Please excuse total noob query regards seeking storm bad signal effect on sat TV

[stonefirewon]

Hi, I have been told this was not possible but I wanted to check with some folks with more experience in these matters. Is it possible to create a rainstorm like bad signal effect on my satellite fed TV? I hope it is possible as I want to use it for an art project. I was also told by another that it might be possible by inserting a potentiometer between the satellite dish and the receiver. Any help is greatly appreciated!

 

[Externet]

Better try shaking aluminium foil in front of the dish or feedhorn... Leave wiring alone.

 

[(*steve*)]

You could probably start with a variable attenuator. It may be difficult to find a level of attenuation that doesn't completely cut off the signal unless either the attenuation or the signal strength is varied.

 

[stonefirewon]

You could probably start with a variable attenuator. It may be difficult to find a level of attenuation that doesn't completely cut off the signal unless either the attenuation or the signal strength is varied.

Thank you. Any idea what type of attenuator might work best for this?

 

[(*steve*)]

I would recommend you find someone who installs satellite TV and ask them. It probably depends on your signal source.

With digital transmissions, there is very little range from an almost perfect signal to no signal at all.

If your signal source is an antenna, a fixed amount of attenuation may give you a perfect signal one day, one that fades in and out on another, and no signal in a third. Presumably for your art project you want it to fade in and out all the time?

The signal you need to attenuate is very high frequency, and a simple potentiometer won't likely work well.

Looking on eBay, there are many variable attenuators available. The problem you may face is getting adapters from whatever called you have to the connections these have.

The other problem is based on the signal strength issue. If the effect of adding and removing a lot of attenuation is acceptable (try it by manually connecting and disconnecting the signal source) then there may be a simpler solution using either an rf or even regular relay to periodically interrupt the signal.

 

[(*steve*)]

Better try shaking aluminium foil in front of the dish or feedhorn... Leave wiring alone.

I like that.

 

[Ylli]

The aluminum foil is a good suggestion. Otherwise you could try mis-aiming the antenna; Just be sure you know how to get it back to where it belongs.

 

[stonefirewon]

I would recommend you find someone who installs satellite TV and ask them. It probably depends on your signal source.

With digital transmissions, there is very little range from an almost perfect signal to no signal at all.

If your signal source is an antenna, a fixed amount of attenuation may give you a perfect signal one day, one that fades in and out on another, and no signal in a third. Presumably for your art project you want it to fade in and out all the time?

The signal you need to attenuate is very high frequency, and a simple potentiometer won't likely work well.

Looking on eBay, there are many variable attenuators available. The problem you may face is getting adapters from whatever called you have to the connections these have.

The other problem is based on the signal strength issue. If the effect of adding and removing a lot of attenuation is acceptable (try it by manually connecting and disconnecting the signal source) then there may be a simpler solution using either an rf or even regular relay to periodically interrupt the signal.

Thank you for that explanation. Information is always helpful.

Yes i was told of the very fine line of signal/no signal. Yes I looked on ebay also. It seems there is quite a variety. I have no idea which one might be best for this project unfortunately. I have previously tried putting in non variable attenuators. What I got was zero signal and the attenuators got very hot rather quickly. Is there any kind of clue in there?

I will try locating a satellite person to talk to about this. A very good idea! Any and all information is great and very helpful!

Messing with the dish is not an option for this as it is on the roof. Although perhaps that was a joke, not sure.

 

[Ylli]

"Is there any kind of clue in there?" YES!!!!! You are putting the attenuator in a line that is also carrying DC to power the preamp/converter at the antenna. Is there a separate power injection point (would look a bit like a splitter connected to a wall wart) , or does the power come directly from the receiver? If the power is coming directly from the receiver, you are out of luck. If there is a separate injection point, you need to place the attenuator on the receiver side of the injector, not the antenna side.

 

[davenn]

"Is there any kind of clue in there?" YES!!!!! You are putting the attenuator in a line that is also carrying DC to power the preamp/converter at the antenna. Is there a separate power injection point (would look a bit like a splitter connected to a wall wart) , or does the power come directly from the receiver? If the power is coming directly from the receiver, you are out of luck. If there is a separate injection point, you need to place the attenuator on the receiver side of the injector, not the antenna side.

