Author Topic: Which barometer would you get and why...  (Read 5867 times)

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Offline blizzardof78

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Re: Which barometer would you get and why...
« Reply #25 on: May 13, 2020, 07:30:36 AM »
I'm always curious to see what folks have as a set-up. Have you ever placed photos of the DBX1 and 2 on here or could you? Just curious. Thanks!
Me too! I hope when you get your barometer you'll post some pictures and a report. I wonder what the OP bought? They never posted again in the thread.

Hi Jim S. I was wondering about what he may have purchased as well. I looked and noticed he was active yesterday around noon eastern time, so maybe he will chime in and tell us about his new barometer (2 years old now LOL) if he decided on one that is.

Yes as soon as I have mine up and running I'll take a few photos and a video and post if anyone wants to take a look. Thanks for your interest. I anticipate it being this weekend.


Offline blizzardof78

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Re: Which barometer would you get and why...
« Reply #26 on: May 16, 2020, 06:20:05 PM »
I'm always curious to see what folks have as a set-up. Have you ever placed photos of the DBX1 and 2 on here or could you? Just curious. Thanks!
Me too! I hope when you get your barometer you'll post some pictures and a report. I wonder what the OP bought? They never posted again in the thread.

Hi Jim... I've included three photos along with this reply. I'm in the process of learning the Barometer before putting together a video to publish. I do anticipate this being done this weekend.

I must say I am very please with the performance of the unit so far.

Here is the link to the first video I did... the unboxing, set-up, etc.

https://youtu.be/5hrd9KkISNs

Offline CW2274

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Re: Which barometer would you get and why...
« Reply #27 on: May 16, 2020, 06:42:06 PM »
Even though the measurements were very close, be aware that the airport value is the altimeter setting. I see SEA on your display, so I'm assuming you're using SLP. Just be aware there is a difference.

Offline blizzardof78

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Re: Which barometer would you get and why...
« Reply #28 on: May 17, 2020, 10:31:59 AM »
Even though the measurements were very close, be aware that the airport value is the altimeter setting. I see SEA on your display, so I'm assuming you're using SLP. Just be aware there is a difference.

Yes I am aware of that, and thank you for pointing it out. I have generally used SLP over the years so it's what I do, so to speak lol. I am very impressed with this instrument as it is quite sensitive and seems to be on the move most of the time either higher or lower. I had my eye on possibly buying one of their DBX1 units many years ago but didn't have the funds to do so then. I like this DBX2 unit much better I think.

Offline Jim_S

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Re: Which barometer would you get and why...
« Reply #29 on: May 17, 2020, 05:52:19 PM »
Hi Jim... I've included three photos along with this reply. I'm in the process of learning the Barometer before putting together a video to publish. I do anticipate this being done this weekend.

I must say I am very please with the performance of the unit so far.

Here is the link to the first video I did... the unboxing, set-up, etc.

Thanks! I enjoyed seeing the video and the pictures. I hope it gives you years of enjoyment.

Regarding Altimeter vs SLP, since calculating SLP requires knowing the outside air temperature (not the temperature at the device) the DBX2 is almost certainly using Altimeter and just calling it "SEA".  One of the previous posters said the manual provides a description of the exact method used but I can't find the DBX2 manual online.

If you want to calculate true SLP this site does it: https://www.starpath.com/barometers/baro_cal.php
The above site will also provide a list of nearby weather stations with SLP data.

When checking pressure I like to use this site, which shows hourly Altimeter and SLP (if it's available) : https://w1.weather.gov/obhistory/KZZV.html  (just replace KZZV with your local station... it is case sensitive) 

I love barometers and have a collection of old aneroid ones but my precious is a working Fortin mercury barometer. Not as accurate or precise as yours but when it tells me the station pressure is 27.59 in/Hg, I'm really looking at a 27.59" column of mercury. :grin:


Offline CW2274

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Re: Which barometer would you get and why...
« Reply #30 on: May 17, 2020, 06:07:00 PM »
Hi Jim... I've included three photos along with this reply. I'm in the process of learning the Barometer before putting together a video to publish. I do anticipate this being done this weekend.

I must say I am very please with the performance of the unit so far.

Here is the link to the first video I did... the unboxing, set-up, etc.
the DBX2 is almost certainly using Altimeter and just calling it "SEA". 
If so, it should be corrected. Sounds like they're "dumbing it down" which is ridiculous for a piece of this caliber.

