Date   

Re: Earths Doppler

Paul White
 
Edited

On Tue, Mar 2, 2021 at 12:59 AM, James Brown wrote:

This should be clear enough

Piss off

Educating stupid people can be fulfilling and productive.
Trying to educate rude, stupid people is boring and futile.


Winradio G39DDC

Simon Brown
 

So,

 

Dig out your G39DDCs, we’ll be testing later today. Listening to 80m DX as I type…

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Earths Doppler

oldjackbob@...
 

I just lost 3 minutes of my life reading this that I will never recoup.
You both owe me!


Re: Earths Doppler

 

This should be clear enough

Piss off

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Monday, March 1, 2021 14:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

mv James\ Brown /dev/null
He does not speak English with any rigor at all.

{^_^}

On 20210301 09:37:04, James Brown wrote:

Wikipedia has a pretty good description of the siren/ambulance effect
find ‘Sirens’

 

https://en.wikipedia.org/wiki/Doppler_effect

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of n2msqrp
Sent: Monday, March 1, 2021 08:43
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

We can test this by monitoring a low earth orbiting satellite.

 

Mike N2MS

On 03/01/2021 10:41 AM James Brown <jim@...> wrote:

 

 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 

 

 


Re: Earths Doppler

jdow
 

mv James\ Brown /dev/null
He does not speak English with any rigor at all.

{^_^}

On 20210301 09:37:04, James Brown wrote:

Wikipedia has a pretty good description of the siren/ambulance effect
find ‘Sirens’

 

https://en.wikipedia.org/wiki/Doppler_effect

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of n2msqrp
Sent: Monday, March 1, 2021 08:43
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

We can test this by monitoring a low earth orbiting satellite.

 

Mike N2MS

On 03/01/2021 10:41 AM James Brown <jim@...> wrote:

 

 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}

On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}

On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?




 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 

 



Re: Earths Doppler

jdow
 

You are NOT describing Doppler Shift. You are describing the change in Doppler Shift. Those are two different but intimately related quantities. Get that distinction in your head and you and I will violently agree. Otherwise you are Humptying the discussion with words meaning what you say they mean rather than what they mean to the rest of the world.

"When I use a word,' Humpty Dumpty said in rather a scornful tone, 'it means just what I choose it to mean — neither more nor less.'"  from Alice in Wonderland by Lewis Carroll.

{^_^}

On 20210301 07:41:35, James Brown wrote:

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 



Re: Earths Doppler

jdow
 

However, the derivative of the Doppler Shift in astronomy is "always" downward. (There may be times of the year when the derivative may do a dance to the negative as the Earth's rotation on its axis and its rotation around the Sun align "just right." I've not tried to work out such edge cases due to lack of motivation.)

{^_-}

On 20210301 06:14:49, Siegfried Jackstien wrote:
Ambulance towards you shifts up
Ambulance away from you shifts down
... In circles... Stays the same as long as the ambulance is not a supersonic jet
Dg9bfc sigi 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:
Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}



On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}



On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?






 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 





Re: Accessing Either Of Two Radios: How, Please ?

Tony_AD0VC
 

Running two radios at the same time can be done with "Identities". Start SDRC, open settings ("Gear" Icon upper right corner), select identities, enable and define as many as you wish, close, exit SDRC. Start SDRC you should get identities window. Select one to start. Start SDRC again (your desktop icon or start menu) and select a second identity to start.

Tony


From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of rmrrgs <rgsrose@...>
Sent: Monday, March 1, 2021 11:58 AM
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Accessing Either Of Two Radios: How, Please ?
 
Hi All,

First, a sincere thanks, as always, for the help.

Will have to try the running of both simultaneously as Kriss suggested.
Funny, but I was wondering if this was possible a while back.
Too embarrassed to ask, as it seemed next to impossible, I thought.

Will be fun trying it out.

Sure do wish the Airspy had more than a single ant. input.

Thanks again,
Bob


Re: Accessing Either Of Two Radios: How, Please ?

Kriss Kliegle KA1GJU
 

Bob,
Don't forget, you can always place a diplexer in there to separate HF antenna from your VHF/UHF antenna. I put the following inline here on Super Station #1 & #3 to give users more access to VHF/UHF listening, a Comet CF-360 Duplexer (yes, the name is duplexer).

