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Text File | 1994-11-27 | 25KB | 515 lines

Transcribed from printed pages by the Field Services Department of the American Radio Relay League, Inc., 225 Main St., Newington, CT 06111, (203) 666-1541. Subject: TELEPHONE INTERFERENCE SURVEY February 28, 1994 Telephone Interference Survey Background The Federal Communications Commission (FCC) receives 25,000 complaints per year from individuals who are unable to use their telephones because nearby radio stations interfere with the proper operation of the telephones. Whenever the radio stations are on the air, the telephones pick up their transmissions which then override any ongoing telephone conversation. The FCC's Field Operations Bureau (FOB) has done an informal survey to obtain information about telephone interference such as: - which telephones are affected - what type transmitting stations are involved - the power levels at which the stations were transmitting - whether commonly available filters would be effective in eliminating the interference - whether specially designed telephones would be effective in eliminating the interference In setting forth the results of its informal survey, FOB emphasizes that, because this survey is based on a random sample it cannot be claimed that identical results would be derived under scientific surveying and testing, nor should the results be construed as FCC endorsement or criticism of any particular manufacturer's product. Rather, FOB believes these results to be a good "first look" at the problem. Procedure Thirty-five FCC field offices across the country participated in the survey. Each office was to choose three recent complaints of telephone interference on a random basis, and then to investigate the complaints. At the transmitting station FOB staff would determine the type of station (i.e., amateur, citizens band, broadcast, etc.), measure the station power, and obtain information on antenna height, antenna gain, and distance from the complainant. At the complainant's location, FOB would disconnect all telephones, take them to a chosen telephone jack, and plug them in one at a time while the station was transmitting. FOB would then record which telephones received interference and which did not. FOB also tested the effectiveness of several commercially- available telephone filters, connecting the filters to telephones which were receiving interference while the radio station was transmitting. Finally, FOB connected "bulletproof" telephones to the telephone jacks and observed whether these telephones received interference. A "bulletproof" telephone is one that is specially designed to be immune to interference. Findings Types of Transmitting Stations FOB inspected 108 transmitting stations which were involved in the telephone interference complaints, as follows: Citizens Band 47 Amateur 27 AM Broadcast 23 FM Broadcast 10 International Broadcast 1 Power Levels The power levels of the radio transmitting stations varied from two watts to half a million watts. One-third of the transmitting stations operated with less than ten watts, and one-third of the interfering stations were broadcast stations using between 3000 and half a million watts. Attachment 1 lists the power levels of the transmitting stations. Types of Telephones FOB tested 241 telephones found in the complainants' residences for interference. Of the 241 telephones 68 percent received interference. Attachment 2 lists the telephones tested. FOB did not observe interference on 32 percent of the telephones it tested. These telephones are listed in Attachment 3. Types of Filters FOB tested the effectiveness of the AT&T Z100B1 filter on 138 telephones receiving interference. After connecting the filter to the