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Anatomy of a low frequency aviation radio beacon

Discussion in 'Amateur Radio News' started by KX4O, Aug 25, 2020.

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  1. WW5F

    WW5F Ham Member QRZ Page

    Nothing you put outside or in the water is waterproof. Water always finds a way. It's just a matter of time. This is why boats still need bilge pumps. As for these special N connectors, they're probably something that comes with the install kit out of Hanscom. I see there're new contractors for AF ILS's now since I retired.

    https://www.afcea.org/content/thales-preparing-deployable-instrument-landing-system-air-force
    https://www.af.mil/News/Article-Dis...ract-for-lightened-instrument-landing-system/

    The older ILS's are getting more and more expensive to maintain, so these newer ones have probably started to replace the older ones at fixed installations.

    When I was in E&I, we were finally getting smarter on where to buy stuff. For example, which makes more sense? A $10,000 (remember this term? Donkey ....) broad banded VHF antenna or a $300 Cushcraft? At first, there was push back from my team chiefs. Team Chiefs derive great pleasure and senses of accomplishment installing something that is monumental and lasts "as installed" well after retirement. But after talking with them, they saw the light. An antenna that lasts maybe 20 years at $10,000 or a Cushcraft that, even if having to be replaced by the local ground radio guys every 3 years was still a lot cheaper (and better if tuned.)

    AF E&I was gutted. It was a great organization to be part of during its peak. Today, the 38th Wing is now a Group with only two GSUs focusing on bigger comm issues. The comm squadrons around the world are pretty much left to fend for themselves these days. But they're not really by themselves, their MAJCOMs provide the support today that E&I no longer provides.

    https://www.tinker.af.mil/About-Us/...th-cyberspace-engineering-installation-group/

    I know it annoys a bunch of retirees who seem to think their work was invalidated by a bunch of "higher ups" these days, but it's a different time now. When President Reagan threw a bunch of money at the military in the 80's, several contractors created "one of a kind" comm systems and became monopolies which turned into financial disasters. For example, TRITAC. A bunch of HEAVY GREEN BOXES that WEREN'T INTEROPERABLE with commercial equipment. (Worked well when connected to the Army, though.) I worked with AN/TTC-39's and AN/TYC-39s for a while and annoyed my fellow team members when I was surprised at their reaction to the "new and improved" TTC-39 coming with the latest and greatest Intel 8080 processor! This was in 1989. The 8080 processor was already old then. When the Air Force moved to REDCOM telephone switches (8U 18" rack mounts), I saw a bunch of old TRITAC folks getting angry. Again, the price difference was astronomical and you could hook a REDCOM switch into the PSTN without any special "converter box" that still prevented secure phones from working.

    New LORAN systems on that side of the world should be a big red flag for us.

    The navigators I knew in the Air Force started off with celestial navigation. It was a test. If they didn't or couldn't figure that out, they were re-assigned to some other AFSC. My bet is they're still doing this. Today's navigator is pretty bored sitting behind the pilot and copilot these days. Mostly, they're there to double check what the pilot does and if the feces hits the screw, then that's when they become really important. There are still sextants and sextant ports on most cargo planes. There are probably at least a half dozen methods of navigation on our cargo planes these days and the sextant is the last one on the list. But it's still there. And it's standard to watch at least two of them to make sure they're saying the same thing. The "one seaters" have 3 or 4.

    I could go on. I'm pretty sure there are some folks in the AF keeping an eye on the bigger picture and at least have plans if we lose the big three: GPS, Internet and Cell Phone.

    Bottom line: the rate of change is going to remain at the breaking point for the foreseeable future. The only thing you can rely on is what's happening today. Tomorrow, it'll be different.
     
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  2. KE4IKY

    KE4IKY Ham Member QRZ Page

    The connector definitely had a Mil-C number associated with it.
    Yes, the specific antenna was a Donkey _____. Which I always thought was interesting since the much smaller PRC-113 dual band antenna was known as an elephants ----.



    I wish I could be more enthusiastic about the bigger picture plans... I believe there is a thing called "super-competence" where people imagine the government is way more capable than it is. I, and I assume you, have been in too many situations where just one person has kept a disaster from occurring (or caused one for that matter).

    The TTC-39's I remember were about the size of a shipping container (maybe 30 feet long though), and in the 90's could have been replaced by a box the size of a PK-232.

    Even though I never dealt with tri-tac equipment (Weather and Navaids), I kind of liked its inter-operability, specifically how a single cable hock change could switch 16 hard wired phones at once.

