Evenly spaced RFI.


Paul Egan <paul@...>
 

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC


jdow
 

7.059 MHz? Or might that be a typo on 7.159 MHz. That would be the second harmonic of the old NTSC color subcarrier which more or less lives on with the ATSC 59.94 Hz frame rate and its harmonics etc. It could, in principle, be a very old TV monitor on an old computer such as a Commodore PET at 7.159 MHz.

{^_^}

On 20220118 18:29:30, Paul Egan wrote:
I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC


Paul Egan <paul@...>
 

Thanks for the info, but it wasn't a typo. 7.059 and every 47 khz up and down.
Not sure what it could be but it's been there every night for years. Where is that "planned obsolescence when you need it?

73. VA3ZC


Simon Brown
 

A screenshot as an attachment would help ūüėä .

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Paul Egan
Sent: 19 January 2022 14:55
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Evenly spaced RFI.

 

Thanks for the info, but it wasn't a typo. 7.059 and every 47 khz up and down.
Not sure what it could be but it's been there every night for years. Where is that "planned obsolescence when you need it?

73. VA3ZC


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


Mag loop Simon
 

Hi

Whatever it is as you say won’t really matter apart from curiosity.
But as you can null it out..means you can remove it!
You have options..use a separate rx antenna ( 1m loop) with preamp..ie ccw, wellbrock, Lz1aq.. this you can mount on your condo and use gor rx only nulling out the smpsu.
Or make/ buy a phaser/ noise cancellation unit and null it out that way..
I use both..without here in London I would hear nothing but noise..
( soon to be moving next to Simon in the sticks, so hopefully noise issue hone.)

Other Simon g0zen


Brent Seres/ VE3CUS
 

Sounds like it could be the 2nd harmonic of an old NTSC color burst signal from an old TV





-------- Original message --------
From: Paul Egan <paul@...>
Date: 2022-01-19 01:35 (GMT-05:00)
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] Evenly spaced RFI.

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC


Paul Egan <paul@...>
 

Thanks for the comments, everyone. Here are a couple of images.

The first one shows a before and after the RFI source starts:


The second one shows a few hundred khz. of bandwidth and the 47khz. spacing:



The antenna is a magnetic loop and you can see the hump where it is tuned to. The RFI has a strong buzz or hum. I'm guessing a TV or monitor of some sort.

I was just curious if anyone has come across this annoying form of RFI.

Thanks again.
73,
Paul VA3ZC


Frank Eichel
 

The "After" image suggests a plasma television is causing the interference. I had the same interference on 20 metres (right on top of 14.200 Mhz). I used a portable AM radio to find it and convinced the neighbour who was watching it at the time to buy a new TV.

73, Frank VE7AWV 

On Wed., Jan. 19, 2022, 7:11 p.m. Paul Egan, <paul@...> wrote:
Thanks for the comments, everyone. Here are a couple of images.

The first one shows a before and after the RFI source starts:


The second one shows a few hundred khz. of bandwidth and the 47khz. spacing:



The antenna is a magnetic loop and you can see the hump where it is tuned to. The RFI has a strong buzz or hum. I'm guessing a TV or monitor of some sort.

I was just curious if anyone has come across this annoying form of RFI.

Thanks again.
73,
Paul VA3ZC


jdow
 

That might well be 47.06 kHz, the 150th harmonic is 7.059 MHz. Lemme see, NTSC was 15754200 kHz horizontal sweep rate, roughly. 47.06 is roughly 3 times that rate. 3 times 640 is 1920. So, yes, it is likely horizontal sweep rate related. Perhaps it would be the H sync signal on a VGA monitor. A hand held receiver might help you get yourself shot er pardon me, prowl the neighborhood looking for where the signal peaks. Odds are it is a neighbor close to your antenna if it is not your own living room equipment.

{^_^}

On 20220119 06:54:59, Paul Egan wrote:
Thanks for the info, but it wasn't a typo. 7.059 and every 47 khz up and down.
Not sure what it could be but it's been there every night for years. Where is that "planned obsolescence when you need it?

73. VA3ZC


jdow
 

100kHz off.
{^_^}

On 20220119 08:31:13, Brent Seres/ VE3CUS wrote:
Sounds like it could be the 2nd harmonic of an old NTSC color burst signal from an old TV





-------- Original message --------
From: Paul Egan <paul@...>
Date: 2022-01-19 01:35 (GMT-05:00)
Subject: [SDR-Radio] Evenly spaced RFI.

