List of meters that meet the MIL-STD

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[ARCHIVED THREAD] - List of meters that meet the MIL-STD

Posted: 5/19/2018 5:13:47 PM EDT

Below is the list of meters that meet the MILSTD 1474D.

- B&K 2209
- B&K Pulse
- Larson 800B
- Roin NA-42 *Sampling frequency 250 kHz*

- National Instruments
- Adlink USB-2405
- RogaDAQ 4
- Measurement Computing DT9837 Series

Posted: 5/19/2018 5:14:33 PM EDT

[#1]

Quoted:
Below is the list of meters that meet the MILSTD 1474D.

- B&K 2209
- B&K Pulse
- Larson 800B
- Roin NA-42 *Sampling frequency 250 kHz*

- National Instruments
- Adlink USB-2405
- RogaDAQ 4
- Measurement Computing DT9837 Series

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That's an interesting first post...

Posted: 5/19/2018 7:39:28 PM EDT

[#2]

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Quoted:
That's an interesting first post...

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Quoted:

Quoted:
Below is the list of meters that meet the MILSTD 1474D.

- B&K 2209
- B&K Pulse
- Larson 800B
- Roin NA-42 *Sampling frequency 250 kHz*

- National Instruments
- Adlink USB-2405
- RogaDAQ 4
- Measurement Computing DT9837 Series

That's an interesting first post...

Indeed.

What are the specs on the Larson 800B?

National Instruments has like a million DAQ boards - which ones in particular meet the standard?

For kicks, which ones meet MIL STD 1474E?

Posted: 5/19/2018 11:33:02 PM EDT

[#3]

Even better, how about amending it with pricing and availability info?

Posted: 5/20/2018 2:11:07 AM EDT

[#4]

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Quoted:

Indeed.

What are the specs on the Larson 800B?

National Instruments has like a million DAQ boards - which ones in particular meet the standard?

For kicks, which ones meet MIL STD 1474E?

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Quoted:

Indeed.

What are the specs on the Larson 800B?

National Instruments has like a million DAQ boards - which ones in particular meet the standard?

For kicks, which ones meet MIL STD 1474E?

According to http://www.arl.army.mil/www/pages/343/MIL-STD-1474E-Final-15Apr2015.pdf analog meters like the B&K 2209 and Larson Davis 800B would need to be able to do the following:

The measurements shall be made with a sound level meter capable of making peak sound pressure level measurements with the total rise time of the instrumentation not exceeding 200 microseconds (µs). The rise time of the peak detector shall be such that a single pulse of 200 µs duration produces a meter indication within 2 dB of the indication produced by a pulse having a duration of 10 µs and equal peak amplitude. The amplitude of the 10 µs reference pulse shall be such as to produce a meter deflection 1 dB below full scale.

From what I've seen, an unsuppressed LMT MWS .308's shot rise time is about 11 microseconds.

Digital recording systems for impulsive noise must have a sampling rate of at least 192khz and 16-bit resolution. This applies to analog to digital DAQ systems like Pulse, NI, etc:

Equipment for capturing and storing impulsive noise shall have a minimum of 16-bit resolution, with 24-bit resolution preferred, and a sampling rate of a minimum of 192,000 samples per second. The analog signal shall be filtered, using a Bessel type with a 40-kHz cutoff frequency. The roll-off rate shall be not less than 36 dB/octave.

Adlink USB-2405 and MC DT9837 do not have high enough sampling rates. NI has a few modules that can do 200khz or better at 16-bit resolution.
Also, impulsive noise measurements should include unweighted measurements (in addition to A and C weighted):

Peak unweighted sound pressure levels (dBP) shall be determined for any impulsive noise source.

Posted: 5/20/2018 4:33:08 PM EDT

[#5]

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Quoted:
Even better, how about amending it with pricing and availability info?

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DT9847: 24-bit, 216 kHz price $2,305
Roin NA-42: 24-bit, 250 kHz price $6000
NI USB-4431: 24-Bit, 105 kHz price $3000
RogaDAQ4: 24-bit, 192 kHz price $6000

Posted: 5/20/2018 6:39:47 PM EDT

[#6]

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DT9847: 24-bit, 216 kHz price $2,305

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This looks interesting. Does anyone have first hand knowledge of this one for sound testing?
I would definitely like to step up to a digital system without dropping 30k.
Thanks for posting, 77.

Posted: 5/21/2018 4:38:43 PM EDT

[#7]

What mic would meet this spec with a NI DAQ system? We have used mics from PCB Piezotronics for similar testing but found that capacitance limits the rise time such that the results do not meet MIL specifications. Our B&K 2209 is the gold standard.