    The Troposcatter sets (TRC-170's) have largely been replaced with humvee mounted high data rate troposcatter sets.

    Before the weather and navaids thing, I was digital flight simulation, many pilots were transitioning from F-4s to the F-16. The older pilots would walk into the simulator with a stopwatch around their neck to time their turns, which is also why they liked to fly at multiples of 60 (360, 480 etc... knots ie 8 miles a minute at 480 knots).

    I had looked up celestial navigation, its actually relatively easy for basic nav. It just takes too long unless you are actively doing fixes. Even with an accurate watch and a protractor some simple celestial nav can be accomplished (its actually in the AF survival books)

    static.e-publishing.af.mil/production/1/af_a3/publication/afh10-644/afh10-644.pdf

    is the latest one,..... the old one didn't convert very well to reading on a computer.

    Although E and I probably was a good job a long time ago, in the early 1990s I felt like an unemployed construction worker. When I finally made it to a Combat communications unit I was much happier.

    Thanks
    Joel
     
    WW5F likes this.
  3. K1RFD

    K1RFD XML Subscriber QRZ Page

    Just curious, in what way does the Internet rely on GPS? You mean, for certain kinds of clock synchronization?
     
    Last edited: Sep 2, 2020
  4. K6CLS

    K6CLS Ham Member QRZ Page

    Yes

    And banks. And stock exchanges. And telcos especially wireless. It's used more for timing than for position these daus.
     
  5. PA0MHS

    PA0MHS Ham Member QRZ Page

    Any system can fail. Redundancy can be built in. The fact that GPS has hardly (has it ever?) failed is proof of a well designed system. There are enough satellites out there to ensure an always working system, unless of course several satellites fail at once in the same quandrant of the hemisphere. Very very unlikely. Besides, Galileo is coming too. So even more redundancy.
     
  6. N1IPU

    N1IPU Ham Member QRZ Page

    Given the accelerated weakening of the magnetosphere lesser solar storms create the danger of damage to satellites and a lot more. Both ESA and NASA have confirmed that our shields are weakening very recently and as it progresses the protection it give satellites lessens. With GPS the question of redundancy is moot if as you say a quadrant fails. Navigation is the minor issue because now almost all of our ground infrastructure and communication relies on the timing from the same system. Very little to nothing is being done about that. Same goes for us Amateurs, Our digital comms will go to shite so I am thankful for the developer of JS8 Call Has thought it out. Not many are thinking ahead of the danger we face.
     
  7. K1RFD

    K1RFD XML Subscriber QRZ Page

    Certain services on the Internet do indeed use GPS as a convenience for time reference, but I'm not sure it's accurate to say that the Internet as a whole "relies" on it. There are GPS-based NTP servers, but also NTP servers that use other types of time reference.
     
  8. K2ORS

    K2ORS Ham Member QRZ Page

    Nice article. You are correct, the transmitter is in fact in the yellow box on the right and the matching unit is on the left. They are made by Southern Avionics. I know because I bought an identical NDB transmitter and matching unit from Ebay, which I converted to 630 meters. The transmitter cabinet has two transmitters for redundancy, if one goes bad the other is switched in. Frequency is synthesized and selected using thumb wheel internally. There is a low pass filter board that you can configure for a particular frequency range using jumpers. The transmitter runs class-D. I disabled the Modulated CW and run regular CW.

    I also have two Nautel NDB transmitters. The Nautels are actually ssb transmitters where the carrier is not completely nulled, an audio oscillator is keyed and fed into the balanced modulator to create MCW. They have a microphone jack for voice. I nulled the carrier and use them on ssb and digital.

    73 Warren K2ORS


     
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  9. W4XA

    W4XA Ham Member QRZ Page

    Most cargo planes? Which cargo planes are you talking about? (asking for a friend);)
     
  10. WW5F

    WW5F Ham Member QRZ Page

    C-130 has 'em still, I think. That plane was originally designed in the 1950s. I've been out of the Air Force coming up on 13 years now.

    Google "sextant port" and it shows a few others, like the KC-135 and the 747.

    But it looks like they're doing away with them...

    I guess people are feeling confident in the electronic displays in the cockpit now.

    I've heard a story of an F/A-18 pilot losing all lights and displays in the cockpit at night. Literally flying by the seat of his pants. The only thing that saved him was following the bio-luminescent trail left behind the carrier.

    I don't know. I'm sure there are people still doing risk assessments on all this stuff.
     
