Re: [time-nuts] How can I measure GPS Antenna quality?

Hi Atilla, Read the document below https://www.ngs.noaa.gov/ANTCAL/docs/NGSantcalprocedures.pdf And the reference within         antenna_README.pdf Antennas are generally not calibrated individually by the user. You make sure the antenna you buy are in the ANTCAL or Geo++ lists. Any use of a snow

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

I haven't used one personally but a spirent gps simulator would let you do a try it and see. It will be interesting to see if out of the growing sdr community an open source gps simulator emerges. On Mon, Nov 21, 2016 at 1:01 PM Dr. David Kirkby (Kirkby Microwave Ltd) <

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 10:10 AM, Tom Van Baak wrote: For the equipment hobbyists usually have, the phase center is not that important. Most antennas have a variation <5mm. Even 10mm would lead to just a ~33ps variation. I agree. And besides, for those of us here in Oregon/Washington, the very ground is

Re: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

Hi If the part is 50 years old that pre-dates the invention of the SC cut. AFIK, all of the QK glass bottle crystals date to the “pre SC” era. The BT is about the only other alternative from that era. HP made it their “goto cut” for OCXO’s back then. Others may have followed along …. Bob

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 2:58 PM, Attila Kinali wrote: On Mon, 21 Nov 2016 08:22:50 -0800 jimlux wrote: I'm not sure about whether an anechoic (which is really "hypoechoic") chamber is going to get you the data you need. Calibrating the chamber to the needed level of accuracy might

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

On 11/21/16 3:11 PM, Attila Kinali wrote: On Mon, 21 Nov 2016 14:36:49 -0500 Bob Camp wrote: The reflection issue ahead of the antenna is a reflection of the signal from a single satellite. The multipath reflection makes that satellite appear to be further away than it really

Re: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

Hi Thanks for the pictures !!! Another possible thing to watch for: It may take a *long* time for the oven to stabilize at the correct temperature. Bob > On Nov 21, 2016, at 6:31 PM, Michael Ulbrich wrote: > > Hi all, > > thanks a lot for your helpful suggestions and

Re: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

A comparison between AT and SC cuts' temperature stability can be found here: On Mon, Nov 21, 2016 at 4:21 AM, Bob Camp wrote: > Hi > > If the frequency drops as the oven warms up, you have an AT cut crystal. If > the frequency

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

p...@phk.freebsd.dk said: > I think the installation manual for Trimbles timing products say you can use > either 75 or 50 Ohm cable... I think they suggest using RG-6, the classic cable TV and/or satellite dish cable. It's widely available at low cost. The loss due to impedance mismatch is

Re: [time-nuts] 53132 replacement fan

Adrian wrote: This one's pretty quiet. But the airflow is a bit lower. This one moves a little more air than the original (7.7 cfm) and is somewhat quieter than the original (by 2dB): If you want to improve cooling, this one moves much more air

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

On Mon, 21 Nov 2016 14:36:49 -0500 Bob Camp wrote: > The reflection issue ahead of the antenna is a reflection of the signal from > a single satellite. The multipath > reflection makes that satellite appear to be further away than it really is. > In the case that the reflected

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

Sorry... I pressed the wrong button while editing the Mail and cut short... Continuing where I left off > In the case of a mismatched cable, there is no “single satellite” issue. > Everything is impacted by the mismatch. > Even if the mismatch is pretty bad, the “primary” wave is the one that

Re: [time-nuts] How phase stable is rg59 or alternate coax

At one point I contemplated running Andrews "Heliax" for my GPS antenna. Part of the rationale was due to the data presented in page 2 of the following paper. http://ivs.nict.go.jp/mirror/meetings/v2c_wm1/phase_stability.pdf I subsequently decided to stay with my existing run of plenum rated

Re: [time-nuts] How can I measure GPS Antenna quality?

On Mon, 21 Nov 2016 08:22:50 -0800 jimlux wrote: > I'm not sure about whether an anechoic (which is really "hypoechoic") > chamber is going to get you the data you need. Calibrating the chamber > to the needed level of accuracy might be harder than doing field >

Re: [time-nuts] Question about AD9832 "I out Full Scale" (what does it mean?)

