Jump to content
sandyk

DTV Interference from a Desktop PC

Rate this topic

Recommended Posts

Of necessity I have to use an indoor UHF antenna for my TV in fairly close proximity to my W10/64 Desktop PC and 23" monitor. 

 This has always resulted in certain UHF groups of channels being unwatchable with the PC switched on, and even the slightest movement of any PC leads can cause different groups to be affected,

 often with a Weak Signal message, despite using an RG6 quad shield 75 ohm cable.

 In certain atmospheric conditions even normally watchable channels may become unwatchable when the PC is switched on, even when idle.

 This evening I found the article at the link, and tried replacing the generic HDMI cable to my 23" monitor with the HDMI cable that came with my Oppo 103.

 Presently, all available channels are completely watchable with no visible artifacts , but I have yet to try it with Processor intensive tasks on all channels .

Click on the image for a larger image.

Alex

 

HDMI Cables and EMI

https://interferencetechnology.com/hdmi-cables-emi/

 

HDMI RF-EMI.jpg


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

Incidentally, if this wideband UHF crap can even get into an adjacent RG6 quad shield 75 ohm cable, it certainly is capable of getting into nearby PC leads including USB cables etc.


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

Depending on country DTV signals are broadcasted either in H, V or both polarizations. In case your HDMI cable acts as an interferer by radiating EMI then only by changing the way the cable lays ( Vertical <-> Horizontal ) you will gain from 15dB to 30dB rejection.

You may also change your UHF antenna's position .

Share this post


Link to post
Share on other sites
12 minutes ago, Arpiben said:

Depending on country DTV signals are broadcasted either in H, V or both polarizations. In case your HDMI cable acts as an interferer by radiating EMI then only by changing the way the cable lays ( Vertical <-> Horizontal ) you will gain from 15dB to 30dB rejection.

You may also change your UHF antenna's position .

 

 I am well aware of that, but it's not always feasible to do this.

 I had already tried rerouting the HDMI cable as much as possible, even running part of it's length tied to the metalwork of my PC desk, which I had connected to the case of my earthed PC.

My indoor antenna has to be near this particular window due to a metallic flyscreen on the other window.

 

Neither do I like the thought of all this stray wideband UHF energy with varying modulation, getting into the PC audio leads.(Coax SPDIF or USB)


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

Well, Wifi, mobile phones, Telecom networks are already generating much more electromagnetic energy inside your home versus the one you are wondering about. Not even talking about the trend for the following years.

Share this post


Link to post
Share on other sites
18 minutes ago, Arpiben said:

Telecom networks are already generating much more electromagnetic energy inside your home versus the one you are wondering about

 

But not in such close proximity.

 Many members are finding USB audio in particular, highly susceptible to RF/EMI.

It makes sense to reduce the levels of this interference as much as possible, including the use of internal screened SATA cables instead of the generic 7 wires side by side, for example.

 Even disconnecting (switching the input) of a Broadband Router can result in small audible improvements.


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

I had similar experience when I moved from flat to house without any cable internet and cable TV connection. As the first temporary solution I bought the strongest indoor active TV antenna and tried it with my TV. After some experiments to find the best place for the antenna I could receive 4 different DVB-T multiplexes, but every with a little different antenna position. Funny part is that an old brass mortar which I have after my grant parents helped with signal reception, but again for each multiplex slightly different antenna + mortar configuration was needed, including pounder position in the mortar. :DA you can see, the signal reception was so so sufficient and sometimes it was insufficient.

And now to EMI and PC. At first I found I cannot watch TV stations of some multiplexes when room lights are on in the part of a big room, where the TV and antenna are placed. More interesting thing is, that mouse moving and maybe mouse clicks caused distortion on TV screen, which is distant about 3 meters  from my notebook and about 4 meters from the antenna. I disconnected from mobile LTE internet. Nothing changed. I am using optical mouse, bluetooth was disabled on my notebook. That time I didn't use WiFi nor LAN in my house. It was simply influence of my notebook + DVI connected monitor on DVB-T signal receipt.

Share this post


Link to post
Share on other sites

Yes, there is no such thing as "eliminating" interference - all you can do is attenuate it, by a major amount if you do the right things. And the "strangest things" can cause that interference: we are on the lee side of a hill from Sydney, and I have to point the antenna in a quite bizarre direction to pick up signals from there - many times a channel will become borderline. Anyway, we have large aluminium sliding doors near the TV; the antenna is way up on the roof, long ways off - going up and opening one can cause the reception to completely drop out momentarily, very repeatable. Static, vibration, some strange reflection anomaly - who knows? :)


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Ahhh, Mankind ... Porsche intellect, Trabant emotions ...