Offline Jim_S

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Re: Which barometer would you get and why...
« Reply #31 on: May 17, 2020, 07:17:08 PM »
If so, it should be corrected. Sounds like they're "dumbing it down" which is ridiculous for a piece of this caliber.
How so?

I wasn't able to find a manual for the DBX2 but the manual for the other precision barometer mentioned in the OP (Mintaka Duo) says this:
Quote
There are several ways to define sea level pressure, which go beyond the even more complex concept of mean sea level itself. For now we assume the reference level is clear, but we look at the ways to describe the equivalent pressure at this level when observed at a higher elevation.

The most common way is to base the pressure change with elevation on the Inter-national Standard Atmosphere (ISA). This offers a fixed relationship between pres-sure and elevation that applies to all locations and all atmospheres. The ISA elevation values can be obtained from a formula or from tables, readily available online. This is the method that is used by essentially all electronic barometers that offer a correction to SLP based on the instrument elevation, and it is also the one used by the Mintaka Duo.

It is also the same procedure used in US airports to report altimeter settings to aircraft, which use the measured pressure to determine altitude so all aircraft are using the same reference. It is sometimes abbreviated as QNH, and in aviation appli-cations, this value of sea level pressure is called the altimeter pressure or just altimeter. This same abbreviation system (called Q-codes, which originated in early radio and telegraph applications) uses the letters QFE to label station pressure.

Thus the pressure reported by the Duo (and almost all electronic barometers) as SLP is the same as the altimeter reading one might see in aviation weather reports. It is also the same pressure that is usually referred to in print and broadcasts as the sea level pressure. 

Here is a link to the manual: http://www.weems-plath.com/core/media/media.nl/id.166263/c.449809/.f?h=e6ea8cc1fcbd52114505
See Appendix A2 on page 39.

I don't see this as "dumbing down" more like following industry standard.

Offline openvista

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Re: Which barometer would you get and why...
« Reply #32 on: May 17, 2020, 07:18:44 PM »
Most mariners, the intended demographic for this device, assume when you are talking about sea-level pressure, you mean altimeter. Just visit NDBC or Tides & Currents and you'll see "pressure" reports (from the Coast Guard and NOAA buoys) invariably in altimeter format. It makes sense since barometers used on boats historically could only sense atmospheric pressure, not temperature. 

"SLP" is only one of several valid methods to reduce pressure at elevation at sea level.  Anyone truly expert in pressure would NOT assume only "SLP" could mean "SEA". Nor would they demand that a primarily sea-faring device report anything other than the accepted mariner pressure format.


 
« Last Edit: May 17, 2020, 07:28:03 PM by openvista »
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Offline openvista

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Re: Which barometer would you get and why...
« Reply #33 on: May 17, 2020, 07:40:32 PM »
Apparently, Aquatech's website is down. Here's an alternative link to the manual: https://www.dropbox.com/s/nj3r2clt46bwk9n/ASI%20DBX2%20MANUAL_V1W.pdf?dl=0

You'll see on page 14 that it refers to the "SEA PRESSURE" formula as "QNH" which is altimeter-formatted pressure.
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Offline CW2274

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Re: Which barometer would you get and why...
« Reply #34 on: May 17, 2020, 08:09:36 PM »
Argue all you want. This is my post on page 1 from over two years ago.

This is from the NWS:

"ALTIMETER SETTING: This is the pressure reading most commonly heard in radio and television broadcasts. It is not the true barometric pressure at a station. Instead it is the pressure "reduced" to mean sea level using the temperature profile of the "standard" atmosphere, which is representative of average conditions over the United States at 40 degrees north latitude. The altimeter setting is the pressure value to which an aircraft altimeter scale is set so that it will indicate the altitude (above mean sea level) of the aircraft on the ground at the location for which the pressure value was determined. The altimeter setting is an attempt to remove elevation effects from pressure readings using "standard" conditions.

MEAN SEA LEVEL PRESSURE: This is the pressure reading most commonly used by meteorologists to track weather systems at the surface. Like altimeter setting, it is a "reduced" pressure which uses observed conditions rather than "standard" conditions to remove the effects of elevation from pressure readings. This reduction estimates the pressure that would exist at sea level at a point directly below the station using a temperature profile based on temperatures that actually exist at the station. In practice the temperature used in the reduction is a mean temperature for the preceding twelve hours. Mean sea level pressure should be used with caution at high elevations as temperatures can have a very profound effect on the reduced pressures, sometimes giving rise to fictitious pressure patterns and anomalous mean sea level pressure values."


