALLATIONS.

Although only one example of several installations have been shown in this installation guide, there is always more than one way to successfillly wire in L-Band systems depending on how the building is designed. The installer's experience and local installation practices will always be a major factor in any successftil system installation. In this guideline, there are some possible installations shown on pages from 5 through 15. Note: Home-run installation is referred to as all cables return back to mainswitch.

1) BASIC HOME INSTALLATION Five Basic Installations (H-1, H-2, H-3, H-4, H-5)

2) HOME-RUN INSTALLATION Five Basic Installations (HR-1, HR-2, HR-3, HR-4, HR-5)

3) COMMERCIAL MDU INSTALLATION -Six Basic Installations (MDU-1, MDU-2, MDU-3, MDU-4, MDU-5, MDU-6)

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