Engineering Radio; the satellite reaiming tour 2017!

As previously discussed, the migration from AMC-8 to AMC-18 is in full swing. There is less than two weeks left to complete the re-aiming process.  All totalled, we have 24 of these things to re-point and all but two of them  are done.  Toward that end, I have this down to an art:

  • Go inside and make a note of the signal strength on the satellite receivers on AMC-8
  • Look up the elevation angle on dish align app for AMC-8 then compare that to what the inclinometer reads, note the difference between the calculated and actual readings
  • Look up the elevation angle on the dish align app for AMC-18, apply the difference noted above to the final value
  • Connect the XR-3 satellite aiming tool to the LNB, make sure LNB power is on and the unit is set to AMC-18, C-band
  • Elevate the dish to the AMC-18 final elevation angle calculated above
  • Note the azimuth on the dish align app, look at the satellite picture and pick out a land mark.  Swing the dish towards the land mark
  • As you start to see signal from various satellites, swing more slowly.  If the elevation angle is set correctly, when the dish passes AMC-18 at 105 degrees W, the XR-3 will lock on
  • Peak the signal (azimuth and elevation)
  • Rotate the LNB feed horn for maximum signal to noise ratio
  • Go inside, check satellite receivers, reprogram carrier frequencies as necessary

It is pretty easy. I can do the whole thing in about thirty minutes if there are no rusted bolts, etc. I wonder how many small station owners will wake up on July 1st with no satellite programming?

Comtech Satellite dishes, WABC transmitter site, Lodi, NJ

The Applied Instruments XR-3 (XR-S2ACM-01) VSAT-ACM  satellite signal meter with AMC-18 locked.  This hand held tool is great and makes aiming any dish a snap.  As the sky around AMC-18 is a wee bit crowded, it is easy to mistakenly find the wrong satellite.  With the Identify function, the satellite the dish is aimed to will be displayed, then the dish can be adjusted accordingly to the correct bird.

Applied Instruments XR-3 satellite signal meter

There are many different flavors of dishes; Comtech, Patriot, Prodelin, etc.

Prodelin 3.7 Meter satellite dish

These are all about the same to work with, the only difference is the degree of rust and deterioration on the mounting hardware, the age of the LNB and number of bees nests that need to be removed.

Commercial Radio Networks changing Satellites

Lockheed Martin A2100 series satellite
Lockheed Martin A2100 series satellite

Westwood One, Premiere, Skyview Networks, et al. will be changing their satellite from AMC-8 at 139° W to AMC-18/SES-11 at 105° W longitude.  More from AMC8transition.com. There are several considerations for this move:

  • Dish design and two degree compliance
  • Obstacle clearance
  • Transponder frequencies
  • Timing

Two degree compliance is going to be an issue for many stations.  Those old 2.4 and 2.8 meter mesh dishes are going to have issues with 105º West because that is a very crowed part of the sky.  From New York, it looks something like this:

Satellite Longitude Inclination Azimuth Elevation Distance
TELSTAR 12 (ORION 2) 109.21° W 0.491° 227.46° 31.09° 38596.91 km
TELSTAR 12 (ORION 2) 109.21° W 0.491° 227.46° 31.09° 38596.91 km
MSAT M1 107.72° W 7.430° 231.14° 38.16° 38011.55 km
ANIK G1 107.33° W 0.013° 225.25° 31.96° 38518.62 km
ANIK F1 107.31° W 0.020° 225.22° 31.95° 38513.76 km
ANIK F1R 107.28° W 0.052° 225.22° 32.02° 38510.37 km
ECHOSTAR 17 107.11° W 0.019° 225.01° 32.08° 38503.29 km
AMC-15 105.07° W 0.025° 222.76° 33.28° 38400.67 km
AMC-18 104.96° W 0.027° 222.64° 33.34° 38400.16 km
GOES 14 104.66° W 0.198° 222.21° 33.38° 38394.57 km
AMSC 1 103.44° W 9.810° 228.37° 43.31° 37616.42 km
SES-3 103.01° W 0.041° 220.41° 34.42° 38307.12 km
SPACEWAY 1 102.90° W 0.032° 220.25° 34.43° 38299.87 km
DIRECTV 10 102.82° W 0.017° 220.17° 34.51° 38292.86 km
DIRECTV 12 102.78° W 0.035° 220.12° 34.50° 38292.93 km
DIRECTV 15 102.71° W 0.009° 220.05° 34.56° 38290.50 km
SKYTERRA 1 101.30° W 3.488° 219.07° 36.33° 38131.32 km
DIRECTV 4S 101.19° W 0.011° 218.24° 35.35° 38228.26 km
DIRECTV 9S 101.15° W 0.014° 218.18° 35.36° 38228.57 km
SES-1 101.00° W 0.016° 218.02° 35.45° 38217.56 km
DIRECTV 8 100.87° W 0.036° 217.88° 35.54° 38211.02 km

Generally speaking, dishes need to be 3.7 meters (12.14 feet) or larger to meet the two degree compliance specification.  For many, this means replacing the current dish.  This is especially true for those old 10 foot aluminium mesh dishes that were very popular in the 90’s because of the TVRO satellite craze.

