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Docket No. 18627




25 F.C.C.2d 654




September 11, 1970 Released


Adopted September 9, 1970








[*654] 1. On August 8, 1969, a Notice of Proposed Rule Making (FCC 69-853) was released in the above-entitled matter proposing to adopt specific rule standards for licensing radio call box systems in the Public Safety Radio Services in the 72-76 MHz band. The Notice solicited comments by September 15, 1969, and replies by September 25, 1969. By subsequent Order (Mimeo No. 41085), released November 10, 1969, we extended the comment and reply comment periods until December 5 and December 20, 1969, respectively.

2. Briefly, the 72-76 MHz band is between television Channels 4 and 5. Radio call box systems, as well as other radio users, have been licensed in this band upon a prescribed special showing intended to prevent harmful interference to television reception on those channels. However, the Commission had concluded tentatively in its Notice that a number of factors existed which required special rules to govern the operation of radio call box systems in that band. Thus, we proposed to authorize radio call boxes in the 72-76 MHz band on a regular basis under the following proposed standards: The maximum radiated power would be limited to one watt; the maximum height of the antenna propose would be 20 feet above ground, antenna gain would be limited to unity and only vertical polarization would be permitted; call boxes would transmit only one-way tone signals of short duration (two seconds maximum) and the signal from any one transmitter could be repeated only after one minute interval; and, finally, applicants for call boxes would be required to select a frequency with the greatest possible frequency separation from channels 4 or 5. With the standards and, more importantly, because of the extremely low duty cycle of call box systems as well as the complete absence of any complaints of interference from existing call box systems, we expected that the interference potential to television reception would be inconsequential. Therefore, we did not propose to impose specifically [*655] a responsibility on call box system licensees to eliminate interference to television reception, should any occur.

3. Comments were submitted by the Academy of Model Aeronautics, Inc. (AMA); Associated Public-Safety Communication Officers, Inc. (APCO); California Public Safety Radio Association, Inc. (CPSRA); Eagle-Picher Industries, Inc.; the Electronics Industries Association (EIA); Motorola Communications and Electronics, Inc.; National Broadcasting Company, Inc. (NBC); Northern California Chapter of the Associated Public Safety Communication Officers, Inc. (NCAPCO); RCA Corporation, Solid State Technology; Chronicle Broadcasting Co. (Chronicle); The Association of Maximum Service Telecasters, Inc. (MST), WJXT of Jacksonville, Florida (WJXT) and WLAC-TV, Inc., of Nashville, Tennessee (WLAC-TV).

4. MST, Chronicle, WJXT and WLAC opposed our proposal. All of the other parties who filed comments supported it some with reservations, n1 while other suggested a number of modifications which are discussed and are disposed of below. Those who opposed our proposal argued mainly that widespread use of radio call boxes in the 72-76 MHz band could result insignificant interference to television reception on Channels 4 and 5. MST and others argued, for example, that the interference potential of a radio call box is greater than we had indicated in the Notice; that our proposal would be "a fundamental change in the allocation principle governing the use of frequencies in the 72-76 MHz band, that of non-interference to television reception...", and urged that... "the Commission should continue to require an adequate technical showing of the likelihood of non-interference before deleting even the engineering criteria of Section 89.101 c), (4), and (5)." Finally, MST and others urged that, if the Commission decides to permit radio call boxes in the 72-76 MHz band, it should continue to require licensees to "satisfy interference complaints."

n1 Motorola Inc., for example, argued that call box systems, to be fully effective, should be capable of two-way communications and suggested that our proposal to permit radio call boxes in the 72-76 MHz band would not meet fully the requirements of public safety officials. It urged that the Commission act favorably on the petition (RM-1509) filed jointly by the States of Rhode Island and Connecticut and the Commonwealth of Massachusetts asking the Commission to authorize radio call boxes for two-way voice communication on highways on the four pairs of frequencies in the 450-470 MHz band which have been reserved for possible future use in connection with a highway safety communications system.

