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Author Topic: Audio-Sine Part 15 AM transmitters (history)  (Read 1994 times)

Offline tybee

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Audio-Sine Part 15 AM transmitters (history)
« on: October 11, 2020, 0508 UTC »
The first certified part 15 AM transmitters came into existence in 1971 which were marketed by Info Systems Inc.There were three different models from 1971 to 1974, they were manufactured by International Telephone and Telegraph (ITT), Digital Thechnologies Inc (DTI), and Technical Systems Inc. {TSI). In 1974 the National Park Service quit buying from the Info-Systems company which caused them to go out of business.

So who was manufacturing part 15 whip and mast transmitters for the next 20 years before the LPB AM-2000 (aka TS-100 Trans-AM) transmitters came out around 1994?.. The use of part 15 whip and mast transmitters continued to increase quite substantially throughout the US by the NPS on through the 1970s-80s, but I could find no mention of where those transmitters came from.. but now I think know..

Around the same time that Info Systems went out of business (1974), a new company arose called Audio-Sine Inc. with their own part 15 whip and mast transmitters. Apparently they came out in 1974 to create "Talking Billboards", but the same transmitters were also utilized by government agencies,

Other than that, don't know much about them, Presumably these were certified units, (wish I could find a picture or something of one).. Anyone know anything about them?

Audio-Sine later became a primary supplier of ten-watt AM transmitters in 1978 shortly after TIS was established by the FCC in 1977, but I only found two specific examples of their part 15 transmitters being used (shown below), but I highly suspect it must also be what the NPS was using during those years. One would think these might turn up occasionally on eBay, but I've never seen one.

Anyway, here are two examples of the Audio-Sine Part 15 transmitters being used:


Star Tribune from Minneapolis, Minnesota · July 26, 1974 , Page 6
Staff Photo by John Croft
(Image shows girl on a bicycle looking up at billboard)
caption: Drivers of vehicles without radios can't hear the talking billboard at 66th and Nicollet.

Talking billboard makes debut on its own frequency
By Don Lewis Staff Writer

At last. A billboard that says something literally. It glares in bold black, white and yellow, boasting its novelty and soliciting listeners. The curious motorist who responds and turns on his car radio is introduced to a male voice accompanied by background music. "This is a talking billboard, the first of its kind in the Twin Cities," the sign declares. "Look for talking billboards throughout this area in the near future."
Described by its conceiver as "a new dimension in sound," the signboard-orator has made its Minneapolis debut performing since Tuesday atop the Hub Shopping Center, W. 66th St. and Nicollet Av.

The concept, according to Mort Garren, vice president of Audio-Sine, Inc., is as easy to understand as turning on your radio. Behind the poster rests a low-power one milliwatt AM radio transmitter and a tape player, which broadcasts a 40-second message. Any motorist within four to eight blocks of the sign can tune his radio to the frequency posted on the sign and hear the recorded message. "There is no equipment like this in the billboard industry," said Garren, who explained that his idea might lead to creative, custom-designed billboard advertising that a driver can receive without taking his eyes off the road.

The sign was activated this week by Audio-Sine, a Minneapolis electronic communications firm, and Naegele Outdoor Advertising Co., of Richfield. "It's a beautiful application" of mobile sound equipment, according to Garren, who hopes the idea will catch on, particularly with public service advertisers.

Naegele president Bob Naegele jr. called the sign a "novelty item" in the experimental stage. Though it is too early to evaluate the idea and its chance of success, Naegele admitted it might have some potential. "Give the advertiser a strong visual and a strong audio, and you get a double," he said.

One obvious drawback, Naegele explained, is that the advertising audience is limited to motorists who own car radios and who then make the effort to tune in. In any case, "it's a lot of fun just driving by," Naegele said. Garren agreed. "We're going to let the board sell itself. And I think it will."


Analysis and Design Guidelines for Highway Advisory Radio: ...
...The other HAR transmitter located on top of the Houston Airport Hotel operates at low power at a frequency of 1100 kHz. It operates under Part 15 of the FCC Rules and Regulations. It, too, consists of an Audio-Sine transmitter and power supply and has a Morad vertical monopole antenna system. Its location ideally covers the main airport parking lots. This frequency was selected for its mid-range on a car AM radio dial. The audio for both systems is supplied via leased telephone lines..



Operational Site Survey and Broadcast Equipment Guide
Report Date April 1979

Houston Airport HAR
In April 1978, the Houston Intercontinental Airport (HIA) was granted an FCC
 TIS allocation to operate a 1610 kHz AM station. Prior to this, the airport utilized an 1100 kHz AM station under FCC part 15. Currently, both of these stations are used to inform motorists of airport parking lot status and provide live "on-the- air" broadcasts in an undue emergency...

