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
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:
|TELSTAR 12 (ORION 2)
|TELSTAR 12 (ORION 2)
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
Dish is 2°compliant? (Y/N)
Distance to receiver location:
Dish Azimuth (T):
Dish Azimuth (M)
Dish Height AGL:
(permanent or removable? Owned or not owned?)
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.
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.
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
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 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:
||C band Vertical beacon (MHz)
||L band (LNB) Vertcial beacon (MHz)
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
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…
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
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
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
If this is a new installation, using Satellite Finder makes the rough aiming much easier.
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
The end result, Eb/No is 17.5 with the AG of 54. All in all, a happy satellite receiver.
Something that almost every radio station has but no one really thinks about; the satellite down link. I think radio stations began installing satellite down link equipment around 1982. Before that, all network programming was carried hither and yon via Ma Bell’s extensive terrestrial microwave network.
Those early dishes were almost always Scientific Atlanta 9000 series 2.8 meter antenna system, which went with the SA 7300 DATS satellite receiver. Fast forward 31 years and things have changed. The satellite constellation is now spaced at one degree and those old SA 9000 dishes are not one degree compliant.
Scientific Atlanta 9000 series satellite dish
Therefore, when it came time to re-aim a dish at AMC8, something new was required. A Prodelin 1374 3.7 meter center fed C band dish was ordered up.
The first thing to do is look at the dish specifications and decide if the suggested mounting procedure is a good one. The soil in this area is sandy loam. The mounting design calls for six inch schedule 80 steel pipe at least six feet into the ground. This calls for renting an excavator, digging a six foot deep hole, buying a 36 inch sono-tube and a 16 foot piece of 6 inch schedule 80 steel pipe and a couple of yards of concrete from a truck. This work all being done on the ground system for the WDCD antenna array. All the while, abandoning the old pad and dish in place. Seems like a lot of money and wasted materials. Re-using the old pad and part of the old mount seemed to make more sense. I did some rough calculations on paper regarding wind forces, this was the results:
WDCD satellite dish mount design
The maximum static force is 1,555 N on the back bolts of the mounting ring into the concrete pad. Maximum wind force is 5,603 N, a maximum wind from bearing 76° T will exert a force of 7,158 N or 730 Kg force on the back bolts of the mount. The concrete that the mounting bolts is embedded in will withstand 4,267 Kg of force at six inches deep. The the existing pad and 3/4 inch J bolts are well within their rating to handle this load, so it seems like a good design. Putting that to practical use:
Scientific Atlanta 9000 series dish mount
First, we unbolted the azimuth mounting ring and removed the old dish, leaving the bottom of the mount. I drilled down 6 inches into the old concrete pad and inserted 1/2 inch re-bar. These re-bar are somewhat diagonal toward the center of the tube towards the new mounting pole.
Scientific Atlanta 9000 series dish mount reuse
Then, we placed the 6 inch by 8 foot schedule 80 pipe in the center of the tube and attached it to the tube with 1/2 inch all-thread. We used the all thread to adjust the 6 inch pipe so that it was vertical.
Next, we filled the old mount up with 4,000 PSI (280 Kg/square cm) ready mix concrete and let it cure for one week.
New mount for Prodelin dish
While that was curing, I bolted the new Prodelin 1374 dish together on the ground. Follow the directions closely on this one, there are many pieces of hardware that look the same and are almost the same but will not work if exchanged.
Prodelin 1374 dish about to be lifted
We used a loader with a lifting bar on it to sling the new dish into place. I was going to video tape this evolution, but we were short handed and I ended up helping bolt the dish on the mount once it was placed there.
Prodelin 1374 dish, installed
Once the dish was mounted, I installed the feed horn and LNB.
WDCD Albany, NY, Prodelin 1374 dish installed
Then there was the aiming; this dish is pointed at AMC-8, for which I found this information from dishpointer.com most helpful:
WDCD AMC-8 information, courtesy of dishpointer.com
This is a crowded neighborhood and finding the right satellite took a bit of trial and error.
I remember, back in the day, when we all used Scientific Atlanta 7300 satellite receivers. There were two flavors of decoder cards; DATS and SEDAT. Starting about 1982 or so, satellite distribution of network audio was a quantum leap over the old TELCO circuits used previously. The use of satellite downlinks allowed radio stations to receive an almost unlimited number of programs from every network under the sun.
The SA 7300 receivers gradually gave way to the SA 3640, which gave way to the Starguide, Starguide II and Starguide III series which finally lead to the XDS and MAX receivers used today.
XDS satellite receivers
The newest generation satellite receivers are yet another quantum leap over the last, with on board hard drive storage that allows time shifting of entire shows. Another nice thing is the web interface. Before you know it, everything in the broadcast plant will have a web interface.
