Re: How Do You Rate Wireless Mic Technology?

Mark <makolber@xxxxxxxxx> writes:


  2. The required link resources. Analog FM is going to be orders of
  magnitude less efficient in both power and bandwidth than a comparable
  digital modulation with FEC.

This is not obvious to me.
Analog FM can use a class C Tx output stage.

This is not what I was referring to by efficiency, Mark. What I'm saying
is the transmit SNR and/or bandwidth required for analog FM to achieve a
desired output SNR and/or bandwidth is going to be much higher than that
predicted by Shannon's capacity formula, and since it is possible to
approach the limit these days with digital systems, the digital system
will be more power efficient.

Most analog FM wireles mic systems use companding and can achive the
required S/N and range with a 10mW to 50 mW Tx output power. And the
FM modulator / Tx is very small and simple and reliable.

I believe we need to differentiate between two classes of products.
Representative of one class is a church where the pastor wants to
be connected wirelessly. Sure, in this sort of venue, folks don't
care about 16 bit performance (or higher).

The other class would be studio work, where ambient noise levels are way
down and you're recording in high-resolution (digital) multi-track. Do
you really think people are going to want to run their $7000 microphones
through a companding stage?

It is this latter class of product I am considering targeting.

I aggree digital is more power efficent for cellphones where the low
voice quality allows for low bit rate vocoder etc and you can turn off
the Tx during speech pauses etc, but that is not the case for a hi
quality wireless mic system.

I disagree, based on the points covered above.
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Relevant Pages

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