719
FCC GG--!;,!I
BEFORE THE
FEDERAL COMMUNICATIONS COMMISSION
In the Matter of
,\:KESf)3IENT OF PART 7;-} OF THE CO':U3nSSIOX'R
RrLES AND REGULATIONS To REQrrRE Fl\I
HRO.\DCASTST~\TIOXSEXGAGIXG IX 11rLTI- I) J Y
l'LEX STEREOPlJOX!C PROGlLDrIXG OR 8C..:\ Ol' .;::et l'O.1;~I'+O-1-
OPEIL\TIOX To IxsTALL TYPE ArPltOnD Fmc-
QO:x,Y AXD '\IoDTIL_wIOX ,\IoXITORS C"U'A-
BLE OP MOXITORIXG SUB,ARRIEIt OPERATIOX
REPORT .-\XD OnDER
(Adopted '\lay 2", HIGG)
By THECo.:~r.\n:s.slox:
1. The Conl1uissioll has before it for consideration its noticE' of
proposed rnlemaking (FCC G+-298) released on .\pril 2, 19(i4, and
COU'llllellts filed inrespOll~ethereto by a lllullber of]icell~ee~of F)1
broadcast stations, equiplllellt llHll1ufaetul'ers. organizations, and in-
diYicluals having an interest in the broadcast ilLdnstrv.
1
'
:2. The notjee of proposed rlllenlaking in this procee'ding~etforth
our belief in the need of FM broadcast st ations engaged in stereo 
phonie broadcasting and in the tranSlllission of additional prognnns
under a, subsidiary cOllununicationsauthorization~for type appl'oYed
frequency and modulation monitors to assist them in establishing the
teellllic'l] adequacy of such operations. This belief \,-as g-enernlly sup 
ported \,-ith respect to the need for multiplex moduhtion monitors.
a. On the other haud. howeYer, 11lOst C0111nlents questioned the need
for a. mllltiplex frequellcy monitor. The general consensus. as ('x 
pressed by Olle party was:'~Itis unnecessary for a crystal oscillator to
continuously check the frequenc-y of a silnilnr crystal oscillator:' .As
an altel'natiY8, occasional checks of frequency ,yere suggested to assure
proper frequency stability.
+.l~ponreexamination of this question, ,ye are not persuaded that
n need for freqnency monitors in connection with stereophonic brond 
casting: and the SeA subcnrrier operation has been estnhlished. lYe do
l)f~1ieve,hu\Yevel'. that the licensee 11lUSt have antilahle a 111eal1S of
determining that the pilot sllhcnrrier and SeA suhearrier frequencies
nre maintained \yithin proper limits. Our experience in the field of
1 Commcnts 'wcre filedb~·the followinJ';': Electronie Industries ASBociution, \Va>;hington.
D.C'.: ZPllith Rrtdio Corp.. Chicago. IlL:WFPG-F~I,Atlantic City. N ..I.:\VJ~ID.Bf'tlH"sda.
Md.. Bf'lar Electronjcs Laborator;l. Drexel HilL Pa.: 'Collins Radio Co., Dallas, Tex.;
"\",,,,odntion of Ff'derul Communication", Consnlting Engineers. Washington. D.C.. "1\[(' 
}Iartin Industries Inc.. Omaha. XelJr.: Radio Corp. of America. Kew York. K.Y.: KEEZ.
Ban .·\.ntoni". Tex.. 2\ationul Associatinll of Broadcasters. 'Vashington. D.C.: Ro:v H.
Trnmbul1 Corte Madera, Calif.; Robert J. Carpenter. Rockville. Md.; "DET-F)'l. Detroit.
),[ich.
3 F.e.C.~c1
10n-;-;40-(;U--1
720 Federal Conm,unioation.s Cmnn,i.'!8ion Nfl'''!'h
television broadeasting is pertinent in this regard. Onr eonc.:lusiull
there was that a separate frequency Inonitor isulllleee~,"3ar'yif the
licensee checks the operating frequency on a daily basis using a simple
procedure which will indicate that the operating frequeucy- is within
authorized limits.