telephones, 62 percent of the telephones continued to receive interference. The filter did eliminate interference on 38 percent of the telephones. A number of other filters were also tested on 82 telephones receiving interference. As a group these filters eliminated interference on 29 percent of the telephones. They did not eliminate interference on 71 percent of the telephones. Attachment 4 lists the filters which eliminated the interference. Bulletproof Telephones The FCC tested "bulletproof" telephones at 52 locations where the individuals were receiving interference to their telephones. The "bulletproof" telephones eliminated interference at 96 percent of the locations. Conclusions The transmitting stations most likely to cause telephone interference are citizens band, amateur, and broadcast stations. Citizens band stations accounted for half the telephone interference cases. Amateur stations and broadcast stations accounted for the other half. The power levels used by the radio transmitting station did not appear to be a significant factor in causing telephone interference. Power levels of 10 watts or less caused telephone interference in a third of the cases. A large portion of the residential telephones appeared to be susceptible to interference from nearby radio transmitting stations. Although some telephones did not receive interference, the limited nature of the testing performed in conjunction with this survey would not support the conclusion that they would always reject interference. Telephone interference filters cannot be relied upon to eliminate telephone interference: in two out of three cases in the test sample, they did not work. Manufacturers can design telephones to be interference free. "Bulletproof" telephones were immune from interference virtually all of the time. A Final Note Notwithstanding the 25,000 reports of telephone interference the FCC has received to date, it is FOB's experience that, as large as this number is, it probably represents only a fraction of the actual instances in which this interference occurs. Given the enormous numbers of instances in which this type of interference is experienced by consumers, it is our hope that this survey, notwithstanding its informality, will serve as a catalyst for affected parties to productively address and resolve this problem. As always, FOB remains ready to assist in that effort. ATTACHMENT 1 FIELD OPERATIONS BUREAU TELEPHONE INTERFERENCE SURVEY POWER LEVELS OF INTERFERENCE SOURCES UNKNOWN 2 sources 2 watts 4 sources 3 watts 7 sources 4 watts 14 sources 5 watts 7 sources 6 watts 1 source 7 watts 4 sources 12 watts 2 sources 26 watts 1 source 30 watts 1 source 35 watts 1 source 50 watts 1 source 53 watts 1 source 54 watts 1 source 57 watts 1 source 75 watts 1 source 80 watts 1 source 100 watts 5 sources 101 watts 1 source 110 watts 2 sources 114 watts 1 source 131 watts 1 source 150 watts 1 source 160 watts 1 source 200 watts 1 source 250 watts 1 source 438 watts 1 source 462 watts 1 source 500 watts 3 sources 600 watts 1 source 800 watts 1 source 1,000 watts 3 sources 1,500 watts 2 sources 3,000 watts 2 sources 5,000 watts 5 sources 8,000 watts 1 source 10,000 watts 4 sources 16,000 watts 1 source 25,000 watts 1 source 50,000 watts 11 sources 51,000 watts 4 sources 54,000 watts 1 source 100,000 watts 1 source 500,000 watts 1 source Total sources: 108 ATTACHMENT 2 FIELD OPERATIONS BUREAU TELEPHONE INTERFERENCE SURVEY TELEPHONES RECEIVING INTERFERENCE fo fil ix power att oth fcc make model DL N AMA 800 N N Y (UNKNOWN) (UNKNOWN) AL N CB 4 N N Y (UNKNOWN) (UNKNOWN) PL N CB 2 N N Y AT&T (NONE) DT N CB 5 N N Y AT&T (NONE) (FCC AS593M-70230) LR N AM 1000 Y AT&T 100 KI N FM 3000 N AT&T 1306 KI N AMA 100 N AT&T 1504 DV N AM 5000 Y Y Y AT&T 150E NY N CB 3 