While talking with a friend in the subject of today’s usage of satcom and HF traffic, something really peaked my interest. Some of the older equipment is still in use which is amazing which shows the quality of technology back in the day compared to throw away technology today. A lot of companies have gotten away from quality and moved toward quantity for more profit and with that in mind, the parts used have gotten cheaper and cheaply made as well. Being a ham radio operator, working satellites for ham radio has been an interest for quite some time. Even build a satellite, is an interest but right is still too expensive. A ham radio operator could build a cube sat for low cost these days but there is still a learning curve that needs to be looked at. So I just rely on my Arrow antenna for 2 meter / 440 and have fun anyway. 🙂
As part of the discussion, it was mentioned that while the fltsatcom birds were still active, they were used more by “Brazilian Pirates” speaking in Portuguese. There are a few articles on the internet which discuss how Brazilian Pirates found a way to use Navy Fltsatcom F7 and F8 satellites to talk to each even in the most remote areas was interesting. Disturbing, yes, but interesting to say the least. The Fltsatcom satellites were put in the air in the 1970’s and 1980’s and the transponders are still active today. These satellites were placed into a geosynchronous orbit, about 22,250 nautical miles above the Earth’s equator. Most satellites today, especially ham radio satellites and low earth orbit (LEO) and are moving around the earth as we speak. The Fltsatcom system may or may not be used much anymore by the military as technology has moved forward so much lately, but some of the satellites themselves are still alive.
Essentially, some time back, when all of this started, the Pirates have found a way to modify ham radio 2 Meter rigs to move into the a section of the 200-300 range by doubling the frequency. There is no way that I am going to modify my 2 Meter radios for something like this. Apparently, they were using some sort of makeshift frequency doubler which not only doubled the frequency that they were using but also the bandwidth itself. For instance, if 2 meter radios were set to use 5KHz then the doubler were change that to 10KHz in the milair bands. This made for crap audio because they would splatter on the channel in use. As a ham radio operator, this peaked my interest to see what was still in use in that part of the spectrum, so I decided to see what I could hear by using my RTL dongle instead of doing any modifications to my ham gear. It is too risky to make those types of mods and could jeapordize a ham radio license. With a homebrew 3 element yagi antenna and the RTL dongle, I was highly surprised at the results.
I want to thank Mark for the help with the antenna specs that I used and the tips to gets things to work so that I could experiment in this part of the band. There have been some trials and issues, but all have been worked out. The original 3 element yagi used a loop dipole as the driver and I believe that when I tried it here, I was unable to hear anything. Now, at the time when I did try to hear something, I really didn’t understand the whole azimuth and elevation thing about listening to the Fltsatcom satellites. I decided to change the driver element slightly and went with a dipole type driver which works real well.
Mark recommended that metal coat hangers get used as they are flexible, cheap and most have them around the house. As you can see below, I did go with the hangers for the director and reflector elements on this antenna. I am going three element for now to see how this works and to see what I can hear out there. As this is my first iteration of this, here are the dimensions used which were converted from what Mark gave me.
PVC Pipe (23 – 25″ Long)
75 Ohm cable – RG59 or RG6 (Maybe 10 – 15 feet)
Metal clothes hangers (Maybe 10 to start off with)
A way to mount the elements to the boom, either drill the boom or use a material to attach them. I drilled the boom for the director and reflector element and separated the driver by placing it onto a piece of material that I had in the garage.
Director – 19.96″
Driver – 10.72″ each side for a total length of 21.44″.
Note: The driver, in this case, need to be a folded dipole as shown below.
Reflector – 22.72″
Book Length – 21.61″ or longer
Distance from Director and Reflector Elements – 20.62″
Distance from Driver and Reflector Elements – 9.25″
Note: The center conductor of the coax must be on the left side of the driver element and the shield of the coax on the right side. Make sure that if you are using a metal material for your boom that you DO NOT place the driver element on that boom as you will cut down the effective db of the antenna.
If going with a folded dipole type of drive for the antenna, here are some things to help.
– Use RG59 or RG6 center lead wire for more flexibility and is very cost effective. I use some RG6 that I had laying around which has the same effect as the RG59.
– From the curve circles around to the other end of the element, make sure that each side has a spacing no more than 1/4 to 1/2 inch spacing. Below shows an example. I used electrical tape to keep the spacing where I needed it.
Change to the Change: ;-D
I decided to try a different approach to the drive element which does seem to work real well. I went with a split driver element which is 11″ on each side. The center conductor is still on the left side of the antenna, with the antenna facing away from you, and the shield of the cable is still on the right. Below shows the finished antenna with the split dipole at 11″ on each side, totalling 22″ across.
Now that we have the antenna built, it is time for some listening fun. There are many things floating around out heads which have some interesting sounds and stuff coming from them. If you are not familiar with what is going on with the “transponders” as I needed clarification as well, then let me try to explain. If was explained to me that the satellite transponders are like opening windows and letting air come through. They are a way for the communications to get from one location to another. As you can see in the images below, the wide, light blue bars, which are constant happens to be that windows allowing any station access that can reach the satellites. Thanks Mark for the explanation, BTW.
The first that I want to bring up is the sound of a waterfall dripping through your receiver. This can be heard on 243.810. It is a spread spectrum transmission from FLTSAT which is constant. It does have a sound like a waterfall or dripping water in the radio. Below shows what the dripping looks like within HDSDR.
The pirate which have taken over the satellite transponders are loud and like to yell at each other from what I can tell. From the articles that I have read, these people can be anywhere from secluded areas of Brazil to the most populated areas and could be truckers on the road as well. As some of you may know, truckers are notorious for being very loud on the radio and I believe that this is out of habit. One thing that you will notice is that these are not just short conversations, but they sound like they are writing a book, hahaha. That is how long they can go. It sounds like cell phone conversations over satcom. I remember back in the day that government entities would be unable to speak over Satcom because that these pirate would splatter all over the place and end up on channels that they were not supposed to be on. That is still happening today. Anyway, below shows what the pirate active looks like on the transponder channels.
Some have asked where to point the yagi and that is dependant on where you live. From where I am, I point the yagi at around 146 degrees West for the following to come into view. Since these are geostationary satellites, the position should be pretty close.
A satellite beacon:
I learned something new, which I should have known while working ham radio satellites and that is with geostationary satellites, these don’t move but there are two in close proximity to each other, if pointing south. 105W and 99W. Each of these have different traffic but you will find that the pirates are saturating things quite a bit. I point somewhere around 146 degrees West for some things and around 220 – 240 degrees West for CONUS stuff. I still try to keep the elevation at around 17 degrees. I may have to adjust that though.
Below shows what the transponders look like for the 248 and 249Mhz range. These are different from others and seem to include encrypted data streams. Cool to see though. This open up other transponders around the UHF spectrum as well and yes, there are still pirates around others as well. (Those Pirates – “shake fist hard”)
This images shows a close up of the 248MHz transponders and you can see that some data is flowing through.
Some frequencies of interest to see what is going on:
243.810 – Waterfall (Spread spectrum transmission – If you can hear this, then you should be able to hear the rest)
255.550 – Common Usage for Pirate Slow Scan TV (SSTV)
252.150 – SSTV Usage (Have Not Heard Anything, Yet)
269.650 – Radio Cuba (Yes, I said Radio Cuba) They are transmitting 24/7 on this one
Some resources to check out