Broadcasting NBTV

Forum for discussion of narrow-bandwidth mechanical television

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Postby Harry Dalek » Sun Jul 28, 2013 5:06 pm

Does any one know what the bandwidth of the Short wave NBTV transmissions are normal AM or SSB ? am i right in saying it should be a wide band 40khz but do they narrow the band width to a normal 10khz am voice transmission?
Any speculation ?
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 DrZarkov » Sun Jul 28, 2013 5:30 pm

AM, but the amateur radiocannels are usually only 5 kHz wide. AM broadcast in Europe uses 9 kHz.
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Postby Harry Dalek » Sun Jul 28, 2013 5:49 pm

DrZarkov wrote:AM, but the amateur radiocannels are usually only 5 kHz wide. AM broadcast in Europe uses 9 kHz.


Thanks dr Z just was not sure so they are using SSB then as in voice and better DX.
Now NBTV should be 30 or 40 khz wide 5khz must mean a large loss a sacrifice resolution as in the amateur tv guys sort of doing the same with a 6 mhz normal video band width and as you see in this link getting it down to 300khz
http://www.ka7oei.com/r7ktvfilt.html

This is in the reciever dropping the IF ....i used to do it on my analog satellite tv reciever to dig the harder to get satellites out of the snow.

Wonder what the limits are to NBTV bandwidth wise .
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 » Sun Jul 28, 2013 5:50 pm

Depends on who is doing it - if Vic Brown it could very well be VSB
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Sun Jul 28, 2013 6:29 pm

gary wrote:Depends on who is doing it - if Vic Brown it could very well be VSB


I had to google that one Gary i am still living in the 70s 80s with radio and side band transmitting .

:roll: \\

I like analog and i know you could transmit any thing at a lowwer bandwidth at a slow speed in digital but i like real time or real space time my self .

I wasn't sure they could transmit it in a side band at 5khz thats pretty good to know .

I have been experimenting with using the sound card as a V L F radio receiver using one of my mechanical RF Alternators as a transmitter looks
promising hearing the carrier wave.
I see theres side bands to this transmitter perhaps if i can get it to modulate the carrier wave i might be able to transmit to a Garry Big Picture receiver ..
Just been putting the idea in a case for experiments .

Here by the way is a VLF Radio program to use your sound card as a radio suppose a head amp would be helpful i am just going to try an antenna where the mic would go seems to work on close range.
Attachments
saqrx06.zip
VLF radio
(25.57 KiB) Downloaded 213 times
SAQ_V09.zip
This one is very interesting been changed the last file exe example is a received signal for show so thats not live ..don't get excited
(1.75 MiB) Downloaded 205 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 gary » Sun Jul 28, 2013 6:39 pm

Sorry Harry, I should have made it clearer - Vic has documented his experiments in Vestigial Sideband in recent newsletters - I have also posted (somewhere) some results of those transmissions.

I have been working with him in developing pc based filters for same.
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Sun Jul 28, 2013 7:07 pm

gary wrote:Sorry Harry, I should have made it clearer - Vic has documented his experiments in Vestigial Sideband in recent newsletters - I have also posted (somewhere) some results of those transmissions.

I have been working with him in developing pc based filters for same.


OH i am still an out cast Gary i would of missed those i know what i am going to ask for a X mas gift Darn i forgot for the birthday :oops:

That sounds interesting its not a thing most of us have looked at good luck with the software sounds like another trip to your web site one day soon.

Heres my idea at the moment ,the first radio voice transmitter was using the same idea just with a carbon mic to modulate the carrier wave..and you can change frequency with adjusting the dc motor speed so it can be pretty basic.
Attachments
P1050567.JPG
mechanical Rf transmitter...i am working on casing
P1050567.JPG (389.89 KiB) Viewed 3176 times
P1050564.JPG
P1050564.JPG (335.44 KiB) Viewed 3176 times
Last edited by Harry Dalek on Sun Jul 28, 2013 11:48 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 Harry Dalek » Sun Jul 28, 2013 8:48 pm

Heres a link to a 2006 go at doing the Alternator transmitter ..
http://www.hammondmuseumofradio.org/fes ... ation.html
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 Aug 01, 2013 1:38 pm

I haven't got a carbon mic handy or found one so far but been testing with a magnetic one and crystal mic .

I wanted to start and see if i could get a microphone to work with the Alternator transmitter which is running at slow speed (using the pc power supply the high speed running on 24 volts...needed the Ground so 12volts half supply)

I should think Mr Fessenden in 1906 must of used a some sort of passive amplifier horn with hes mic ? as i would need one for sure with out electronic amplification .

The below Gif i am just blowing hard into my crystal mic hooked up to the RF Alternator seems to work at that very low frequency bandwidth no luck with hearing speech yet .

You can gets lots of Harmonics if you ground test one of the other stepper motor connections ....other wise you can get 2 or 3 larger frequencies.

Any one trying the same and or the flying spot scanner idea with a laptop you need to ground your plug .

Didn't know he transmitted voice in 1900 with a spark gap transmitter

http://www.ewh.ieee.org/reg/7/millenniu ... eless.html
Attachments
first test.gif
Blowing hard into a crystal mic
first test.gif (152.99 KiB) Viewed 3066 times
2.gif
lots of harmonics
2.gif (5.48 MiB) Viewed 3049 times
radio_telephone.jpg
This answers my Question...hes mic
radio_telephone.jpg (21.31 KiB) Viewed 3039 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 » Sat Aug 03, 2013 12:23 am

Well playing around today with amplification i used a radio to to retransmit in VLF...
The VLF radio programs i posted i have been testing perhaps has to low a bandwidth widest is 4 khz..its to narrow to hear any thing to clear but got it to transmit sound.

Something i was not expecting was i can transmit the RF vlf just with sending the Amplified audio via the little audio transformer one end grounded other to the antenna and again to the receiving antenna on the mic input of the laptop .. short distance test shows that works .

I am interested to see if i can get any nbtv transmitting just for the hell of it.

Heres a test today with using the radios amplifier .
Attachments
Untitled.avi
well got it to transmit my radio needed a quick amp handy saves me shouting into a mic
(2.33 MiB) Downloaded 199 times
P1050577.JPG
the modulating is done between one of stepper windings and antenna ,i have a audio transformer between the 2
P1050577.JPG (343.91 KiB) Viewed 3001 times
Screen 00000.jpg
This spark version is same sort of idea for the modulating
Screen 00000.jpg (68.14 KiB) Viewed 3001 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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