PitchBlue RF/SATCOM Questionnaire and Explanations
Posted by - NA - on 22 October 2009 07:19 AM

RF/SATCOM QUESTIONNAIRE and EXPLANATIONS

ANTENNA INFO
Receive Antenna Type/Size (meters)
• If "Other" enter size or take Photo
This is needed for determining the expected parameters and performance of the station downlink EIRP; Which will tell the RF engineering staff if the antenna has sufficient theoretical gain minus IFL (inter-facility link) loss to meet specified L-band levels at the PitchBlue/MagnuBox. Different make/model(s) of satellite antennas have somewhat different geometries, sizes and efficiency ratings directly related to the overall Noise figure* of the antenna, and signal to noise (S/N) factor at different levels and angles. Additionally, using optimum null cross pole technique to ensure proper and consistent pole placement at each position measurements are taken.

• Antenna Mount Type: __________This information will assist us if repositioning of the antenna is required. Additional information on advanced antenna installation, pointing, and set-up is included in Appendix B.

• Manufacturer/Make This is a general question that gives us a better understanding of what stability the antenna system may or may not have if problems like jitter is noticed in the carrier. Enter Model Name/# If you have the information it may be easier to take a photo and post it on the Linear Support ticket

• Tracking System Type__________ will tell us if the antenna is capable of tracking a satellite, however programming of that tracking computer will have to be known if a signal issue is found. Tracking systems are usually set and forgotten and often programmed with an incorrect setting for the current satellite it may be pointed at. There are by nature of the Sat tracking industry as many names for the same function IE; TRACK MODE on a Vertex 7200 could be INCLATRACK on an ETE model. Knowing the type will aid in resolving these kind of issues.

• Deicing System Y/N:_________
Deicing System Type This is more important than you may believe. There are several types of De-Ice systems: Electric Pads, Covers, Spray coatings, Hot-air hard rear covered, Hot-air front canvas covered, Feed horn covered electrical, feed horn canvas covered electric. As you can see, there are several combinations that can be used.
We are interested in the type to understand the relationship the De-Ice system may have to a problem, in reference to the performance function of the antenna system. The rear Walton aluminum shell or rear cover Deice system is usually mounted on Satellite dishes nine meter and above mostly due to the fact they can handle the extra weight without deforming the shape factor of the parabolic. As weight is added to the antenna frame structure it tends to force the total weight in the center portion up and down the dish thus elongating the parabolic detuning the antenna surface reflecting area and can affect gain as much as half or 3db. Front covers attenuate the received signal by different amounts. Light, dry snow is much less problematic than wet, heavy snow. Of course, depth of the snow coverage is directly proportional to attenuation of the signal. Ice accumulation in any amount is significantly worse than just snow, due to the changes in the geometry of the actual receive surface of the reflector. Freezing rain, “anchor frost,” and their rapid accumulation is a definite problem that must be addressed asap to prevent rapid degradation of the signal.

• Motorized Y/N: __________
This lets us know what ability the site has to re- point the antenna system and technique to utilize. It is also good to know whether the antenna is re-pointed to alternate satellites regularly, or is essentially fixed on the proper spacecraft.

• Movement: Will the antenna movement be polar arc tracking or AZ/EL adjustable. This is important to know for re-peaking of the antenna.

• Feed Assembly Modle:# ___________This will tell us the configuration of the LNB’s, filter placement, polarity changes, cable routing. In addition, this will determine what adjustments are possibly needed, can be done, and the technique to employ for troubleshooting. Photos could be used if access is restricted.

• Terrestrial RF Interference (TI) Filter Y/N: ________
This will dictate whether a new, or replacement filter will correct or improve the received signal. Specific parameters and make/model are provided for the PitchBlue/MagnuBox deployment.

• C/KU-BAND LNB Make/Model:#_______________ This information is useful to ensure the installed LNB meets the recommended specifications for the “commercial grade” PLL LNB necessary. This is uniquely important if there is a 4 port feed down linking both C-Band and Ku-Band signals.

• If "Other", please Enter C-BAND LNB Model Name/#________________See Appendix A for specified make/model. Again, this information will determine whether the installed LNB is compliant to pre-specified parameters.

