How did we think? Microphone DM30


Eric Wiebols


Hardware designer


Most fun with what I do?:

When I manage to achieve a balanced mix of the many times contra dictionary design requirements; performance (i.e. low audio noise, radio interference immunity etc.), cost and battery life.

What was the most important thing that we succeeded with in the developing of the microphone?

The companion unit “push to talk” function. It ensures that students will not interrupt each other’s radio transmissions (to the teacher) in the class room situation. We solved this with our unique feature FCR!

FCR – Free Channel Request. FCR is a great feature introduced in the Digisystem family. FCR prevents DM10 from sending on frequencies already occupied by other transmitters. Ignoring an occupied frequency and start transmitting will introduce interference to the receiver and is prevented by the FCR feature. This is usually the case when several DM10 are set to “Push to talk”. If the air is occupied by other transmitters on the same frequency, this is highlighted in the display and transmission is not possible.

Why does the microphone look like it does?

We wanted to make a robust microphone with an easy push-to-talk button. We actually made the Microphone DM30 a little bit bigger to get extra battery time.

What was the most challenging with the development of the product?

To be able to combine one radio transmitter and one receiver, without having problems with interference.

If you would dream…which product feature do you want to apply to Comfort Digisystem?

I would like to have a “remote push to talk” function with which the teacher (master unit) can select the student microphone (companion unit) to be an active transmitter, just by looking at it.