What will Happen to you when GPS goes Down

[Wotname]

Originally Posted by socaldmax

To keep it simple, the Omega transmitters transmitted a special signal that the receiver would then receive and calculate the time delay from each of at least 3 receivers. Those signals are no longer being transmitted. There is no signal for your receiver to receive. That's it.

Just because a transmitter is still in existence doesn't mean it's still transmitting. Look it up in Wikipedia if you have any further questions.

You keep talking about Omega transmitters and we both know that they don't transmit anymore; however the long range nav receivers I repaired (and used) would also receive the CW from VLF transmitters and resolve a position in the same manner as it would from from an Omega transmitter (i.e. measuring the wavelength for 3+ transmitters thus giving 3+ circular LOPs. Once triangulated, you have a unique position. So if I can receive CW from 3 active VLF transmitters, I will still get a position. As the VLF service is still active for providing comms to submerged subs, then it should be possible to use the system as it was previously used.

I accept that a serviceable receiver would be hard to find and I accept that perhaps it might be difficult to receive RF concurrently from three VLF transmitters but other than that, I need a technical explanation why it isn't so - wikipedia doesn't cut the mustard in this case

[JPA Cate]

It is unnecessary to start a post with, "to keep it simple". Socaldmax, maybe you might want to re-consider your posts with an eye to not appearing condescending? You may be a really nice guy, but sometimes the way you phrase things makes people feel denigrated or even angry. Just sayin"

Ann

[sailorboy1]

None of this is going to matter much once the alien space fleet shows up!


Sent from my iPhone using Cruisers Sailing Forum

[Snowpetrel]

Originally Posted by IslandHopper

To this day if you want to become a Master Mariner (Unlimited) in Australia you will still have to do the full Navigational course, including CN...and trust me, the Nav for the RYA Yachtmaster is a breeze compared to the Master Unlimited...

Ask me how I know...

Ha, never bothered with my master mariners, decided I didn't want to work away on bigger ships, and certainly didn't want to push paper like most of the masters I sailed with.. But my fellow cadets that plodded though got the last laugh, most of them are now on offshore vessels earning big dollars in exciting jobs. I do have a reliable source though that tells me the CN component of the masters these days is pretty lax, or rather the standard and interest of the students is.. A shame really.

For what its worth the RYA seemed at least as hard as the old Master 3 (close to the master 500 ton) that I taught and similar to what I remember of the scotvecs navigation for my second mates FG. Certainly much harder than the master 4 and master 5 nav, or master less than 35 or 24 m as they are now called. Last time I played with the RYA stuff was 10 years ago. Hopefully their high standard has not dropped since then. Never had anything to do with the RYA ocean, except the qualifying passage because we could and a few of our crew needed it. Cheers

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[DeborahLee]

You might want to think about getting into the tech age. Boat US mag just had an article about the CG using Virtual ATONs displayed through your AIS. It won't be happening overnight but I can see in the future with the cost of tending buoys and commercial vessels required to have AIS you won't be needing your binoculars anymore.

[K_V_B]

Originally Posted by Jammer Six

No. You'd only have to kill one.



It's starting to be remarkable that they haven't all gone down.

Explain. Why?




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[gcaptain]

Originally Posted by Snowpetrel

Ha, never bothered with my master mariners, decided I didn't want to work away on bigger ships, and certainly didn't want to push paper like most of the masters I sailed with.. But my fellow cadets that plodded though got the last laugh, most of them are now on offshore vessels earning big dollars in exciting jobs. I do have a reliable source though that tells me the CN component of the masters these days is pretty lax, or rather the standard and interest of the students is.. A shame really.

