A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: LORAN-C to be shut down.
From: Gary LaPook
Date: 2009 Dec 9, 02:23 -0800
From: Gary LaPook
Date: 2009 Dec 9, 02:23 -0800
You might like this site which calculates loop antenna data. http://www.mindspring.com/~loop_antenna/amloop_calc4.htm gl On Dec 6, 8:01�am, Apache Runner
wrote: > Another enhancement, which is perhaps cheaper is the so-called sportsman's > antenna. � It consists of a large wire loop and tunable capacitor. � You put > the loopstick radio inside this - properly oriented. � �The idea of the > sportsman's antenna came from the days when radio and TV stations close to > pro-sports games were blacked out, and people would build these antennas to > enhance the signal, so they could listen in on distant stations. > > It turns out that these are highly directional with very deep and well > defined nulls. � There's an article about this at the following PDF > > http://www.dxing.com/tnotes/tnote09.pdf > > Here you could take a radio like Gary's Grundig and place it inside the loop > antenna and use it as an RDF. �I'm curious about the precision one can reach > with a device like this. > > On Sat, Dec 5, 2009 at 8:58 PM, Lu Abel wrote: > > �Why build your own?? � Many cheap AM receivers use a loop antenna which is > > fairly directional. > > > I also wonder what benefit one gets (other than "yes, it can be done" > > satisfaction) of creating a RDF with 3 degree accuracy. � Each degree of > > bearing inaccuracy gives 100' of inaccuracy per nautical mile of distance > > from the station. � Shoot a station from 10 nm offshore with your proposed > > RDF and you have a 1 nm inaccuracy in your LOP! > > > Apache Runner wrote: > > > Although this is a completely out-of-the-box idea, I've been working on an > > AM radio receiver/direction finder for fun. � �The FCC publishes the > > lat/long for all stations in the US. > > > I haven't seen a variable capacitor in ages, but managed to find some > > beauties online, and am making my own antenna. � �Right now, I think I can > > get an accuracy of maybe 3 degrees, but that's just a guess. > > > I'll post something when I have it up and running. > > > On Sat, Dec 5, 2009 at 3:03 AM, glap...---.net wrote: > > >> I know we have some commercial air pilots on the list and was > >> wondering if > >> they thought an aircraft RDF unit could be easily mounted on a boat. > >> The > >> aircraft industry seems to be the only ones making small units these > >> days. > >> I might go ocean cruising with a friend who is presently re-fitting > >> his > >> boat, and I am a big fan of redundancy, and thought this might be a > >> workable > >> solution. > > >> --------------------------------------------------------------------------- > > >> An ADF will work on a boat but they aren't cheap, the readout is only > >> marked every 5 degrees and the antenna has to be mounted somewhere. If > >> you want RDF capability just by an inexpensive digitally tuned > >> portable radio that covers the LF band such as the Grundig G5 which > >> also covers HF and has SSB capability so you can get your time > >> signals �too. These all have ferrite rod internal antennas which are > >> highly directional. Get one and tune a distant station. Then orient > >> the radio in different attitudes and rotate the radio until you get a > >> null which will let you know the orientation of the ferrite rod. Then > >> you can use the edge of the radio to indicate the direction to the > >> station. Place it on top of a universal plotting sheet to use as a > >> compass rose placed on a table or nav station desk and rotate the > >> radio to get a null. You may want to make a calibration table for it. > >> Don't worry about the lack of a sense antenna which are really only > >> needed by an ADF since a human can easily determine which is the > >> correct bearing, the 180 degree ambiguity, which is a big problem for > >> an ADF, is not a problem for a human. > > >> �gl > > >> On Dec 4, 11:48 am, Bruce Hamilton wrote: > >> > If GPS goes dark, Jeremy will be in a great position to negotiate a > >> salary > >> > raise. > > >> > �I had great hope for