larry@kitty.UUCP (Larry Lippman) (01/25/91)
In article <541@cow.ecs.oz>, bmp@cow.ecs.oz (Bruce Paterson) writes: > A friend is attempting to build (from scratch) a flux-gate compass > for use in a vehicle mounted dead-reckoning navigation system. You might have a difficult time in the design and winding of the flux gate itself, which is not a trivial undertaking if you hope to achieve any reasonable accuracy and linearity! While there are single-phase rectilinear flux gates wound on a straight core, it is more common to see two-phase and three-phase flux gates wound on toroidal cores. I cannot give you any practicable details for winding your own flux gate, however. > We can't really use other methods of navigation like Omega or Nav-Star > since 1) Neither are very well covered here > 2) We need information about the current heading of the vehicle as well. You should be aware that even the best quality military grade flux gates (commonly called a "north seeker", btw) have an accuracy of no better than +/- 1 degree of azimuth, with lesser quality military grade models having accuracies of +/- 3 degrees of azimuth. Commercial devices degrade from there... :-) I point this out because some people incorrectly believe that flux gate devices have greater accuracy than the above. > Has anyone had experience with these beasts ? Likely problems/ shortcomings > etc. > In particular > 1) How do you negate the magnetic effects of the vehicle itself ? > (bearing in mind we have overhead tram lines here !) Using small adjustable compensation magnets, which are internal to some flux gate devices. A traditional marine approach is to use the large ferrous mass of a binnacle, but that is not to practicable for a car. :-) > 2) How do you negate the effects of vehicle tilt (That is, the > verticle component of magnetic field biassing the readings ? Many military and commercial aircraft flux gates are mounted on gimbals to provide pitch and roll tolerance of up to 45 degrees. For further information on flux gate devices, you might wish to try a flux gate manufacturer, such as Humphrey, Inc. or Sperry Navigation Systems. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 [note: ub=acsu.buffalo.edu] uunet!/ \aerion!larry
gibbonsj@iccgcc.decnet.ab.com (01/25/91)
In article <541@cow.ecs.oz>, bmp@cow.ecs.oz (Bruce Paterson) writes: > A friend is attempting to build (from scratch) a flux-gate compass > for use in a vehicle mounted dead-reckoning navigation system. stuff deleted... Why build one from scratch? You can buy a WWII flux-gate compass from a company called JOLLYCO (or something like that) out of Chicago. These are the real thing, minus electronics, for somewhere around $35. If you're interested, I can dig up / verify the company name & phone number. -- John Gibbons Of all the things I've lost, I miss my mind the most...
steveq@syd.dms.CSIRO.AU (Stephen Quigg) (01/25/91)
In article <2939.279ef15b@iccgcc.decnet.ab.com> gibbonsj@iccgcc.decnet.ab.com writes: >In article <541@cow.ecs.oz>, bmp@cow.ecs.oz (Bruce Paterson) writes: >> A friend is attempting to build (from scratch) a flux-gate compass >> for use in a vehicle mounted dead-reckoning navigation system. > >stuff deleted... > >Why build one from scratch? You can buy a WWII flux-gate compass from >a company called JOLLYCO (or something like that) out of Chicago. These >are the real thing, minus electronics, for somewhere around $35. > >If you're interested, I can dig up / verify the company name & phone number. Or buy a complete compass from Tandy (Radio Shack) for $Aus 99. Don't know how good they are though.
rhaar@albert.cs.gmr.com (Robert L. Haar CS50) (01/25/91)
In article <1991Jan25.032656.3794@syd.dms.CSIRO.AU>, steveq@syd.dms.CSIRO.AU (Stephen Quigg) writes: |> In article <2939.279ef15b@iccgcc.decnet.ab.com> gibbonsj@iccgcc.decnet.ab.com writes: |> >In article <541@cow.ecs.oz>, bmp@cow.ecs.oz (Bruce Paterson) writes: |> >> A friend is attempting to build (from scratch) a flux-gate compass |> >> for use in a vehicle mounted dead-reckoning navigation system. |> >... |> >Why build one from scratch? You can buy a WWII flux-gate compass from |> >a company called JOLLYCO (or something like that) out of Chicago. These |> >are the real thing, minus electronics, for somewhere around $35. |> > |> >If you're interested, I can dig up / verify the company name & phone number. |> Or buy a complete compass from Tandy (Radio Shack) for $Aus 99. Don't know |> how good they are though. Wasn't there an article in one of the pop. press magazines (maybe Radio Electronics) about six months ago on how to interface to the Rat Shack flux gate compass> The RS unit is intended as a standalone automotive compass but the main element is a reasonable flux-gate magnetic heading sensor. Note that in addition to sensor inaccuracies, you will have to cope with the magnetic declination - the differnece between magnetic and geographic north - that varies from one location to another. Bob Haar InterNet : rhaar@albert.cs.gmr.com Computer Science Dept., G.M. Research Laboratories DISCLAIMER: Unless indicated otherwise, everything in this note is personal opinion, not an official statement of General Motors Corp.
