European wavelength agreements

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The fear of potential chaos

As the number of radio stations in Europe multiplied in the early 1920s, stations operating on the same wavelength, or on wavelengths very close to each other, suffered from the effects of mutual interference. It did not help that standards of measurement of wavelengths in different countries varied, in some cases considerably, and some stations simply did not adhere to their allocated wavelength with the care that was necessary to avoid interference. The BBC's Arthur Burrows outlined the precariousness of the situation in an article:

The spaces between the wave bands are already so few and so narrow that mutual interference can only be avoided with difficulty. The use of a defective wave meter can blot hundreds of square miles off the wireless map; an experimental transmission undertaken at some distant point without adequate notice and previous consultation with all parties likely to be concerned can easily wreck a programme costing hundreds of pounds. Such happenings have got to be avoided.[1]

This 'heterodyne distortion', manifested itself to listeners in the form of an intense high-pitched whistle which got worse the further away you were from a transmitter. The very real fear of chaos over the European airwaves in 1925 and 1926 encouraged Britain to take a lead in organizing the international control of broadcasting.

UIR created

The IBU regarded radio interference as a uniquely European problem resulting from the "proximity of nations which each make large use of broadcasting".

At a conference in London on 18 and 19 March 1925, the first international broadcasting organisation, the Union Internationale de Radiophonie (UIR), was created.[2] As the biggest and most powerful broadcasting concern in Europe, the BBC was in the driving seat of the UIR and decided Arthur Burrows should be its first Secretary-General and Admiral Carpendale its first president.[3]

At the Geneva Conference in April it was decided to establish a permanent committee of the UIR "to advise the Council on purely technical matters", comprising technical representatives of European broadcasting organisations. They were tasked with drawing-up a plan to allot wavelengths among 16 different countries. The president of the technical committee was Raymond Braillard of Belgium, and the secretary was M Divoire of Brussels University.

July 1925 conference

To deal with the problem of interference, the IBU organised a European Conference of Wireless Engineers in Geneva in July 1925. Radio engineers and broadcasting lawyers from around 13 broadcasting organisations representing some 50 stations attended. Their task in creating a new wavelength plan was considerable: having to reorganise 87 existing stations and include another 37 stations in the short term within the available wavebands between 550 and 270 metres, and long waves between 1,000 and 2,000 metres. They soon decided to focus on medium waves for the time being.[4]

A Committee of seven was formed to conduct trials, particularly to establish what could be regarded as the minimum separation between the wavelengths of two adjacent stations. It suggested the following revision of Scottish wavelengths for the purposes of the trial:

  • Aberdeen: from 495 to 496m
  • Glasgow: from 422 to 420m
  • Dundee: from 331 to 331.5m
  • Edinburgh: from 328 to 327.5m

In order not to interrupt normal broadcasting, tests on the new wavelengths were carried out across Europe on a number of alternate nights in late August/early September between midnight and 2am (BST). After each test listeners were asked to write to the BBC to give their observations and any interference discovery of interference would be at once wired to Geneva, where the Committee would make alterations in the wavelengths as necessary.[5]

For the BBC's part, careful records were made at the International Receiving Station at Hayes in Middlesex, and subsequent comparisons enabled the engineers to check the wavelengths employed by all its stations.[6]

September 1925 conference

The results of the tests were considered at the International Broadcasting Conference of 21 and 22 September in Geneva. The delegates all agreed that the last plan had been too ambitious and came to the acceptance that Europe simply had too many broadcast stations for the waveband allotted to broadcasting (300–500 metres).[7]

The BBC's chief engineer, Peter Eckersley, and Raymond Braillard, the chief technical expert of Belgian radio, evolved the outline of a new scheme whereby a number of wavelengths were allotted to each country according to a formula which took account of area, population, and the volume of telephone and telegraph traffic.

A distinction between two categories of wavelength was made — the first, 'exclusive wavelengths' which could be used by one station only and which were to be separated from each other at a frequency interval of 10 kilocycles; the second, 'ordinary' or 'common' wavelenths which could be used in parallel in different places. The exclusive wavelengths were to be distributed according to the formula; the 'common' wavelengths were to be reserved for low-power stations of ½ kilowatt or less.