If the existing dish is acceptable, then the next issue may be obstacle clearance.  Generally speaking the 105 degree west slot (south of Denver) will be easier to see that the 139 degree west slot (south of Honolulu) for much of the United States.  Still, there may be trees, buildings, hills, etc in the way.  Site surveys can be made using online tools (dishpointer.com) or smart phone apps (dishalign (iOS) or dishaligner (Android)).  I have found that I need to stand in front of the dish to get the best idea of any obstacles.  While you are there, spray all the dish holding hardware with a penetrating oil like WD-40, Rostoff or something similar.  Most of these dishes have not moved since they were installed, many years or decades ago.

Transponder frequencies will not be the same, so when the dish is aligned to the new satellite, those frequencies will need to be changed.  The network satellite provider will furnish this information when it becomes available.  This generally requires navigating around various menu trees in the satellite receiver.  Most are fairly intuitive, but it never hurts to be prepared.

The window of opportunity is from February 1, 2017 (first day of AMC-18) until June 30, 2017 (last day of AMC-8).  Of course, in the northern parts of the country, it may not be possible to install a new dish in the middle of winter.  It may also be very difficult to align an existing dish depending on how bad the winter is.  Therefore, the planning process should begin now.   A quick site evaluation should include the following:

Network Satellite Receive Location Evaluation

Satellite:

Satellite Location:

Dish is 2°compliant? (Y/N)

Distance to receiver location:

Dish Latitude:

Dish Longitude:

Dish Azimuth (T):

Dish Azimuth (M)

Dish Height AGL:

Dish Elevation:

Observed Obstacles:

(permanent or removable? Owned or not owned?)

Comments:

A .pdf version is available here. Based on that information, a decision can be made on whether or not to keep the old dish or install a new one.  We service about 25 studio locations and I am already aware of three in need of dish replacement and two that have obstructive trees which will need to be cut.  This work cannot start too soon.

The Realtek 2832U

In my spare time (lol!) I have been fooling around with one of those RTL 2832U dongles and a bit of software.  For those that don’t know, the RTL 2832U is a COFDM demodulator chip designed to work with a USB dongle.  When coupled with an R 820T tuner a broadband RF receiver is created  There are many very inexpensive versions of these devices available on Amazon, eBay and other such places. The beauty of these things is that for around $12-30 and a bit of free software, one can have a very versatile 10 KHz to 1.7 GHz receiver.  There are several good software packages for Windoze, Linux and OSX.

The one I recommend for beginners is called SDR-Sharp or SDR#.  It has a very easy learning curve and there is lots of documentation available on line.  There are also several worth while plugins for scanning, trunking, decoding, etc.  At a minimum, the SDR software should have a spectrum analyzer, water fall display and ability to record audio and baseband PCM from the IF stage of the radio.

Some fun things to do; look at the output of my reverse registering smart (electric) meter (or my neighbor’s meter), ACARS data for the various aircraft flying overhead, a few trips through the EZPass toll lanes, some poking around on the VHF hi-band, etc.  I also began to think of Broadcast Engineering applications and a surprising number of things came to mind:

  • Using the scanner to look for open 950 MHz STL frequencies
  • Inexpensive portable FM receiver with RDS output for radio stations
  • Inexpensive Radio Direction Finder with a directional antenna
  • Inexpensive Satellite Aiming tool

Using SDR sharp and a NooElec NESDR Mini+ dongle, I made several scans of the 945-952 STL band in a few of our markets.  Using the scanner and frequency search plugin, the SDR software very quickly identified all of the in use frequencies.  One can also look at the frequency span in the spectrum analyzer, but this takes a lot of processing power.  The scanner plugin makes this easier and can be automated.

950 MHz STL frequencies, Albany, NY
Analog and digital 950 MHz STL frequencies, Albany, NY

I also listened to the analog STLs in FM Wideband mode.  Several stations are injecting their RDS data at the studio.  There is one that appears to be -1500 Hz off frequency.  I’ll let them know.

Next, I have found it beneficial just to keep the dongle and a small antenna in my laptop bag.  Setting up a new RDS subcarrier; with the dongle and SDR# one can quickly and easily check for errors.  Tracking down one of those nasty pirates; a laptop with a directional antenna will make quick work.