hbg6@citek.mcdphx.mot.com (01/25/91)
In article <4346@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: > For further information on flux gate devices, you might wish >to try a flux gate manufacturer, such as Humphrey, Inc. or Sperry >Navigation Systems. > Or: KVH Industries, Inc. 850 Aquidneck Avenue Middletown, RI., 02840 (401)847-3327 products include: Toroidial Fluxgate Sensor Coil $100 Toroidial Fluxgate Sensor coil w/gimbal $125 up to a complete digital compass with RS-232 output for around $1000 (note: these prices are old) Good Luck, John ..................................................................... reply to 'from' address; hbg6@citek.mcdphx.mot.com NOT the 'sender' line address! Someday my sysadm will decide this is a 'real' problem. :-) ..................................................................... All opinions expressed are mine and not Motorolas, their loss. .....................................................................
kludge@grissom.larc.nasa.gov ( Scott Dorsey) (01/26/91)
In article <1991Jan25.032656.3794@syd.dms.CSIRO.AU> steveq@syd.dms.CSIRO.AU (Stephen Quigg) writes: >Why build one from scratch? You can buy a WWII flux-gate compass from >a company called JOLLYCO (or something like that) out of Chicago. These >are the real thing, minus electronics, for somewhere around $35. a. The company's name is Jerryco. b. They don't have any flux-gate compasses in their last few catalogues. c. There weren't any flux-gate compasses used in WWII.
cdl@chiton.ucsd.edu (Carl Lowenstein) (01/26/91)
In article <1991Jan25.165409.8299@news.larc.nasa.gov> kludge@grissom.larc.nasa.gov ( Scott Dorsey) writes: >c. There weren't any flux-gate compasses used in WWII. There certainly were flux-gate magnetometers, used for MAD (Magnetic Airborne Detection of submarines). -- carl lowenstein marine physical lab u.c. san diego {decvax|ucbvax} !ucsd!mpl!cdl cdl@mpl.ucsd.edu clowenstein@ucsd.edu
cas@mtcchi.uucp (2668-Charles A Sherwood(Z550900)0000) (01/29/91)
In article <1991Jan25.165409.8299@news.larc.nasa.gov> kludge@grissom.larc.nasa.gov ( Scott Dorsey) writes: >In article <1991Jan25.032656.3794@syd.dms.CSIRO.AU> steveq@syd.dms.CSIRO.AU (Stephen Quigg) writes: > >c. There weren't any flux-gate compasses used in WWII. WRONG WRONG WRONG. I have one!! It was the main nav compass for a B17. I purchased mine from one of the surplus places about 5 years ago. There was an article several years ago in one or the electronics mags about how to play with these. I believe it was in the hardware hackers column. I have not managed to make my WWII flux gate work, for several reasons. 1) lack of doumentation. 2) lack of the electronic section, I have the flux gate and the indicator. 3) Its a three phase system, all new systems are two phase. I believe they used a three phase system, because all they had for indicators were syncro motors. -- Chuck Sherwood cas@mtc.com 708-305-3470 Memorex Telex Corporation Indian Hill Court 1000 E. Warrenville Road, Room 1H315 Naperville, IL 60563 UUCP: ...!att!mtcchi!cas or ...!uunet!mtcchi!cas
keithm@wicat.UUCP (Keith McQueen) (02/05/91)
The REAL question is: If I get one of these and feed it with 1.21 Gigawatts of power from a nuclear reaction, or from a well placed lightning bolt, can it be used as a time travel machine? Or is that only if it is mounted in a DeLorean automobile? :-) -- Keith McQueen, Wicat Systems Inc. , (801)224-6400 | My opinions are | N7HMF @ NV7V.UT.USA.NA (84058), 147.34+, 449.675- | all mine... | UPLHERC!WICAT!KEITHM | ...so there! |
elmquist@nachos.SSESCO.com (Chris Elmquist) (02/08/91)
In article <529@wicat.UUCP> keithm@wicat.UUCP (Keith McQueen) writes: >The REAL question is: If I get one of these and feed it with >1.21 Gigawatts of power from a nuclear reaction, or from a well >placed lightning bolt, can it be used as a time travel machine? > >Or is that only if it is mounted in a DeLorean automobile? I think it has to be a "flux gate *CAPACITOR*" and you probably need the DeLorean too... -- Chris Elmquist, N0JCF Internet: elmquist@SSESCO.com AMPRN: N0JCF@WB0GDB.MN.USA.NA BellNet: (612) 785-3516