NI DAQ does work well for frequency analysis acquisition. We have use very flat response Earthworks mics to acquire data for subsequent FFT analysis. I think there is often too much singular focus on peak amplitude (dB) rather than 'tone' which is the frequency response of the silencer. Ultimately silencers are a filter network and each silencer will attenuate the components of the broad band impulsive noise differently. Tone is hard to quantify & communicate but definitely matters to shooters.

Posted: 5/21/2018 5:12:40 PM EDT

[#8]

SilencerCo used NI USB-4432 102.4 kS/s,
Mic used: G.R.A.S 1/4" Type 40BD-Prepolarised

https://youtu.be/ZpOUjzawar4

Posted: 5/21/2018 9:20:38 PM EDT

[#9]

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Quoted:
What mic would meet this spec with a NI DAQ system? We have used mics from PCB Piezotronics for similar testing but found that capacitance limits the rise time such that the results do not meet MIL specifications. Our B&K 2209 is the gold standard.

NI DAQ does work well for frequency analysis acquisition. We have use very flat response Earthworks mics to acquire data for subsequent FFT analysis. I think there is often too much singular focus on peak amplitude (dB) rather than 'tone' which is the frequency response of the silencer. Ultimately silencers are a filter network and each silencer will attenuate the components of the broad band impulsive noise differently. Tone is hard to quantify & communicate but definitely matters to shooters.

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I've rented a 1/4" PCB mic/preamp combo (378A12) and it worked out fine recording the MWS unsuppressed (and suppressed). I was able to capture voltage changes down to 4-5 microseconds. I ended up buying a G.R.A.S. 46BG, mainly for better (eventual) resale value.

Tone can be done with db bar graphs of 1/3 octaves.

For even more "cred", look into perceived loudness, if you can afford it, look into software that can spit out "sones":
https://community.plm.automation.siemens.com/t5/Testing-Knowledge-Base/Sound-Quality-Metrics-Loudness-and-Sones/ta-p/423283

Posted: 5/21/2018 9:31:31 PM EDT

[#10]

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Quoted:
What mic would meet this spec with a NI DAQ system? We have used mics from PCB Piezotronics for similar testing but found that capacitance limits the rise time such that the results do not meet MIL specifications. Our B&K 2209 is the gold standard.

NI DAQ does work well for frequency analysis acquisition. We have use very flat response Earthworks mics to acquire data for subsequent FFT analysis. I think there is often too much singular focus on peak amplitude (dB) rather than 'tone' which is the frequency response of the silencer. Ultimately silencers are a filter network and each silencer will attenuate the components of the broad band impulsive noise differently. Tone is hard to quantify & communicate but definitely matters to shooters.

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Now you're talking. It would be interested to see a temporal plot across the frequency spectrum as well to see if particular frequencies are constant or oscillating and at what time points they express themselves / decay.

Of course this is all interesting to geeks, but in the end, does it sell any more suppressors for the time and money invested in getting the data?

Posted: 5/22/2018 12:50:20 PM EDT

[#11]

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Quoted:

Now you're talking. It would be interested to see a temporal plot across the frequency spectrum as well to see if particular frequencies are constant or oscillating and at what time points they express themselves / decay.

Of course this is all interesting to geeks, but in the end, does it sell any more suppressors for the time and money invested in getting the data?

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Yes, it would sell more suppressors. No doubt there would be net ROI given how little good information is out there as of now. The fact that the vast majority suppressor manufacturers and especially retailers don't realize this is stunning.

Posted: 5/22/2018 3:42:00 PM EDT

[#12]

I think Roin NA-42 is the best choice
Frequency range: 1 Hz to 100 kHz
Sampling frequency 250 kHz

NA-42 INSTRUCTION MANUAL

Posted: 5/22/2018 6:32:05 PM EDT

[#13]

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Quoted:

Now you're talking. It would be interested to see a temporal plot across the frequency spectrum as well to see if particular frequencies are constant or oscillating and at what time points they express themselves / decay.

Of course this is all interesting to geeks, but in the end, does it sell any more suppressors for the time and money invested in getting the data?

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Quoted:

Now you're talking. It would be interested to see a temporal plot across the frequency spectrum as well to see if particular frequencies are constant or oscillating and at what time points they express themselves / decay.

Of course this is all interesting to geeks, but in the end, does it sell any more suppressors for the time and money invested in getting the data?

It will enable manufacturers to build better suppressors and that is what is interesting to this geek. More data allows more feedback on the product manufactured and the ability to optimize the product for different solutions.