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC


Brent Seres/ VE3CUS
 

Yes, like you said...maybe a typo. Back when I got my ticket in 1971, I only remember three sources of qrm....the TV color burst, my mom's sewing machine,  and the electric mixer. How things have changed....and not always for the better...

73
Brent 





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-01-20 05:49 (GMT-05:00)
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Evenly spaced RFI.

100kHz off.
{^_^}

On 20220119 08:31:13, Brent Seres/ VE3CUS wrote:
Sounds like it could be the 2nd harmonic of an old NTSC color burst signal from an old TV





-------- Original message --------
From: Paul Egan <paul@...>
Date: 2022-01-19 01:35 (GMT-05:00)
Subject: [SDR-Radio] Evenly spaced RFI.

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC


Paul Egan <paul@...>
 

Well, the noise source is definitely not in our unit. I suspect it is a plasma set nearby. I've put up with it for 7 years and it is only a few hours a day. A move from here to a quieter QTH is in the works, so I'll just put up with it for now.

Thanks for your input, gents.
73.


jdow
 

He answered that the original figure is correct and color burst harmonic is 100 kHz higher. I analyzed numbers a bit and concluded it very well could be a TV set or computer monitor with a VGA or RGB connection. It could also be a plasma TV. They are notoriously noisy.

{^_^}

On 20220120 05:15:29, Brent Seres/ VE3CUS wrote:
Yes, like you said...maybe a typo. Back when I got my ticket in 1971, I only remember three sources of qrm....the TV color burst, my mom's sewing machine,  and the electric mixer. How things have changed....and not always for the better...

73
Brent 





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-01-20 05:49 (GMT-05:00)
Subject: Re: [SDR-Radio] Evenly spaced RFI.

100kHz off.
{^_^}

On 20220119 08:31:13, Brent Seres/ VE3CUS wrote:
Sounds like it could be the 2nd harmonic of an old NTSC color burst signal from an old TV





-------- Original message --------
From: Paul Egan <paul@...>
Date: 2022-01-19 01:35 (GMT-05:00)
Subject: [SDR-Radio] Evenly spaced RFI.

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC



Brent Seres/ VE3CUS
 

Seems like everything is noisy now days...





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-01-20 08:30 (GMT-05:00)
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Evenly spaced RFI.

He answered that the original figure is correct and color burst harmonic is 100 kHz higher. I analyzed numbers a bit and concluded it very well could be a TV set or computer monitor with a VGA or RGB connection. It could also be a plasma TV. They are notoriously noisy.

{^_^}

On 20220120 05:15:29, Brent Seres/ VE3CUS wrote:
Yes, like you said...maybe a typo. Back when I got my ticket in 1971, I only remember three sources of qrm....the TV color burst, my mom's sewing machine,  and the electric mixer. How things have changed....and not always for the better...

73
Brent 





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-01-20 05:49 (GMT-05:00)
Subject: Re: [SDR-Radio] Evenly spaced RFI.

100kHz off.
{^_^}

On 20220119 08:31:13, Brent Seres/ VE3CUS wrote:
Sounds like it could be the 2nd harmonic of an old NTSC color burst signal from an old TV





-------- Original message --------
From: Paul Egan <paul@...>
Date: 2022-01-19 01:35 (GMT-05:00)
Subject: [SDR-Radio] Evenly spaced RFI.

I have a problem with RFI. It isn't in my condo and there is probably no real way of determining where it comes from but I'm curious if anyone recognizes this one. It is evenly spaced at 47 khz. and very noticeable between 6 and 8 Mhz. It is only present during the evening hours and is often gone late at night. I'm guessing it is a TV in a neighbouring unit. There is a particularly annoying node at 7.059 Mhz. It is roughly 6khz. wide.

The antenna is a magnetic loop on the balcony. Ironically I can null the noise but then lose the ability to get a decent swr as it is too close to the building.

I know I will have to live with / work around this noise but I was just curious if anyone can identify it for me.

Thanks and 73,
Paul VA3ZC



Kriss Kliegle KA1GJU
 

My temporary desktop, a Dell Optiplex 7020 i7, has birdies in 75m, right on the frequency we have a PM gathering daily on 3928kHz. When I key the mic, it drops in frequency by about 2 kHz. When the ANAN200D goes back to RX, it rapidly drifts back up to 3928.5 with a weird sound as it passes through the audio passband. I have a choke of unknown mix on power cord with no effect, still S7, and currently routing around my shack for the FT-240 31 mix cores I have.
The replacement motherboard for my primary desktop can't come fast enough!