Something that I found interesting is the water fall display for the PPM encoded stations:

WPDH using RTL 2832U and SDR Sharp
WPDH using RTL 2832U and SDR Sharp

Not only can you see the water marking on the main channel, you can also see the HD Radio carriers +/- 200 KHz from the carrier frequency.  That is pretty much twice the bandwidth allotment for an FM station.

WDPA using RTL 2831U with SDR Sharp
WDPA using RTL 2831U and  SDR Sharp

Those two stations are simulcasting.  WPDA is not using Nielson PPM nor HD Radio technology.  There is all sorts of interesting information that can be gleaned from one of these units.

Aiming a satellite dish at AMC-8 can be a bit challenging.  That part of the sky is pretty crowed, as it turns out.  Dish pointer is a good general reference (www.dishpointer.com) and the Dish Align app for iOS works well.  But for peaking a dish, the RTL 2832 dongle makes it easy to find the correct satellite and optimize the transponder polarization.  Each satellite has Horizontal and Vertical beacons.  These vary slightly in frequency, thus, but tuning to the correct beacon frequency, you can be assured that you are on the right satellite.  All of the radio network programming on AMC-8 is on vertically polarized transponders, therefore,  the vertical beacons are of interest.  Here are the vertical beacons for satellites in that part of the sky:

Satellite Position C band Vertical beacon (MHz) L band (LNB) Vertcial beacon (MHz) Comment
AMC-8 139W 4199.5 949.25
AMC-7 137W 3700.5 1450.25
GOES15 135.4W 2209.086 N/A NOAA WX
AMC-10 135W 4199.5 949.25
Galaxy 15 133W 4198 949.00
AMC-11 131W 4199.5 949.25
Galaxy 12 129W 3700.5 1450.25

For those in the continental United States, there is not much else past 139W, so AMC-8 will be the western most satellite your dish can see.  Of course, this can be used in other parts of the world as well, with the correct information. Bringing a laptop or Windows tablet to the satellite dish might be easier than trying to drag a XDS satellite receiver out.

AMC8 vertical beacon output from LNB
AMC8 vertical beacon output from LNB

In order to use the RTL-2832U, simply split the output of a powered LNB, install a 20-30 dB pad in between the splitter and the dongle.  Using the vertical beacon on 949.25 MHz, adjust for maximum signal.

Some other uses; look for the nearest and best NOAA Weather radio station.  Several times the local NOAA weather station has been off the air for an extended period of time.  Sometimes, another station can be found in the same forecast area.  Heck, couple these things to a Raspberry Pi or Beaglebone black and a really nifty EAS receiver is created for NOAA and broadcast FM.  One that perhaps, can issue an alarm if the RSL drops below a certain threshold.

I am sure there are plenty of other uses that I am not thinking of right now…

Satellite Dish Maintenance

Periodic attention is required for most satellite receive only earth stations. This particular dish sticks up above the roof line of a two story building. It acts as a big sail and sometimes, after a particular wind event, it gets slight off of it’s intended satellite, AMC-8.

Comtech 3.7 meter dish
Comtech 3.7 meter dish

The real issue is doing anything with the feed horn assembly, as it hangs way up in the air right over the edge of the roof. An extension ladder does not work, nor does a step ladder on the roof. Thus, we had to call a bucket truck to come and replace the LNB.  Naturally, this work is being done on one of the coldest days of the year (so far).  Temperatures at the start were 4° F or -15° C, which made the hydraulics in the bucket truck a bit reluctant to work.

When the dish was installed in 2000 or so, I swung it so the feed horn assembly was over the roof to work on it. This did not allow me to effectively check the feed horn polarization. With the bucket truck and a good satellite aiming device, I was able to find the correct polarization for the transponders in use by this station.

Bucket truck satellite dish maintenance
Bucket truck satellite dish maintenance

The old LNB was an original California Amplifiers PLL LNB from the mid 1990’s. The temperature was 35° K, which is kind of high these days. It was replaced by a Norsat C band PLL LNB with a 20° K temperature.

The satellite aiming tool used is an AI Turbo S2 by Dawn Satellite.  This unit has software profiles for each satellite which can be updated over the internet.  The 139° W satellite neighborhood is pretty crowded and it is easy to find yourself looking at the wrong bird.  Using the aiming tool prevents that from happening, as it tells the user exactly which satellite it is receiving.

Satellite aiming tool
Satellite aiming tool

If this is a new installation, using Satellite Finder makes the rough aiming much easier.

Dish pointer, AMC-8 aiming information
Dish pointer, AMC-8 aiming information

Also, it one were interested in being very through, consulting the SES center of box page will give the best aiming window times.  To be honest, I have never found this to make much difference.

XDS Eb/No after re-aiming
XDS Eb/No after re-aiming

The end result, Eb/No is 17.5 with the AG of 54.  All in all, a happy satellite receiver.