• IFL Type is important due to manufacture specifications to see if the IFL Type is correct for the distance it being used for. If Waveguide, selecting or noting type and manufacture will indicate the loss and projected VSWR properties of the waveguide used.

• Enter IFL Cable Model #_______________ AND LENGTH________________ (ft) Coaxial cable center conductor type determines the VSWR and loss different manufactures use different grades of material for this purpose, we will use the manufactures data specification sheet to calculate loss.

• Fiber Optic Type (or Color) will assist us in determining type of fiber used; yellow_______ orange _______ Brown_______

• Fiber Optic conversion gear make/Model: #_________________This is important to know if it is amplified or passive and if the unit has AGC which could affect the input level at the PitchBlue/MagnuBox. All these component specifications are required to specify overall IFL capabilities and signal levels the receiver will need to manage under all weather conditions.

• Fiber Optic IFL Frequency: is important to tell us if the frequency is within the IRD’s down converter’s range.

• IFL Connectors used: will tell us if the proper connector is being used and what type of possible losses, or problems may be associated with them.

• Adaptor types in use will let us know if they are the proper adaptors for the frequency range.

• Adaptor Location 1- 4 will be important in trouble shooting loss or signal level issues within the IFL line to the Blue/MagnuBox unit.

• RF/IF Amplifiers in use Y/N ________will help us determine overall loss or gain of the IFL run. Amplifiers also inject noise and jitter causing the digital carrier to output BER errors in the transport stream.


• RF/IF Amplifier Make #______________will tell us the gain of that particular unit and allow us to calculate the IFL Loss which is used in determining the Station Downlink EIRP.

• Enter RF/IF Amplifier Model#_________________ and make will tell us the manufacture rated output range and bandwidth.

• RF/IF Amplifier Location is important since it needs to be positioned as close as possible to cleanest and lowest noise floor signal to allow clean amplification of the carrier.

• RF/IF Splitters in use Y/N________This determines another point and amount of signal loss to the PitchBlue/MagnuBox.

• RF/IF Splitter Make#_________________ is important to determine the gain or loss of the device which will be important in calculating the overall IFL loss.

• Enter RF/IF Splitter Model#______________ will tell us if the device is passive or 0 loss device. This information has to be known before IFL calculation can be determined.

• RF/IF Splitter Ports in use (#) ________once the splitter type is known then ports used will help to determine the calculated gain or loss of the splitter.

• RF/IF Splitter Ports Terminated (#)_________Terminating these unused ports will keep RFI interference from entering the carrier stream and possibly causing BER loss or degradation of the data carried within the carrier.

• Enter RF/IF Splitter Model will tell us if the device is passive or 0 loss device. This information has to be known before IFL calculation can be determined.

RECEIVE LEVELS
• Enter Current Signal Levels (Eb/NO________, S/L_________) at PitchBlue/MagnuBox TSR (via Formatics or front panel display)
• Enter Current Signal Levels (Eb/NO, S/L) at IRD front panel display (if available).
Both of these devices can provide signal level measurements which will enable you to effectively maximize/peak the received signal for optimal functioning.

RF/IF TEST EQUIPMENT AVAILABLE ON SITE
• RF Power Meter Y/N:___________ is used for station downlink EIRP, usually done incardination with a CW signal transmitter of some type that has the ability to reach 0 DBM this will be plugged in to one end of the IFL and the power meter will measure the opposite end of the IFL.

• RF Spectrum Analyzer Y/N: ______________This frequency agile device allows the user to measure analog and digital carriers from the satellite within selected frequency, bandwidth and amplitude ranges. The Spectrum Analyzer allows the user to measure carriers by adjusting the resolution bandwidth and video bandwidth and sweep time to accurately take measurements that will be compared to the C/N and EB/NO that your receiver will also be seeing. Settings for the spectrum analyzer can be very involved if you do not use it often. RF Support should definitely be consulted for assistance locally if available. Basic settings for the best trace are: 300 Resolution Bandwidth, 100 Video Bandwidth at 5dbm per division sweep time auto at whatever frequency is being measured.