Yes, I was going to say the same … a pot or variable attenuator in the coax line isn't a good thing to do
because of the coax carrying RF from the LNA to the receiver and the receiver supplying DC voltage to operate the LNA

In 99% of systems, the PSU for the LNA comes from the receiver and is injected into the coax inside the receiver

I would also experiment with a sheet of aluminium foil cut into strips except for the final couple of centimetres that can be glued to a wooden or metal batten


Dave

 

[73's de Edd]

Sir stonefirewon . . . . .

HEY ! . . . .correct me if wrong, but isn't your signal and receiver /display medium going to be DIGITAL and NOT OLD SCHOOL analog.

In which case, your desired effect is not going to be a desired , and progressively gradiated snowstorm / rain effect.
But a pixelated and progressively tearing frozen frame picture.

To use the attenuated signal effect , use an old VCR for its RF output and use the required degree of attenuated Ch 3/4 RF feed into an old analog TV.

73's de Edd
.....

 

[kellys_eye]

I'm sure there will be simulators for such effects somewhere on t'internet. The TV/video fraternity would be the place to look for them.

Displaying it on a computer monitor would look no different to that of a standard (these days) TV screen.

 

[hevans1944]

Is it possible to create a rainstorm like bad signal effect on my satellite fed TV?

What exactly does this look like? Back in the day, weak signals received from analog TV transmissions often appeared as if the images were taken in a snow storm, along with the images weaving sideways or rolling up or down because of loss of sync signals. Sometimes there were multiple images displaced horizontally because of multiple transmitter-to-receiver paths, effectively producing "ghost" images. Is this the type of video appearance you are looking for?

I have never used a satellite link for television reception, but I have heard that reception can be impaired by rain in the downlink path. Again, back in the day, this was analog television before everything went digital, so microwave signal degradation may have appeared with the same effects as VHF or UHF signal degradation, with the single exception possibly being no "ghost" images through multi-path reception.

With digital transmission, it's "all or nothing" as far as images are concerned. Some receivers have sufficient frame buffer capacity to display ragged, pixelated, images when marginal signals are received, but some recognize the low signal-to-noise ratio and simply refuse to display any images at all.

What are you really trying to DO?

 

[Externet]

Messing with the dish is not an option for this as it is on the roof. Although perhaps that was a joke, not sure.

Not intended as a joke. If a plastic pulley can be installed once on the roof antenna with no danger of falling, the foil can be positioned pulling the string.

A wrong attenuator may also attenuate the voltage supply for the LNBA, and errors/shorts can kill the power supply in the receiver

 

[Alec_t]

A wrong attenuator may also attenuate the voltage supply for the LNBA,

Perhaps couple the attenuator via a capacitor?

 

[Externet]

Wouldn't such block DC ?
The attenuating path should be for RF without affecting DC.

 

[Alec_t]

Wouldn't such block DC ?

If the attenuator is a shunt to ground, rather than being in series with the DC, it would allow DC to pass.

 

[Cannonball]

If it were me I would try putting tinfoil in front in front of the dish. You might could try blocking the signal a little bit at a time. Blocking the signal is what nature does with cloud and anything that gets between dish and the satellite.

 

[stonefirewon]

Thank you ALL SO MUCH! Yes it is the digital pixelated effect I am looking for. Not the snowy screen you sometimes got back in the day. I read in wikipedia that the receiver does power the satellite dish as mentioned, so it does make sense that the attenuator would get hot as mentioned. Hope I did not damage the receiver! I know almost nothing about this stuff but it is fun to learn. The foil in front of the dish might be a possibility if I can get up there. I would much rather be able to do this from inside the house though as the foil might be effective but it will also be rather clunky. The idea is to capture images of the pixelated effect for an art project.

Is there anyway this might be possible? Other then the foil?

Thanks again for all the help!

 

[Alec_t]

The idea is to capture images of the pixelated effect for an art project.

In that case, couldn't you just photoshop some static images (screenshots) and display the results in sequence?