Memories - old technology

In the case of a red phone box BT (or rather, the Post Office) owned them.

Andy

True - but TV sound generally has low dynamics - because of the appalling amps and speakers fitted to most sets.

Good speakers on a TV? That would be a first. Unless you were using external ones.

Thing when comparing NICAM to analogue (apart from NICAM being stereo) is that most TVs had anything but state of the art FM tuners on the audio side. NICAM chips were produced to a rather higher standard.

But absolutely no doubt it was an excellent and very clever answer to a problem.

I'd have thought that with uncompanded raw PCM (like a CD) with 11 bits, it would be the *quiet* sections where you would notice the quantisation noise. With 11 bits total, you are mapping the maximum sound into 11 rather 16 bits, and adjusting the gain accordingly. In your example where the top 6 bits are 0, you've 5 bits of useful signal, whereas with 16-bit true CD, you've got 10 bits. So the waveform of a quiet instrument can only take one of 2^5 = 32 different values - ie -16 to +16. With 10 bits, you've got 2^10 = 1024 different values - ie -512 to +512.

Quantisation makes the sound gritty and metallic. It's the audible equivalent of representing a continuous black-to-white gradient in a picture as a series of different steps - a continuous slope becomes a staircase.

They weren't the private ones then though.

Jim's was just an off the cuff remark, he didn't even say what was wrong with DAB in his opinion, perhaps it was power consumption, I mean how long does your DAB portable run for on a PP3?

My single valve shortwave set using a 1T4 (DF91) warmed up almost instantaneously, Less than one second, and you could hear the thermal stress of the heater in the cans.

"Cuckoo tone"

Yep. As I said, the D series were filament cathodes. 1.5v.

That's correct, BT had no incentive not to bill the user for these calls, remember when implemented, the payphone itself generated the cuckoo tones when any of the allowed operator codes 1xx was dialled.

I actually discovered an exploit on the Landis+Gyr Agifon 50, and I even brought it to the attention of the manufactures. It had to have the original old firmware The phone had to be set up for LD dialling

As I recall it went like this, the hookswitch was reasonably protected with a delay so you couldn't "tap-dial" but in some exchanges with a little practice you could use the hookswitch to dial a single "1" you then dialled 0072 on the keypad normally.

The *exchange* would see 10072 which would of course connect you with the operator (the 72 would be ignored of course). The *phone* however would think 0072 had been dialled and that was at one time a prefix for a toll free radipaging service, and the phones firmware treated it the same as 0800 0500 0808, so no cuckoo tone!

'if you love radio don't buy a DAB ....... ' seems pretty clear to me.

I don't have any portable radios in use in this house. Just one I take with me when staying elsewhere. So small enough to fit in the luggage. But not one which runs from a PP3. Very expensive source of battery power.

I am sure Terry was referring to the "Pay on answer" equipment, it was intraduced as early as 1958

I have one of these - which isn't DAB, and costs peanuts to run. I paid less than 50 quid for it, and had the batteries anyway.

Nearly all of the delta-gun sets had that arrangement. The Philips G8 had them under an oversized plastic speaker grille which was fixed by a single screw hidden by a nameplate beneath the grill.

Except when you have a vintage TV and you would like to see it working.

All done with a PC with a suitable display card (an old ATI Radeon HD

and a home made VHF modulator, I'm using this design

Most poeple use an Arora 625 to 405 digital converter which costs about £200 and is far less flexable.

Technical Trading in Brighton, now there's a blast from the past. I can remember avidly waiting foe a parcel from TT when I was a schoolkid, but, I can't remember what it was. There always seemed to be an intervening Bank Holiday to extend the suspense, when I ordered something interesting.

As did its predecessor, the G6. A wondrous piece of over engineered electronics. Partially, at least.

A wireless wireless, what ever next ;-)

yes battery consumption is piss awful whereas my Cokoa pn-204 runs for weeks on six AA batteries...

I have DAB and stand alone internet radios coming out of my ears but I prefer the Russian MW/LW any day.....

not to mention I got two for a pound each brand new and boxed at a Glasgow car boot sale.......complete with the smell of fullers earth ...Mmmmmmm