  11. W4XA

    W4XA Ham Member QRZ Page


    They've been gone for many years now. I was assigned to the 446 AW from 1987 to 2004 flying the C-141. We actually had navigators but they did not fly on "Airland" missions at all. That pretty much ended in the eighties....NAVs only flew on tactical airdrop missions then........ The C-141A had a sextant port (that we all used as a vacuum cleaner!!) When the 141's were lengthened and air refueling was added, the sextant port was eliminated.

    NO USAF pilot was taught celestial navigation as late as 1980 (when I entered UPT) and the Navs I know told me that they stopped issuing the sextants in the late 70's or early 80's. I know the C-5 has a port (also used as a vacuum cleaner) as does the C-130 but no navigators.

    I don't think there's any navigators used anymore in airlift at all now. SAC tankers used them to do the air refueling rendezvous' but when I was teaching air refueling, we (pilots) directed the rendezvous ourselves entirely. In the 90's, SAC (now AMC) tankers started directing the rendezvous again and I know the KC-135's had navigators but I don't think KC-10 did. I don't know what they do now.



    I retired in 2014 flying the C-17 and all navigation is GPS/IRU now. We didn't use VOR, TACAN, ADF, much at all (we did test the heck out if though) We stopped training ADF approaches a LONG time ago! (before 2000)

    I worked for a major airline (1988-2018) which also encompassed my last 21 years in the USAFR, and we did indeed perform ADF approaches until we started using GPS. now the airline uses exclusively GPS with the inertial reference system. (dual GPS and DUAL IRU's)

    While the GPS system can be jammed, I don't think the ground based GPS systems are as easy to jam and for navigation, aircraft can use Inertial navigation that doesn't rely on any outside reference.

    Even in the early 80's, we were able to navigate across the pond without any radio aids using INS (DELCO Carousel INS) and we did it routinely. it was fairly accurate. Once we got a land based "fix" either overflying a known position or TACAN (DME) update, the INS was accurate to about a mile or 2. That was using the old 70's vintage INS.

    The newer current IRU's now are VERY accurate and they also do not require any external source of info. Those that think degradation of the GPS will bring air travel to a halt are simply misinformed.

    The sky is in fact, not falling.

    73/Rick
     
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  12. WW5F

    WW5F Ham Member QRZ Page


    Well there ya go! Welcome to the future. If GPS is EMP'd out, you'd notice it, but it wouldn't be an issue. That's great news. If we can overcome our domestic enemies, we'll be able to overcome our foreign enemies for sure!

    I was in a different Air Force my father was in; the younger folks in the Air Force today are in a different Air Force I was in.

    Edit: Wish I had accepted the offer to XO for the 18th AF CC.
     
    Last edited: Sep 3, 2020
  13. WW5F

    WW5F Ham Member QRZ Page

    @WA6III - always glad to meet a fellow Airman out here in the wilderness! We are so few and far between!

    I befriended a navigator at SOS. He told me a lot.

    If I had accepted the offer to XO for the 18th AF CC, that would have assured Lt. Col for me. But that would have been a 12-16 hour normal duty day for me for 3 years. And then pinning on Lt. Col would have given me a commitment well beyond 30 years TAFMS and my last assignment would have been at the pentagon. Didn't want that.

    Some flyers forget what some of us support guys have to put up with at times. Learned that when I was XO at the 317 AG, Dyess. (That's where I was noticed by the 18th AF CC.)
     
    Last edited: Sep 3, 2020
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  14. W4XA

    W4XA Ham Member QRZ Page

    Well,

    if there was an EMP, I would venture to guess that lack of GPS would be low on the list of things "Fracked up"! (all my tube gear would be fine though!!

    My wife reminded me of that for nearly 30 years! I only did 24 years in the USAF. She did 28 and her last job was MSSQ CC @ KTCM
     
  15. K6CLS

    K6CLS Ham Member QRZ Page

    that may have happened to an F-18 pilot. It c ertainly happened to Jim Lovell, heroic Gemini and Apollo astronaut. F2H Banshee, looking for USS Shangri La. Great story!

    https://www.airspacemag.com/history-of-flight/in-the-museum-space-capsules-180958440/

    I'm sure WW2 pilots may have a similar story.

    One of the joys of offshore sailing, night watch, is my completely dark adapted eyes, and the Milky Way is soooo beautiful... and the bioluminescent trailing the boats.... just you and the rhythm of the waves, and the msgnificent canopy overhed, feels like a glimpse of eternit. Many folks stand a shift, then won't get out of th4e cockpit, so amazing. Sailors, astronomers, divers, cavers, are very protective of their dark adapt4d eyes and night vision.
     
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