1、QUESTION ITU-R 245/7*,*Interference to the standard frequency and time signal service in the low-frequency band caused by noise from electrical sources (2006) The ITU Radiocommunication Assembly, considering a) that the number of standard frequency and time signal (SFTS) service systems in the low-f
2、requency (LF) band (20-90 kHz), and the number of radio-controlled clocks that receive this service, are increasing; b) that the number of sources of electrical interference is also increasing, and such interference has been reported to affect severely the receiver environment of low-frequency SFTS;
3、 c) that the level of electro-magnetic interference to the LF band from all sources has not yet been clearly determined and criteria for interference from electrical sources are necessary to maintain the usefulness of the SFTS service, decides that the following Question be studied 1 How are signal
4、strength and signal-to-noise ratio measured in the LF band and what instrumentation should be used? 2 What evidence is available for the effects of electro-magnetic interference from all sources on SFTS reception in the LF band? 3 What level of emission in the LF band from all sources would cause ha
5、rmful interference as defined in section 7 paragraph 1.169 of the Radio Regulations to the reception of SFTS by radio-controlled clocks? 4 What methods can be adopted to reduce the effects of harmful interference in the LF band on the reception of SFTS by radio-controlled clocks? further decides 1 t
6、hat the results of the above studies should be in Report(s); 2 that the above studies should be completed by 2011. Category: S2 _ *In the year 2009, Radiocommunication Study Group 7 extended the completion date of studies for this Question. *This Question should be brought to the attention of Radiocommunication Working Party 1C.
