Re: [time-nuts] Crude Survey Technique

I'd also go for a compass if you want magnetic north, but then I have a good one, a "medium landing compass". Mine dates from WWII but they are still made http://www.sirs.co.uk/ground/landing_compasses/patt2/landing_resource These are used to align the standbay and remote reading compasses on air

Re: [time-nuts] Upcoming Loran shutdown

Rich as they say its been great while it lasted. Yes still on tonight and I have checked my local references against it so I am good for another 6 months. Good job on catching it in the first place. How are you finding information like the test period will start or stop?? Regards Paul WB8TSL On T

[time-nuts] Off-Topic Question -- German Composition Resistors

My sincere thanks to those who responded to my request for help. The link to a chart provided by Ernie allowed me to recognize I was looking at five-stripe resistors with three significant figure stripes followed by a multiplier stripe and spaced a little further away a red stripe indica

[time-nuts] Crude Survey Technique

Brooke Clarke wrote: "Most low cost hand held and car GPS receivers can only display direction based on changes in position." True, but the Garmin 62s handheld that I use for geocaching and hiking ($200-$400) has a 3-axis, tilt-compensated electronic compass that shows your heading even when

Re: [time-nuts] Crude Survey Technique

On 11/21/13 3:28 PM, Chris Albertson wrote: On Thu, Nov 21, 2013 at 11:11 AM, Don Latham wrote: Lord no, John. No red wagon is needed. Use a pole and the equation of time, and a good watch or clock. At local noon, a shadow will be a n-s line. How accurate do you need to be? The above requir

Re: [time-nuts] Crude Survey Technique

That's my point. 'Coriolis force' was invented to make it appear that Newtons laws were valid in an Earth based frame. On Thu, 21 Nov 2013 18:06:54 -0700, Don Latham wrote: >Coriolis ain't a force :-) >> >> Newtons laws are NOT valid in a noninertial frame. (That's why the >> Coriolis force

Re: [time-nuts] Crude Survey Technique

Southward (toward equator) deflection would actually improve the geometry. All non-north vectors would be lengthened in proportion. On 11/21/2013 6:37 PM, Bill Beam wrote: > On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote: > >> If you need a very tall pole that is 100% vertical the

Re: [time-nuts] Crude Survey Technique

Coriolis ain't a force :-) A real tall pole isn't required, just another person Bill Beam > On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote: > >>If you need a very tall pole that is 100% vertical then hang a >>weighted rope from a tall support. Then go to the other end and watch >>the s

Re: [time-nuts] Crude Survey Technique

An interesting technique for improving the accuracy of single band gps is embodied in an open source program/project called rtklib. Essentially it uses one GPS receiver in a fixed location that has been very carefully surveyed (gps reported location averaged over a long period) as a phase refere

Re: [time-nuts] Crude Survey Technique

On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote: >If you need a very tall pole that is 100% vertical then hang a >weighted rope from a tall support. Then go to the other end and watch >the seconds tick down. Be carefull!... A plumb bob does not hang vertically (point to center of Ea

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Hi To be clear - the idea of going to a non-100 ns multiple is a good one. You probably should avoid multiples of 1/10.24 MHz as well. Bob On Nov 21, 2013, at 8:00 AM, Azelio Boriani wrote: > Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to > take PPSes measurements . >

[time-nuts] Upcoming Loran shutdown

Loran followers; This test period is scheduled to end sometime on the 22nd, so don't panic when it disappears! Also on the X secondary a message is being sent on the 9th pulse for those with a scope attached. Regards; Rich ___ time-nuts mailing lis

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to take PPSes measurements . On Thu, Nov 21, 2013 at 1:34 PM, Bob Camp wrote: > Hi > > The counter and offset generator both should be quite accurate at a 1 us > offset. That’s large enough that you are outside the range of most

Re: [time-nuts] Crude Survey Technique

As I said before, the RA and Dec of Polaris is well known. Spherical trig and the Siderial Time will give you the offset from the true pole in Az and El. With corrections for refraction, this is good to better than an arc-second. -John == > On Thu, Nov 21, 2013 at 12:45 PM, wr