The 1610 kHz TIS station consists of a 10-watt AM transmitter and a MORAD
 vertical monopole antenna. The transmitter and the antenna are installed on the air conditioning shroud of an FAA office building on Kennedy Boulevard .

The 1100-kHz AM station consists of a 100-milliwatt transmitter impedance
 matched to a citizens band whip antenna. The 1100-kHz station hardware is
 installed atop a hotel at HIA.

Both AM transmitters are modulated simultane
ously from an 8-track tape recorder situated in the HIA Terminal A operations room. To interconnect the 8-track tape recorder to each transmitter, zero loss leased telephone lines are utilized. Both systems are currently maintained by a local communications firm,.. ..Since HIA was the first operating agency to obtain a TIS authorization, HIA has generated considerable interest in HAR by the airport operations community ....

Offline Kingbear Radio

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Re: Audio-Sine Part 15 AM transmitters (history)
« Reply #1 on: December 25, 2020, 0041 UTC »
That is a great and fascinating history you have dug up tybee!! I've been reading up on everything about low power and part 15 transmitters for years, and read anything about those early uses, and if there was something printed, it would amount to just one sentence in a construction article for a transmitter or where to receive such stations, such as schools, drive in movies, a car wash, I can recall those.

I tried to tune in to 530 and 1610 stations going by those articles, and didn't hear a thing, and wondered if what they were saying was even real. Later I did manage to hear a few low power, and then HAR stations on trips.
K-Bear Radio

Offline tybee

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Re: Audio-Sine Part 15 AM transmitters (history)
« Reply #2 on: January 05, 2021, 0256 UTC »
 I found another obscure whip and mast part 15 transmitter from the mid 1970s, it was called Metacomm Model 8008 - 10A, and the fact that it came out when it did apparently saved the 15.219 rule from elimination in the nick of time.

Now keep in mind that in 1973 any existing part 15 transmitters being utilized bye the department of the interior have been issued and experimental license with increase in power and morad antennas, and a hold was placed on ordering additional units as the FCC worked towards establishing a new license TIS service. This had caused the info systems company,  which previously had been the only firm manufacturing these whip and mast transmitters to go out of business by 1974... So as far as the FCC knew there were no other businesses manufacturing these Whip and mass transmitters anymore. So the FCC took advantage of the situation to remedy the problem 15.219 had created...

In 1975 the FCC put forth requirement that all manufactured part 15 transmitters conform  15.209 field strengths and could no longer take advantage of the alternative 15.219 rule, but Metacomm objected because they had just manufactured and put on the market a new transmitter and felt got the FCC had not forwarned them about any restrictions about utilizing an additional ground lead.

The FCC's response, I have truncuated considerably to post here but if you want to read it in it's entirety it's in the
Volume 62, Second Series page 643..

F .C .C . 76 -860
WASHINGTON , D . C . 20554
For reconsideration of staff interpretation or waiver of Section 15.113(c )
September 14 , 1976

Gentlemen :
This is in reply to your letter of May 5 , 1976 , requesting on behalf of the Bristol Division of American Chain and Cable, Inc. (ACCO), reconsideration of a staff interpretation , or alternatively waiver of Section 15 .113( c) of FCC Rules, to permit the certification and marketing of a low power communication device, Metacomm Model 8008 - 10A. ....the critical deficiency, which according to your letter would make the system unusable for its intended purpose , is the requirement in Section 15.113 (c ) which limits the combined length of the antenna , transmission line and ground lead to 3 meters.

Waiver of Section 15.113 (c ), specifically waiver of the restriction on the length of the ground lead, is requested on the grounds that this requirement was added in an Order (FCC 74 - 1221) released March 7 , 1975 after the equipment had been designed and placed on the market.
You allege that the Order,.. did in fact contain a substantive change to the detriment of your client. Prior to the release of this Order, you state that the equivalent provision (formerly designated Section 15.204) limited only the combined length of the antenna plus transmission line to 3 meters...

In the case of a device operating on a frequency below 1600 kHz, the basic technical restriction (Section 15.111) is a limit on the amount of RF energy radiated into space... the Commission established , as an alternative, Section 15.113 where the primary technical restriction is power ( instead of field strength ) into a radiating element of fixed length of 3 meters for devices operating in the frequency range between 510 and 1600 kilohertz. Measurement of power into the final stage of a transmitter is a much simpler test that does not require special test equipment or expertise. Although simpler, it also does not indicate how much RF energy will actually be radiated into space.

The technical parameters in Section 15.113 were selected on the assumption that a 3 meter radiating element at frequencies below 1600 kHz makes an inefficient radiator... The original provision did not consider the possibility that the addition of an extended ground lead would increase the level of radiation from the device and thereby increase its interference potential. This was discovered in tests at our laboratory...

