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I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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No, but they are often powered with a switching power supple which is.
73 Kent WA5VJB/G8EMY
On Saturday, January 23, 2021, 01:27:16 PM CST, G8ZHA via groups.io <g8zha-1@...> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Andy G4JNT
Which ".... can be ..." not "... is ..."
On Sat, 23 Jan 2021 at 19:41, KENT BRITAIN < WA5VJB@...> wrote:
No, but they are often powered with a switching power supple which is.
73 Kent WA5VJB/G8EMY
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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No, but they are often powered with a switching power supply which is.
73 Kent WA5VJB/G8EMY
On Saturday, January 23, 2021, 01:27:16 PM CST, G8ZHA via groups.io <g8zha-1@...> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Well, I hope he is powering his PGA-103 with a linear PSU. Kent
On Saturday, January 23, 2021, 01:43:39 PM CST, Andy G4JNT <andy.g4jnt@...> wrote:
Which ".... can be ..." not "... is ..."
On Sat, 23 Jan 2021 at 19:41, KENT BRITAIN < WA5VJB@...> wrote:
No, but they are often powered with a switching power supple which is.
73 Kent WA5VJB/G8EMY
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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The 12V to 5V is a 7805 linear reg, but the 12V is probably via a SMPS. I will make sure I have some filtering on the 12V input at the preamp. Rich
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of KENT BRITAIN
Sent: 23 January 2021 19:47
To: UK Microwaves groups.io; UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Are LEDs a noise source Well, I hope he is powering his PGA-103 with a linear PSU. On Saturday, January 23, 2021, 01:43:39 PM CST, Andy G4JNT <andy.g4jnt@...> wrote: Which ".... can be ..." not "... is ..." On Sat, 23 Jan 2021 at 19:41, KENT BRITAIN <WA5VJB@...> wrote: No, but they are often powered with a switching power supple which is. I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
On 23 January 2021 at 19:27 "G8ZHA via groups.io" <g8zha-1@...> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Andy G4JNT
LEDs do not generate noise. Being forward-biassed, there is no noise generation mechanism. Gordon. you are referring to regulators, aren't you. They suffer from instability if not decou[led.
Specs call-up minimum of 0.22uf on the output and a few uF on the input if more than a few cm away from the supply. The Question was about LEDs
Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
On 23 January 2021 at 19:27 "G8ZHA via groups.io" <g8zha-1=blueyonder.co.uk@groups.io> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Well , I am sure that I have seen some noise generation circuits , using the 'normal , Zener diode ' .... and Led .
The normal operating voltage of an Led is a , depending on the colour , is nominall 2.7 Volts , meaning , that similar to a Zener diode , , it works on an avalance breakdown principle ............ to produce photons ..... so , the Led , regardless of colour , should be decoupled , as should , a Zener .............
Three terminal voltage regulators , a minimum caoacitance ( National Semiconductors ) of 0.68uF , each side .
Thus endeth the 2021 lasson from the old git .
HNY !
On 23 January 2021 at 20:35 Andy G4JNT <andy.g4jnt@...> wrote:
LEDs do not generate noise. Being forward-biassed, there is no noise generation mechanism. Gordon. you are referring to regulators, aren't you. They suffer from instability if not decou[led.
Specs call-up minimum of 0.22uf on the output and a few uF on the input if more than a few cm away from the supply. The Question was about LEDs
Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
On 23 January 2021 at 19:27 "G8ZHA via groups.io" <g8zha-1= blueyonder.co.uk@groups.io> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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Andy G4JNT
NO ! An LED is a Forward Biassed junction. The reason for the higher forward voltage is the higher band-gap required for shorter wavelength generation
If you don't believe it, look at the reverse characteristic - a reverse biased LED is just like any other reverse biased diode. You mention a Zener in your text They are noise generators par-excelence! As is any junction in REVERSE breakdown
Well , I am sure that I have seen some noise generation circuits , using the 'normal , Zener diode ' .... and Led .
The normal operating voltage of an Led is a , depending on the colour , is nominall 2.7 Volts , meaning , that similar to a Zener diode , , it works on an avalance breakdown principle ............ to produce photons ..... so , the Led , regardless of colour , should be decoupled , as should , a Zener .............
Three terminal voltage regulators , a minimum caoacitance ( National Semiconductors ) of 0.68uF , each side .
