Ultrasonic flying spot scanner NBTV

Forum for discussion of narrow-bandwidth mechanical television

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Postby Harry Dalek » Tue Sep 03, 2013 10:10 pm

Just been looking at a Spectrum Analyser of the i phone crystal mic frequency sweep test from last night .

You may be able to see something i can't but what i see the mic and speaker must be doing about 10khz trying then to understand what the problem would still be on the nbtv side of things...i do see the decibels vary as the sweep gos higher perhaps this is more the problem ? at different points ..not sure why there is a gap at the 7khz range perhaps mic movement via me .

BTW on the transducers the bandwidth is 5khz minimum ..... its 1 khz either way for a 40 khz they resonate at so the 3 khz for sstv makes sense now.
Attachments
1 00003.jpg
1 00003.jpg (170.02 KiB) Viewed 5406 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Wed Sep 04, 2013 5:37 pm

Heres a look at Gary clean sweeps what i see is no loss in decibels .....well it isn't being transmitted so thats the best case closed system i suppose .

I just had a quick look at my sweep via the transducers from the other day with the short nbtv signal at the end ...theres a decibel loss for sure but there is a signal week to 10khz they seem to be happy at a 4khz bandwidth with a strong signal .......looking at the NBTV at the end you can see the signal getting to 5 or 6 khz at times and any thing higher looks weak ..

I am finding this a good tool to use power sound editor if any one has an interest its free which is good !
Attachments
1 00004.jpg
Garys to 13khz nbtv sweep
1 00004.jpg (100.04 KiB) Viewed 5395 times
1 00005.jpg
Garys 1 hz to 10 khz sweep
1 00005.jpg (130.61 KiB) Viewed 5395 times
1 00006.jpg
Heres the ultrasonic transmitter and receiver test from the other day
1 00006.jpg (233.56 KiB) Viewed 5395 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Wed Sep 04, 2013 9:14 pm

I found the power sound editor software does filters of different types .
This shows me in the best case what happens when you lower the bandwidth and what to expect interesting and helpful for me .

I used a low pass filter

I stopped at 4khz as we know what going to happen .

I used a simple test card but sort of works below 10khz ?
Attachments
1 00010.jpg
1 khz bandwidth NBTV letters ...not much on 1khz
1 00010.jpg (16.34 KiB) Viewed 5387 times
1 00009.jpg
2khz bandwidth start to make out letters
1 00009.jpg (25.82 KiB) Viewed 5387 times
1 00008.jpg
3khz bandwidth there it is little ruff
1 00008.jpg (26.15 KiB) Viewed 5387 times
1 00011.jpg
4khz bandwidth
1 00011.jpg (25.98 KiB) Viewed 5387 times
1 00013.jpg
3khz
1 00013.jpg (31.28 KiB) Viewed 5384 times
1 00015.jpg
10khz
1 00015.jpg (34.85 KiB) Viewed 5384 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Thu Sep 05, 2013 12:43 pm

I have been looking at the iphones bandwidth today looking at nbtv wavs direct to laptop seems a bit fussy need a tighter adjustments to just playing the wav from laptop direct even adjusting every thing ...
I was thinking the iphone audio might have a lower bandwidth but looks fine ...might be something to do with the laptops input and its sample rate is set for this 2 channel 16 bit 48000hz dvd quality ....

I am going to try next time willing just the transducer receiver and iphone speaker and try what i have handy to play back to airwaves other than the iphone speaker then i am just testing one transducer ...i know it will not have the correct bandwidth but i would like to see what it can do ..you don't try you never know ..
Attachments
1 00016.jpg
results i get with direct cable iphone to laptop
1 00016.jpg (29.2 KiB) Viewed 5363 times
1 00017.jpg
Seems to have the bandwidth
1 00017.jpg (171.62 KiB) Viewed 5363 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Thu Sep 05, 2013 6:43 pm

I got first ever results from a speaker and a 1960s reel to reel tape mic i had no electronics between them just testing microphones.....

Still not great but theres enough band width to display something better than i have ever got ....gives me hope to try more .

I displayed on big picture V2 alpha ...i uses windows 7 i find i have to load a good nbtv wav file before i can display load wavs that are a bit off no idea why must be a windows 7 thing.

Heres the original and the iphone mic transmitting wav.
Attachments
NBTV card7-48000-NBTVA-p-II.wav
Paris Eiffel Tower original wav file
(1.06 MiB) Downloaded 222 times
micspeaker3.wav
This is a 60s mic very close to the iphone speaker wav poor but its there
(1.26 MiB) Downloaded 210 times
1 00021.jpg
original
1 00021.jpg (22.24 KiB) Viewed 5349 times
1 00022.jpg
poor but there
1 00022.jpg (17.05 KiB) Viewed 5349 times
Last edited by Harry Dalek on Thu Sep 05, 2013 7:02 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby gary » Thu Sep 05, 2013 7:01 pm

Harry, If you have a NBTV wave file that is difficult to play, turn sync processing off - bad syncs are the main cause of display problems. With PC generated NBTV wave files there really is no reason to use syncs at all, although if you are coming off tape there probably would be some wow and flutter introduced and syncs definitely help in that case - none-the-less turning sync processing is definitely a good "debugging" tool as you will always get some sort of picture if there is one - and you can then normally see where the problems are.