Re: [time-nuts] Crude Survey Technique

On Thu, Nov 21, 2013 at 12:45 PM, wrote: > If you want true north, set up a camera that has time or bulb shutter at the > south end of your property. Put in a marker stake. take a time exposure at > night with the camera facing north. If you expose for about 30 minutes, you > will get a landsc

Re: [time-nuts] Crude Survey Technique

On Thu, Nov 21, 2013 at 11:11 AM, Don Latham wrote: > Lord no, John. No red wagon is needed. Use a pole and the equation of > time, and a good watch or clock. At local noon, a shadow will be a n-s > line. How accurate do you need to be? The above requires a very tall pole to case a 300 foot lon

Re: [time-nuts] Crude Survey Technique

FWIW, my Garmin Nuvie 40 (el cheapo) only takes moving maybe 10' to get a rough compass direction. I doubt it has any gyro or accelerometers. -John === > Hi Neville: > > Most low cost hand held and car GPS receivers can only display direction > based on changes in position. > While

Re: [time-nuts] Crude Survey Technique

The INS has to be 'aligned' before takeoff. Remember, the earth is spinning on an axis, and the INS's platform is stable in Inertial space. If you know the INS is sitting on the ground (or even deep in a mine shaft) it's just trig. Nothing external needed, not even stars. -John

Re: [time-nuts] Crude Survey Technique

Hi Neville: Most low cost hand held and car GPS receivers can only display direction based on changes in position. While on vacation in Japan I was using a hand held Garmin 12-channel GPS, but when standing still the compass did not work, I needed to run a block to get a bearing. My Honda van G

Re: [time-nuts] Crude Survey Technique (johncr...@aol.com)

Hi John: I have a web page devoted to Finding North, see: http://www.prc68.com/I/North.shtml Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html ___ time-nuts mailing list -- time-nuts@febo.com To u

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

May be a bit of drift and reading back to front. Some years ago we bought a quantity of moulded carbon compostion resistors from a top US manufacturer. A sample check showed that none of them met the 10% tolerance. The maufacturer said "bake them for a day two"! The resistors then passed. Why no

Re: [time-nuts] Crude Survey Technique

The simplest ones do it by difference in position from one fix to another. no need for a map for True North, just trig. For Magnetic North you need a map with variation data. More advanced units have magnetic sensors and accelerometers. An interesting question that I once spent some hours discus

Re: [time-nuts] Crude Survey Technique

How do the car mounted GPS guidance devices find North? Is it by deciding which direction you are moving on the map that they have stored? It is amazing how quickly they show the orientation of the map/your direction of travel. Do they have a sensor to register when you turn a corner? What they d

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

Hi Bruce, no. Same color code here. However, certain carbon composition resistors from the 60's/70's are notoriously unreliable. The common effect is drift to significantly higher values. Besides that, they can get pretty noisy. Adrian brucekar...@aol.com schrieb: While tracing out a PC board

Re: [time-nuts] Crude Survey Technique

If you want true north, set up a camera that has time or bulb shutter at the south end of your property. Put in a marker stake. take a time exposure at night with the camera facing north. If you expose for about 30 minutes, you will get a landscape with the stars rotating around the north star.

Re: [time-nuts] Crude Survey Technique (johncr...@aol.com)

My thanks to all that contributed ideas, especially Don's sundial approach. You all have established that if there is an excessively? complex approach I will be sure to think of that first. Let see what else pops up. -73 john k6iql -Original Message- From: time-nuts-request

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Hi The counter and offset generator both should be quite accurate at a 1 us offset. That’s large enough that you are outside the range of most GPS jumps. If you are going to move things around, you might as well move out to that vicinity. Bob On Nov 21, 2013, at 6:20 AM, Tom Van Baak wrote:

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

et the time by twice the amount I set it to. Which > is why I initially thought it might be a firmware thing. I suppose > multipath is a good explanation, it is just odd that the time error is > exactly 100ns. > > URL: <http://www.febo.com/pipermail/time-nuts/attachments/20131121/

Re: [time-nuts] Crude Survey Technique

I've done this and your best option is to go out at night with a home made tripod, plumb bob and sight from one place to another with polaris and the plumb bob string. The farther the better, then keep your reference points with a couple of iron posts. You will be well under 1/2 deg and probab

Re: [time-nuts] Crude Survey Technique

On Thu, Nov 21, 2013 at 12:52 PM, wrote: > I wish to establish a north south line on my property to an accuracy of > +/- 2 degrees. > Could this be done by loading a T-bolt, Antenna, Power source, and laptop > into my > little red wagon? The idea being to find two positions several hundred ft >

[time-nuts] OT: Putting the Wolfram Language (and Mathematica) on every Raspberry Pi

Putting the Wolfram Language (and Mathematica) on every Raspberry Pi http://blog.wolfram.com/2013/11/21/putting-the-wolfram-language-and-mathematica-on-every-raspberry-pi/ and it's free. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsig

Re: [time-nuts] Isolation achieved by opamp based isoamp?

One thing to keep in mind is that isolation through shielding usually results in much greater capacitance to ground (actually to the shield) from both input and output windings. Therefore, the actual isolation in practice is totally driven by how good the ground to the shield is. At RF, any induc

Re: [time-nuts] Crude Survey Technique

For something that crude, I'd consider taking a sight on Polaris. If you note the time and do the math, you can probably do better than your bounds. Also, there is almost certainly an app somewhere to do the math for you. I think tha reeuction info was in Bowditch or the Nautical Almanac. FWIW,

Re: [time-nuts] Crude Survey Technique

Lord no, John. No red wagon is needed. Use a pole and the equation of time, and a good watch or clock. At local noon, a shadow will be a n-s line. If you don't have a decent clock, like your cellphone, put in a pole at one end of your line. Near local noon, which depends on where you are in the tim

Re: [time-nuts] Crude Survey Technique

John: for local noon: http://education.illinois.edu/noon-project/noontime.html Don johncr...@aol.com > I wish to establish a north south line on my property to an accuracy of > +/- 2 degrees. > Could this be done by loading a T-bolt, Antenna, Power source, and > laptop into my > little red wagon?

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Looking quickly at the prints on the site, the isolation is provided by the transformer, not the active circuitry. The transistors/op-amps are just buffers for the output. That means that the isolation is determined, for the most part, by the transformer design, so: A bifilar wound torroid would

Re: [time-nuts] Crude Survey Technique

In message <8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com>, johncroos@ aol.com writes: > I wish to establish a north south line on my property to an >accuracy of +/- 2 degrees. First of all, at that level of precision you will have to decide what you mean by "north south" ? Magnetic ?

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

> The 100ns is exactly one cycle at 10 MHz. GPS receivers use this, or > something very close, as an internal clock. Joe, The vintage Oncore VP used a 9.54 MHz clock (which is why its sawtooth is about +/- 52 ns). Stephan is using the newer M12+T (~40 MHz clock, which is why its sawtooth is

[time-nuts] Crude Survey Technique

I wish to establish a north south line on my property to an accuracy of +/- 2 degrees. Could this be done by loading a T-bolt, Antenna, Power source, and laptop into my little red wagon? The idea being to find two positions several hundred ft apart where either LH or T-bolt Mon report the same

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

On Thu, Nov 21, 2013 at 12:49 AM, Stephan Sandenbergh wrote: ... > Using a single antenna and splitting it is an idea, but then I still need > to devise something to inject the antenna DC power at the other end of the > splitter etc. And, we are trying to measure the relative offset between the >

Re: [time-nuts] DIY antenna

Alain, Look here. http://lea.hamradio.si/~s53mv/navsats/analog.html It's essentially 2 loops of different size connected together at the top to give 50 ohm Z. The amp I used is also bandwidth limited. I should put it next to my PCtel antenna with a switch and see which works better. _

[time-nuts] Isolation achieved by opamp based isoamp?