e-loran as going to a single system with no > >> redundancy > >> > seems risky at best. Even when Loran C coverage was poor, even the > >> > information from a single chain would give you something to work with. > >> In > >> > the middle of Lake Superior, coverage was always spotty, and on the East > >> > Coast of Canada we would often be on a single chain only 50 miles off > >> the > >> > coast. > > >> > Jeremy, do you still have a working RDF? �I used them on aircraft all > >> the > >> > time, but must admit the one on the first ship I was on was not often > >> used > >> > and this was pre-gps. I have a working portable (Ray Jefferson) RDF that > >> I > >> > am going to try in a friend's boat. It is a pity that the technology got > >> > left behind in the GPS age as the modern RDF's are apparently very good > >> and > >> > very quick. The signal from the multiple antennas is instantly processed > >> and > >> > you get an bearing read out. �The Canadian Coast Guard use them to get > >> > instant fixes from distress signals in pre-GMDSS days. They have remote > >> > stations they use to get a cross bearings from. No GPS required. > > >> > I know we have some commercial air pilots on the list and was wondering > >> if > >> > they thought an aircraft RDF unit could be easily mounted on a boat. The > >> > aircraft industry seems to be the only ones making small units these > >> days. > >> > I might go ocean cruising with a friend who is presently re-fitting his > >> > boat, and I am a big fan of redundancy, and thought this might be a > >> workable > >> > solution. > > >> > A fine page of old RDF units < > >>http://www.angelfire.com/space/proto57/rdf.html> > > >> �> On Fri, Dec 4, 2009 at 8:09 AM, wrote: > >> > > �I read the following on a maritime forum site. �Looks like LORAN-C > >> > > systems run by the US will be shut down sooner than we thought. > >> > > ----------------------------- > >> > > The US Coast Guard released an internal message advising of the > >> imminent > >> > > termination of the long range aid to navigation Loran-C. Current plans > >> call > >> > > for the termination process to commence on 4 January 2010. The process > >> is > >> �> > expected to take several months. ALCOAST 675/09< > >>http://www.uscg.mil/announcements/alcoast/675-09_alcoast.txt>(11/25/09). > >> > > *Note: This will mark the end of an era that started during World War > >> II. > >> > > The Loran system has improved greatly over the years and was on the > >> edge of > >> > > yet another advance: to enhanced Loran (eLoran). It is unclear how > >> other > >> > > nations, which operate their own independent Loran-C systems, will > >> react to > >> > > this development. * > >> �> > Courtesy: Bryant�s Maritime Blog � 1 December 2009< > >>http://bryantsmaritimeblog.blogspot.com/2009/12/bryants-maritime-blog..> > >> > > ------------------------------ > > >> > > Not that this will affect many large ships. �My ship hasn't had LORAN > >> > > capabilities since the antenna broke 3 years ago and the captain was > >> too > >> > > afraid to order a new antenna. �Most merchant ships are utterly > >> dependent on > >> > > GPS at this point, and would have a tough time remembering how to use > >> the > >> > > sextant if it came down to that point. �It will only get worse when > >> the > >> > > younger generations take command, having never known a time without > >> GPS. > > >> > > JCA > > >> > > -- > >> > > NavList message boards:www.fer3.com/arc > >> > > Or post by email to: NavList@fer3.com > >> �> > To unsubscribe, email NavListemail@example.com > >> > > >> -- > >> NavList message boards:www.fer3.com/arc > >> Or post by email to: NavList@fer3.com > >> To unsubscribe, email NavListfirstname.lastname@example.org > > > -- > > NavList message boards:www.fer3.com/arc > > Or post by email to: NavList@fer3.com > > To unsubscribe, email NavListemail@example.com > > > �-- > > NavList message boards:www.fer3.com/arc > > Or post by email to: NavList@fer3.com > > To unsubscribe, email NavListfirstname.lastname@example.org > > -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To unsubscribe, email NavListemail@example.com