Well, here is response from ADI: Quote: If I remember correctly, this part implements a differential DAC current source, but only one of the outputs is bonded externally. In this case, the current settle by Rset should be divided by 2..., which explain your results. I'll update the DS as

Re: [time-nuts] 53132 replacement fan

Hi The bigger issue when you replace the fan: Do the best job you possibly can cleaning out the power supply. Also check the soldering and the rest of the workmanship on the power supply pc board. It’s the weak link in the counter. You don’t have to give it much of a look to figure out HP

Re: [time-nuts] Need for a document comparing time interval counters

On 11/21/2016 1:10 PM, Bob Camp wrote: Hi With both counters running on the same external standard (and no internal OCXO), the 53230 beats the 53132 both on frequency and time. It also has slightly better isolation of the 10 MHz internals so the “dead zone” at 10 MHz is not quite as bad. I

Re: [time-nuts] Need for a document comparing time interval counters

Hi With both counters running on the same external standard (and no internal OCXO), the 53230 beats the 53132 both on frequency and time. It also has slightly better isolation of the 10 MHz internals so the “dead zone” at 10 MHz is not quite as bad. I have no idea how either one works with

Re: [time-nuts] How phase stable is rg59 or alternate coax

When I first took a look at some of the coax datasheets I couldn't find anything. I was able to find the following paper "phase stability of typical navy radio frequency coaxial cables" http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table from the last page. They estimate RG59

Re: [time-nuts] 53132 replacement fan

Hi All; Mouser has more then 200 of the EFB0412MD OEM fans in stock. 10.93 in singles. I have so many fans running in my lab I do not worry much about a little more noise. But a noisy fan is a major concern because of overheating if the fan fails, and although I usually go for an OEM parts in

Re: [time-nuts] 53132 replacement fan

This one's pretty quiet. But the airflow is a bit lower. http://www.frozencpu.com/products/9367/fan-587/Sunon_MagLev-Vapo_40mm_x_20mm_Fan_w_TAC_Sensor_Wire_-_Bare_Wire_HA40201V4--C99.html?tl=c15s560b53=mrFX8Rvo On Mon, Nov 21, 2016 at 5:57 PM, jimlux wrote: > On

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

I believe that reflections inside the cable (that is, after the antenna) are very different from reflections before the antenna. GPS receivers do their calculations based in the different arrival times of the satellites signals to the antenna center, so delays caused from different paths

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

In message

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

I believe that reflections within the cable doesn't matter regarding the GPS measurements, unlike the reflections coming from outside the antenna. The measurements are made from the differences in the arrival times of the different satellite signals to the antenna and delays after that

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

Hi Based on extensive testing of the line mismatch issue, the answer turns out to be “it does not matter”. The reflection issue ahead of the antenna is a reflection of the signal from a single satellite. The multipath reflection makes that satellite appear to be further away than it really

Re: [time-nuts] How phase stable is rg59 or alternate coax

Several years ago I measured the delay of about 80 feet of LMR400 feeding a GPS antenna, much of which was lying on a black shingle roof in the Georgia sun. I checked in early afternoon when the sun was beating, and in the wee hours of the morning, to get the greatest temperature delta. My

Re: [time-nuts] How can I measure GPS Antenna quality?

> For the equipment hobbyists usually have, the phase center is not that > important. Most antennas have a variation <5mm. Even 10mm would lead to > just a ~33ps variation. I agree. And besides, for those of us here in Oregon/Washington, the very ground is moving northwest at several inches per

Re: [time-nuts] 53132 replacement fan

Tom wrote: EFB0412MD Airflow 7.17 CFM 6300 RPM Noise 24 dBA FBK04F12U Same exact form factor. Air Flow 9.2 CFM 9500 RPM Noise 42 dB(A) Note the 18dB greater noise (that's a HUGE difference). Even with bad bearings in the original fan, it is probably considerably quieter (by 10dB or more)

Re: [time-nuts] How phase stable is rg59 or alternate coax

On 11/21/16 6:38 AM, Scott Stobbe wrote: If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? Figure it's copper, so 16 ppm/deg C. velocity factor is about 2/3, so 30 ft is about 45 nanoseconds. about 1ps/degree Really,

Re: [time-nuts] 53132 replacement fan

Thanks, all for the tips. Glad to know it's a standard size so there's plenty of choice. John On 11/21/2016 12:57 PM, jimlux wrote: On 11/21/16 6:39 AM, Charles Steinmetz wrote: Tom wrote: EFB0412MD Airflow 7.17 CFM 6300 RPM Noise 24 dBA FBK04F12U Same exact form factor. Air Flow

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 8:38 AM, Bob Camp wrote: Hi On Nov 21, 2016, at 9:54 AM, Attila Kinali wrote: On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: If I gave you a pile of data, how would you compute a quality number? Can I just sum up the S/N slots

Re: [time-nuts] How can I measure GPS Antenna quality?

When I was doing VHF and UHF direction finding antenna design, I would drive out to the highest readily accessible hilltop for testing. Once I came up with a low sidelobe design, I started picking up things like lamp posts, trees, and bushes in the parking lot, aircraft over LAX and John Wayne

Re: [time-nuts] How phase stable is rg59 or alternate coax

In message

Re: [time-nuts] 53132 replacement fan

On 11/21/16 6:39 AM, Charles Steinmetz wrote: Tom wrote: EFB0412MD Airflow 7.17 CFM 6300 RPM Noise 24 dBA FBK04F12U Same exact form factor. Air Flow 9.2 CFM 9500 RPM Noise 42 dB(A) Note the 18dB greater noise (that's a HUGE difference). Even with bad bearings in the original fan, it is

Re: [time-nuts] Inductor core material aging (was: Rohde & Schwarz XSD 2.5 MHz crystal gone bad?)