For what its worth the RYA seemed at least as hard as the old Master 3 (close to the master 500 ton) that I taught and similar to what I remember of the scotvecs navigation for my second mates FG. Certainly much harder than the master 4 and master 5 nav, or master less than 35 or 24 m as they are now called. Last time I played with the RYA stuff was 10 years ago. Hopefully their high standard has not dropped since then. Never had anything to do with the RYA ocean, except the qualifying passage because we could and a few of our crew needed it. Cheers

Sent from my GT-P5210 using Cruisers Sailing Forum mobile app

As a Master Mariner who worked offshore most of my career I can say, yes the money is great, but the job isn't exactly exciting... More paperwork and gps coupled with Dynamic Positioning has eliminated nearly all need for ship-handling skills plus satellite internet means that todays master's are slaves to shoreside managers who can (and do!) call/email them 24/7.


I think part of the reason cel nav still exists is that many are secretly hoping for the crash of technology and a return to simpler times. Either that or the fact there is a certain pleasure in ending your day with a pinwheel fix.


John Konrad

[zboss]

Actually, I would take the GPS failure and turn around and make a billion dollars by selling a better system, or by selling snake oil... whichever is easier.

[CaptainPatty]

GPS is merely an aid to navigation, you should be plotting your positions at least q 3 hrs, know how to determine set and drift, dead reckoning and if off shore knowledge and use of a sextant is ideal.


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[ka4wja]

I'm not sure if it is appropriate to wade into someone else's specific discussion....but, perhaps I can politely add some info/comment that might help clarify some things???



I don't wish to complicate things, and certainly do NOT wish to drift this thread off topic (but, it seems it's mostly all tongue-in-cheek anyway..

1- I think Wotname may have some sort of precise DF (Direction Finding) antennas (which would quite an accomplishment for the average sailor / radio operator) with his VLF receivers...and socaldmax may not be aware of this, or he may be aware of it, but understands that even a VERY SLIGHT error in direction will result in VERY LARGE errors in position fixing, as the distances from the transmitters are very long...
Remember that a ONE DEGREE error in direction, from 10,000 miles away is a difference of +/- 175 miles....and even from a station 3000 - 4000 miles away, the position error would be 50 - 70 miles.....and this is with only a ONE DEGREE error...a pointing error of 5 degrees would result in LOP's being 500 to 1500 miles wide....now that's not exactly "precise"...
So, even IF you did have very precise DF antenna system, trying to use old VLF stations (assuming they were still transmitting) from 1000's of miles away for position fixing would, in MY opinion, be a waste of time....as just looking at the sky with your naked eyes and knowing approx. what time of day it is would give you as good or better accuracy of position....and certainly using a compass and DR would be orders of magnitude better!!


AND--OR--


2- I think Wotname may not be aware that VLF position fixing (whether Omega, or other) did not rely on the receivers calculating a position based on
some bearing, etc. but rather on TIMING and PHASE of the signals received....
And, it was the precise timing of the Omega transmitters (and the near constant velocity of propagation of 10.2khz, 13.6khz, and 11.33khz signals, around the earth, day-and-night, over land and sea...as well as the phase stability of these signals), that allowed the receivers to calculate a LOP, which would be plotted on an Omega chart....AND, only if these VLF "cw transmitters" actually had some sort of precise timing (that is know to the user of these receivers), could they effectively be used for position fixing over great distances...

(although my use of Omega was in the 70's, with early units....I was told that later Omega receivers actually had Lat/Lon displays that did not require dedicated Omega charts...but, I never used one of those "fancy" new Omega receivers...)

Originally Posted by Wotname

....however the long range nav receivers I repaired (and used) would also receive the CW from VLF transmitters and resolve a position in the same manner as it would from from an Omega transmitter (i.e. measuring the wavelength for 3+ transmitters thus giving 3+ circular LOPs. Once triangulated, you have a unique position. So if I can receive CW from 3 active VLF transmitters, I will still get a position. As the VLF service is still active for providing comms to submerged subs, then it should be possible to use the system as it was previously used.