They make another one with coax on the common and SO-239's on the low and high band pass ports:


Specs are the same for either one:

HF/6M – 440MHz Duplexer

                        Band Pass        Ins Loss           Max Power
Low Pass:    1.3-30MHz            0.2dB                  600W PEP
High Pass:   49-470MHz            0.2dB                  600W PEP

 

Isolation: 45dB minimum

Only issue is my antenna is in attic of house, near a Raspberry Pi computer operating as an ADSB server for FlightRadar24, damn thing makes a racket on upper bands. 
The Ethernet cable feeding it is already wrapped numerous times around a FT240-31 ferrite ring, so it's quiet on HF as far as Ethernet noise. The rest is from the Raspberry Pi
computer, since it's not in a grounded metal case.

You would just need to pick up some adapters to go from SMA to PL-259 or SO-239, depending upon which unit you buy:

https://www.amazon.com/DHT-Electronics-coaxial-cable-assembly/dp/B00CP11O3E/ref=sr_1_13?dchild=1&keywords=pl-259+to+SMA&qid=1614626038&sr=8-13

https://www.amazon.com/DHT-Electronics-coaxial-adapter-female/dp/B00CVQOOAI/ref=sr_1_4?dchild=1&keywords=SO-239+to+SMA&qid=1614626212&sr=8-4


Or get a mix bag and you'll have some for future growth on the antenna/SDR farm:
https://www.amazon.com/SMA-UHF-Connectors-Nickel-Plated-Converter/dp/B01MQNJVMT/ref=sr_1_3?dchild=1&keywords=pl-259+to+SMA&qid=1614626304&sr=8-3

When you are done, it will be like this:



73 Kriss KA1GJU
\


Re: SDR Console does not open Pluto

Jacques RAMBAUD
 

no success on a different port, same problem with a second Pluto. On the USB ports I can use other software if I want , looks like the USB ports are OK , the Pluto are OK .

It as been working for month

73 Jacques F6BKI



Le 01/03/2021 à 18:11, Simon Brown a écrit :

Try a different USB port.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jacques RAMBAUD
Sent: 01 March 2021 16:05
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] SDR Console does not open Pluto

 

Hello,

Was runing a Pluto with SDR Console without any problem and one day SDR Console start to freeze doing Select Radio , if used on an other PC the same Pluto is recognized doing Select Radio and working fine with SDR Console .

On the PC where it is not working I have re installed the Pluto Windows drivers , re installed SDR Console , no success . I can see the Pluto under C:  .

PC is an I5 runing W10.

any ideas ?

Tks

jacques F6BKI


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Accessing Either Of Two Radios: How, Please ?

rmrrgs
 

Hi All,

First, a sincere thanks, as always, for the help.

Will have to try the running of both simultaneously as Kriss suggested.
Funny, but I was wondering if this was possible a while back.
Too embarrassed to ask, as it seemed next to impossible, I thought.

Will be fun trying it out.

Sure do wish the Airspy had more than a single ant. input.

Thanks again,
Bob


Re: Earths Doppler

Re Claudio
 

Being the Universe globally in expansion the “red shift” is absolutely dominant respect to the “blue shift” .

Perhaps this is related to the question of James Brown ?

Nice SETI site James , my compliments .

73 Claudio Re I1RFQ  


Mail priva di virus. www.avast.com


Re: SDR Console does not open Pluto

Simon Brown
 

Try a different USB port.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jacques RAMBAUD
Sent: 01 March 2021 16:05
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] SDR Console does not open Pluto

 

Hello,

Was runing a Pluto with SDR Console without any problem and one day SDR Console start to freeze doing Select Radio , if used on an other PC the same Pluto is recognized doing Select Radio and working fine with SDR Console .

On the PC where it is not working I have re installed the Pluto Windows drivers , re installed SDR Console , no success . I can see the Pluto under C:  .

PC is an I5 runing W10.

any ideas ?

Tks

jacques F6BKI


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Re: Earths Doppler

Jeff Kelly
 

Just to add a thought.