The core of the inductors are commonly powdered iron (of various alloys), held together with a plastic binder. The early plastics shrank and changed shape with time, changing the inductance over decades. Later binders are much more stable. Not much you can do about it, other than change the

[time-nuts] How phase stable is rg59 or alternate coax

If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? On Sun, Nov 20, 2016 at 7:04 PM Hal Murray wrote: > > Is that even a sensible question? Is there a better way to phrase it? > > > The problem I'm

[time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

People state it is desirable to have a GPS antenna well clear of obstructions, which I believe is to stop reflections. But there is another source of reflections which I suspect could be just as problematic. Whilst the input impedance of the antenna input terminal on a GPS receiver is probably

Re: [time-nuts] Inductor core material aging (was: Rohde & Schwarz XSD 2.5 MHz crystal gone bad?)

Hi > On Nov 21, 2016, at 9:23 AM, Attila Kinali wrote: > > Hoi Bob, > > On Sun, 20 Nov 2016 22:21:29 -0500 > Bob Camp wrote: > >> 50 year old inductors may have been made with core materials >> that aged more than just a little bit. I have empirical data on

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 6:54 AM, Attila Kinali wrote: On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: If I gave you a pile of data, how would you compute a quality number? Can I just sum up the S/N slots for each visible/working satellite? There are multiple issues. As

Re: [time-nuts] 53132 replacement fan

On 21-Nov-16 6:14 AM, John Ackermann N8UR wrote: Does anyone have a part number for the 53132 fan (or equivalent)? Mine is getting pretty noisy. Thanks! John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 4:15 AM, Bob Camp wrote: Hi At spectrum analyzer bandwidths, the GPS signals out of the antenna are more than 20 db below the noise floor. You can’t see them with an analyzer. You need to run things into the equivalent of a receiver to turn it into anything you can see above the

Re: [time-nuts] How can I measure GPS Antenna quality?

On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: > If I gave you a pile of data, how would you compute a quality number? Can I > just sum up the S/N slots for each visible/working satellite? There are multiple issues. As already mentioned, SNR is only a part of

[time-nuts] Inductor core material aging (was: Rohde & Schwarz XSD 2.5 MHz crystal gone bad?)

Hoi Bob, On Sun, 20 Nov 2016 22:21:29 -0500 Bob Camp wrote: > 50 year old inductors may have been made with core materials > that aged more than just a little bit. I have empirical data on this :) Do you have that data available somewhere? I would be very much interested in it.

Re: [time-nuts] How can I measure GPS Antenna quality?

In message <2974f356-3729-448e-a428-dc4d340ff...@n1k.org>, Bob Camp writes: >If I put up a handful of antennas on the back porch, I can indeed hook them >up to various receivers and cables. I actually had a chance to do that once: http://phk.freebsd.dk/raga/ I was very careful

Re: [time-nuts] Need for a document comparing time interval counters

I had a 53230 the last few years I worked for Agilent. The oven oscillator in it is inferior to a 10811. Its only claim to fame IMHO is that it can measure Allan Deviation. Turns out that we really needed Hadamard, but it doesn't do that. It is very expensive. The old Santa Clara Division with

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/20/16 7:41 PM, Mark Sims wrote: When I was developing the precision survey code for Lady Heather, I used a lot of antennas. My definition of antenna quality boiled down to how well the results of a 48 hour survey compared to the cm level survey point that I had for my antenna position

Re: [time-nuts] How can I measure GPS Antenna quality?

Hi At spectrum analyzer bandwidths, the GPS signals out of the antenna are more than 20 db below the noise floor. You can’t see them with an analyzer. You need to run things into the equivalent of a receiver to turn it into anything you can see above the noise. What you will see on an

Re: [time-nuts] 53132 replacement fan

try this site: http://www.eevblog.com/forum/testgear/replace-fan-on-53131a-counter-with-quieter-version/msg727690/#msg727690 Götz Am 21.11.2016 um 02:43 schrieb Christopher Hoover: I was able to cross it easily to a well-known fan manufacturer's part. If someone doesn't chime in, I'll dig

Re: [time-nuts] How can I measure GPS Antenna quality?

Yo Hal! On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: > Is that even a sensible question? Yes, it is a good question. I have been buying a lot of cheap GPS antennas for testing on RasPis. I plug the antenna into a GPS, then just wait until the GPS gets a good