5. IVe reach a simihr eonclusiori in thispr-oeeeding a, reflected ill
new paragraphs (i) of seetion 73.295, and (b) of section 7;}.2\l7 of the
appeudix. In this context, however, it becomes necessary to specify
a permissible tolerance for nrriations in the resting frequency of the
SC....~subearrier, since there is no reference point in the- present rules.
The figure ehosen (i.e., 500 cycles per second) is, we belieYe, reasou.
able and well within the confines of good en,g-ineeriug practice. Sec.
tions 7i).28;1,7;-).~~5,7;).r)b;),and 7iLflU5 are heIng alllE:wJed to Pl'oyide
for the daily logging" of the necessary re<.Hlings.
6. 'Yith respect to lnodulatioll 111onitors, sections7:1.~;-):~(a), 7:1.332
(b), and 73.553 (a) are being amended to recognize the existence of
three different types: (a) Those for nonmultiplex operations, as
presently provided for; (b) monitors for stereophonic operation: ane!
t c) Inonitors for SC..:-\ operations. 'Ye <If-,yree \yithth(J~t:'",Yl1O(,Oln~
mented adversely on our proposal to identify these monitor3 as c1a&\
A, B, and 0, however, and have modIfied note 1 to sectIOns 7:E!;,3 ane!
7;3.55:> to refer to them merely as nonmultiplex, stereophonic, and SeA
111onitors.
7. In adopting our notiee of proposed rulemaking in this lllatter, we
had anticipated a relatively short period for the sulHuission of CO)l1 
ments and adoption of an appropriate report and order, and had SUa.
crested approximatel:y () rllonths as the tirne necessary forInanllfu~~
furers to obtain type approval of the monitors and to supply F:\I
broadcast stations requiring these J!ew monitors. lYe note, however
that since the institution of stereophonic broadcasting by FMstation~
in .Tune of 1961, at least three manufacturers han produced a stereo.
phonic modulation monitor. In examining the specifications of each
of these currently produced items we note that none will fully meet
the specifications we are here adopting. In view of the equipment
modificahons which eNentually will be necessary, the subsequent sub 
mission of the monitors for type approval and the necessary time for
stations to obtain the type approved model, we are adopting an effec 
tive date of .Tune 1, 1967, and specify this date in note 2 to sections
7:).2Ml(a) and 7.3..5.'):)(a). However, becanse our action in this pro 
ceeding has been delayed in conseqnence of which manufactnrers have
prodnced stereophonic and SeA modulation monitors in reliance lrpon
our ultimate adoption of specifications for type apprO"al, and because
a considerable number of licensees have purchased and installed these
lnonitors while awaiting our decision in this Inatter. we arE' providing
in note 2 to section 7:).25:) (a) that these licensees may continue to nse
such monitors until .T,muarv 1, 1\)72. lYe do this, howe"er, with the
underst>mding that the installation and use of these non-type-approved
monitors does not in any way relieve the licensee of the responsibility
for maintaining stereophonic or SCA operations in compliance with
the apPl'onriate technical 1'n]es (see sees. 7:1.:i2:2 and 7:1.?tH) of the
rules). lYe do not belieye it necessary, however, to set n future effec-
3 F.C.C. 2d
Jlonitor8 for FJl :'S'uorGj'}';eJ' UpeJ"{(!;o}i.';'
721
tin date for the measurement of stereophonic pilot snbcarrier and
:"CA subcarrier frequencies, as discussed above, because the procedures
there are relatively sirnple anu the necessary additional equiplllent, if
not already in possession of the licensee, is readily available.
s. lYe turn now to a detailed consideration of modulation monitor
specifications (sec. 73.332 of the appendix). In general. those ,vllO
cOlnmented in this proceeding were in agreenlent with these paragraphs
as proposed in our notice. lYe have found it necessary to make changes
in certain subparagraphs as described more fully herein, both because
of comments received and because of a reexamination of the level of
aceuracv which we believe necessary and desirable.
