The NARBA treaties have been substantially superseded by the " Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 " ( Rio Agreement ), which covers the entire Western hemisphere, and was signed at Rio de Janeiro, Brazil in 1981, taking effect on at 08 : 00 UTC . The interference protection criteria in the Rio Agreement are significantly different from NARBA's, and the concept of clear channel stations is eliminated.
42.
As negotiations were taking place the deal fell through leaving Osborn's and Hadfield's to merge, with the foundry being located on Hadfield's East Hecla ( Vulcan Road ) site, and Edgar Allen's to purchase Jessop's, relocating Jessop's special alloy ( medium frequency ) melting on Edgar's Sheffield Road site and the 3-ton electric furnace at one end of the Tropenas Melting Shop.
43.
The 1950 NARBA provisions are still in effect for the Bahamas, the Dominican Republic, and United States because those countries have not formally abrogated NARBA . The United States also has active bilateral agreements with Canada ( " Agreement Between the Government of the United States of America and the Government of Canada Relating to the AM Broadcasting Service in the Medium Frequency Band " ( 1984 ) and Mexico ( " Agreement Between the Government of the United States of America and the Government of the United Mexican States Relating to the AM Broadcasting Service in the Medium Frequency Band " ( 1986 ) ).
44.
The 1950 NARBA provisions are still in effect for the Bahamas, the Dominican Republic, and United States because those countries have not formally abrogated NARBA . The United States also has active bilateral agreements with Canada ( " Agreement Between the Government of the United States of America and the Government of Canada Relating to the AM Broadcasting Service in the Medium Frequency Band " ( 1984 ) and Mexico ( " Agreement Between the Government of the United States of America and the Government of the United Mexican States Relating to the AM Broadcasting Service in the Medium Frequency Band " ( 1986 ) ).