The nations regarded this as a temporary compromise, however. The reality was that a number of stations would have to be closed. "Certain countries having a large number of wavelengths will have to sacrifice their claims in order to provide channels for countries having none." The Geneva experts were uniformly sympathetic towards the idea of building up broadcast schemes in terms of fewer high-power stations covering large areas, rather than many small low-power ones. This was interpreted as spelling the end of the BBC's relay stations. Head office officials told one newspaper that "probably the best arrangement for Scotland would be one high-power station erected on a suitable central site which would cover the entire country".[8] Speculation on possible sites included Perth, which would give crystal reception from Newcastle to Cromarty; or Kingussie, which would be capable of incorporating many of the islands (except for Shetland).[9]

In a broadcast talk on the BBC's London station, 2LO, Eckersley explained that the majority of stations would change their wavelengths slightly, but certain stations would be forced to continue to work on the same wavelength as another station (so-called 'common wavelengths').[10]

December 1925 conference: formula agreed

By the December meeting, the draft plan had been reworked into a "logical" formula, from which an "equal" allocation of frequencies could take place, and this formula was accepted by the Council of the UIR.[11]

The IBU's technical staff suggested that a separation of 9–10 KHz would create a sufficient "border" between stations to prevent interference. Using this measurement, IBU technicians then calculated the number of available wavelengths on the spectrum and developed a formula for dividing them up between nations.

Each IBU member would receive at least one exclusive wavelength (if not several) as well as the use of several common wavelengths. The number of wavelengths assigned to each country would be weighted according to a variety of factors: a nation's geography, its population, its degree of economic development, and its existing telecommunications infrastructure. This formula, while intended to be "scientific", clearly left room for subjective assessments of a nation's needs. Countries with older radio stations could claim sovereignty over particular wavelengths, a strategy that Britain and Belgium both manipulated to their advantage. These decisions necessitated regular testing and, consequently, each country was required to have a calibrated wave-meter.[12]

Further experiments began in early 1926, designed not only to test the effects of the rationing of wavelengths but the efficacy in practice of 'exclusive' and 'common' wavelengths.

Implementing the 1926 Geneva Plan

The final 'Geneva Plan' was accepted by the Council of the UIR in July 1926. For technical reasons, however, the date of operating the plan had to be postponed twice, first from September to October and then from October to 14 November. The reason at this stage was not lack of goodwill but inadequate "international wave metres to ensure the maximum success for the plan".[13]

Before the plan came into effect the BBC had been using 20 medium wavelengths, some shared with other countries; it would now use ten exclusive medium wavelengths, and five 'common' wavelengths below 300 metres.[14] (Britain's single long wavelength at 5XX Daventry would continue as before.)

Under the original scheme, all the principal BBC stations had been allocated exclusive wavelengths, and the relay stations were to share wavelengths with distant European low-power stations. But, with the object of keeping full control over British transmissions, a re-shuffle was made by the BBC, the relay stations all being placed on the British exclusive wavelength of 288.5 (with the exception of Leeds and Bradford, presumably due to the close geographical proximity of the transmitters); and Birmingham and Aberdeen sharing the wavelength of 419.8m. The Scottish changes were as follows (former wavelengths in brackets):

  • Aberdeen: 491.8 (497.5), shared with Birmingham
  • Glasgow: 405.4 (421.6)
  • Edinburgh 288.5 (??)
  • Dundee: 288.5 (315)

Impact on Scotland

Peter Eckersley admitted that "many people will be adversely affected by the new plan" and predicted an immediate "outcry".

Previously, a difference of 13 metres between the wavelengths of the Edinburgh and Dundee stations was quite sufficient to enable listeners to separate them, but now that they were sharing the same wavelength their coverage areas were confined largely to their city boundaries. Anyone outwith a radius of three to four miles from the transmitter was liable to be adversely affected. This was a particular problem for listeners in Fife, equidistant between the Edinburgh and Dundee stations. The BBC advised people in Fife to take their programmes from Glasgow or Daventry instead.

Listeners in Perth, who previously enjoyed excellent reception of the Dundee station, found it impossible to get anything like satisfactory results after the changeover. A largely-signed petition was sent to the the BBC asking that the Dundee station be allocated a separate wavelength.[15]

The BBC had a change of heart, and on 5 December 1926, Edinburgh was moved to a wavelength of 294.1 metres.[16]

But also, as a result of Aberdeen sharing a wavelength with Birmingham, the former's efficient radius was reduced to about 25 miles. This deprived listeners in the rest of Scotland from a programme that had always specialised in Scottish programmes. Likewise, listeners in the south of England now found Aberdeen blotted out by Birmingham, and vice-versa.[17]

Exckersely assured listeners that no-one would lose out and that the effectiveness of the long-wave station at Daventry, 5XX, would be increased as a result:

I want to assure readers of The Radio Times that in no case, under the new regime, has service through an alternative channel been denied, and that Daventry will be the mainstay of those listeners who are left out in the cold with regard to the relay stations and, incidentally, Aberdeen and Bournemouth.

Listeners to the Glasgow station were the only ones not affected by the changes.