Inasmuch as the change in Section 15.113( c ) was merely intended to clarify our intent and not intended to cause an economic hardship to a company manufacturing under the previous rule section and since this equipment is intended to be operated in remote areas where the likelihood of interference to radio communication is small, the Commission hereby grants waiver of the ground lead limitation in Section 15 .113(c ) of the Rules for the subject equipment. Accordingly , certification of Metacomm Model 8008 - 10A is granted...

This waiver applies only to devices manufactured prior to the effective date of the rules that may be adopted in our proceeding in Docket No. 20780 which proposed to terminate the availability of the alternative provisions in Section 15.113 to persons manufacturing and marketing low power communication equipment for operation in the band 510 - 1600 kHz. After such effective date, low power communication devices operating in the band 510 - 1600 kHz which are manufactured for marketing will be required to meet the technical specifications in Section 15.111 as revised in the proceeding in Docket No. 20780.



Okay, now note that although the FCC gave them a waiver, they also concluded by saying any transmitters after 1975 would have still have to conform to 15.209 field strength. But as we all know that did not happen, and manufacturers were permitted to continue manufacturing under 15.219... Why this happened is still rather unclear, but it's interesting to note that they did make two additions to the certification rules sub parts, those being 15.135 and 15.136 which only seemed to make sense if the 15.29 rule had indeed been eliminated.

Those two sub parts remained as part of the rules for the next 10 years, until which time it was deemed obsolete and deleted. I just find this rather interesting. Below is a copy and paste of those sub parts, followed by another copy and paste official deleting of those rules in 1984. That's all for me for now, hope this didn't bore anyone.

 § 15.131 Certification required for devices that are
marketed or built in a quantity greater than 5
and not marketed .
( a ) A low power communication device manufac
tured between December 31, 1957 and October 1, 1975
which is marketed or which is built in a quantity
greater than 5 and not marketed , shall be self-certifi
cated pursuant to the provisions of 15.135–15.136.
( b ) A low power communication device manufac
tured after October 1 , 1975 which is marketed or built
in a quantity greater than 5 and not marketed shall be
certificated pursuant to Subpart B of this part.

§ 15.135 Certification procedure: Device manufac
tured between December 31, 1957 and October 1,
A low power communication device manufactured
between December 31, 1957 and October 1, 1975 shall
be self- certificated as follows :
( a ) The owner or operator need not certificate his
own low power communication device, if it has been
certificated by the manufacturer or distributor.
( b ) Where certification is based on measurement of
a prototype, a sufficient number of units shall be tested
to assure that all production units comply with the
technical requirements of this subpart.
( c ) The certificate may be executed by a technician
skilled in making and interpreting the measurements
that are required to assure compliance with the re
quirements of this part.
( d) The certificate shall contain the following
information :
( 1 ) The operating conditions under which the device
is intended to be used .
( 2 ) The antenna to be used with the device.
( 3) A statement certifying that the device can be
expected to comply with the requirements of this sub
part under the operating conditions specified in the
certificate .
(4 ) The month and year in which the device was
manufactured .

8 15.136 Location of certificate on devices manufac
tured between December 31, 1957 and October 1,
1975 .
The certificate shall be permanently attached to the
device and shall be readily visible for inspection.


AGENCY: Federal Communications
ACTION: Final rule.
SUMMARY: This document deletes self-
certification and labelling requirements for low power communications devices
manufactured before October 1, 1975.
These requirements have become
obsolete and are therefore being
deleted. The intended effect of this
action is to remove the subject
unnecessary requirements from the FCC
EFFECTIVE DATE: December 3,1984.
ADDRESS: Federal Commumcations
Commission, Washington, DC
List of Subjects m 47 CFR Part 15
Communications equipment labelling.


In the matter of Part 15 requirements pertaining to certification and labelling of low
power communication devices produced before October 1,1975.
Adopted: October 18,1984.
Released: October 25, 1984.
By the Commission.
1. Sections 15.135 and 15.136, which
specify self-certification and labelling
requirements for low power communication devices manufactured
before October 1,1975, are obsolete.
of October 1, 1975, such devices were
made subject to certification by the
Commission. The old requirements had
been retained beyond 1975 so that, when
checking equipment on dealers' shelves
for compliance, it would be clear which
requirements applied.
 In general, it takes
several years from the date of
manufacture for-low power
communication devices, such as toy
walkie-talkies and radio control devices,
to move through the retail distribution
It is reasonable to assume that by
now all equipment produced prior to
October 1, 1975, has been sold. To the
best of our knowledge, no enforcement
questions concerning equipment that fell
under these requirements have come up in several years. Therefore these
requirements are no longer necessary and should be deleted.
 Deletion of these
requirements would not affect the
operational status of any such
equipment still in use.