I accept that a serviceable receiver would be hard to find and I accept that perhaps it might be difficult to receive RF concurrently from three VLF transmitters but other than that, I need a technical explanation why it isn't so - wikipedia doesn't cut the mustard in this case

3- I hope you see that having LOP's that are hundreds of miles wide, means that your position error would be quite large!!
And, I hope you understand that I wrote everything above off-the-top-of-my-head....so, if I made a few minor errors in explanation, forgive me...

{NO Wikipedia here!!}




So, to sum up....
- I hope I didn't step on anybody's toes...
AND
- I hope my "technical explanation" cuts the mustard without being condescending....



Fair winds...

John
s/v Annie Laurie

[socaldmax]

Originally Posted by Ann T. Cate

It is unnecessary to start a post with, "to keep it simple". Socaldmax, maybe you might want to re-consider your posts with an eye to not appearing condescending? You may be a really nice guy, but sometimes the way you phrase things makes people feel denigrated or even angry. Just sayin"

Ann

I only wrote that because I'm a former Master Training Specialist who taught the operator and maintenance course for the world's most accurate RDF receiver. If I got into the detail that I wanted to, it would take 5 pages and bore everyone to tears. A lot of what I'd like to post is still classified secret, including the name of the system, so there isn't much I can reveal. Deferring to Wikipedia ensures that I don't post something that I remember, but may have forgotten is still classified. It's difficult to remember exactly what is noforn, confidential, secret or TS.

Believe me, I'm not being condescending, just trying to err on the side of caution with regards to what I know vs what I can share. Sometimes it's easier to gloss over it rather than slip up.

[socaldmax]

Originally Posted by Wotname

You keep talking about Omega transmitters and we both know that they don't transmit anymore; however the long range nav receivers I repaired (and used) would also receive the CW from VLF transmitters and resolve a position in the same manner as it would from from an Omega transmitter (i.e. measuring the wavelength for 3+ transmitters thus giving 3+ circular LOPs. Once triangulated, you have a unique position. So if I can receive CW from 3 active VLF transmitters, I will still get a position. As the VLF service is still active for providing comms to submerged subs, then it should be possible to use the system as it was previously used.

I accept that a serviceable receiver would be hard to find and I accept that perhaps it might be difficult to receive RF concurrently from three VLF transmitters but other than that, I need a technical explanation why it isn't so - wikipedia doesn't cut the mustard in this case

OK, long version.

I was a Master Training Specialist in the US Navy. That's an instructor who has received the highest evaluations on the podium and has mastered curriculum development. For the first 2 yrs, I taught Operations and Maintenance on the world's most accurate RDF system, deployed on subs. I cannot tell you the accuracy, frequency coverage, speed, sensitivity or name of the system. It's all secret or above.

After getting out of the Navy, I spent 15 yrs as a Subject Matter Expert for a defense contractor, 1 of 4 in the nation. We traveled to every sub base and groomed or overhauled these systems. We also designed and installed a number of upgrades to increase accuracy, reliability or usability of the system.

Since I cannot tell you any specifics of that system, and how it worked, I can tell you this. It cost over $1.2M. Generally speaking DF accuracy increases with frequency. SHF or EHF DF accuracy is going to be orders of magnitude more accurate than MF, or even HF. Even HF or VHF accuracy is nothing to write home about.

By the time you get down to VLF, the wavelength and antenna would be far too huge (the transmitter antennas are 30 to 40 mi long) for you to deploy one on a yacht, much less get any DF accuracy out of it. Subs use a floating wire, and unless you're on something like a fishing vessel, you don't have the room to deploy and retrieve an antenna that will give you any sort of DF bearings. It's one thing to receive a signal, it's entirely different to get accurate DF bearings out of it.

Let's discuss Lojack, that's in the civilian world. It's a piece of crap relative to what the military uses, but one can learn something from it. It uses an array of 4 antennas mounted on the roof, the look like VHF or UHF frequency range. It's mounted on a vehicle that can be turned almost instantly to try to resolve errors in DF reception.