Quoted:
I think Roin NA-42 is the best choice
Frequency range: 1 Hz to 100 kHz
Sampling frequency 250 kHz

Only one input that I can see. I want two for simultaneous muzzle and ear readings. Also the mic combos seem to limit max db to 164 which will barely work for unsuppressed 556. http://www.enviroegt.com/pdf/14092015013934NA-42%20Measuring%20Amplifier.pdf

Still researching the others.

Posted: 5/22/2018 7:01:14 PM EDT

[#14]

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Quoted:

Only one input that I can see. I want two for simultaneous muzzle and ear readings. Also the mic combos seem to limit max db to 164 which will barely work for unsuppressed 556. http://www.enviroegt.com/pdf/14092015013934NA-42%20Measuring%20Amplifier.pdf

Still researching the others.

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Level range up to 180 DB,Depending on the microphone sensitive .

Posted: 5/22/2018 7:12:48 PM EDT

[#15]

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Quoted:

Level range up to 180 DB,Depending on the microphone sensitive .

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Guess my sped readen skilz ain't what they used to be! 180 is good enough. I have an email in to them for the two input option. Due to time differences I should hear by tomorrow.

Posted: 5/23/2018 9:00:27 PM EDT

[#16]

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Quoted:
I think Roin NA-42 is the best choice
Frequency range: 1 Hz to 100 kHz
Sampling frequency 250 kHz

NA-42 INSTRUCTION MANUAL

http://www.enviroegt.com/galorg/14092015013934NA%2042.jpg

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I would really hesitate on this meter. I looked at the instruction manual. There appears to be 3 detectors: slow, fast, and impulse. While it says it will record peaks, there does not seem to be an actual peak detector. At best, the impulse detector has a response/rise time of 35 MILLIseconds, while for peaks, you need a rise/response time less than 20 MICROseconds. You need to query the manufacturer about the peak rise/response time.

I think it is going to read around 30 dB low. See if you can get a demo with firearms. At 1 meter left of the muzzle with A or C weighting, an M4 carbine should be 164-165 dB, a Ruger 10/22 around 141, a Beretta M9 around 160-162, etc. Unweighted, look at about 5 dB higher.

You need a true peak detector if measuring firearms. A meter without a peak detector may be perfect for accurately measuring commoner sound levels, but not for really short duration peaks. One of the less expensive alternatives that is closer to being right is the Larson-Davis LxT1-QPR with a rise/response time of under 30 microseconds. With A or C weighting, it is close enough at 1-2 dB low (worse unweighted, but weighting is what the industry uses and MIL-STD 1474D permits).

Just my opinion, based on a number of mistakes I made many years ago.

Posted: 5/24/2018 7:07:57 AM EDT

[#17]

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Quoted:

I would really hesitate on this meter. I looked at the instruction manual. There appears to be 3 detectors: slow, fast, and impulse. While it says it will record peaks, there does not seem to be an actual peak detector. At best, the impulse detector has a response/rise time of 35 MILLIseconds, while for peaks, you need a rise/response time less than 20 MICROseconds. You need to query the manufacturer about the peak rise/response time.

I think it is going to read around 30 dB low. See if you can get a demo with firearms. At 1 meter left of the muzzle with A or C weighting, an M4 carbine should be 164-165 dB, a Ruger 10/22 around 141, a Beretta M9 around 160-162, etc. Unweighted, look at about 5 dB higher.

You need a true peak detector if measuring firearms. A meter without a peak detector may be perfect for accurately measuring commoner sound levels, but not for really short duration peaks. One of the less expensive alternatives that is closer to being right is the Larson-Davis LxT1-QPR with a rise/response time of under 30 microseconds. With A or C weighting, it is close enough at 1-2 dB low (worse unweighted, but weighting is what the industry uses and MIL-STD 1474D permits).

Just my opinion, based on a number of mistakes I made many years ago.

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Peak is no time weighting.

Therefore rise time is 0second.

Time weighting is made by LRC circuit.

Peak does not pass these circuit.

Peak detect wave form directly.

For clarification

For instance sample rate 48 kHz [20.8µs]

20.8µs is sampling frequency before root-mean-square.

Sound level meter takes in wave form every 20.8µs.

And Leq, Lmax, Lman, Lpeak are operated before they pass root-mean-square circuit.

Block diagram for a sound level meter

Time weighting and root mean square detection circuit

Posted: 5/24/2018 9:30:34 AM EDT

[#18]

@sas77 - Care to share any of your background pertaining to this topic? You seem to know alot more about the equipment than a casual suppressor enthusiast!