The intern

Isn't it 15.734 ?>:-} ...Jim Thompson

"Mostly harmless."

It's clearly a method of deadly fighting disguised as entertainment. Need more research funds. Much much more.

NT

You'd be analysing the fairly high power non-directional long wave signals and they'd be so weak you'd be stacking, looking for repeated patterns.

The breakthrough would come when you discovered the Greenwich pips, then after more funding was released, Barwick Green.

Close Encounters got the tune badly wrong.

Cheers

In message , Jim Thompson writes

I make it 15.625 or even 10.125

Brian

Highly unlikely.

In the early days of TV you are more likely to get hours and hours of the test card and so be able to determine the planets rotation rate!

On the plus side stacking the constant image would eventually allow them to see a pattern with a girl with a blackboard inside from the UK and whatever test card the USA daytime broadcast to help TV engineers.

A trace with "LGM" marked on and wait for them to get the Nobel prize.

Repetitive signals from pulsars are relatively common in the galaxy and provide a convenient method of describing your position.

Note that you had to be lucky to watch at the right time, when transmitters were high-powered to overcome insensitivity of receivers and waste of power transmitting strong repeated patterns.

When you would look at the same spectrum as transmitted today, it would be less than 1/10th the strength and would look mostly like blocks of noise. Many transmissions you would never be able to decode, even when you understood their structure. (which is a lot harder than with old style TV)

That is one factor which the Drake equation was highly optimistic about. A technological civilisation is only very radio bright for a comparatively short period of time - a few decades between inventing radio and discovering spread spectrum digital signal processing. Once they have fibre to premises they become radio quiet again apart from a few amateur radio hams who like playing with retro kit and methods.

You might detect something as artificial in modern digital TV signals but they are a heck of a lot weaker now than in the good old days. Your chances of decoding the signal even if it were perfect would be almost nil unless your computers were far in advance of anything we have.

TDR radar ranging and imaging of Earth crossing asteroids by the likes Arecibo is the last remaining high power beacon that we broadcast.

one might conclude that the SUN is actually a high power digital transmitter and the data appears to us as "white noise" simply because we don't know how to decode it.

Since the TV stations try to beam all their power close to the horizon, thus a foreign observer would only see stations at the rim of the earth, some of which move towards the observer and some moving away from the observer. Thus, they will have different doppler shift, the first group with a positive doppler and the second group with a negative doppler. The absolute size of the doppler also depends on the latitude of the TV station.

If you have determined the rotation period somehow, from the doppler you get the rotation rate and the planet diameter (assuming there are stations on the equator).

We've been radio bright for close to a century so far. Radio will continue to have a future for mobile data for a long time. And perhaps a huge chunk of radio spectrum may be used to mass broadcast the most popular data at an y given moment, augmenting other data channels.

decoding isn't needed, just work out that it's not random.

NT

The problem is that the radio emissions we make more and more closely resemble noise. It is not like in the early days when we wasted a lot of power sending a carrier or sync pulses. Almost all transmissions are migrating towards OFDM and DSSS.

But that is now much more difficult than it used to be. The more optimal a transmitter uses a channel, the more the transmissions resemble noise.

I believe the original black and white was 15,750, later revised to

I believe the original black and white was 15,750, later revised to

I believe I'll have another beer.

It changed when color was introduced. It was 15750Hz for the dawn of black & white TV.

That's for British 625 line and the obsolete 405 line systems.

AFAICR: the French system was 819 line and there's the US 525 line system.

I know. I grew up in a radio & TV repair shop. ...Jim Thompson