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Transmission Delay in TV Signal - Why?

02/22/2010 5:24 AM

I have a satellite dish TV connection at my home. My neighbour has a conventional cable television (we in India call it cable TV). When viewing the same TV programme, i find that he gets the picture first and the same picture is seen in my TV after a delay of about 30 to 45 minutes and some occassions about a minute or so. Why is this proppogation delay. My doubt is I am recieveing the sateliite signal directly through my dish antenat and whereas my neighbour recieves the signal through cable (the signal is recieved by some cable operator located far away) but he is recievinbg the signal first. (Of course I am now having a stereo effect of audio due to this time delay). Can any one explain me?

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#1

Re: Transmission delay in TV signal - Why?

02/22/2010 7:39 AM

Well, the broadcast satellites are in geosynchronous orbit. They may not be directly overhead, but at an oblique angle from your antenna.

Still, the distance, from the perspective of the speed of light, is pretty close.

Geosynchronous orbit has a radius of about 42,200 km. That puts a geosynchronous satellite about 38,000 km directly above your head, but probably closer to 40,000 km in reality.

Speed of light is 300,000 km/s, so the propagation delay to and back from the satellite is about 80,000 km/300,000 km/s = .267 seconds.

The delay you are witnessing is done by the broadcast station since they can rebroadcast the event at the time of their choosing.

Just to put things in perspective, a radio signal from Earth would take just over 30 minutes to reach Jupiter at its closest approach to Earth.

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#10
In reply to #1

Re: Transmission delay in TV signal - Why?

02/23/2010 5:33 AM

A Good Answer.

I like to add:

All the data is transmitted in packets not on one route but enormous routes & recombines in the Centre. Bandwidth limits are some times too small to run a constant streem.

You may have noticed at times like "Freeze" of reception.

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#2

Re: Transmission Delay in TV Signal - Why?

02/22/2010 8:12 AM

Just for ha ha's, when I'm watching a game on T.V. in my kitchen, which is direct cable to the tuner and my wife is watching it on the big screen in the T.V. room (digital box) I'll yell "YES" when a home run is hit and my wife will wonder what I'm yelling at. Five seconds later, she see's what I've seen. Same company, different timing.

Funny, it seems our roles have reversed. Shouldn't I be in the recliner watching the big screen?

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#3
In reply to #2

Re: Transmission Delay in TV Signal - Why?

02/22/2010 8:14 AM

Too funny!!!

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#11
In reply to #2

Re: Transmission Delay in TV Signal - Why?

02/23/2010 5:37 AM

Regards.

Some programms are transmitted from different studios [of course on different channels]. there Time synch is nowhere. Some are Relaying and delay is in the relay system.

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#4

Re: Transmission Delay in TV Signal - Why?

02/22/2010 9:21 AM

Now if we could just get the @&%$*$#@>"" stations and *$*&E#&*^%^*%$ legislators to regulate the volume of the commercial adverts to be at the same level as regular programming, that would make me happy. Forget the time lag!

Thanks, now I feel better.

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#5
In reply to #4

Re: Transmission Delay in TV Signal - Why?

02/22/2010 10:24 AM

Why does everyone look to the "government" to nanny and cradle them? Not only do they do a lousy job, but they over charge us (taxes) to do it!

Just turn it off. If people stop watching the programs, advertisers and stations would get the message very quickly.

The problem is, people just complain and fail to act. As long as people fail to act, why should stations and advertisers change?

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#7
In reply to #5

Re: Transmission Delay in TV Signal - Why?

02/22/2010 7:53 PM

Don't try to use logic on me, I'm immune!

I'm gonna complain to my Congressman next week, anyway. He writes me often with updates of his good work.

Hell, it doesn't really matter, I can't hear anyway.

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#12
In reply to #4

Re: Transmission Delay in TV Signal - Why?

02/23/2010 6:09 AM

You want to put out of a job the guy at the TV station that turns up the volume for the commercials?