VLF is a whole different story. To duplicate that antenna array, you'd need to spread 4 antennas out 30 - 40 mi ea at 90* to each other, make some very accurate amplitude readings from each of the antennas simultaneously, then use trig to calculate the path of the incoming signal +/- 180*. Not only can the signal be coming from opposite directions simultaneously, the calculations require one to resolve the angle independent of signal strength - antennas cannot tell left from right. They can only tell if the signal is coming in weaker or stronger. Don't forget you'd have to shift the entire array a few times, maintaining 90* separation in order to get meaningful readings.

In addition:

You would need 3 VLF stations transmitting around the same time.
You would hopefully not have any changes in incoming signal strength during your measurements.
You would need to repeat the process for each transmitter.
You'd need to know which transmitter is located where.

After all of your maneuvering and calculating, your best results would still fall +/- the size of Africa, simply due to the errors inherent in receiving a signal with a wavelength that is 40 miles long.

I'm sure you have no intentions of DFing your way around the ocean using non existent VLF signals. This was just an exercise in "what if..."

I hope I gave you sufficient information to convince you it's just not worth it. You would absolutely be better off just pointing the boat based on where the sun rises and sets every day. I'm guessing that method would be at least 10x more accurate.

[socaldmax]

Originally Posted by ka4wja

I'm not sure if it is appropriate to wade into someone else's specific discussion....but, perhaps I can politely add some info/comment that might help clarify some things???



I don't wish to complicate things, and certainly do NOT wish to drift this thread off topic (but, it seems it's mostly all tongue-in-cheek anyway..

1- I think Wotname may have some sort of precise DF (Direction Finding) antennas (which would quite an accomplishment for the average sailor / radio operator) with his VLF receivers...and socaldmax may not be aware of this, or he may be aware of it, but understands that even a VERY SLIGHT error in direction will result in VERY LARGE errors in position fixing, as the distances from the transmitters are very long...
Remember that a ONE DEGREE error in direction, from 10,000 miles away is a difference of +/- 175 miles....and even from a station 3000 - 4000 miles away, the position error would be 50 - 70 miles.....and this is with only a ONE DEGREE error...a pointing error of 5 degrees would result in LOP's being 500 to 1500 miles wide....now that's not exactly "precise"...
So, even IF you did have very precise DF antenna system, trying to use old VLF stations (assuming they were still transmitting) from 1000's of miles away for position fixing would, in MY opinion, be a waste of time....as just looking at the sky with your naked eyes and knowing approx. what time of day it is would give you as good or better accuracy of position....and certainly using a compass and DR would be orders of magnitude better!!


AND--OR--


2- I think Wotname may not be aware that VLF position fixing (whether Omega, or other) did not rely on the receivers calculating a position based on
some bearing, etc. but rather on TIMING and PHASE of the signals received....
And, it was the precise timing of the Omega transmitters (and the near constant velocity of propagation of 10.2khz, 13.6khz, and 11.33khz signals, around the earth, day-and-night, over land and sea...as well as the phase stability of these signals), that allowed the receivers to calculate a LOP, which would be plotted on an Omega chart....AND, only if these VLF "cw transmitters" actually had some sort of precise timing (that is know to the user of these receivers), could they effectively be used for position fixing over great distances...

(although my use of Omega was in the 70's, with early units....I was told that later Omega receivers actually had Lat/Lon displays that did not require dedicated Omega charts...but, I never used one of those "fancy" new Omega receivers...)








3- I hope you see that having LOP's that are hundreds of miles wide, means that your position error would be quite large!!
And, I hope you understand that I wrote everything above off-the-top-of-my-head....so, if I made a few minor errors in explanation, forgive me...

{NO Wikipedia here!!}




So, to sum up....
- I hope I didn't step on anybody's toes...
AND
- I hope my "technical explanation" cuts the mustard without being condescending....



Fair winds...

John
s/v Annie Laurie

Thanks again John for another excellent explanation!

