For measurement projects in large spaces, having the ability to move a mic or mics around without cabling is a huge time saver. Unfortunately there are few options when it comes to wireless systems that are useful for the purpose and they’re all either expensive or require modifications and work arounds. Most wireless systems use a compander circuit that makes the system useless for measurement purposes.
wiki – Companding

The few systems that are capable of providing measurement grade results digitize the signal which avoids compansion. Fortunately, the list of options just grew. Beyerdynamic has announced the TG MM1w measurement capsule that will screw on to their wireless TG1000 series hand held body.

TG MM1w announcement
QUOTE: “The TG MM1w interchangeable measurement microphone capsule completes the beyerdynamic TG 1000 digital wireless system and serves to calibrate ELA and PA systems.
With the TG MM1w, the TG 1000 digital wireless system presents an all-in-one solution. The wireless system can now be used not only to mike speaking and singing voices and musical instruments, but also to calibrate ELA and PA systems in the theatre, at live concerts or at festivals. The TG MM1w interchangeable microphone capsule can be easily fitted on the TG 1000 handheld transmitter and makes it possible to calibrate simply, without needing to lay metres of cable.
The transmission characteristics have been selected to achieve a linear frequency response and therefore natural sound reproduction. The omnidirectional polar pattern of the TG MM1w make it possible to measure the sound equally from all directions. The compact all-metal housing has minimal influence on the acoustic environment and is also very robust.”
Beyerdynamic TG MM1w webpage
Quote: “With the TG MM1w, the TG 1000 digital wireless system presents an all-in-one solution. The wireless system can now be used not only to mike speaking and singing voices and musical instruments, but also to calibrate ELA and PA systems in the theatre, at live concerts or at festivals.
Due to the linear frequency response of TG 1000 the TG MM1w behaves in the same way as the wired version MM1. The interchangeable microphone capsule can be easily fitted on the TG 1000 handheld transmitter and makes it possible to calibrate simply, without needing to lay metres of cable.”
Each microphone is supplied with a printout of an individually measured 0° frequency response curve. The measured data can be requested by sending the serial number of the microphone head to AudioSystems@beyerdynamic.de.”
Beyerdynamic TG MM1w specsheet PDF
Beyerdynamic TG 1000 handheld transmitter webpage