D. Subparagraph (1) of paragl'llph (d), section 7:3.:>;}2. requires that
the type approved modulation monitor indicate the modnlation per 
centage of the carrier produced by the main channel (L+ R) signal
,,,ith all accuracy of plus or Ininus 3 percent for all frequencies £1'01n
50 to 1;),000 c.p.s. To insnre the accuracy of this indication. 've have
fonnd it necessary to expand the proposed rule to prm-ide that the
frequency characteristic be such that the attenuation at the pilot
subcanier frequency (HI ke) is at least 26 db aud the attenuation in
the frequency range of 2;3k(~and above where~~)Isubc.arrier sidebanu
infol'lnation is present is atle~lst4G db. Likewise in subparagraph (2)
of paragraph (d) we have expanded the proposed rule, as snggested by
McMartin Industries. Inc., to require for measurement of modulation
percentage of the carrier produc-ed by the suppressed snbcarrier and
its sidebanus, that the frequeuey chara.eteristic be such that the
atteuuation at 19 am! 57 ke be at. least 26 db and the attenuation at.
15.000 cycles and belmv and at 59 lw and aboye shall be at least +6 db.
These specifications we belieye will enable the accnl'acy of this
indication.
HI. Simihlrly. subparagraph (:3) specifies the requirement that the
modulation monitor indicate the modulation of the carrier by the pilot
subcarrier. This subparagraph is adopted as proposed in our notice.
11. Subparagraph (+) of paragraph (d) relating to the measuring
of total nl0dulation of the carrier ,,,hi<:h 'Y<lS contained in the notice
of proposed rulemaking as paragraph (d) (9) has been expanded to
establish, with greater specificity. the accuracy of the yisual peak
preset indicating deyice (more commonly known as the peak flasher).
This "'e find necessary because the peak flasher is normally more
accurate in indicating lllOdulation pea.ks under program conditions
because it is a peak indicating device, ,yhereas the nloclulation nleter
is a semipeak indicator. Unfortunately, our existing rules (sec. 73.332
(b)) for noml1ultiplex modulation monitors, while requiring the peak
indicating deyice. are not specifie in defining its accuracy. ,Ve do
intend at some future date to correct this deficiency. Mean,,-hile we
belieye. that, since ,ve are. herein establishing new classes of modula 
tion monitors. the. nmv units should be examined for type approval
uncleI' the 1110re specifie acc-uraey requirmnents.
12. In further eonsideration of the discussjon above, ,ye believe it
adyisable to indicate our belief, because of the greater accuracy of
the. peak indicating deyice in indicating modulation peaks. that when
there. is nisagreement between the peak preset innicator and the semi-
3 F.e.e. 2<l
peak lllOdulation n"leter indications, the peak flasher should lit'COll~
siclered the prime indicator. Since this Inatter was not raised in our
notice and since this principle applies equally,,~ellto nonmultiplex
111011itors, we· are not now modifying the rules to incorporate a c1arifi 
cation. but intend to do so in the future.
13. As suggested by Collins Radio Co., we have revisedsubpara~
graph (5) of paragraph (d). ,vhich was paragraph (d) (4) of our
notice. to indicate a maximum variation of the frequencycharacter~
istie of 1 db and have added subparagraph (d) (5) (iv) to provide for
the proper phase relat.ionship bebveen the pilot. sllbrarrier and reg-ener 
ated 38 kc/s subcarrier in the monitor. ,Ve also take this opportunity
to change the permissible harmonic distortion from one-half to 1 per 
cent and to specify that the monitor be capable of reading a separation
of a,) db with an aC{':uracy of plus or minus a db. These changE'S are
both Ininor relaxations of our original proposal.
