digital radios

Let's say the standard delay is five seconds. So the source is five seconds ahead of real time.

The signal destined for FM is delayed by five seconds before it goes to the transmitter. So it's real-time.

The signal destined for DAB is transmitted immediately. The DAB receiver delays the digital signal, using a FIFO buffer, so that the audio is output five seconds after reception. As you've probably worked out by now, I'm not an engineer, so these figures are suspect, but for example: if the decoder takes 2 seconds, the signal must be delayed by 3 seconds before decoding, which if the signal is 720kbps (I wish) would require a buffer of 270kB. Different decoders that work at different speeds would require a different size of buffer.

I've not taken DTTV and DSAT into account because I've no idea what they are: are they radio? My only experience is with FM, DAB, and Freeview.

Reply to
Mike Barnes
Loading thread data ...

You'd have to have two recordings, one with the extra pip/bong

Owain

Reply to
Owain

That might be - and it might be possible to use them. (And jolly good if it can be done.) But I was trying to avoid the possibility that the decoding of those signals, even just the TOD, might take variable time whereas the Anthorn/MSF thing is obviously utterly trivial.

Reply to
Rod

Good one!

Reply to
Rod

Bucket brigade devices were really only a stopgap betwen the tape recorder with a length of tape between two heads and a variable idler, and full digital.

They were - the ones I used - almost total crap.

Reply to
The Natural Philosopher

PAL decoders needed a delay to work IIRC.

A TV relay satellite introduces a significant delay, several frames worth, as it adds ~100,000 miles to the path.

Reply to
dennis

Very strangely, the satellite path would probably be longer. It certainly is now that they use geostationary satellites. I suppose they could have routed the landline around the globe to make it longer. Then add in the conversion between different TV standards.

Reply to
dennis

In message , "Dave Plowman (News)" writes

Along with the rest of the world

They see no difference between england and britain

Indeed, in Indonesian, there is only the word "Ingeris"

The germans just call us "insel affen"

Reply to
geoff

True but propagation down a wire is only about 2/3rds of that in free space. Then of course you have all the amplifiers in the transatlantic cable every few tens of miles, each one having a little bit of delay as the vacuum tubes switch etc. TAT-1 laid in 1955/56 and in service until

1978 used vacuum tube repeators.

Telstar launched July 10 1962 and failed on Feb 21 1963 so TAT-1 could have been used. TAT-2 was avilable as well '59-'82. TAT-3 might have been a bit late '63-'86. T elstar 1 is still in orbit apparently:

formatting link

Reply to
Dave Liquorice

In article , dennis@home scribeth thus

Yes .. what was it now 64 microseconds?..

Around 45,000 miles is nearer the mark.....

Reply to
tony sayer

Please show your working.

MBQ

Reply to
Man at B&Q

I have never watched a game of association football from beginning to end, and don't intend to. I have watched and enjoyed games of rugby. I still think it was played more enjoyably (both for the players and the watchers) in the times of JPR Williams and 'Dusty' Hare 'though.

Regards,

Sid

Reply to
unopened

36,000 km each way = 72000 km Approx 100,000 km. The miles was an error.
Reply to
dennis

...and if you line things up just right you find yourself unable to send email over 500 miles:

formatting link

Reply to
Pete Verdon

Telstar was not geostationary, or even geosynchronous - so the delay up-and-down would be even less. To quote from the (unrealiable) Wikipedia:

"Unlike most of today's communications satellites, Telstar was on an elliptical orbit, which meant the ground antenna had to track the satellite as it came around the world approximately every 2.5 hours. Because the transmitting and receiving radio systems on board the satellite were not nearly as powerful or capable as ones on today's satellites, the ground antenna had to be huge. Morimi Iwama and Jan Norton of Bell Laboratories were in charge of designing and building the electrical portions of the system that steered the antennas. The aperture of the antennas were 3,600 square feet (330 m2). The antennas were 177 feet (54 m) long and weighed 380 tons. The antennas were housed in radomes the size of a 14-story office building. The challenge was to steer the huge antenna to track the satellite that moved up to 1.5 degrees per second with a pointing error of less than a .06 degree."

formatting link
communications satellites are in geostationary orbits, but they don't have to be - the Soviet Union and now Russia uses satellites in Molniya orbits, which are neither geostationary, nor geosynchronous; and Iridium satellites are nowhere near geostationary as they are in Low Earth Orbit.

Cheers,

Sid

Reply to
unopened

I think you'll have Dennis going round in circles now;)...

Reply to
tony sayer

Ellipses, surely...?

Cheers,

Sid

Reply to
unopened

snipped-for-privacy@p36g2000prp.googlegroups.com...

So is the "Approx". I hope that's not how you estimate for your DIY.

MBQ

Reply to
Man at B&Q

Not a chance, I knew Telstar was in a LEO. I have seen a dish that used to track it.

Reply to
dennis

My recently purchased portable Sony DAB radio can auto-set it's time, presumably from something in the DAB signal.

Not sure of the precision, as it only displays the time to the nearest minute

Reply to
chris French

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.