Nonetheless, Eckersley argued that the changes were being made for the good of broadcasting in the longer term:

To leave European broadcasting to expand unchecked along its present lines would be to court final disaster. Just as an apple tree allowed to grow unpruned produces in the end worse fruit, so broadcasting allowed to expand unchecked will in the end react unfavourably upon the service. Early pruning is essential now if the future of European broadcasting, and with it British broadcasting, of course, is to be assured. We have looked in vain for methods to overcome this interim stage without any dislocation in the present service, but to achieve in the end a system using fewer wavelengths and higher power, we have to go through a period of restriction of service to a certain extent.[18]


As for Aberdeen:

After the original plan had been working for about ten days, it became clear that the sharing of one wavelength between Aberdeen and Birmingham was not going to be entirely successful. Reception of both stations daring daylight was satisfactory, but after dark the 'background', due to the unwanted station, was excessive. We had hoped that each station would give an uninterrupted service up to a distance of about twenty miles, but this was definitely not the case. With the agreement of the Geneva authorities, we decided to put Aberdeen on the International Common Wavelength of 500 metres. This means, of course, that Aberdeen is sharing a wavelength with other Continental Stations, but considerably improved reception is now being obtained from both stations.[19]

Occasional problems continued to rear their head, however. In November 1927, it was reported that listeners along the Moray Firth could no longer hear "more than an occasional word or phrase in programmes broadcast from Aberdeen" on account of the wavelength of the station being practically the same as that of many German stations.[20]

Further changes: 23 January 1927

Further changes took place on Sunday 23 January 1927. Edinburgh was given the exclusive wavelength of 288.5m in order to improve reception conditions. Meanwhile, the four relay stations which had been working together on 288.5m — namely, Hull, Stoke, Dundee, and Swansea — were transferred to the international common wave of 294m.[21]


The problem was only going to get worse and it was around this point that the BBC accepted that its future plans would involve the elimination of small relay stations rather than their increase, and their replacement by a few high-power stations, with Scotland having perhaps just one high-power station which would cover the entire country.


The changes were for the best. As a quote from the BBC in May 1927 stated:

The growth of broadcasting in European countries like that in this country, has been rapid, and it would not be practicable for the Scottish broadcasting stations now to revert to the wave-lengths which they used prior to the rearrangement last autumn, as the interference on these wave-lengths would be greater than on those now used.[22]


  1. Arthur R. Burrows, 'A Wireless "Clearing House"', Radio Times, No. 83, 24 April 1925, 195.
  2. It was not until 1927 that the United States Congress passed the Radio Act, which brought into existence the Federal Radio Commission.
  3. Briggs, Vol. 1, 287–8.
  4. Suzanne Lommers, Europe — On Air: Interwar Projects for Radio Broadcasting (Amsterdam: Amsterdam University Press, 2014), 76.
  5. 'Wave-lengths: European Distribution', Glasgow Herald, 27 August 1925, 3.
  6. 'Official News and Views: Standard Wave-Lengths for Europe', Radio Times, 28 August 1925, 408.
  7. The experts weighing the evidence provided by the tests found that to give every existing station a 'clear' wavelength for broadcasting, it would be necessary to utilise all the space in the waveband between 200–600 metres, and also all that between 1,000–2,000 metres — and no government was willing to surrender that much to broadcasting! See 'Overcrowded Ether', Hartlepool Northern Daily Mail, 1 October 1925, 3.
  8. 'Fife and Crystal Reception: Statement by BBC Officer', Evening Telegraph, 13 October 1925, 2.
  9. 'Crystal Reception for All Scotland', Evening Telegraph, 14 October 1925, 11.
  10. Captain Peter Eckersley, 'What Happened in Geneva', BBC 2LO, 10.40 pm, 29 September 1925.
  11. Briggs, 289.
  12. Rebecca P. Scales, Radio and the Politics of Sound in Interwar France, 1921–1939 (Cambridge: Cambridge University Press, 2016), 138.
  13. P. P. Eckersley, 'Britain's New Wave Lengths', Radio Times, 12 November 1926.
  14. Briggs, Vol. 1, 290.
  15. 'Perth Wireless Grievance', Courier, 1 December 1926, 7.
  16. 'Sorting Out the Wave-lengths: Another Change for Edinburgh', Courier, 3 December 1926, 5.
  17. 'The New Wave-lengths: Position in Scotland', Scotsman, 13 November 1926, 12.
  18. P. P. Eckersley, 'Britain's New Wavelengths', Radio Times, Vol. 13, No. 163, 12 November 1926, 393–4.
  19. 'The New Wavelengths: Some Modifications and Changes', Radio Times, Vol. 13, No. 167, 10 December 1926, 614.
  20. 'Radio Wave Length Jumble', Courier, 16 November 1927, 3.
  21. 'More Wave Length Changes', Courier, 20 January 1927, 5.
  22. 'Wireless Reception at Arbroath', Courier, 16 May 1927, 3.