14. ,Vhen an FM broadcast station is transmitting an SCA program
in addition to a stereophonic broadcast an undesirable characteristic
which 111ay oecur in an ilnproperly adjusted system is erosstalk from
the SCA and main channels into the stereophonic subchannel and
from the stereophonic subchannel into the main channel. Thus, para 
graph (d) (6) is intended to provide the licensee with a means of
111easuring erosstalk to insure cOll1pliance of his operation with the
rules. Paragraphs (d) (,"i) and (d) (7) of the notice have been com 
bined and result in para,,-raph (d) (6) of the attached appendix. ,Ve
have found it necessary, however, to specify the crosstalk character 
istic and crosstalk indication of the monitor to insure the accuracv of
the imlication ofthis parameter. .
L"i. Paragraph (d) (8) relating to suppression of the subcarrier is
adopted as proposed except that the indication of suppressiou is
chang·e.d from 45 to 46 db and a stipulation is added that the indication
of snbcarrier suppression must be revealed for the frequency range of
subcarrier modulation from 5,000 to 15,000 cycles and for full modula 
tion of thesubcarr~er.,1'e are adding this additional requirement
because our e,xperienee in exmnining' stereophonic tral1sJ11isslon equip 
ment has demonstrated to us that some stereophonic transmitters are
capable of suppressing the 38-kc stereophonic subcarrier to a yalne of 1
percPllt (as required by sec. 7iL:i22) under the condition of no Inodnla 
tion but fail to do so,,~henthe stereophonic subcanier is modulated.
lYe belieye. that a type approved stereophonic modulation monitor
should provide a means of ll1easuring- ste-reophol1i(' subearrieTsnp~
pression over the frequency and amplitude range of subearrier modula 
tion specified.
lH. In the notice of proposed rulemaking ,YO had su,ggested in para 
graphs (d) (10) and (d) (11) that means be provided for measuring
both A)I and FM: noise. Many who commented questioned the need
for such a specifieat:ion on the hasis that this is an occasional proof of
performance measurement which can be accomplished, ,,,hen necessary,
nsing the c.ircuitry of the monitor but an external meter to provide
t.he neceSS:lry indication. tJpon reexan1ination, we agree with these
('0111111ent8.F~fbroadcast stations operating in the 1l1onophonic 111ode.
normally determine the levels of AM and FM noise in the transmitting
3 F.C.C. 2d
723
systenl at least once a year during the allJlual PquiplllE'nt perfOrlll<ll\('t>
measurements (see see. ,;L2,H(b)) and "'hi1e we do not "'ish to illlply
that an anlluallueasllreluellt is sufficient to 11l2.llre cOlupliallct' \yjth the
rule, problems of exeessiyeA~rand.F~rnoise do not usually oc-cur
whenap~)r()printediligence i:s exel'c!:sed.A~'t'ol'dillgly,"we are c1eletillg
the reqmrement that the modul'ltlOn mOllltor proYide, intl'rnallv, a
llleallS for]ne~lsnringA)I and F:\lnoise. ,,-.-(-' are, howeYe!'. tuldii1!! a
new paragraph to stipulate that when signals are brought oul for
external Inetel'lng or nlOllltOl'lllg purposes. they~hallhan' all of the
characteristics required for intei'11al nleterlnp: llurposes and al;-;{) t ltar
any loading by external cireuitry shall ha_ve no eflect 011 the lllOuitol'"s
indications.
1,. Paragraph (e) of the uotiee proposed that the stereophonie pilot
subearrier modnlation be displayed continuously and independently
of the totallnodulation. The eOl1llnents recei,-ed on this proposition
'"ere opposed uec-;luse it is clailneu that pilot subearrier len'.·l i::-- rela 
tively constant once properly set and continuous nlOuitoring is un 
necessary. lYe are impressed by these comments and agree that.. SO long
as an indication of pilot suhcarrier level is available" to the operator
upon demand, continuous display of this parameter isunne~essary.
