GSC: Standardization Advancing Global Communications SOURCE: GRSC Working Party 1 TITLE: Resolution GSC-10/08 Radio Microphone and Cordless Audio Standardization AGENDA ITEM: GRSC 5.5 CONTACT: Brian Copsey bc@copsey-comms.com GRSC(06)_27 Resolution GSC-10/08 Radio Microphone and Cordless Audio Standardization Progress report GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Resolution GSc-10/8 Considering: that various countries and regions have established differing standards and test methods for these devices. Resolves: to facilitate a strong and effective global radio standards collaboration on Radio Microphones and cordless Audio standardization in a technology neutral environment; that given the World wide appeal and use of band 2 micro transmitters, : That GRSC Working Party 1 should examine existing standards and limits and prepare a draft documents for GRSC#11; that given the ITU limits are different in the three regions,: The GRSC Working Party1 should examine the cost benefits of using the most stringent limits for the GRSC standards; that GRSC Working Party 1 should examine the “EMC” method of testing and report back to GRSC#11; that GRSC Working Party 1 should seek members views and comments on band sharing with other services now that the broadcast bands have become congested with simulcasting of analogue and digital transmissions. GSC: Standardization Advancing Global Communications

Resolves 2: Band II Micro Transmitters Following both practical tests and Compatibility studies a power of 50nW appears to strike the right balance between the quality of reception experienced by the user and the prevention of interference to other broadcast reception. GSC: Standardization Advancing Global Communications

Band II Micro Transmitters Measurements on a range of devices from a number of countries suggest that this power is also a mean average of those tested. ETSI TS 102 192 has been modified to incorporate these devices and await approval by WP1 and GRSC GSC: Standardization Advancing Global Communications

Resolves 3: Spurious Limits Consideration has been given to the cost /benefit of the most stringent spurious limits, for all Radio Microphone and the ETSI TS 102 192 will reflect the most stringent, leaving NSO’s to insert any changes required by national legislation GSC: Standardization Advancing Global Communications

Resolves 4:EMC method of Testing Considerable work has been undertaken to validate this method of testing low power devices, Band II micro transmitters are the first to have used the method in the ETSI standard EN 301-357(which is now out for public enquiry ) and this has been reflected in the ETSI TS 102 192 . Copies of EN 301-357 available in WP1 docbox GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications EMC method For low power devices: Maximum erp/eirp is converted to dBmicroVolts/metre at a distance of three metres The new value is given as a relaxation of the EMC limit at the frequency of operation The transmitter mask (modulated) is adapted to the new EMC mask Spurious emissions from the transmitter shall meet the EMC limit GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications EMC example: Tx mask GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications EMC example Transmitter mask 0 – 90dBc EMC limit at 4 nW erp: +40 dBmicroVolts/metre @ 3 metres Relaxed EMC limit for 50 nanoWatts erp +52.2 dBmicrovolts/metre @ 3 metres GSC: Standardization Advancing Global Communications

Resolves 5: Bandsharing Information from the UK Cave Review has been placed in the WP1 docbox: Conclusion of review “sharing is the default position” Following slides show the DVB-T “problem” Work continues in identifying potential spectrum for sharing GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications DVB-T introduction UHF TV frequencies today TV transmitters Radio microphones Today: Analogue TV only Transition: Analog. + DVB-T UHF TV frequencies by 2010 Target: Full DVB scenario New Services GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications UHF spectrum sharing Today we share frequencies... Radio microphones and TV share the UHF frequencies Exclusive frequency ranges for radio microphones do not exist world wide and in Europe. The main goal of regulation is to save frequency resources with DVB-T! The distribution of TV signal concept has changed from roof antenna to in door receiving equipment. As result the radio microphone receiver interferences will be increased. TV will give up UHF frequencies by 2010 to new services! That reduces the available frequencies for radio microphones. ... tomorrow we will struggle GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Basic interference principle for radio microphones Interference to radio microphones generated by DVB-T Transmitter: A DVB signal in same channel like radio microphone (e.g. Transmitter on wide distance). DVB adjacent channel noise (Unwanted transmitter side band or wideband noise). Interference generated by radio microphone components: Receiver desensitising by multi channel microphones system to them self. Unwanted signals generated by Intermodulation. Additional receiver noise (e.g. blocking). Intermodulation on microphone transmitter output. GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications The effect of external interference produced by DVB-T noise DVB-T transmitters, which use same channel as radio microphones, affect the reception of radio microphones only with a part of their spectrum (IF BW). Outside of the DVB-T channel the transmitter emissions decrease rapidly. Out of band DVB-T emissions can only be filtered at the DTV transmitter! All Interferences reduce the range of the wireless microphones substantially. GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications The unwanted emissions between two DVB-T transmitters Between two DVB-T transmitters the noise floor is much higher. Here is the wireless microphone quality of reception substantially reduced. GSC: Standardization Advancing Global Communications

DVB-T is a multi carrier signal DVB-T signal interferes with radio microphone receiver with about 7000 carriers GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Typically protection distance caused by noise & Intermodulation In which frequency spacing can a microphone be used again? ---- Left DVB-T edge ---- ETSI DVB-T spectrum Mask ---- 1st applicable microphone channel Radio microphones need to be separated by 800 kHz from the edge of the DVB-T mask! GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Wireless microphones RF performance made by hardware Important components in the microphone receiver A high signal quality reduce adjacent channel disturbance This units are fundamentally for the RX sensitivity and the receiver interference immunity Oscillator UHF filter Pre Amp UHF filter Mixer IF-Filter Band pass filters define the receiver frequency range and reduce out of band disturbances Filter for the used signal and adjacent channel disturbance The quality of each and every component in this chain define the audio quality and performance of a wireless microphone system GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Simplified test arrangement for interference examination Test procedure: An artificial microphone signal is fed into the free field and thus the effects of the DVB-T transmitter with different frequencies is observed. The quality limit for a radio microphone receiver is the S/N of at least 80dB(a). The FM generator level will be tuned to 80dB(a) on receiver. GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Examples of measurement results Interference to wireless microphones by DVB-T transmitters Two TV channels are occupied by DVB-T. Each color shows another test receiver. Shown is the receiver input signal for 80dB(a) measures by spectrum analyzer: GSC: Standardization Advancing Global Communications

Required frequency resource @ multi channel operation (MHz) ( Ch ) Every receiver gets the same input level / Intermodulation product distance = 100kHz GSC: Standardization Advancing Global Communications

Sharing Spectrum in the UHF band: That’s a practical situation UHF frequency allocation by TV at Athens in May 2006: The situation: Almost all UHF channels are used by TV stations The Job: Installation and operation of multi channel radio microphones and IEM GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Conclusion DVB-T is coming and continues to grow. Spectrum is getting rare day by day. Clever spectrum management is the way forward in the DVB-T environment. For the microphone manufacturers substantial investments are necessary to fulfill the rising customer requirements and allow sharing spectrum between DVB-T transmitters. New frequency resources are required. Don’t forget the multiplicity of the applications called “Radio Microphone” Consider the immense length of the creation of value added chain begun with wireless microphones to the home TV, MP3 player, Sport event and much more. GSC: Standardization Advancing Global Communications

GSC: Standardization Advancing Global Communications Future: Resolves 1:to facilitate a strong and effective global radio standards collaboration on Radio Microphones and cordless Audio standardization in a technology neutral environment Continue work on the issues of digital equipment and appropriate test methods Continue work on bandsharing GSC: Standardization Advancing Global Communications