Thus endeth the 2021 lasson from the old git .
HNY !
On 23 January 2021 at 20:35 Andy G4JNT <andy.g4jnt@...> wrote:
LEDs do not generate noise. Being forward-biassed, there is no noise generation mechanism. Gordon. you are referring to regulators, aren't you. They suffer from instability if not decou[led.
Specs call-up minimum of 0.22uf on the output and a few uF on the input if more than a few cm away from the supply. The Question was about LEDs
Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
On 23 January 2021 at 19:27 "G8ZHA via groups.io" <g8zha-1= blueyonder.co.uk@groups.io> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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On a DMM , Diode range , a Led will read a nominal 650mV , in forwards tch! There must ne someone in the group who will test one using a noise meter >>>>>>>>>>>> or this saga will cause some exsasperations .............. andnow , I'm having another ale ............... a quiet one .........
On 23 January 2021 at 21:59 Andy G4JNT <andy.g4jnt@...> wrote:
NO ! An LED is a Forward Biassed junction. The reason for the higher forward voltage is the higher band-gap required for shorter wavelength generation
If you don't believe it, look at the reverse characteristic - a reverse biased LED is just like any other reverse biased diode. You mention a Zener in your text They are noise generators par-excelence! As is any junction in REVERSE breakdown
Well , I am sure that I have seen some noise generation circuits , using the 'normal , Zener diode ' .... and Led .
The normal operating voltage of an Led is a , depending on the colour , is nominall 2.7 Volts , meaning , that similar to a Zener diode , , it works on an avalance breakdown principle ............ to produce photons ..... so , the Led , regardless of colour , should be decoupled , as should , a Zener .............
Three terminal voltage regulators , a minimum caoacitance ( National Semiconductors ) of 0.68uF , each side .
Thus endeth the 2021 lasson from the old git .
HNY !
On 23 January 2021 at 20:35 Andy G4JNT < andy.g4jnt@...> wrote:
LEDs do not generate noise. Being forward-biassed, there is no noise generation mechanism. Gordon. you are referring to regulators, aren't you. They suffer from instability if not decou[led.
Specs call-up minimum of 0.22uf on the output and a few uF on the input if more than a few cm away from the supply. The Question was about LEDs
Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
On 23 January 2021 at 19:27 "G8ZHA via groups.io" <g8zha-1= blueyonder.co.uk@groups.io> wrote:
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on 1090MHz. The preamp will be mounted up on a pole, directly underneath a PCB antenna, in a plastic tube. I feed 12V up to the preamp and have 5V regulator next to the preamp. I usually include a LED on the 5V shining down at the ground, so I can confirm that the preamp is powered. Do LEDs generate any noise? Rich G8ZHA
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"Do LEDs generate any noise? "
I'd never thought about this, but as the Ultra-Bright LEDs do strobe the element to get the high brightness, it's be surprising if they weren't noisy.
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Brian Howie GM4DIJ
In message <003301d6f1bd$c136b7f0$43a427d0$@co.uk>, G8ZHA via groups.io <g8zha-1=blueyonder.co.uk@groups.io> writes
I have just built a G4DDK PGA-103 preamp to use for ADSB receive on
1090MHz. The preamp will be mounted up on a pole, directly underneath a
PCB antenna, in a plastic tube. I feed 12V up to the preamp and have
5V regulator next to the preamp. I usually include a LED on the 5V
shining down at the ground, so I can confirm that the preamp is
powered.
Do LEDs generate any noise?
Only shot noise due to the forward current . I recall a noise generator using an LED but can't find it . There's one here, but not the one I remember. http://www.n5ese.com/noise.htmThis one uses an LED illuminating a photodiode. Https://electronicprojectsforfun.wordpress.com/making-noise/noise-sources -i-have-built/a-led-photodiode-noise-source/ I'm surprised by the size of the 1/f component though. Sorry, I've gone off at a tangent. Brian GM4DIJ -- Brian Howie
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It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
toggle quoted messageShow quoted text
-------Original Message-------
From: Andy G4JNT <andy.g4jnt@gmail.com>
To: UK Microwaves groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Are LEDs a noise source
Sent: Jan 23 '21 20:36
LEDs do not generate noise. Being forward-biassed, there is no noise
generation mechanism.