Accordingly, pamgraph (e) is modified to provide that "'hen switeh 
ing is utilized to display the parameters set forth in paragraphs (d) (1)
through (d) (5) of the appendix, the ,-ismI peak flasher for total
lllOtlu]atlol1 must ,be independent. of this switching so that it contin-
uOllslv a1fords an indication of total modulation. -
18.' IYith respeet to type approval specifications for SeA mo(lula 
tionlllonitors, paragraph (f) (1) was not contained in our notiee bnt
was added because of onr belief, as demonst!·Hted by most SeA mon 
itors now being prodw'ed, that the licensee enga::ring in SC..:.\ Opel'..l 
tioll desires a single monitor '1'hich \Yill exhibit Inain,c1wnnel modllla 
tion as well as SO"\. modnlation. To insure the aecuracV of this main
channel indication \ye ha"e specified thatthefrerjueney ;'haracteristics
he suchtlmt,tJle attenuation in the SO.\. range· from~iJto ,.)
kc he at least -J.(; db. ' .
10.Pal'a~nlph(f) (2) -adopts our proposal for a llleans of (It·t.er 
lllllllug lllodulation of the lllaill carrier by each :":"C..::tSlll)('arl"iel'~Imt
\H' hi:ln:l founel itne('essnry~to insure pl'oper ft('('urH('Y, to he more
~;pe{'iticill dplineatill1I tllt'. lllollitor frequeuey ('lwrnctPri2tic.
~f).Liki.>\,"ise. sllbparagTaph on of paragTaph (f)relatilt~.. to the
indication of total lllOdulatiOIl is adopted a:=; ('ontained in Ollr lloti('e
(SPE' par. (1") (:2) therein). IIo\\"e,Ver, as des(Tilwd iIi paragraph1~
nl)()\~l'-~l'elnting to stereophonic lllOnitors, '1'8lH']ien~it" llf'C'eSS:ll'y to
pstablish with ,!.!.:n·atpl' specilicity the ope-l'atjoll of tlw yi2tlal peak
pl't'cet indicating' de,-ice Hnd have pl'm-ided additional cl'iteria ,yhich
rhi c de" icc nJllst llleet.
~1.Paragmph (f) (+) is H(lopted as propoced ill paragraph (f) 0))
of the notice.
2:2. Tlw(,l'()~stnlklllPasl1ring llwans proposed in paragruph (f) (-4-)
of the lloticei~,Hlopted '''ltll clal'ifiecl ,Yording nnd a specifieatioll for
the l'eqnil'ecl (Tosst,l1k(']l(lrade-ri~ti('of the monitor. and~lrpe-al'::;as
p"ragraph (f) (,-,) of the attHched appendix.
3 F.C.C. :l.d
724 Federal Communicati0118 C01nmi,,,,ion Rel'01'tS
2a.Para~raph(f) (6) of section n.aa2 was not included in our
notice, but has been added, as we have described in paragraph 16, in
connection with stereophonic modulation monitors, to permit external
Iueterillg' or 11lonitoring provided that any loading" by external cir 
cuitry shan have no effect on the monitor's indication.
24. Paral'raph (1') is adopted as proposed in our notice with the
added stipulation, as described in paral'raph 17 above, that the peak
preset indicator (peak flasher) of total modulation must be independ 
ent of anys,vitchin~functions and must afford a continuous display.
~5.Sections73.5M~,73.58B, 73.595. and 7S.5Dfl are anlended in slffi 
ilar fashion to that described above' tn cnnfonn the mnnitm require 
lllents for 11011('ollllnereial educationalF~Istations to those, for rom 
mercial F:JI stations with the exception that note 2 to section 7(1.;)03
rloe~not permit the continued use, until .Tannary L 1972, of those non 
type-apprm'ed monitors which were purchased and installed prior to
.Tuly 3. 19fi6. Becanse of the limitednnmber nf nnncommerclal edu 
cati'onalF~Ibroadenst. stations eng-aging in stereophonic and SC-,-l
operations, we do not feel this exemption is necessary. and we will
grant waivers for these stations uponreque..~t.
