Radio Reading Services
and FM Subcarriers

Radio Reading History

In fact, a leader of a major organization for the blind in New York City told Ms. Cerf that the blind "are not the least bit interested in a special program; we get along very well with what is available to us."

For several years, Ms. Cerf met with various people around the country, pursuing the goal of creating a radio channel just for people who couldn't read normal print.

In the late '60s, two men in Minnesota had the same idea. The difference was they were both amateur radio enthusiasts, and with their vast knowledge of the technical problems involved, they were able to put on a service almost as soon as they could find a radio channel available. Stan Potter was visually impaired, and had a personal interest in such a service, and his friend Bob Watson became his partner in the endeavor. By 1969, they had begun the first Radio Reading Service in the world, using the FM subcarrier(s) of Minnesota Public Radio.

During a visit to the Library of Congress, Ms. Cerf learned of the Minnesota operation, and provided the funding to create a similar service in Kansas. With the help of Mr. Potter, she was able to get Audio-Reader on the air. She presented the idea to the University of Kansas, with an offer to fund the operation for the first two years if KU would administer the program. The General Manager of KANU radio, Dick Wright, flipped the switch to activate the subcarrier on Monday morning, October 11th, 1971.

Because the FM signal contains so much more bandwidth than that required to send one high fidelity signal, there were options that had not been implemented. (An AM station occupies 10 kiloHertz of bandwidth, and stations are spaced every 10 kHz. This allows a frequency response almost up to 10 kHz, providing quite good fidelity to a decent AM radio (a rare breed in this day and age). However, an FM station is allowed 100 kHz of bandwidth, and stations are spaced 200 kHz apart. The frequency response is extended only up to 15 kHz, so much of the extra space was unused on mono FM. Even a stereo FM station only uses about 55 kHz of bandwidth.)

To provide extra channels that could be sold, the FCC created SCA. Originally the commission specified very precisely the SCA frequencies and bandwidth, but now broadcasters are allowed to place any kind of signal, digital or analog, at any frequency and bandwidth, as long as it doesn't damage the main channel signal or extend the bandwidth of the FM station (much) beyond the 100 kHz allocation.

A typical traditional SCA channel is an FM carrier wave (basically a high-pitched whistle at, say, 41, 67 or 92 kHz) carrying voice signals (frequency response up to about 5 kHz), being carried on a much higher frequency carrier wave (at maybe 91.5 mHz, as in the case of KANU).

In the early days, FM stations could put up two SCA channels, each with less fidelity (both frequency response and signal-to-noise ratio) than AM radio. A trip up and down the SCA band in a major city during the '50s, '60s and '70s would have shown three or four kinds of easy background music, a field dominated by Muzak. ADT was a major background music supplier, with their background music a part of a security package that could be installed in offices and shopping malls.

Then, the FCC added to the capabilities of FM radio by implementing a standard for stereo broadcasting. Like color TV on black-and-white receivers, it was important to create a new expanded signal that could be received with no change by all the existing mono receivers. So the new stereo encoding technique involved the main channel as it always was, adding a carrier at 38 kHz (an octave above the best human hearing) with a channel called L-R (Left minus Right). When this channel is added to the main channel, you get the left stereo channel. When it is subtracted (electrically phase-reversed and added) you get the right stereo channel. To help your radio find this channel and turn on a STEREO light, there is a strong pilot signal (about 10% of the FM station's signal) at 19 kHz. That frequency is just high enough that you shouldn't hear it, but your dog might. It is also possible for some of this signal to slip out your radio when you're recording a cassette, and confuse the Dolby noise reduction circuitry; that's why most good cassettes have a FILTER setting on the Dolby switch.

The problem with stereo FM was that it took up SCA space. Mono stations could transmit 2 SCAs, but stereo stations could only send one. That is one reason so many broadcasters resisted "going stereo" until the big FM boom of the '70s, when people began to depend on the Stereo light as an indication they had found a station. Around 1970, 75% of radio listening was on the AM band. By the end of the decade, almost 75% of listening was FM.

By that time, the SCA market was exploding, and Radio Reading Services were afraid of losing their carriers. Most RRS SCAs are provided for free (just like the end product to the listener) or at very little expense to the RRS, but the same carriers began to be worth at least a couple thousand dollars a year to commercial interests. In the '70s, many voice and data signals began to appear on SCAs. Agriports used voice channels (and later data transmission) to bring commodity prices to their network of grain elevators, brokers, etc. Physician's Radio Network created a national audio network of advertiser-supported news reports. The Bonneville Corporation created a high-speed data service with commodity prices. Many large cities became homes of ethnic stations, with music and news in Chinese, Greek, Korean and other languages. Some companies tried pagers. (In fact, Seiko is one of the major leasers of SCA channels because of the success of their pagers around the US.) Power companies considered controlling "load shedding" programs from SCAs, allowing them to turn off some large air conditioners and other big-draw equipment during peak periods. Cities wanted stoplight control on SCA.

As a result, the Association of Radio Reading Services sought protection from the FCC. Most services were based on carriers which were supplied free or cheap, but could be taken away the moment a lucrative lease opportunity arose. The Commission finally decided, in Docket 82-1, that a non-commercial FM had an obligation to provide to a radio reading service, if requested, one SCA channel for a fee that would only cover the station's actual costs, if the station was selling or leasing an SCA channel for profit. Enforcement is not simplified by any form of codification, such as what actual costs can be charged, or what penalties could be.

With the advent of the SAP channel on broadcast television, some services adapted the idea, or even based their entire system on TV SAP. Technically, the SAP (Separate Audio Program) channel is much like radio's SCA, although the sound is better. However, the real difference is in the reception. SCAs are usually heard by people using borrowed specialized radios; the actual radio is owned by the service, which presumably knows where the radios are and who's listening. Conversely, almost all stereo TVs (most TVs sold today) can receive the SAP channel.

Some services have worked out an agreement with their local PBS TV station to carry the RRS signal until PBS transmits a TV show with Audio Description of the events. During the show, the SAP channel is devoted to Audio Description, then back to the radio reading service when broadcasting shows that don't have SAP channel information. Then again, more and more programming is being provided with a Spanish soundtrack on the SAP channel; if this trend is taken up by PBS, more SAP hours will be taken from the "radio" service.