5. We have considered all of the comments carefully and we have concluded that the public interest would be served by permitting the operation of radio call box systems in the 72-76 MHz band essentially under the standards proposed but with some modifications, discussed below, which appear desirable in light of the comments. The reasons for our decisions are essentially the same as those recited in the notice and nothing offered in the comments persuades us to depart from the basic proposition.

6. We agree, at least in part, with those who argued that a signal from a radio call box operating under the proposed standards potentially could interfere with the reception of television signals on Channels 4 or 5 at distances greater than the 200 feet we indicated in the Notice, depending on a number of factors including the distance from the television transmitter. Generally, the radius of interference potential will increase as the distance from the television transmitter increases. [*656] Nevertheless, the potential for harmful interference to the reception of television from call fox systems operating under the proposed standards would be minimal at worst, certainly not enough to require barring radio call boxes from the 72-76 MHz band. We reach this conclusion because, in our view, the extremely low duty cycle of call box systems, the brevity of each transmission together with the technical limitations we have adopted would insure against any significant interference to television reception. Eagle-Picher, a manufacturer of radio call box equipment, for example, stated that its experience with street fire alarms indicate that a system of 75 to 100 boxes can be expected to transmit "... 6 to 10 messages per month, or roughly 20 to 30 seconds of air time." Further, each message is to last no longer than two seconds so that, even assuming that every signal interferes with television reception, the interference would not be more disruptive than that caused by passing airplanes, ignition noise, and other such sources of interference.

7. Experience with existing call box systems supports these conclusions. A survey of licensees conducted in the summer of 1969 showed that call boxes installed even on busy highways for use by motorists had a low duty cycle. For example, call box activation in a system operated on the Maryland portion of the Capital Beltway, the largest call box system authorized, has been slightly more than once a day per mile. There are four boxes in approximately one mile of the highway. Generally, fire alarms systems are used less frequently. Of equal, or perhaps greater, significance, is the complete absence of any interference to television reception from existing radio call box operations. None of the existing call box licensees we surveyed reported any complaints of interference. Also NBC, which operates television stations on Channel 4 in Washington, D.C. and in Los Angeles, California, where radio call box systems have been authorized, reported in its comments that there has been no interference with its operations. We note that those who opposed our proposal offered no factual evidence of any interference to television reception from existing systems. Accordingly, requests that we impose a non-interference condition on call box use are denied. However, call box licensees will be expected to cooperate in alleviating interference problems.

8. In sum, our action here is not making a "fundamental change in the allocation principle" for the use of the frequencies in the 72-76 MHz band, as MST argued. We are promoting the fuller use of the frequencies in that band in the public interest consistent with our desire to protect from harmful interference television broadcasting on the adjacent Channels 4 and 5.

9. We recognize, however, that our experience with radio call box systems in the 72-76 MHz band is limited and, therefore, we believe that the better course to follow is to proceed cautiously particularly in urban areas. Thus, we think that, for the time being, it is desirable to limit the size of the system we will authorize until we get more experience not only with respect to the interference potential of call box systems but also with respect to the utility and the demand for large scale use of such systems. Accordingly, we will not authorize systems of more than 250 units in any call box system. This should accommodate [*657] substantially the needs indicated so far, primarily in suburban and other relatively small communities and to a more limited extent on parts of densely traveled highways.

10. We now turn to the comments directed more specifically to the proposed technical standards. It was urged that we permit higher power and antenna height in order to increase the reliability of call box systems. However, it has not been shown that more power and higher antennas are necessary. Call box transmitters now available are about 2.5 watts input or one watt output and systems conform generally with the proposed standards. The available evidence indicates that the power and antenna height limits are adequate. There is no indication, either in the comments or in the responses to our survey of existing licenses, that these call boxes have been unreliable because of these aspects. In fact, except for the City of Los Angeles which is converting its radio call box system to telephones for reasons unrelated to power and antenna limitation, licensees report that call box systems are highly dependable. Additionally, reliability is likely to be augmented since adoption of rules for licensing radio call boxes on a regular basis should encourage equipment manufacturers to develop even more efficient and reliable systems than are being marketed today. For all of these reasons, we find that the basic proposed power and antenna height limitations should be maintained, but we are including a provision for transmitters of 2.5 watts plate input power.