Share this post


Link to post
Share on other sites

Let's start a gofundme account to send Frank over to Alex's house!


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

Share this post


Link to post
Share on other sites
1 hour ago, Ralf11 said:

Let's start a gofundme account to send Frank over to Alex's house!

 

Better still, raise a lot more and send him to your place  ! :P


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

he might not survive here


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

Share this post


Link to post
Share on other sites
4 minutes ago, Ralf11 said:

he might not survive here

 

Then again, it could be the other way around ! :D


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites

The difference in your audio system and these interference sources is the audio system isn't set to resonate and amplify signals in the way TV or radio receivers are.  So something TV or radio can pick up wouldn't be enough to matter by just impinging on an audio system.  


To paraphrase Rick James, "sighted listening is a helluva drug".

Share this post


Link to post
Share on other sites
38 minutes ago, esldude said:

So something TV or radio can pick up wouldn't be enough to matter by just impinging on an audio system.  

 

Dennis

 There is always the possibility of inadvertent rectification by something in the chain .

 It may not be just SMPS crap getting into USB leads and causing problems for some members.

 Years ago I was working on a new  amplifier module, and I moved it to another location with the DMM leads still connected across the output terminals. I was surprised to see a steady several mV reading on the DMM. We had a FM stereo station transmitter a KM or so away, which MAY have been the cause. (?)

 I have also seen Analogue TV transmitters several KM away (Gore Hill in Sydney) cause varying hum levels in an audio system, ("Frame Buzz") getting in via the speaker leads acting as an antenna, into the negative  feedback area. I was even able to verify which TV station it was by the picture content.  Looping the speaker leads through a large toroid fixed that problem.

It's not even unknown for AM radio signals to be rectified by teeth and annoyingly  heard at odd times by their owner ! O.o

Alex


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

Share this post


Link to post
Share on other sites
2 hours ago, sandyk said:

 

Dennis

 There is always the possibility of inadvertent rectification by something in the chain .

 It may not be just SMPS crap getting into USB leads and causing problems for some members.

 Years ago I was working on a new  amplifier module, and I moved it to another location with the DMM leads still connected across the output terminals. I was surprised to see a steady several mV reading on the DMM. We had a FM stereo station transmitter a KM or so away, which MAY have been the cause. (?)

 I have also seen Analogue TV transmitters several KM away (Gore Hill in Sydney) cause varying hum levels in an audio system, ("Frame Buzz") getting in via the speaker leads acting as an antenna, into the negative  feedback area. I was even able to verify which TV station it was by the picture content.  Looping the speaker leads through a large toroid fixed that problem.

It's not even unknown for AM radio signals to be rectified by teeth and annoyingly  heard at odd times by their owner ! O.o

Alex

While I agree with what you are describing, and have seen most of them or something similar, the emissions from a PC to a DAC usually doesn't show up in the output.  The USB cables are balanced which helps quite a lot.  

 

I had an amp which would decode an illegally strong CB transmitter from a neighbor if connected to my ESL's (Acoustats at the time), but wouldn't with box speakers.  But no issues on the digital end. 


To paraphrase Rick James, "sighted listening is a helluva drug".

Share this post


Link to post
Share on other sites

Most audio systems, when working to a higher level, can be heard to react to almost everything! :P This will drive one nuts ... so, decide if you're "hearing things" x-D; or, drop back to a lower standard of playback where these aspects disappear;  or ... fix 'em up ... your call.


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Ahhh, Mankind ... Porsche intellect, Trabant emotions ...

Share this post


Link to post
Share on other sites
14 minutes ago, fas42 said:

Most audio systems, when working to a higher level, can be heard to react to almost everything! :P This will drive one nuts ... so, decide if you're "hearing things" x-D; or, drop back to a lower standard of playback where these aspects disappear;  or ... fix 'em up ... your call.

If you fix'em up, they'll be even more sensitive and need fixing up again when the barometric pressure drops or humidity changes or the neighbor gets a new wifi router.  


To paraphrase Rick James, "sighted listening is a helluva drug".

Share this post


Link to post
Share on other sites
18 minutes ago, esldude said:

If you fix'em up, they'll be even more sensitive and need fixing up again when the barometric pressure drops or humidity changes or the neighbor gets a new wifi router.  

 

The good news is, this doesn't happen! Seriously, ... :)

 

The recording content becomes king, and overrides everything else - yep, there will still be audible variations, but these are now so far down in the "pecking order" that it doesn't matter any more. Semente's finding that a particular USB setup caused a major jump in listening pleasure is a classic example of this progression.


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Ahhh, Mankind ... Porsche intellect, Trabant emotions ...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...