{"id":221,"date":"2011-07-07T14:31:30","date_gmt":"2011-07-07T19:31:30","guid":{"rendered":"http:\/\/swling.com\/blog\/?p=221"},"modified":"2011-07-07T19:09:11","modified_gmt":"2011-07-08T00:09:11","slug":"between-broadcasts-exploring-interval-signals","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2011\/07\/between-broadcasts-exploring-interval-signals\/","title":{"rendered":"Between Broadcasts-Exploring Interval Signals"},"content":{"rendered":"<p><em>Lately, I&#8217;ve been listening to a plethora of shortwave broadcasts as I&#8217;m about to review several new radios. I&#8217;ve noted so many great interval signals that are still in use.\u00a0The following is a reprise of a previous post&#8211;from over two years ago&#8211;about interval signals. If you&#8217;ve never heard of interval signals, this post offers an introduction.\u00a0<\/em><\/p>\n<p>What are interval or tuning signals? Often the most recognized sounds in the shortwave bands are the repetitive tones and musical interludes heard between broadcasts, known as interval signals. These are simply characteristic\u00a0 musical phrases that broadcasters play between programs.\u00a0 In fact, for me, nothing is more nostalgic than to hear the interval signals of some of my favorite broadcasters from my youth. Here are a few classic examples of interval signals:<img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-254\" title=\"Analog Radio Dial\" src=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/swdial.jpg\" alt=\"Analog Radio Dial\" width=\"219\" height=\"148\" \/><\/p>\n<ul>\n<li><a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/bbc_ws.mp3\">BBC World Service<\/a><\/li>\n<li><a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/rta_el.mp3\">Radio Algiers<\/a><\/li>\n<li><a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/trt_el.mp3\">Voice of Turkey<\/a><\/li>\n<li><a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/rhc_el.mp3\">Radio Havana Cuba<\/a><\/li>\n<\/ul>\n<p>Interval signals usually include station and program identification, and are often in multiple languages. Not only do they help identify the station, but in the days of crowded international broadcast bands, interval signals helped listeners tune in and adjust their radios prior to program commencement.<\/p>\n<p>Broadcasters have been using interval signals since the 1920s, but there has been a decline with the advent of digitally tuned radios which, unlike analog tuners, take the guesswork out of tuning into a specific frequency.<\/p>\n<p>So, in this digital age, are interval signals still around? Sure. Many broadcasters believe an interval signal is still the best way to announce station and program identification; one might say their interval signals have become audio &#8220;logos.&#8221;<\/p>\n<p>Here is an audio clip I recorded on April 23, 2009, of the interval signal for the new Happy Station Show: [<a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/happystationintervalsignal.mp3\">Click here to listen<\/a>]<\/p>\n<p>For comparison, listen to this audio clip of the Happy Station Show from Jan 20, 1980, when it was a part of Radio Netherlands: [<a href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/rni_hap.mp3\">Click here to listen<\/a>]<\/p>\n<p><strong>Listening for Signals<\/strong><\/p>\n<p>Where can you hear interval signals today?\u00a0 Fortunately, they can be heard all over the shortwave broadcast spectrum. The best times to hear interval signals are on the top of the hour and sometimes at the half or quarter hour.<\/p>\n<p>Another great place to hear interval signals are on the web. There are several interval signal databases where you can listen to a wide variety of interval signals. One of my favorites is the <a title=\"IntervalSignals.org\" href=\"http:\/\/www.intervalsignals.org\">Interval Signal Database<\/a>. This site is in German and <a title=\"IntervalSignals.org English Homepage\" href=\"http:\/\/www.intervalsignals.org\/html\/e_index.html\">English<\/a> and is well categorized and searchable. In fact, Bernhard, the webmaster of the <a title=\"IntervalSignals.org\" href=\"http:\/\/www.intervalsignals.org\">Interval Signal Database,<\/a> gave me permission to publish several of his audio clips above. [<em>Danke<\/em>, Bernhard!]<\/p>\n<p>Here is a list of interval signal websites:<\/p>\n<ul>\n<li><a title=\"IntervalSignals.org\" href=\"http:\/\/www.intervalsignals.org\">IntervalSignal DataBase<\/a><\/li>\n<li><a title=\"IntervalSignals.net\" href=\"http:\/\/intervalsignals.net\">IntervalSignals.net<\/a><\/li>\n<li><a title=\"http:\/\/www.asahi-net.or.jp\/~RP4N-KWMR\/bcl\/index.html\" href=\"http:\/\/www.asahi-net.or.jp\/%7ERP4N-KWMR\/bcl\/index.html\" rel=\"nofollow\">Nobuyuki Kawamura&#8217;s Interval Signal Library<\/a><\/li>\n<\/ul>\n<p>Since he&#8217;s somewhat of an interval signal guru, I asked Bernhard for his favorite interval signal recording. He pointed out <a title=\"Click here to go to page, then stream audio.