The one issue I have had with nearly every single XDS receiver is the fan going bad. The manufacture must have laid into a supply of defective fans. A bad fan is noted with the fault light turns red and the unit will return a “Fan stopped” error message. The network will send a replacement fan if you let them know. I have carefully replaced several of these fans without turning the receiver off.
Otherwise, the web interface is pretty intuitive. Drop down menus allow for programming the audio ports on the receiver and setting up the delayed recording and playback function.
XDS satellite receiver weekly programming grid
Any required network closures are configured in the relay screen. The programming clock provided by the network will specify which relays are used for each show.
XDS relay maping screen
Each receiver has two DB-37 connectors that have 16 relays each for a total of 32 output closures. That should be enough to cover almost any programming situation.
Finally, the receiver’s overall operating condition can be monitored via the health screen:
XDS satellite receiver health screen
Something like this can greatly speed up any remote diagnostic trouble shooting by eliminating (or pinpointing) a satellite system failure as the reason for a station being off the air. I also make sure that all automation systems have some type of remote access like VNC so that I don’t have to needlessly drive to the studio to fix a silly computer problem.
Then there is one more neat tool, for those XDS receivers that do not have any front panel user controls (one certain network uses these), called the “XDS discovery tool.” I have found this bit of software to be very helpful from time to time.
Satellite dishes have been a part of radio station technical equipment for years. I am surprised at the number of broadcast engineers that do not consider center of box when aiming dishes. As dishes get larger and focal points get smaller, center of box aiming is not a nice thing to do, it is a necessary thing to do. The latest generation of satellite receivers, (AKA XDS) have a somewhat less than lively RF front end, they require higher E/B than the previous generation Starguide receivers to stay locked.
For years, the majority of commercial radio networks were carried on AMC-8 or its predecessors living at 139° W. On the east coast, particularly in the Northeast, that makes aiming points relatively low to the horizon, anywhere between 8-10° elevation.
3.2 meter COMTECH satellite dish
This all means that precise aiming the satellite receive dish is critical for satisfactory performance. SES Americom owns AMC-8 and thus they have a web page about all of there satellites and important operating information. SES Center of box for AMC-8 is available in one month blocks, which makes scheduling the aiming chore fairly easy.
Large satellite dish aiming diagram
I have always used a spectrum analyzer though a 3 dB splitter to look at the 950 MHz LNB output. This aiming setup allows the best combination of Azimuth/Elevation/polarization. Using the satellite receiver to confirm and maintain signal lock, peak the wave form that the receiver is locked to. It is pretty crowded up there, so there will be lots of signals on the spectrum analyzer trace.
It is a pain in the rear end to lug all that equipment out to the satellite dish, especially if it is on the roof. That is why it only need be done once; the right way the first time.
Any shortcuts will likely lead to those annoying chirps and drop outs or complete loss programming, particularly when the weather turns bad.
More bee related RF stories. This happens often this time of year, the paper wasps have worked hard all spring to build their nests up in size and during July, they become large enough to block the aperture of the antenna mounted on a satellite dish. As the nest fills up with eggs and larva, it becomes denser and blocks more RF from the antenna. Soon, the signal on the satellite receiver drops and audio dropouts occur.
I have noticed that the newer generation satellite receivers are not as good as the older Starguide III and II units. The Starguide receivers were pretty light duty when compared to the Scientific Atlanta 7300 or 2300 series units. Those things were build like tanks, took up a lot of rack space, and so long as one replaced the power supply capacitors every so often, never failed. The newer satellite receivers are very intolerant of phase shifts or any carrier disruptions. Many times, the signal strength might look to be above the drop out threshold (usually 4.5 to 5 dB), but the audio still occasionally cuts out. That symptom is almost always bees in the feed horn.
3.2 meter COMTECH satellite dish
This dish is mounted up high above the roof of the building on 6 inch well casing. In order to service the feed horn, one has to either rent a cherry picker or loosen the azimuth bolts and spin the entire dish around so the feed horn is over the roof area. Then an eight foot step ladder is need to get to the feed horn. Luckily, it is a flat roof. Needless to say, I made sure the feed horn had the proper cover over it so that no bees could get in.
Satellite dish feed horn with insect cover installed
Bee fade is best cured with a can of Raid hornet and wasp spray. The culprits are almost always paper wasps, which, I can tell you from experience, have a nasty sting. Once the nest is cleaned out of the antenna aperture, a proper cover must be installed. If one finds that they don’t have a proper cover, I have found that a top from a spray paint can will work as a temporary cover until a proper one can be installed. I would not call a spray paint can cap a permanent solution because the sun will eventually degrade the plastic and it will fall apart.