Hi, I'm curious about the level of isolation that is achieved by an opamp based isoamp. I'm referring to ones described here on Bruce Griffiths' page: http://www.ko4bb.com/~bruce/IsolationAmplifiers.html Anyone has a number for this? I've tried googling it, but the results are mostly filled with

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

If it had 4 color bands 2701 you are likely reading it backward. 1072 would be 10.7K Bob L. > > From: "brucekar...@aol.com" >To: time-nuts@febo.com >Sent: Thursday, November 21, 2013 1:11 PM >Subject: [time-nuts] Off-Topic Question -- German Composition Resist

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Hi, Bjorn, it is good to know such splitter devices exist. This is really neat. I'm using the built-in offset function of the M12+, and not an offset generator. I'm currently redoing the measurement to see if it has similar issues. And yes, I was also interested to see what would happen at other

Re: [time-nuts] DIY antenna

Hi Dave, your antenna is somehow surprising to me. If you do not want to have a large band of frequencies, you can adapt the two loops of this QFH (in the band of doppler effect naturally), at the same GPS frequency; if think this will improve the gain. I do not see how do you realised the isola

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

Hi Bruce, sorry but the server removed the embedded pics. here is a link http://www.diyaudioandvideo.com/Electronics/Color/ Rgds Ernie. -Original Message- From: Brucekareen To: time-nuts Sent: Thu, Nov 21, 2013 7:17 pm Subject: [time-nuts] Off-Topic Question -- German Composit

Re: [time-nuts] Isolation achieved by opamp based isoamp?

A good transformer has very high CMRR. The purpose of the interwinding shield is to prevent CM on the input swide, coupling through to the buffer input, and yes, it should be well grounded. However, even if the shield is not perfectly grounded, it greatly reduces the interwinding coupling capacitan

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

Basic resistor has three color codes - two significant digits and a multiplier - and then likely silver or (more commonly today) gold band. Silver is 10%, gold is 5%. A high -spec resistor can have extra color bands to denote things like tempco, reliability, etc. and may have a non-silver and non-

Re: [time-nuts] Off-Topic Question -- German Composition Resistors

Hi Bruce, try to use this one Resistor Color Code Identification Rgds Ernie. -Original Message- From: Brucekareen To: time-nuts Sent: Thu, Nov 21, 2013 7:17 pm Subject: [time-nuts] Off-Topic Question -- German Composition Resistors While tracing out a PC board from an instru

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Corby wrote: This opamp buffer has 80-90db isolation. That is typical at 5 to 10 MHz *if* (i) all of the splitting is done on the input side (i.e., each output has its own op amp), and (ii) the splitter and all of the construction (grounds, shielding, etc.) is done correctly. If any split

[time-nuts] Off-Topic Question -- German Composition Resistors

While tracing out a PC board from an instrument manufactured in Germany, I quickly discovered the color code on 1/4-watt composition resistors is not the same as that commonly used in the US For example, I would measure about 10,000-ohms across a presumably good resistor that appeared to be

[time-nuts] Isolation achieved by opamp based isoamp?

Try looking here. http://www.cliftonlaboratories.com/z1_buffer_amp.htm This opamp buffer has 80-90db isolation. Corby ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts an

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

> Below is a plot so you could see exactly what I measured. What is peculiar > is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS > receiver decides to offset the time by twice the amount I set it to. Which > is why I initially thought it might be a firmware thing. I suppose > m

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Hi Stephan, > Using a single antenna and splitting it is an idea, but then I still need > to devise something to inject the antenna DC power at the other end of the > splitter etc. And, we are trying to measure the relative offset between > the > antenna/receiver pairs for calibration. Most gener

Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

Hi, I'm using three Motorola GPS Timing 2000 Antennas. They are co-located on the roof of our building with a clear view of the skies. The view is almost 360deg but a mountain is blocking off a small bit of it to the South-East side. I'd assume some multipath is possible, but I'd thought that the