Here's an idea: Build a device with a microphone and infrared transmitter that detects the increase in volume and turns it down to say half volume - then restores the level when the commercial volume increase is over. This requires no modification to your TV set.

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#13
In reply to #4

Re: Transmission Delay in TV Signal - Why?

02/23/2010 7:12 PM

Regards.

While in my country we had been listening about ADDs Blanking & Mute a large ...

While I am here in UK nothing such thing is except HD, HD all the time.

Secondly it was told that the Channels who run ADDS need not any subscription !!!!

3rdly The Courts has decided not to give add beyond some limits.

Nothing I can see here.

In USA & Canada public is suffering non standard product. Large hue & cry on discussion groups. No remedy anywhere.

While I visited West Germany in 60s a cartoon in papers was very popular.

Two dogs sitting on Wall of Berlin; Westren & Eastren.

Westren: You are very healthy & Fat.

Eastren: Lot of food but cannot Bark !

Here every body has freedom to ...

but nobody cares ...

Have a fine day for 20 minutes ADDs during 30 mins program....+++

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#19
In reply to #13

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:09 PM

Westren & Eastren

Seems you know chinese also. Ren /ran is man or people. Westren: Man from west?

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#6

Re: Transmission Delay in TV Signal - Why?

02/22/2010 6:09 PM

Did you mean 30-45 seconds up to 1 minute?

Varying delays are usually caused by the specific providers signal processing systems. Signal propagation delays alone should be small (<1 sec), but digital processing/buffering can be any value. There are also delays in the HOME from DVR buffering. My DVR buffers the signal about 3 seconds from the actual feed. The echo/delay is actually quite annoying when 2 sources (delay buffered and normal) can be heard at the same time.

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#15
In reply to #6

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:02 PM

Sorry it may please be read as seconds instead of minutes

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#8

Re: Transmission Delay in TV Signal - Why?

02/22/2010 10:44 PM

Are you sure that sometimes the delay is 35 to minutes?

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#14
In reply to #8

Re: Transmission Delay in TV Signal - Why?

02/23/2010 10:59 PM

Sorry please read it as seconds instead of minutes.

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#9

Re: Transmission Delay in TV Signal - Why?

02/23/2010 5:26 AM

this page discusses the matter at some length. however, I can't see the delay you're saying - 30 to 45 minutes?

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#16
In reply to #9

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:03 PM

sorry it may please be read as seconds instead of minutes

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#17
In reply to #9

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:04 PM

sorry it may please be read as seconds instead of minutes

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#18

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:08 PM

Thanks for all the replies. However, I feel that i have not got my doubts cleared. My doubt was why should I recieve the signal after a delay when I am recieving the signal directly from the satellite through my dish antena (or) how is my neighbour getting the same signal earlier, thoough he is not recieving the signal directly from satetllite but through a cable and that too the signal is being receved by a cable TV opeartor who is recieving signal and located at a far away place from his home. Hope I am making myslef clear

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#20
In reply to #18

Re: Transmission Delay in TV Signal - Why?

02/23/2010 11:39 PM

Hi

Just confirm that the connections between you and your neighbour with dish and cable are not reversed outside.

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#21
In reply to #20

Re: Transmission Delay in TV Signal - Why?

03/02/2010 1:44 AM

Thanks for the suggestion. But I am sure that the connection from my dish antena is comong direct to my TV and hence there is no doubt abiut connections.

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#22
In reply to #18

Re: Transmission Delay in TV Signal - Why?

03/20/2010 10:18 AM

dear the problem you mentioned here is bcoz you are using DTH service, in DTH transmission dealy is more bcoz, first the dth company receives the signal from the c-band satellite, process it, mix it and then again uplink to the satellite again for transmission which is received by you, so in your case signal travels two time through space, but in case cable oprators ,they receives the signals from c-band directly and send directly to the users home after some processing.that's the reason of delay...

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