§ Mr. Lubbock
asked the Postmaster-General (1) if he is aware that since the new Cambridge radio telescope began operations in November, 1963, about one-third of the observing time has been ruined by interference; and what action he proposes to take to prevent this;
(2) if he will make representations to the operators of a powerful radar source, situated outside this country, who are using the 406–410 megacycle per second wave band, to avoid interference with radio astronomy observations;158W
(3) if he will set up monitoring stations so as to identify the sources of interference with radio astronomy on the 406–410 megacycle per second wave band.
§ Mr. Bevins
The 406–410 megacycle per second band is allocated to various radio services. The Radio Astronomy Service was permitted to share the band following the 1959 international Administrative Radio Conference, but while all practicable steps are taken to protect the service from harmful interference from other authorised radio users it is not always possible to do so.
Radio astronomers use exceptionally sensitive receivers, and radio noise which could be tolerated by receivers of other radio services in this band can cause interference to radio telescopes. Interference can be caused by transmitters operating on frequencies within the band used or by spurious radiation from equipment operating on another band. Radio astronomers have no claim to protection under the Radio Regulations if the interference is caused by a radio service operating in accordance with those regulations, although in this country we try to help the radio astronomers as much as we can when a case of interference arises. The frequency spectrum is too crowded to reserve this band exclusively for radio astronomers.
When the new Cambridge radio telescope began to operate and interference was experienced, the source of the interference was traced and steps were taken to remedy it. Since then other interfering signals have been received and my officials are investigating these complaints. I would not be justified in establishing monitoring stations to identify interference to radio astronomy. We must continue to rely on radio astronomers to furnish adequate data themselves to enable this to be done.
The International Telecommunication Union recommends radio astronomers to maintain close co-ordination with their national administrations on matters of frequency usage. In order to effect closer liaison with radio astronomers my officials lave established a series of regular meetings with their representatives. The difficulty over the 406–410 Mc/s band was discussed in detail only last month and is under active joint examination.159W
§ Mr. Lubbock
asked the Postmaster-General if he will now allocate the 606–614 megacycle per second wave band to radio astronomy on a permanent basis; and if he will propose to the Inter-Union Committee on Allocation of Frequencies that other nations should do the same.
§ Mr. Bevins
It has recently been agreed by the International Telecommunication Union that in Europe the 606–614 megacycle per second radio frequency channel may be used by radio astronomers on a permanent basis. In reaching this decision the Union took full account of the views of I.U.C.A.F. The channel is, however, part of a radio frequency band allocated by the I.T.U. wholly for the broadcasting service. In order to assist the radio astronomers the I.T.U. asks administrations to avoid using the channel for broadcasting services for as long as possible and thereafter to avoid the use of such effective radiated powers by broadcasting stations as will cause harmful interference to radio astronomy observations. At the present stage of development of television in the United Kingdom I cannot go further than this.