Let me add that if one were to build an RDF receiver in the HF range, accuracy of +/- 10* would be quite a feat. If one were to try to build one in the VLF range and used all of the latest tech to physically shrink the antennas down to a reasonable size, accuracy would surely suffer because the physical distance between the antennas is of major importance for incoming signal resolution, and the problem is massively compounded by the sheer size of the VLF wavelength. A VLF RDF receiver would be orders of magnitude less accurate than an HF one.

It's the absolute wrong end of the spectrum to be trying to DF.

[StuM]

Originally Posted by DeborahLee

You might want to think about getting into the tech age. Boat US mag just had an article about the CG using Virtual ATONs displayed through your AIS. It won't be happening overnight but I can see in the future with the cost of tending buoys and commercial vessels required to have AIS you won't be needing your binoculars anymore.

And how long before Virtual ATONs are installed throughout the South Pacific and SE Asia , just to name a couple of areas?

[Cormorant]

Apparently we came close to losing GPS back in 2012 . . .

How a solar storm two years ago nearly caused a catastrophe on Earth

On July 23, 2012, the sun unleashed two massive clouds of plasma that barely missed a catastrophic encounter with the Earth’s atmosphere. These plasma clouds, known as coronal mass ejections (CMEs), comprised a solar storm thought to be the most powerful in at least 150 years.
“If it had hit, we would still be picking up the pieces,” physicist Daniel Baker of the University of Colorado tells NASA.


Fortunately, the blast site of the CMEs was not directed at Earth. Had this event occurred a week earlier when the point of eruption was Earth-facing, a potentially disastrous outcome would have unfolded.
“I have come away from our recent studies more convinced than ever that Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did,” Baker tells NASA. “If the eruption had occurred only one week earlier, Earth would have been in the line of fire.”


A CME double whammy of this potency striking Earth would likely cripple satellite communications and could severely damage the power grid. NASA offers this sobering assessment:

Analysts believe that a direct hit … could cause widespread power blackouts, disabling everything that plugs into a wall socket. Most people wouldn’t even be able to flush their toilet because urban water supplies largely rely on electric pumps.
. . .
According to a study by the National Academy of Sciences, the total economic impact could exceed $2 trillion or 20 times greater than the costs of a Hurricane Katrina. Multi-ton transformers damaged by such a storm might take years to repair.

CWG’s Steve Tracton put it this way in his frightening overview of the risks of a severe solar storm: “The consequences could be devastating for commerce, transportation, agriculture and food stocks, fuel and water supplies, human health and medical facilities, national security, and daily life in general.”
Solar physicists compare the 2012 storm to the so-called Carrington solar storm of September 1859, named after English astronomer Richard Carrington who documented the event.
“In my view the July 2012 storm was in all respects at least as strong as the 1859 Carrington event,” Baker tells NASA. “The only difference is, it missed.”
During the Carrington event, the northern lights were seen as far south as Cuba and Hawaii according to historical accounts. The solar eruption “caused global telegraph lines to spark, setting fire to some telegraph offices,” NASA notes.
NASA says the July 2012 storm was particularly intense because a CME had traveled along the same path just days before the July 23 double whammy – clearing the way for maximum effect, like a snowplow.
“This double-CME traveled through a region of space that had been cleared out by yet another CME four days earlier,” NASA says. ” As a result, the storm clouds were not decelerated as much as usual by their transit through the interplanetary medium.”
NASA’s online article about the science of this solar storm is well-worth the read. Perhaps the scariest finding reported in the article is this: There is a 12 percent chance of a Carrington-type event on Earth in the next 10 years according to Pete Riley of Predictive Science Inc.
“Initially, I was quite surprised that the odds were so high, but the statistics appear to be correct,” Riley tells NASA. “It is a sobering figure.”
It’s even more sobering when considering the conclusion of Steve Tracton’s 2013 article: Are we ready yet for potentially disastrous impacts of space weather? Tracton’s answer: “an unequivocal, if not surprising, no!”