How would a country indepedently jam/scramble a fta signal?

[mdovell]

I've heard that in Iran somehow the government is jamming or scrambling up foreign media tv. I'm just wondering how it could be done with tv. With radio I guess if you broadcast on the same frequency and use more power you can override it but how can an entire footprint be scrambled.

I'm just following what's going on a bit there and they definatly don't want communication channels to be cut. They've pressured twitter to delay maintence, supposedly they are trying to monitor anything identifying people on the internet...

 

[turbosat]

Wasn't it OUR govt who asked twitter to delay regular maintenance downtime? I've been watching what Russia Today, Al Jezeera and others have been saying about the election/protests in Iran too. I'm sure countries like that one have had systems in place for years to disrupt internet/phone/cellphone services-look at what China did on the anniversary date of 'their' last uprising.

 

[SatelliteAV]

To wipe out a satellite signal one could simply introduce RF "noise" on the downlink frequency to decrease the Signal to Noise ratio and increase the signal errors. Quite easy to wash out a 100+ watt signal that has just traveled 23,000 miles!

 

[mdovell]

To wipe out a satellite signal one could simply introduce RF "noise" on the downlink frequency to decrease the Signal to Noise ratio and increase the signal errors. Quite easy to wash out a 100+ watt signal that has just traveled 23,000 miles!

O I didn't know...thanks.

 

[skysurfer]

yes, you can use a c-band test transmitter like my friend used to have to test c-band systems (wiped out c-band transmissions in a 200 foot radius

or you can overpower the transponder to create enough interference to make the digital signal too messed up to lock.

 

[AcWxRadar]

I've heard that in Iran somehow the government is jamming or scrambling up foreign media tv. I'm just wondering how it could be done with tv. With radio I guess if you broadcast on the same frequency and use more power you can override it but how can an entire footprint be scrambled.

I'm just following what's going on a bit there and they definatly don't want communication channels to be cut. They've pressured twitter to delay maintence, supposedly they are trying to monitor anything identifying people on the internet...

Hey, Look what one channel has done here in North America! LEO-1 blocked a lot of people from viewing RTN Feed channels. And this was unintentional (or so I think). Imagine what you could do if you tried!

RADAR

 

[USDownlink]

I'd like to take this opportunity to add to the discussion, perhaps (most respectfully, of course) disagree with the general feeling of the ease of 'shutting down' satellite transmissions via RF, and point out something which is important.

Apologies if this is not news to anyone reading.

The short story: For quite a while, the Chinese language New Tang Dynasty TV had been broadcasting via Eutelsat W5 into Asia, and in particular, China. NTDTV was, um - shall we say - quite unpopular with the communist Chinese government for a number of reasons. Not the least of which is that they had absolutely no control or influence over it's content, and NTDTV had a tendency to report and broadcast anything and everything. Essentially, NTDTV was a thorn in the side of the communist government for approximately 6 or 7 years. As it stands, the consensus is that the CEO of Eutelsat made the decision to shut down the transponder NTDTV was using as a favor to the Chinese government, in return for preferential treatment regarding future launches and carrier contracts.

For a more complete back story, if you are interested, start here:
Asia Times Online :: China News, China Business News, Taiwan and Hong Kong News and Business.
Eutelsat Continues to Evade Inconsistencies Regarding Its W5 Capacity ? New Tang Dynasty Television

Anyway, on to why I brought this up. Three reasons:

<> If RF interference was as easy as it's been stated in this thread, then this story as it has evolved would never have been. Given the resources and the power of the Chinese government, if they wanted it "jammed", it would have been done long ago.
<> An alternative, novel answer to the OPs question: It turns out that an entire signal can be eliminated via simple political pressure. No technology required.
<> We should all be concerned about such developments. Free speech is something most of us in the west take for granted - it is not so to our FTA viewing brethren around the world. This transgression just happens to be FTA related, and we should be aware and prepared on some level.

 

[B.J.]

A couple additional aspects of this. The original poster mentioned "but how can an entire footprint be scrambled". The simple answer is that at satellite frequencies, it cannot be done using the downlink frequencies. The microwave freqs just don't have enough range. You'd need transmitters all over the place. Maybe with a country as small as Iran, you could do it, but not over the entire footprint of a satellite.
HOWEVER, the other aspect of it is that basically all the sats up there transmit in the same C and Ku bands (and KA now). We get different sats separately because our dishes aim specifically at one sat. This means that first of all, a terrestrial based interferrence wouldn't be coming from the direction of the sat, and even if it were strong enough to wipe out reception, it would wipe out reception on ALL satellites, not just the one they were trying to eliminate.

Because of the above reasons, I think the only reasonable way they could eliminate reception of a sat over a large area, would be to transmit on the uplink freqs, such as the Captain Midnight thing taking over HBO. However any country doing this intentionally would pretty much be committing an act of war on the rest of the world. Ie that's a serious offense against international agreements.

 

[Juan]

I remeber the "playboy" incident in the 1980's

 

[Mr Tony]

Hey, Look what one channel has done here in North America! LEO-1 blocked a lot of people from viewing RTN Feed channels. And this was unintentional (or so I think). Imagine what you could do if you tried!

RADAR

if you had the recommended dish maybe not

RTN for affiliates say 1.2m dish minimum

 

[eurosport]

if you had the recommended dish maybe not

RTN for affiliates say 1.2m dish minimum

COOL! I have the recommended dish! :up

 

[Mr Tony]

found the thread that mentions it

guy here who owns 2 LP stations that are RTV affiliates
http://www.satelliteguys.us/free-air-fta-discussion/166478-dish-good-enough-rtn.html

 

[guapoharry]

Hey, Look what one channel has done here in North America! LEO-1 blocked a lot of people from viewing RTN Feed channels. And this was unintentional (or so I think). Imagine what you could do if you tried!

RADAR

if you had the recommended dish maybe not

RTN for affiliates say 1.2m dish minimum

Blocked?

You could say that.

Or, what about an arguement where one says the receiving setup wasn't selective enough?

:tux: (duck)

!protest