The wireless cassette deck - Grundig CF-IR

[cmjones01]

Originally Posted by paulsherwin

It's just marketing speak for a brushless DC motor controlled by electronics. The motor itself isn't 'digital'. They are now widely used in domestic appliances as they are light and easier to run at high speeds.

Without wishing to continue an off-topic discussion, I feel I can usefully add to this. I have a professional interest in brushless motor drives, and I own at least one appliance which claims a "digital" motor. What distinguishes it technologically is that it only has a single stator winding rather than the usual three phases, and uses high-speed digital signal processing to model the rotation of the permanent magnet rotor in order to commutate the drive to the stator at the right times as the load varies. This results in a motor which is very small and light but rotates at very high speed and delivers a lot of power. In this respect its operation, as well as its marketing, is somewhat more "digital" than most motors.

I've just referred to the service manual of the Grundig and it helpfully includes a reprint of the user manual. This explains that the IR signals can travel a maximum of 10cm between components and - gasp! - you're allowed to put a glass shelf between them too. Otherwise, I presume, they just have to levitate. The possibilities are endless!

Chris

[jjl]

Originally Posted by knobtwiddler

Was the transmission 16-bit? 14-bit?

If this uses an optical form of normal S/PDIF then the link can can carry 20 bit audio samples, not all bits would necessarily be used though.

John

[cmjones01]

Originally Posted by jjl

If this uses an optical form of normal S/PDIF then the link can can carry 20 bit audio samples, not all bits would necessarily be used though.

The ADCs it uses are the SAA7366 in the tuner and CS5336 in the cassette deck and amplifier. The SAA7366 claims 18-bit resolution and the CS5336 16-bit resolution. In the end, all the audio that gets to your ears comes through a CS4330 DAC in the amplifier which claims 18-bit resolution.

I can see nothing to indicate that the IR connection carries anything less than the full resolution of the converters.

Chris

[G6Tanuki]

I remember that you used to be able to get IR-linked headphones... I wonder if that was part of the reasoning ? Link your cassette-player direct to your headphones so you could do things unencumbered by a trailing wire?

[cmjones01]

Originally Posted by G6Tanuki

I remember that you used to be able to get IR-linked headphones... I wonder if that was part of the reasoning ? Link your cassette-player direct to your headphones so you could do things unencumbered by a trailing wire?

That would seem sensible, but there's nothing in the service or user manuals to indicate that any of the components have the ability to send the IR beam anywhere but up/down/left/right to the other components at short range. Any incidental "scatter" of the IR beams probably wouldn't be a lot of use to headphones because there are likely to be signals passing in two directions simultaneously (the amplifier clearly provides an output for the cassette deck to record) so much digital confusion would result...

Chris

[Graham G3ZVT]

I had a Thinkpad laptop that could access the Internet via an IR link to my Sony Ericsson GPRS phone. The two devices could be almost anywhere in a small hotel room and work reliably, no doubt via reflections from walls.

[dglcomp]

I understand Ir headphones were a modulated analogue link, the Philips ones I had certainly would behave like a radio when the signal is lost. Light is just a higher frequency than the ones that used radio waves at 863-865Mhz.