The North American Radio Broadcasting Agreement, usually referred to as NARBA, is a treaty that took effect in March 1941 and set out the bandplan and interference rules for mediumwave AM broadcasting in North America. Although mostly replaced by other agreements in the 1980s, the basic bandplan of NARBA has remained to the present day. Among its major features were the extension of the broadcast band from its former limit of 1500 kHz to 1600 kHz, (now 1700 kHz) and the shift of most existing AM stations' frequencies to make room for additional clear-channel station allocations for Canada and Mexico.[1]
The agreement eventually governed AM band use in the United States, Canada, Mexico, Cuba, the Dominican Republic, and Haiti. In accordance with the treaty, clear channel frequencies were set aside across the radio dial, at a rate of about one per 100 kHz, and the 1230, 1240, 1340, 1400, 1450, and 1490 channels were reserved mainly for local stations. The agreement also officially expanded the upper limit of the AM broadcast spectrum from 1500 kHz to 1600 kHz. It required that most existing AM stations change frequencies, resulting in a massive shuffling of radio station dial positions.
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Although a 1933 conference on the subject failed, a 1937 North American Radio Conference in Havana agreed on the principles for frequency allocations. In late 1937, the Inter-American Radio Conference agreed to protect U.S. AM stations by eliminating Mexican border blasters. In mid-1938, the United States Senate ratified the Havana treaty and asks for it to take effect a year after the treaty is ratified by three of the four participating countries of Canada, Cuba, Mexico, and the U.S. At first, the Mexican Senate refused to ratify. Nevertheless, the U.S. and Canada completed a frequency agreement in 1939, based on the Havana Treaty, and Mexico ratified the NARBA treaty at the end of the year.[2]
In the United States, the new frequencies took effect at 3:00 a.m. Eastern[1] on 29 March 1941.[2]
A three-year NARBA agreement in 1946 gave Cuba five U.S. clear channel allocations. A November 1950 NARBA agreement, signed by the Bahamas, Canada, Cuba, the Dominican Republic, Jamaica and the U.S., gave Cuba the right to use six, and Jamaica two, U.S. clear channel allocations.[2]
Among the most significant changes were:
Old Freq. (kHz) |
Station(s) | Moved (kHz) |
New Freq. (kHz) |
Notes |
---|---|---|---|---|
540 | CBK | unchanged | 540 | Canadian clear |
550-680 | all | unchanged | 550-680 | |
690 | all, except CFRB | unchanged | 690 | Canadian clear |
CFRB | 860 | |||
700-720 | all | unchanged | 700-720 | |
730 | all, except CFPL | unchanged | 730 | |
CFPL | — | 1570 | ||
— | new Canadian clear | 740 | allocated to CBL which moved from 840 | |
740-790 | all | up 10 | 750-790 | |
— | new Canadian clear | 800 | allocated to CKLW which moved from 1030 | |
790-830 | all | up 20 | 810-850 | |
840 | CBL | — | 740 | |
— | new Canadian clear | 860 | allocated to CFRB | |
850-870 | all | up 20 | 870-890 | |
— | new Canadian clear | 900 | allocated to CHML (and CJBR) | |
880-970 | all | up 30 | 910-1000 | |
980 | KDKA | up 40 | 1020 | |
990 | WBZ | up 40 | 1030 | |
1000 | WHO | up 40 | 1040 | |
1010 | KQW (now KCBS) | 740 | KQW did not move until 1947 | |
1020 | KYW | up 40 | 1060 | |
1030 | CFCN (now CBR) | down 20 | 1010 | |
CKLW | 800 | |||
1040 | WTIC KRLD KWJJ |
up 40 | 1080 | |
1050 | all | up 20 | 1070 | CBA became a new Canadian clear on 1070 |
1060 | WBAL | up 30 | 1090 | |
WJAG | up 40 | 1110 | this was later traded for 780 with KFAB | |
1070–1150 | all | up 30 | 1100–1180 | |
1160 | WOWO | up 30 | 1190 | |
WWVA | up 10 | 1170 | ||
1170 | WCAU (now WPHT) | up 40 | 1210 | |
1180 | KEX | up 10 | 1190 | |
KOB (now KKOB) | 770 | |||
WDGY (now KFAN) | down 50 | 1130 | ||
WINS | 1010 | |||
1190 | WOAI | up 10 | 1200 | |
WSAZ | 930 | |||
WATR | 1320 | |||
1200–1450 | all | up 30 | 1230–1480 | |
1460 | KSTP WJSV (now WWWT) |
up 40 | 1500 | |
1470 | KGA WLAC WMEX (now WWZN) |
up 40 | 1510 | |
1480 | KOMA WKBW (now WWKB) |
up 40 | 1520 | |
1490 | KFBK WCKY |
up 40 | 1530 | |
1500 | all | down 10 | 1490 | |
1510 | CKCR (later CHYM) | down 20 | 1490 | |
1530 | W1XBS to WBRY (later WTBY, then WQQW; now dark) |
up 60 | 1590 | Since 1934 U.S. frequencies above 1500 had been allocated only to four experimental stations that broadcast with a signal 20 kHz wide for "high fidelity." The stations were converted to regular broadcasting (and regular call signs) with the NARBA frequency move. |
W9XBY to KITE (now dark) |
up 20 | 1550 | ||
1550 | W2XR to WQXR (now WQEW) |
up 10 | 1560 | |
W6XAI to KPMC (now KNZR) |
up 10 | 1560 | ||
— | new Canadian clear | 1570 | allocated to CFPL (AM) |
NARBA has been substantially superseded by the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (which was signed in Rio de Janeiro in 1981 and took effect on 1 July 1983 at 08:00 UTC). The interference protection criteria in the Rio agreement are significantly different from NARBA, particularly in that the concept of clear-channel stations is eliminated. NARBA countries the Bahamas, Canada, Mexico, and the United States are also signatories of the Rio agreement. In that agreement, the Bahamas and Canada also declared their intent to denounce NARBA.[3] However, NARBA still officially remains in effect between the Bahamas, Dominican Republic, and United States[4] because those countries have not formally abrogated NARBA.[5] The United States also has bilaterial agreements with Canada and with Mexico: the 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 the 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).[5]