11. Other comments questioned the proposal to limit each transmission to two seconds and to permit reactivation of each transmitter only after a minimum of one minute intervals. Eagle-Picher and RCA urged that we permit repetition of the signal three or four times within about 30 seconds. They note that Standard No. 73 of the National Fire Protection Association, which is followed for municipal fire alarm systems, states that "Boxes transmitting a coded indication shall send three or four rounds of the box number." We find that provisions for a series of automatic repetitions of radio call box transmissions is warranted to help assure that the message is received. Two additional two-second transmissions spaced within the 30 seconds following the initial signal should be sufficient and will be permitted. However, as proposed, a one minute interval for reactivation of the signal cycle will be retained. In addition, in order to prevent interference caused by malfunctioning equipment, we will require that each call box provide automatic means to de-activate the transmitter in the event the carrier remains on for a period in excess of three minutes.

12. The 68 frequencies in the 72-76 MHz band which would be available for call box operations include five frequencies which may be aso assigned in the Citizens Radio Service for model aircraft control. n2 The AMA requests that these frequencies be assigned for call boxes only only after it is shown "that none of the remaining frequencies was available in the area, and that the use of one or more of these five frequencies would be less likely to result in mutual harmful interference than would the use of a frequency otherwise available." However, this request must be denied as inconsistent with Section 95.41(c)(2) [*658] (ii) of the Commission's Rules which provides that protection will not be afforded for model aircraft control from interference due to the operation of fixed stations in other services on the same frequencies. Nevertheless, it can be expected that applicants will give consideration to this possibility of mutual interference in their own interest as well as with regard to the model aircraft control problem when they make their frequency selection.

n2 By a Further Notice of Proposed Rule Making, released on June 12, 1970, in Docket 18733 (FCC 70-603), it is proposed to allocate two additional frequencies in this band, 72.16 and 72.32 MHz, for model control in the Citizens Radio Service.

13. Comments suggesting that the tone system used in a particular call box installation be required to be specified in the application and be shown on the authorization or included within the Commission's data base have been considered. We are aware that some problems have been caused due to the use of tone controlled squelch systems in land mobile installations. In the call box case, however, the signaling systems employ digital methods and it appears extremely unlikely that the system of one manufacturer would falsely activate the readout device employed by another. We are currently reviewing the uses of tone coding devices and we may propose standards for these devices. We would, at that time, conform our licensing of call boxes to whatever data elements prove to be required to alleviate unwanted unlocking of receivers.

14. Finally, the question was raised as to whether the proposed standards should apply to radio call box systems to be operated at substantial distances from television stations on Channels 4 or 5. We believe this would be desirable. First, as we have stated, the power and antenna limits we have adopted are adequate for satisfactory service. Secondly, in the absence of a compelling need for varying standards, it is desirable to apply the same standards across the board for ease in administration and to promote equipment standardization. Accordingly, the same rules will apply to all call box systems authorized in the 72-76 MHz band.

15. In view of the foregoing, we conclude that the public interest would be served by adopting the rules set forth in the attached Appendix. Authority for our action is contained in Sections 4(i) and 303 of the Communications Act of 1934, as amended.

16. Accordingly, IT IS ORDERED, That effective October 19, 1970, Part 89 of the Commission's Rules IS AMENDED as shown in the attached Appendix. IT IS FURTHER ORDERED that this proceeding IS TERMINATED.









I concur in the adoption of the rules in this proceeding, largely because of the infrequent and short duration of any likely interference to television reception.

However, I cannot give weight to a failure to have received complaints of interference to television receivers in this, or any similar, situation.

The public is accustomed to interference to TV reception, has no way in which to ascertain its source, and does not know where to lodge a complaint were it to be sufficiently impelled to do so. In short, interference complaints to television service is a pretty poor allocation criterion.