BTW, and this is quite important, whenever recording NBTV *ALWAYS* use 48kHz or an integer multiple (like 24 or even 32). Using 44.1kHz or a multiple of that will always introduce some level of drift because the sound card has to do a sample rate conversion - and the standard implementation of that in a sound card is not that accurate (clock wise) and generally introduces some drift which is not noticeable in audio files but is significant in video.
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Thu Sep 05, 2013 7:12 pm

hi gary just a quick one have to go out it was not a reel to reel recording but iphone wav to speaker to mic to laptop.

old reel to reel mic used .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby gary » Thu Sep 05, 2013 7:17 pm

No worries Harry, I just mentioned that in case that was something you were considering doing. It has no significance in what I was saying.
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Thu Sep 05, 2013 9:56 pm

gary wrote:Harry, If you have a NBTV wave file that is difficult to play, turn sync processing off - bad syncs are the main cause of display problems. With PC generated NBTV wave files there really is no reason to use syncs at all, although if you are coming off tape there probably would be some wow and flutter introduced and syncs definitely help in that case - none-the-less turning sync processing is definitely a good "debugging" tool as you will always get some sort of picture if there is one - and you can then normally see where the problems are.


With the first Big picture it runs pretty well on my windows 7 just the Alpha version does do what you say need to turn off the sync on these poorer NBTV wavs ..i just have this other problem where just loading you get an error message but if i load a good wav file it likes then do a new load of the file that gave me the error message it then works ..one of those things no problems it still works ....i like the Alpha version with the framing controls.

BTW, and this is quite important, whenever recording NBTV *ALWAYS* use 48kHz or an integer multiple (like 24 or even 32). Using 44.1kHz or a multiple of that will always introduce some level of drift because the sound card has to do a sample rate conversion - and the standard implementation of that in a sound card is not that accurate (clock wise) and generally introduces some drift which is not noticeable in audio files but is significant in video.


This i am going to have to come back to for advice thats good advice on the recording side ..
I think power sound editor when you do a recording it starts as that 44`but i saved it on some thing half that ....so i have stuffed up there !
I will look into this next time i try it ...
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby gary » Thu Sep 05, 2013 10:23 pm

just loading you get an error message


What is the error message?

There is a bug in that version that requires you to load a valid NBTV file prior to loading something that isn't standard.
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Thu Sep 05, 2013 10:53 pm

What is the error message?


Format not supported comes up

There is a bug in that version that requires you to load a valid NBTV file prior to loading something that isn't standard.


Yes that i find works .....i use both big screens and even the first little viewer at times to.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby gary » Thu Sep 05, 2013 10:56 pm

Well I think it is a problem only for the pre-release version - but anyway - just load a normal wave file first and you should then be OK
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Postby Harry Dalek » Fri Sep 06, 2013 7:15 pm

gary wrote:Well I think it is a problem only for the pre-release version - but anyway - just load a normal wave file first and you should then be OK


I was using it today to frame these files before screen grabbing them...so for me works fine .

I tried today a different 60s reel to reel mic seems better than the last i am fairly close to the speaker for this to all work so i would like to get a little distance .
Attachments
1 00023.jpg
test card girl via new 60s mic
1 00023.jpg (22.45 KiB) Viewed 5286 times
1 00027.jpg
1 00027.jpg (20.94 KiB) Viewed 5286 times
1 00033.jpg
1 00033.jpg (20.86 KiB) Viewed 5286 times
popeye2.wav
Heres the mic to iphone speaker Popeye and woody woodpecker
(4.43 MiB) Downloaded 207 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Sun Sep 08, 2013 12:09 am

I tried a second 60's mic as the iphone speaker today it seems to have more bandwidth but of cause volume gos down ...which i think my wife and kids are happy about :lol:
Attachments
1 00034.jpg
bit better
1 00034.jpg (11.15 KiB) Viewed 5259 times
micmicnbtv.JPG
heres a shot of the old microphones setup live working
micmicnbtv.JPG (287.66 KiB) Viewed 5259 times
jlb.JPG
JLB
jlb.JPG (280.03 KiB) Viewed 5259 times
micmic.wav
wav of the mic to mic
(886.16 KiB) Downloaded 221 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Fri Sep 13, 2013 6:37 pm

Better get back to ultrasonic idea ,i sort of understand the problems of air transmitting NBTV now ...

So i would like to see how hard it is to try and make a some sort of ultrasonic image with mechanical scanning ..see if its possible or not least with my poor skills see what the best i can do.

Since its AM i can stick with the electronics and transducers made so far ...and use a flying spot scanning idea .

If i can get it to work big if ! i would expect no more than some sort of shape perhaps .

As Gary pointed out no 2d there so needs to be a 3d thing 3d letter or easy shape to make out .

I will give it a go ...and i have sort of worked out what i would like the scanner to work like ...using a H and V scanning idea .

The size of the polygon and square more so i am thinking the square might be to small as i think the ultrasound scanning line will be pretty thick but i will see what happens with the idea for now ..

There are mirrors on the polygon line motor for this dual transmitter receiver idea ...i need to see whats happening and doing away with syncing problems using the same motors as the ultrasound camera ....the square one is the rotating screen i might have to put mirrors on this as well as the modulated laser light can get pretty dim at high speeds..but rather not depends on what i have left in my laser junk box !
Attachments
P1050735.JPG
P1050735.JPG (314.29 KiB) Viewed 5204 times
P1050739.JPG
P1050739.JPG (318.19 KiB) Viewed 5204 times
P1050741.JPG
P1050741.JPG (307.56 KiB) Viewed 5204 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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