Listening to the recent QSO Today Podcast with guest John Ackerman N8UR,
he mentions Time and Frequency measurement. (~41:00)
Ho touches on frequency stability of WWV and states that WWV
frequency over a few days will shift 1 hz due to doppler from atmospheric changes.
(crude paraphrase!)

Jeff
K2SDR

On Mar 1, 2021, at 11:42 AM, n2msqrp <mstangelo@...> wrote:

We can test this by monitoring a low earth orbiting satellite.
 
Mike N2MS
On 03/01/2021 10:41 AM James Brown <jim@...> wrote:
 
 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 
 
 
 
 
 


Re: Earths Doppler

 

Wikipedia has a pretty good description of the siren/ambulance effect
find ‘Sirens’

 

https://en.wikipedia.org/wiki/Doppler_effect

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of n2msqrp
Sent: Monday, March 1, 2021 08:43
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

We can test this by monitoring a low earth orbiting satellite.

 

Mike N2MS

On 03/01/2021 10:41 AM James Brown <jim@...> wrote:

 

 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}

On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}

On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?




 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 

 


Re: Earths Doppler

n2msqrp
 

We can test this by monitoring a low earth orbiting satellite.
 
Mike N2MS

On 03/01/2021 10:41 AM James Brown <jim@...> wrote:
 
 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 

 


SDR Console does not open Pluto

Jacques RAMBAUD
 

Hello,

Was runing a Pluto with SDR Console without any problem and one day SDR Console start to freeze doing Select Radio , if used on an other PC the same Pluto is recognized doing Select Radio and working fine with SDR Console .

On the PC where it is not working I have re installed the Pluto Windows drivers , re installed SDR Console , no success . I can see the Pluto under C:  .

PC is an I5 runing W10.

any ideas ?

Tks

jacques F6BKI


Re: Earths Doppler

Conrad, PA5Y
 

I am very active on EME and as the moon rises there is a positive doppler shift, at zenith there is no doppler and as the moon sets the doppler is negative. Is that relevant? I only skim read the thread but James if you are saying that doppler is always down that cannot be true.

73

Conrad PA5Y


From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of James Brown via groups.io <JIM@...>
Sent: 01 March 2021 16:41
To: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
Subject: Re: [SDR-Radio] Earths Doppler
 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 


Re: Earths Doppler

 

Its quiet. Not a sound can be heard.
Suddenly an ambulance crests a hill a mile away and you hear its siren.
It comes at you with a steady pace. As it gets closer does the pitch go up?
It passes you. Does the pitch go down?

Did it ever go up?

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Monday, March 1, 2021 06:15
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Ambulance towards you shifts up

Ambulance away from you shifts down

... In circles... Stays the same as long as the ambulance is not a supersonic jet

Dg9bfc sigi 

 

Am 01.03.2021 06:28 schrieb jdow <jdow@...>:

Depends on whether you are babbling or communicating, doesn't it?

{^_-}

On 20210228 21:00:53, James Brown wrote:

Humm.
… and yet it moves

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 14:48
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

No I do not. I would agree if you preceded it with "The change in". You are conflating a quantity and its (calculus) derivative.

Doppler shift is not the change in Doppler shift, which you are talking about.

{^_^}

On 20210228 14:29:09, James Brown wrote:

So you agree that the Doppler shift from the Earth’s rotation is always down – right?
or are we still talking past each other.

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Sunday, February 28, 2021 13:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Earths Doppler

 

Terminology problems are bumping around here.

The absolute Doppler shift is higher if the emitter is approaching you and lower if it is receding from you. As long as constant motion is involved the change in Doppler shift will tend downwards from above normal to below normal as the emitter's relative vector to the observer changes. So I still take exception to your aphorism. "The change in Doppler shift is always down in frequency" is more accurate than "Doppler shift is always down in frequency".

{^_^}


On 20210228 06:46:10, James Brown wrote:

Check this out and tell me what you think
https://tinyurl.com/ry6n6w67
Regards…….. Jim

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of jdow
Sent: Saturday, February 27, 2021 21:35
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Earth's rotational Doppler is as often up as down. Earth's orbital Doppler should also be up or down. They should be easily separable on long term observation. The former changes faster than the latter.

