1. State-Of-The-Art PMSE
C-PMSE – Improving frequency utilization and coexistence for PMSE systems by cognitive procedures
Demonstration 2:
State-Of-The-Art PMSE
Dr. Axel Schmidt
Sennheiser electronic GmbH & Co. KG

2. Introduction to PMSE PMSE: Programme Making and Special Event
Services ancillary to programme making (SAP)
Services ancillary to broadcasting (SAB)
Electronic news gathering (ENG)
Outside broadcasting (OB)
Professional Wireless Microphone System
unidirectional wireless audio link
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

3. Professional Wireless Microphone System
Requirements
High audio quality
Low latency (analogue audio in -> analogue audio out)
Robustness
Technology
Analogue FM / several digital transmission schemes
200kHz channel bandwidth (according to ETSI EN )
Typical maximum output power of 17dBm (50mW)
IrDA interface for synchronization audio link settings between RX and TX over short distances (not during operation)
Frequency range
Secondary user in UHF (470MHz – 790MHz)
1.8GHz (in Germany only)
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

4. Multi-Channel Application
Available frequency range is divided into useable wireless audio channels which must not interfere each other
One audio channel occupies 200kHz bandwidth
It needs a minimum distance to its neighbour channel of e. g. 600kHz
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

5. Multi-Channel Application
Two audio transmitters produce intermodulation products when coming close to each other
Spectrum potentially occupied by IM3 products is not usable for high quality audio transmission
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

6. Multi-Channel Application
Similar problem at receiver side on first intermediate frequency when front end has low intercept point
Two strong signals produce intermodulation products and reduce SNR of wanted signal
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

7. Multi-Channel Application
N audio channels generate N*(N+1) IM3 products
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

8. Multi-Channel Application
But there are some more intermodulation products
IM5 products
IM3 products of 3 transmitter …
which all reduce the usable frequency range
Frequency planning is necessary to make multi-channel applications possible
Software tools for initial planning, monitoring and controlling wireless systems (WSM)
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG

9. Current Limitations Static frequency assignment
Predefined spare frequencies / links in case of emergency
No / limited remote control of audio mobile terminal during operation
No possibility to react on dynamical changes in spectrum allocation
Dr. Axel Schmidt, Sennheiser electronic GmbH & Co. KG