Gordon. you are referring to regulators, aren't you. They suffer from
instability if not decou[led.
Specs call-up minimum of 0.22uf on the output and a few uF on the
input if more than a few cm away from the supply.
The Question was about LEDs
Andy
www.g4jnt.com
On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
<gordonj.reason=virgin.net@groups.io> wrote:
> Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>
>> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>>
>> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>> on 1090MHz. The preamp will be mounted up on a pole, directly
>> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>> preamp and have 5V regulator next to the preamp. I usually include
>> a LED on the 5V shining down at the ground, so I can confirm that
>> the preamp is powered.
>>
>> Do LEDs generate any noise?
>>
>> Rich G8ZHA
>
>>
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Andy G4JNT
toggle quoted messageShow quoted text
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
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Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
--
Robin Szemeti - G1YFG
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-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?) I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used . Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .
It's Bloody clever stuf .
73 John G0API
On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG < robin@...> wrote: Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
--
Robin Szemeti - G1YFG
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Andy G4JNT
No, It WAS done yonks ago in Oz, using WSPR just after it first came out
They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.
I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics. It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?) I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used . Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .
It's Bloody clever stuf .
73 John G0API
On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG < robin@...> wrote: Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
--
Robin Szemeti - G1YFG
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Yes , I know it was done Yonks ago , but the new software was mentioned in the last issue of the EME Newsletter as one of the "other" uses used to test the software system before general release - using more modest light sources . I saw a video on TV (Winterwatch) showing a man flushing Starlings out of Italian Trees to prevent Poomagedon .Looked like a solid torch but emitting narrow beamwidth Laser light ? Now a bit of websearching and modulation interfacing it could be possible to do some handheld OTH comms ....
John
No, It WAS done yonks ago in Oz, using WSPR just after it first came out
They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.
I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics. It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?) I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used . Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .
It's Bloody clever stuf .
73 John G0API
On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG < robin@...> wrote: Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
--
Robin Szemeti - G1YFG
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I was also done along the Gulf of Mexico in the 1970's using Xenon flash tubes and light intensifiers. No digital processing and got 300 km on clear nights. Sea level to sea level, just scatter. Certainly another 30 or 40 dB more power in the sources. Be sure to have deep 100 Hz and/or 120 Hz filters. Hard to think of a common incandescent light bulb as a frequency doubler, but they do respond to both peaks in a sine wave. I have 6 systems we used several times during VHF/UHF contests. We used the Lasers out of CD players. IR and power adjustable. The best detectors were made by Texas Instruments for Laser guided bombs, but a panel of solar cells also worked well. LOTS of capture area.
Kent
On Sunday, January 24, 2021, 10:25:33 AM CST, Andy G4JNT <andy.g4jnt@...> wrote:
No, It WAS done yonks ago in Oz, using WSPR just after it first came out
They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.
I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics. It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?) I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used . Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .
It's Bloody clever stuf .
73 John G0API
On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG < robin@...> wrote: Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N
On Sun, 24 Jan 2021 at 14:34, John E. Beech < john@...> wrote: It could be argued that LEDs produce noise at nanometer wavelengths.
de John G8SEQ
> -------Original Message-------
> From: Andy G4JNT <andy.g4jnt@...>
> To: UK Microwaves groups.io <UKMicrowaves@groups.io>
> Subject: Re: [UKMicrowaves] Are LEDs a noise source
> Sent: Jan 23 '21 20:36
>
> LEDs do not generate noise. Being forward-biassed, there is no noise
> generation mechanism.
> Gordon. you are referring to regulators, aren't you. They suffer from
> instability if not decou[led.
>
> Specs call-up minimum of 0.22uf on the output and a few uF on the
> input if more than a few cm away from the supply.
> The Question was about LEDs
>
> Andy
> www.g4jnt.com
>
> On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
> <gordonj.reason=virgin.net@groups.io> wrote:
>
> > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
> >
> >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
> >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
> >>
> >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
> >> on 1090MHz. The preamp will be mounted up on a pole, directly
> >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
> >> preamp and have 5V regulator next to the preamp. I usually include
> >> a LED on the 5V shining down at the ground, so I can confirm that
> >> the preamp is powered.
> >>
> >> Do LEDs generate any noise?
> >>
> >> Rich G8ZHA
> >
> >>
>
>
--
Robin Szemeti - G1YFG
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