Part 89 of the Commission's Rules is amended as follows:

1. Section 89.101(c) is amended to read as follows:

89.101 Frequencies.

* * *

(c) Except as provided in Section 89.102, the following frequencies in the band 72-76 MHz may be authorized and used only in accordance with the criteria set forth in subparagraphs (1) to (6) of this paragraph.

* * *

2. New Section 89.102 is added to read as follows:

89.102 Radio Call Box operations in the 72-76 MHz band.

(a) The frequencies listed in Section 80.101(c) of this chapter may be assigned in the Local Government Radio Service for operation of radio call boxes to be used by the public to request fire, police, ambulance, road service and other emergency assistance subject to the following conditions and limitations.

(1) Maximum transmitter power either 2.5 watts plate input to the final stage or one watt output.

(2) Antenna gain may not exceed zero dBd [referred to a half-wave dipole] in any direction.

(3) Only vertical polarization of antennas may be permitted.

(4) The antenna and its supporting structure must not exceed 20 feet in height above the ground.

(5) A1, A2, F1, or F2 emission only may be authorized.

(6) Transmitter frequency tolerance shall be 0.005 percent.

(7) Except for test purposes, each transmission must be limited to a maximum of two seconds and may be automatically repeated not more than two times at spaced intervals within the following 30 seconds; thereafter, the authorized cycle may not be reactivated for one minute.

(8) All transmitters installed after December 10, 1970, shall be furnished with automatic means to deactivate the transmitter in the event the carrier remains on for a period in excess of three minutes. The automatic cut-off system must be so designed that the transmitter cannot be re-activated until manually reset.

(9) Frequency selection must be made with due regard to reception of television stations on channels 4 (66-72 MHz) and 5 (76-82 MHz) and should maintain the greatest possible frequency separation from either or both of these channels if they are assigned in the area.

(10) Until further order of the Commission, the maximum number of radio call boxes that may be authorized in any call box system is 250.

(b) Radio call box systems authorized before December 10, 1970 may continue to be authorized subject to the provisions of Section 89.101(c) of this chapter.



The following call box transmitters have not been shown to be capable of compliance with the timing requirements of 89.102(a). In addition, those noted by asterisk (*) have rated power in excess of the limitations of 80.102(a)(1). These transmitter types will not be acceptable for new installations on or after December 10, 1970, and will be so noted in the Commission's Radio Equipment List. Any manufacturer or licensee wishing to provide a showing of compliance by his equipment with these requirements may file appropriate data for consideration by the Commission as to whether the particular transmitter type should be reconsidered for its acceptability for use in any such new installation.



HOFFMAN ELECTRONICS CORP: *EC-T-267-A; EC-T-267-A2; EC-T-267-A3; EC-T-267-A4; *EC-T-267-B; EC-T-267-B3; EC-T-267-B4; *EC-T-267-C; EC-T-267-C3; EC-T-267-C4; *EC-T-267-D; EC-T-267-D3; EC-T-267-D4.


RCA CORP: VTC-C-102-A; VTC-C-102-B; VTC-C-102-C; VTC-C-102-D; VTC-C-103-A; VTC-C-103-B; VTC-C-103-C; VTC-C-103-D; VTC-C-103-E; VTC-C-104-A; VTC-C-104-B; VTC-C-104-C; VTC-C-104-D; VTC-C-104-E; VTS-C-101-A; VTS-C-101-B; VTS-C-101-C; VTS-C-101-D.

SPENCER-KENNEDY LABS: PA-T-0-1; PA-T-0-2; PA-T-0-3; PA-T-0-4; PA-T-1; PA-T-1-1; PA-T-1-10; PA-T-1-11; PA-T-1-12; PA-T-1-2; PA-T-1-3; PA-T-1-4; PA-T-2; PA-T-2-1; PA-T-2-2; PA-T-2-3; PA-T-2-4; PA-T-3; PA-T-3-1; PA-T-3-2; PA-T-3-3; PA-T-3-4; PA-T-4; PA-T-4-1; PA-T-4-2; PA-4-3; PA-T-4-4.

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