\" href=\"http:\/\/www.intervalsignals.org\/db\/d_detail.php?Audio=oey21\">this one<\/a> from the Cold War era:\u00a0 it is a recording of a special low-power (1kW) training station of the Austrian military. Bernhard informed me that in times of crisis, <a title=\"Click here to go to page, then stream audio.\" href=\"http:\/\/www.intervalsignals.org\/db\/d_detail.php?Audio=oey21\">this station<\/a> was to serve as a back-up for the Austrian Radio ORF.<\/p>\n<p><a title=\"Leave a comment--click here!\" href=\"http:\/\/swling.com\/blog\/?p=221#respond\"><strong>Leave a comment:\u00a0 What is your favorite interval signal, and why?<\/strong><\/a><\/p>\n<p>\u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 \u2022<\/p>\n<p><em>On a side note&#8211;Bernhard also pointed out one of his favorite non-interval signal recordings.\u00a0 <a title=\"Click to play recording\" href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/ert_tuer.mp3\">In this recording<\/a>, the news reader started the German language news by reading the frequencies, then noticed that the studio door was open.\u00a0 You can <a title=\"Click to play recording\" href=\"http:\/\/swling.com\/blog\/wp-content\/uploads\/\/2009\/05\/ert_tuer.mp3\">clearly hear<\/a> her getting up to close the door in the recording.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lately, I&#8217;ve been listening to a plethora of shortwave broadcasts as I&#8217;m about to review several new radios. I&#8217;ve noted so many great interval signals that are still in use.\u00a0The following is a reprise of a previous post&#8211;from over two years ago&#8211;about interval signals. If you&#8217;ve never heard of interval signals, this post offers an [&hellip;]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[8,56,442],"tags":[104,60,95,94,103,4100,443,105,96,97,106],"class_list":["post-221","post","type-post","status-publish","format-standard","hentry","category-articles","category-broadcasters","category-music","tag-bbc","tag-happy-station-show","tag-interval-signal","tag-interval-signals","tag-intervalsignal-database","tag-music","tag-primer","tag-radio-algiers","tag-tuning-signal","tag-tuning-signals","tag-voice-of-turkey"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-3z","jetpack-related-posts":[{"id":65726,"url":"https:\/\/swling.com\/blog\/2026\/04\/bbc-interval-signals-then-and-now\/","url_meta":{"origin":221,"position":0},"title":"BBC Interval Signals \u2013 Then and Now","author":"Thomas","date":"April 3, 2026","format":false,"excerpt":"by Dan Greenall A half century ago, the BBC World Service used a number of different interval signals. \u00a0 A few minutes prior to the start of a broadcast, a recognizable, often repeating tune would be played that would enable listeners to more easily locate the BBC in a crowded\u2026","rel":"","context":"In &quot;News&quot;","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2026\/04\/BBC-Ascension-1970-front.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2026\/04\/BBC-Ascension-1970-front.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2026\/04\/BBC-Ascension-1970-front.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2026\/04\/BBC-Ascension-1970-front.jpeg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2026\/04\/BBC-Ascension-1970-front.jpeg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":31361,"url":"https:\/\/swling.com\/blog\/2018\/03\/interval-signals-radio-astronomy-bliss\/","url_meta":{"origin":221,"position":1},"title":"Interval Signals + Radio Astronomy = Bliss","author":"Thomas","date":"March 28, 2018","format":false,"excerpt":"Yesterday, I spent part of the better part of the day at the Pisgah Astronomical Research Institute (PARI): a place that has begun to feel like a home away from home. As you might imagine, radio astronomy observatories are places with very low levels of radio frequency interference. Since I\u2026","rel":"","context":"In &quot;Mediumwave&quot;","block_context":{"text":"Mediumwave","link":"https:\/\/swling.com\/blog\/category\/mediumwave\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/03\/PARI-Radio-Telescope-Dish-Astronomy.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/03\/PARI-Radio-Telescope-Dish-Astronomy.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/03\/PARI-Radio-Telescope-Dish-Astronomy.