If they're the same, why two distinctive definitions? Because they're not.

Offline openvista

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Re: Which barometer would you get and why...
« Reply #35 on: May 17, 2020, 09:06:03 PM »
Clearly they are NOT the same.

However, they are each valid methods of reducing pressure at higher elevations to sea level. Thus it is fair to refer to any such method as "SEA" or sea-level pressure.

To quote from your quoted definition of ALTIMETER SETTING:

Quote
Instead it is the pressure "reduced" to mean sea level using the temperature profile of the "standard" atmosphere...
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Offline CW2274

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Re: Which barometer would you get and why...
« Reply #36 on: May 17, 2020, 09:08:06 PM »
Clearly they are NOT the same.
Clearly.

Offline blizzardof78

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Re: Which barometer would you get and why...
« Reply #37 on: May 17, 2020, 09:21:16 PM »
Wow! Thanks for chiming in everyone. The Aquatech site is indeed down.

I'll make this brief as I'm a "simple" kind of guy (no jokes necessary LOL  :lol: )

I do weather on local TV five days a week. I've followed weather since grade school and I'm in my 50s now. As long as the device tells me what I wanna know and is accurate, I won't argue much over what it's called, be it SEA or ALT or whatever. As long as it's in InHG and accurate, that's my main concern.

Have a good evening and catch ya all later!

Offline CW2274

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Re: Which barometer would you get and why...
« Reply #38 on: May 17, 2020, 09:50:33 PM »
I won't argue much over what it's called, be it SEA or ALT or whatever. As long as it's in InHG and accurate, that's my main concern.
Fine and dandy. If I were to pay this much for a barometer, I'll be damned if I wouldn't want to know exactly what reduction it's using. Even my "lowly" Vue console (which it is in comparison) gives me the satisfaction of that. :roll:

Offline Jim_S

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Re: Which barometer would you get and why...
« Reply #39 on: May 17, 2020, 10:00:52 PM »
I do weather on local TV five days a week. I've followed weather since grade school and I'm in my 50s now. As long as the device tells me what I wanna know and is accurate, I won't argue much over what it's called, be it SEA or ALT or whatever. As long as it's in InHG and accurate, that's my main concern.
When I was 6 years old my mom bought a barometer (with green stamps, remember those?). I thought it was cool and have loved them ever since. Like you I think in InHg and I'm too old to change now.

Offline CW2274

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Re: Which barometer would you get and why...
« Reply #40 on: May 17, 2020, 10:07:24 PM »
I do weather on local TV five days a week. I've followed weather since grade school and I'm in my 50s now. As long as the device tells me what I wanna know and is accurate, I won't argue much over what it's called, be it SEA or ALT or whatever. As long as it's in InHG and accurate, that's my main concern.
When I was 6 years old my mom bought a barometer (with green stamps, remember those?).
https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcQp4XBHNjWloJUsSb0Tvgxwy4DgonJ9ceJtNBMRzHIbAry25rf8&usqp=CAU

Offline openvista

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Re: Which barometer would you get and why...
« Reply #41 on: May 18, 2020, 07:03:09 AM »
Fine and dandy. If I were to pay this much for a barometer, I'll be damned if I wouldn't want to know exactly what reduction it's using. Even my "lowly" Vue console (which it is in comparison) gives me the satisfaction of that. :roll:

Just in case anyone other than you insists on assuming, despite all the facts and context, that "SEA" must equal "SLP"... once again it's clearly stated in the manual on page 14 which pressure reduction is being used and even gives the formula. 
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Offline CW2274

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Re: Which barometer would you get and why...
« Reply #42 on: May 18, 2020, 04:10:11 PM »
Fine and dandy. If I were to pay this much for a barometer, I'll be damned if I wouldn't want to know exactly what reduction it's using. Even my "lowly" Vue console (which it is in comparison) gives me the satisfaction of that. :roll:

Just in case anyone other than you insists on assuming, despite all the facts and context, that "SEA" must equal "SLP"... once again it's clearly stated in the manual on page 14 which pressure reduction is being used and even gives the formula.
And that's all I'm trying to do...get the facts straight. I didn't see that manual til now, so they do indeed use the altimeter setting, but call SLP. AFAIC that's incorrect nomenclature, but at least ya know what ya got.

https://www.weather.gov/media/epz/wxcalc/altimeterSetting.pdf

 

anything