§§ 15.135 and 15.136 [Removed]

2. In light of the above, notice and
comment on whether to retain these
requirements are considered
unnecessary. Accordingly, it is ordered
that § § 15.135 and 15.136 are removed in
their entirety, effective December 3,
3. For further information concerning
this Order, contact Julius P Knapp,
Office of Science and Technology, (202)
(Sees. 4, 303.48 Stat., as amended, 1066, 1082
47 U.S.C. 154, 303)

Federal Communications Commission.
William J. Tricarico,
[FR Doe. 84-29F28Fled 12-2-4: &45 am]
BILNG CODE 6712-01-M


Offline Kingbear Radio

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Re: Audio-Sine Part 15 AM transmitters (history)
« Reply #3 on: January 09, 2021, 0651 UTC »
That was unknown information! I've only seen references to Part 15 from those times from the odd newspaper article talking about a small station run in some unique way, to make it a local interest story, but those are always so lacking in information about where the transmitters come from, and being into radio I'd wonder about it, and think they must have a kit, or technician or ham build it for them.

The other place I'd get some information were scientific catalogs, with more professional looking stations, like one from Numark, that seemed to be an audio and sound reinforcement company in the 70's.

I really didn't know that there was anything more professional in those dark days. Well, I heard LPB was around, high power for the campus station market, not 100 milliwatts.

It's great that whip and mast concept was saved, and by such a small oversight too. It shows how the FCC would listen to users and companies who would be inconvenienced back then. Now the FCC must want the small users to go away by ignoring them. You file petitions and just get back crickets.
K-Bear Radio

Offline tybee

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Re: Audio-Sine Part 15 AM transmitters (history)
« Reply #4 on: January 11, 2021, 0944 UTC »
In this case, actually came across the deletion of that certification rule first, the search for the 15.135 rule ultimately led to the discovery of that obscure transmitter and how it apparently secured manufactured 15.219 devices.

You mentioned LPB being around that that time, in fact they submitted several comments concerning the proposals for a new TIS classification during the mid-1970s. I highly suspect, yo I'm not been able to confirm it, that LPB where are manufacturing part 15 transmitters during the late '70s on into the 80s... What's the ones we actually know of did not arrive till the 1990s... Speaking of which, mention is made of those in the following FCC document, under their rebranded name

I'm not really an agreement with your last point, I think there is no difference in the manner in which the FCC considers proposals or petitions now or then.

Federal Communications Commission FCC 08-50

Adopted: February 12, 2008 Released: March 14, 2008

By the Commission:

1. The Commission has before it the captioned, mutually exclusive applications of...  ; Zion Bible Institute (“Zion”);  Brown Student Radio (“BSR”); and Providence Community Radio (“PCR”), each seeking a construction permit for a new station in the Low Power FM (“LPFM”) Service  in the Providence, Rhode Island, area......


2. BSR Petitions to Deny.. alleges that those applicants are each not entitled to a comparative point for “established community presence”...argues that both Casa and Ephese are “pure” churches that did not exist as educational organizations, and therefore, are not eligible for the subject construction permit.

Section 73.853 of the Commission’s Rules (the “Rules”) provides that an LPFM station may be licensed
to a non-commercial educational (“NCE”) organization for the advancement of an educational program....
9. We have examined both Casa’s and Ephese’s application exhibits in which each describes how
its proposed station will be used to advance educational purposes. We find that both applicants have
demonstrated that they are nonprofit educational organizations, with distinct educational objectives, and
that they will use their stations’ programming to further those objectives. Accordingly, Casa and Ephese
are each eligible to hold an LPFM authorization.....

15. BSR also claims that a principal of Casa appears to have been involved in the unlawful operation of an unlicensed radio station, in violation of Section 73.854 of the Rules.39 In its Opposition, Rev. Eliseo Nogueras, Casa’s President, has declared under penalty of perjury that “Casa operated a legal unlicensed 100 mW Tran-AM Radio Transmitter TA100, serial number 14075” but discontinued operation because coverage was so poor.40  BSR has not established a prima facie case that Casa’s short-lived attempt to operate this 100 mW low-power AM radio station violated any of the Rules.41  Consequently, BSR’s argument is without merit.

 See Casa Opposition at Exhibit 1. Casa states that the “whole city” involved was Central Falls, which is one mile in diameter.

See, e.g., 47 C.F.R. §§ 15.209, 15.219, and 15.221; Public Notice, “Permitted Forms of Low Power Broadcast Operation,” Mimeo No. 14089 (July 14, 1991); OET Bulletin No. 63, “Understanding the FCC Regulations for Low-Power, Non-Licensed Transmitters” (Feb. 1996). Section 15.219 permits operation of an unlicensed 100- milliwatt AM transmitter on a secondary, non-interfering basis, provided that the total length of the antenna and ground lead does not exceed three meters.


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