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/03\/PARI-Radio-Telescope-Dish-Astronomy.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":42146,"url":"https:\/\/swling.com\/blog\/2020\/02\/help-brian-identify-this-1970s-era-interval-signal\/","url_meta":{"origin":221,"position":2},"title":"Help Brian identify this 1970s era interval signal","author":"Thomas","date":"February 23, 2020","format":false,"excerpt":"[Mystery solved! Click here to read the update.] Many thanks to SWLing Post contributor, Brian (W9IND), who writes: I want to thank you for stirring a memory that I never thought I\u2019d relive \u2013 even though it still doesn\u2019t solve the mystery of what the heck I was listening to\u2026","rel":"","context":"In &quot;News&quot;","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/09\/SX-99-Dial-Nar.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/09\/SX-99-Dial-Nar.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/09\/SX-99-Dial-Nar.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/09\/SX-99-Dial-Nar.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":60019,"url":"https:\/\/swling.com\/blog\/2024\/06\/can-you-help-dan-identify-this-mystery-interval-signal\/","url_meta":{"origin":221,"position":3},"title":"Can you help Dan identify this mystery interval signal?","author":"Thomas","date":"June 17, 2024","format":false,"excerpt":"Many thanks to Dan Greenall, one of our dedicated Shortwave Radio Audio Archive contributors, who writes: Hi Thomas I was going over a few of my old cassettes today and discovered what seems to be an interval signal, but I cannot seem to place it. Recording: Unfortunately, all I can\u2026","rel":"","context":"In &quot;News&quot;","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"Photo by Sai Harish on Unsplash","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/Casette-Tape-1.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/Casette-Tape-1.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/Casette-Tape-1.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/Casette-Tape-1.jpeg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/Casette-Tape-1.jpeg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":62314,"url":"https:\/\/swling.com\/blog\/2025\/03\/finding-the-kookaburra-on-shortwave-past-and-present\/","url_meta":{"origin":221,"position":4},"title":"Finding the Kookaburra on Shortwave\u2014Past and Present","author":"Thomas","date":"March 9, 2025","format":false,"excerpt":"Many thanks to SWLing Post contributor, Dan Greenall, who writes: Hi Thomas I still have warm memories of tuning into Radio Australia on 9580 kHz at sunrise during my early days of shortwave listening. They would sign on with their Waltzing Matilda interval signal and the sound of the kookaburra\u2026","rel":"","context":"In &quot;News&quot;","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/03\/Photo-by-Matthew-Willimott-1.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/03\/Photo-by-Matthew-Willimott-1.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/03\/Photo-by-Matthew-Willimott-1.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/03\/Photo-by-Matthew-Willimott-1.jpeg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/03\/Photo-by-Matthew-Willimott-1.jpeg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":42243,"url":"https:\/\/swling.com\/blog\/2020\/03\/dean-solves-second-interval-signal-mystery\/","url_meta":{"origin":221,"position":5},"title":"Dean solves second interval signal mystery","author":"Thomas","date":"March 9, 2020","format":false,"excerpt":"In response to our second mystery interval signal challenge, SWLing Post contributor, Dean Bianco replies: Mystery solved! This is the \u201cinterval signal\u201d (more accurately, a placeholder with a musical station identifier) for the Compa\u00f1\u00eda Telef\u00f3nica Nacional de Espa\u00f1a (CTNW) from Madrid, Spain. They were a point-to-point HF radiotelephone terminal that\u2026","rel":"","context":"In &quot;News&quot;","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Compania-Telefonica-Nacional-de-Espana-642x1024.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Compania-Telefonica-Nacional-de-Espana-642x1024.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Compania-Telefonica-Nacional-de-Espana-642x1024.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/221","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=221"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/221\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=221"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=221"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}