73 Kriss KA1GJU


Jerry Lofstead W3CDE
 

Kriss,

My 7040 has a pulsing wide band noise from 3925.5 to 3828.5..  8=(  I just measured it on my FTDX101MP.
I got this PC for it's low power requirements.

Jerry
W3CDE


On Thu, Jan 20, 2022 at 8:50 AM Kriss Kliegle KA1GJU <kliegle@...> wrote:
My temporary desktop, a Dell Optiplex 7020 i7, has birdies in 75m, right on the frequency we have a PM gathering daily on 3928kHz. When I key the mic, it drops in frequency by about 2 kHz. When the ANAN200D goes back to RX, it rapidly drifts back up to 3928.5 with a weird sound as it passes through the audio passband. I have a choke of unknown mix on power cord with no effect, still S7, and currently routing around my shack for the FT-240 31 mix cores I have.
The replacement motherboard for my primary desktop can't come fast enough!

73 Kriss KA1GJU


Brent Seres/ VE3CUS
 

Just as a matter of interest,  when I worked for Department of Communications back in the 70s and 80s, we would measure color burst and horizontal sweep of a TV station by connecting a Racal HF receiver to a loop located under color TV set. The receiver was tied to a frequency standard referenced to WWVB, and we used a lissagous pattern on a scope as an indicator 





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-01-20 05:47 (GMT-05:00)
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Evenly spaced RFI.

That might well be 47.06 kHz, the 150th harmonic is 7.059 MHz. Lemme see, NTSC was 15754200 kHz horizontal sweep rate, roughly. 47.06 is roughly 3 times that rate. 3 times 640 is 1920. So, yes, it is likely horizontal sweep rate related. Perhaps it would be the H sync signal on a VGA monitor. A hand held receiver might help you get yourself shot er pardon me, prowl the neighborhood looking for where the signal peaks. Odds are it is a neighbor close to your antenna if it is not your own living room equipment.

{^_^}

On 20220119 06:54:59, Paul Egan wrote:
Thanks for the info, but it wasn't a typo. 7.059 and every 47 khz up and down.
Not sure what it could be but it's been there every night for years. Where is that "planned obsolescence when you need it?

73. VA3ZC


Kriss Kliegle KA1GJU
 

Upon further testing, the birdie is internal to the ANAN 200D! Antenna or dummy load the noise is there. Awaiting response from Apache Labs forum for help.

73 Kriss KA1GJU


James Redding WA9VEZ
 

The NTSC/RS-170 genlock starting frequency was 14.318318 mhz, 4X the subcarrier. 3579545 Hz burst freq. It all goes back to 1953 when the FCC authorized NSTC which became EIA RS-170a.

Some of the newer switching voltage regulators with internal free running clocks run (+/- a few khz) at 260 khz, 380 khz. Very obvious to an AM BC portable receiver.

Fortunately, Panasonic plasma TV's are finally beginning to die (hardening of the electrolytic capacitors) and there are few OEM spare parts due to the shortage of "unobtanium".. 

--
WA9VEZ / Jim
N 39.1766  W 86.2693
Ham since 1962 /Radio fanatic since 1952


jdow
 

Factoid - color subcarrier was 5 MHz / 88 * 63, exactly. This was suggested as a means of delivering precise time and frequency via TV signals before the GPS era.

{^_-}

On 20220121 11:53:04, James Redding WA9VEZ via groups.io wrote:
The NTSC/RS-170 genlock starting frequency was 14.318318 mhz, 4X the subcarrier. 3579545 Hz burst freq. It all goes back to 1953 when the FCC authorized NSTC which became EIA RS-170a.

Some of the newer switching voltage regulators with internal free running clocks run (+/- a few khz) at 260 khz, 380 khz. Very obvious to an AM BC portable receiver.

Fortunately, Panasonic plasma TV's are finally beginning to die (hardening of the electrolytic capacitors) and there are few OEM spare parts due to the shortage of "unobtanium".. 

--
WA9VEZ / Jim
N 39.1766  W 86.2693
Ham since 1962 /Radio fanatic since 1952