'26. 'Ve call attention tn the fact that we have taken th€ opportunity,
while amending sections 7a.297 and 73.596 relating tn stereophonic
broade-asting-. to delete the requirement that stations so operating shall
notif~'us nf the lwurs of stereophonic broadcasting and any change
therein. AJ the time of adnption of the original rule. we feIt it desira 
ble to be infnrmed as to the extent nf sterenl,hnnic broadcasting. At
the present time we believe such operatinn is progressing in satisfac 
torY fashion, and see nn furtber need to be infnrrned nf the hnurs of
stereophol1ic~broadcasting_ Since this is a. relaxation of an existing 
requirement, we find that prior notice of such change would serve
no public purpnse.
27. Certain nf the cnmments submitted by the National Association
of Broadcasters (NAB) expressed a yiew tllat the adequacy of existing
nonmultiplex monitors should be examined as part of this proceeding.
'Ve have, in cooperation with the broadcast industry, examined several
different types of modulation monitors under actual operating condi 
tions and haye reached the cnnclusinn that our rules relating tn non 
multiplex nwnitnrs should be modified. Howeyer, in order nnt to
delay this procee.clinl' fnrther, we haye decided to establish specifica 
tions for stereophonic andSC..<-~modulation monitors now~and, at
an ellrly date, ,ve plan to reexamine the spee-ificat-ions for nonu1ultiplex
monitors.
28. 'Yhen 'lnestinninl' the perfnrmance of existing nonmultiplex
monitors. X AB also dnnbted the propriety of nnr actinns in issuinl'
C'E'rtain \,ioLltion notIces for excessive lllodnlation (violation of sec.
7'J.~68).The point in dispnte concerns onr nse nf measnring: equip 
ment which eli/l'eI'S from the nwdnlatinn mnnitnr we reqnire to he
installed at bmackast stations. In this cm1l1ection. ,,'r point ont that
our present rules reqnire that each mnnitor be equipped with bnth a
1110dnlation peak indicating device and a semipeak indicator (sees.
7;JXJ~(b)(~)and (3)). lYe obsen-e that the KAB comment pre 
sumes that only the. semipeak indicatm is used for setting modlllatinn
3 F.e.e. 2<1
J[onitoT8 fa I' FM S"beal'"i,,, Opemti01I,'
725
lel'els and appears to O\"erlook the peak-reading dey;re. Our em 
phasis. on the other hand, is with the latter deY;c" which is int"nded
to dea.l with those transient peaks of program material which cannot
be indicated. reliably by the semipeak meter. The. disputed violation
noti('e~concerned the transient peaks of frequent recurrence "hieh
exeeeded the peak modulation le,"els permitted under section 73.26,',
of our rules. The facilities w"e use in enforcing the proyisions of this
:-;prtion include a cathode ray oscilloseope aeeurately calibrated in tenus
of modnlation peak amplitudes. lYe beliere that this method. which
stresses modulation measurement in terms of pe.ak amplitudes, is fully
r(lll~istentwith the proyisionsof section '73.33:2 (b) (2) .
:W. Exnnlination of the instruction books supplied ",Yith Inostexi~t­
ing' (vpe apprcwec1 Inodulation IHonitors reveals that users of this
(''1"il'ment are eautioned to calihrnte the monitors properly and to use
discretion in relying- on the 111eter and peak flasher indications of the
]lloniror uncle,r prOQTfUn conditions. 'Ye,belieYe~fron1 our study of
the problem, that few discrepancies occur between the indications re"
naled by the Commission's monitoring equipment and the station
Hlodnlation monitor indications if due consideration isgi,~ento proper
cal ibrntion of t1,.. modulation monitor.
~10.For the reasons stated above, -we are of the opinion that it is in
the public interest to adopt the proposals set forth in the notice, as
revised in the manner discussed above.
:n. Authority for the adoption of the amendments herein is con 
tained in sections 4(i). 303 (f), (e), and (r) of the Communications
Act of 19:34.·as amended.
:12. In view of the foregoing, It ;8 ordered, That, effective July 5,
H;{jG, part 73 of the C-ommission's rnles and regulations AI'e amended
:lnd the proceeding /8 teT·mhwtf'd.
3 F.e.e. 2d