How do you get "Doppler shift is always down in frequency?"

{^_^}


On 20210227 21:26:27, James Brown wrote:

It took me a long time and some advice from experts but I finally got it running.

I know the pointing angle of my antenna, it tracks whatever target it is set to, so with a bit of Trig I calculate the fall in frequency because of the Earth’s rotation at that angle, second by second. When the sum of the change reaches 1 Hz I move the receiver frequency down by 1 Hz.

Each 20 kHz chunk of spectrum gets scanned usually 10,000 times and a buffer is built from these scans. At the end of 10,000 scans I average each of the FFT bins and then look for average bins that pop up from their neighboring bins 5 on each side.  No hits – I move up band to the next 20,000 kHz chunk. If hit – I stay on this frequency and repeat five more time. All data is saved to my server and can be viewed here:
https://tinyurl.com/2jawwc83

A complete scan of the 100 MHz wide Waterhole at this rate will take somewhere on the order of 6 million hours.

p.s. Did you know that Doppler shift is always down in frequency?





 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Siegfried Jackstien
Sent: Saturday, February 27, 2021 20:07
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

doppler effect is mturn of the earth ... move of the earth, position of moon and sun ... etc etc

difficult to calculate all that

we have the qo100 sat ... and it drifts around 40hz up down every day (like the tide in the ocean does)

and ... from earth ist stationary (more or less) ... only moon and sun in that system moves

now add turning earth ... and move of earth in space ... and different view angle of antenna (az and el) ... how do you calculate that??

dg9bfc sigi

Am 27.02.2021 um 21:37 schrieb James Brown:

Thanks for the question Roy.

The technique I use to discriminate terrestrial signals from  Extraterrestrial ones makes use of the fact that signals coming in from outside the Earth will be shifted down in frequency do to the Doppler effect from the rotation of the Earth. Carl Sagan outlined this technique in a book “Communication with Extraterrestrial Intelligence” back in 1971.

So if you look at a waterfall of the same 20 kHz chuck of the spectrum over a long period of time, say half and hour, all the local signals will be straight up and down lines. The extraterrestrial ones will curve down in frequency over that time. So the trick is to sort the two types.

What I do is chirp the receiver down in step with the calculated Earth rotational Doppler, which is dependent on the antenna pointing angle. Right now I see that my receiver is chirping down at 0.112 Hz/Sec. That way all the local signals in the waterfall appear to curve up and the Extraterrestrial ones stay in a straight line. This make the software *much* easier. Then I search through the buffer for vertical lines rather than curved ones. It does depend on a stable receiver for sure.

That’s the first order detection filter that I use.

 

Regards….. Jim

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Roy VE7DH
Sent: Saturday, February 27, 2021 12:32
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Pluto Pluto+ minimum tuning

 

Hi James,

I took a look at your very interesting web site. One thing I don't understand is why you need to tune the receiver at all.

Could you not look at the entire 20 khz spectrum in one chunk, as you say, and then examine each 1 hz portion entirely in software?

This way, there is no tuning requirement, just a stability requirement.

Of, course I may have no idea what I'm talking about...

regards, Roy

 

 

 

 

 


Re: Accessing Either Of Two Radios: How, Please ?

Kriss Kliegle KA1GJU
 

You need to build a 'definition' of it, just like you did with the SDRPlay so long ago.
Just a few steps:




Once a definition is built and saved, go back to step #1 and then choose which radio you want to use by itself.
If your computer is up to the task, you can run another copy or "instance" I believe is the term, by left clicking on the
round file tree "looking thingy", then click on "New Instance".





For running two at the same time, left click and drag (click on white bar across the very top of the app) and drop it on either side edge of the screen, it will flicker and show a ghost image filling half the screen. When it does, release the left mouse button and voila... you have a reduced image on your screen. Do the same
with the other instance and drag it to the opposite side. Now you can do side by side comparisons of your SDR's and or antennas! The radio controls (AGC, Gain, Attenuator, Visual Gain) are available, just have to click on the green dot due to operating on half a screen width:




I am not a coder/programmer, so please excuse my lack of technical terms for various items on the SDRC screen! 
I'm sure JDOW is cringing! 😁

73 Kriss KA1GJU

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