Y Y AT&T 1510 PO N AMA 35 Y N AT&T 1521 BS N AM 10000 Y N AT&T 1532 GI N AMA 53 N N AT&T 1611 DL Y CB 5 N Y AT&T 1618 KI N AMA 100 N AT&T 210 KI N AMA 100 N AT&T 210 DS N AM 5000 Y AT&T 210 DS Y AMA 500 N Y AT&T 210 NF Y CB 3 Y N Y AT&T 210 PL N AMA 1000 Y Y Y AT&T 530 DL N AMA 800 Y Y Y AT&T 5455 GI N AMA 101 N AT&T 610 BF N AMA 100 N Y AT&T 710 KI N CB 5 N AT&T 720 CG N AMA 1000 Y Y AT&T 720 KC Y CB 4 N Y AT&T 725 GI N AMA 101 N AT&T 725 PA N CB 3 N Y AT&T 732 HL N AMA 462 N N AT&T 732 MA Y AMA 600 N AT&T AOM9RN 10451-TE-E LR Y CB 4 N AT&T AS 550Z 71597 MA N AMA 50 N AT&T ASSS0Z-71597-TE-E DT N AM 438 N AT&T MODEL 1506 NY N AM 25000 N N AT&T PRINCESS BM N CB 7 N N Y AT&T PRINCESS AS 550 Z-71322 PA N CB 3 N Y AT&T SPKK REMOTE & ANS MACHINE PO N AM 50000 Y Y AT&T SW204 BM N FM 16000 Y N Y AT&T TRIMLINE 210 BF Y AM 50000 N Y AT&T TRIMLINE 210 DL N CB 5 Y Y AT&T TRIMLINE 220 NF N AMA 1500 Y Y Y AT&T TRIMLINE AS550Z-71597-T ST N AM 10000 Y N Y AUDIOVOX AT-11 PO N AM 50000 Y N BELL FAVORITE PL N AM 5000 Y BELL TT-51490 KI N CB 5 N BELL PHONES 100-5800 AT Y CB 160 N N Y BELL SOUTH 2000 BS N AM 50000 Y N BELL SOUTH 227V DT N CB 3 BELL SOUTH 473 KI N CB 5 N BELL SOUTH 473 DS N AM 5000 Y BELL SOUTH 473 MA N AMA 600 BELL SOUTH CWIMLA-61669-ANN OR N AMA 100 N Y BELL SOUTH DPK-62W70687-TE-T AT N IB 500000 N Y BELL SOUTH HAC 572 PS Y AMA 150 N N Y BELL SOUTH TP-201 L-10 SF N AM 50000 Y CANON FAX-350 PO Y AMA 500 Y CODE-A-PHONE 1610 LA Y AM 50000 N N COMDIAL 25270-IY SF N AM 50000 COMDIAL VOICE EXPRESS ST N CB 75 N N Y CONAIR PR 1000 AT Y CB Y Y CONAIR PR 5001 LV N CB 57 N N CONAIR SW 2502 TP N CB 5 CONAIR SW204 BE N AMA 80 N CONAIR SW204A PO N AM 50000 Y CONAIR TR101 AN N FM 51000 Y Y CONAIRPHONE PR1006 PO Y AMA 500 Y CONAIRPHONE PRIMA SERIES DT N CB 3 N N Y CONAIRPHONE SW-102 HL N AM 10000 DELTA HEK-EB-200DSIHF-EXT SD N CB 12 N FORTEL CORP RECORD A CALL #2140 SF N CB 2 N N GENERAL ELECTRIC 12-MEMORY 2-9240A PO N AM 50000 Y N GENERAL ELECTRIC 2-9051LRA MA N CB 6 N GENERAL ELECTRIC 2-9166B CG N AM 50000 Y Y GENERAL ELECTRIC 2-9166B TP Y CB 4 N Y GENERAL ELECTRIC 2-9167A KC N CB 2 Y Y GENERAL ELECTRIC 2-9212BLB LV Y CB 4 N N GENERAL ELECTRIC 2-9243 DT N AM 438 GENERAL ELECTRIC 2-9243C KC N FM 8000 N GENERAL ELECTRIC 2-9355A LV Y CB 5 N N GENERAL ELECTRIC 2-9356 VB N AMA 100 Y GENERAL ELECTRIC 2-9400C HL N FM 54000 GENERAL ELECTRIC 2-94050A HL N FM 54000 GENERAL ELECTRIC 2-94050A HL N FM 54000 GENERAL ELECTRIC 2-94050A HL N FM 54000 GENERAL ELECTRIC 2-94050A MA N CB 6 N GENERAL ELECTRIC 2-9420A HU N FM 100000 N GENERAL ELECTRIC 2-9675A PS Y CB 5 Y Y Y GENERAL ELECTRIC 2-9892A DV N CB 2 Y Y Y GENERAL ELECTRIC 2-9895A LV N CB 4 N N GENERAL ELECTRIC 29270 A DV N AM 5000 Y GENERAL ELECTRIC 7-4700A LA N AM 5000 Y Y GENERAL ELECTRIC CRYSTAL CLEAR PLUS BF N CB 5 N Y GENERAL ELECTRIC MEMORY MODEL 21 MA N CB 6 Y GENERAL ELECTRIC NO 29420A SD N CB 54 N N GENERAL ELECTRIC SPEAKER PHONE 2-9375F CG N AMA 1500 GENERAL ELECTRIC TL-5/TPS PO N AMA 35 Y N GTE 58821 ST Y FM 51000 N N Y GTE 7400 GI N AMA 101 Y GTE AUTO ELEC - WALL PHONE GI N AMA 101 Y GTE AUTOMATIC ELECTRIC PL N AM 5000 N IMA (NONE) AL Y AM 5000 N N Y ITT (CORINTH 3480 FEATURE TELEPHONE TELECOM. CORP) DS N FM 3000 Y N Y LENOX SOUND P4316 PL N AM 5000 LLOYDS (PHONE- T510 CLOCK-RADIO) HU N CB 110 N LONE STAR 912 PA N CB 4 Y LONE STAR TRIMLINE BS N CB 5 N N LOTEL 5020 DUEL LINE BS N CB 5 N N LOTEL 5020 DUEL LINE FE N AMA 131 N NORTHERN TELECOM FCC REG #AB6982-68817-TE-T AN N FM 51000 Y Y NORTHERN TELECOM NT3L00AA DT Y CB 5 Y N Y NORTHERN TELECOM SYMPHONY 3000 PS N AMA 200 N N Y NORTHWESTERN BELL "EASY TOUCH" SD Y CB 12 N NORTHWESTERN BELL BASIC TGT 51450 LV N CB 4 N N PAC BELL TR 2203 CHAC PO Y AM 50000 N N PACTEL FE5700 DS N AMA 500 N Y PANASONIC EASA-PHONE VA-8205 NY N AMA 100 Y Y PANASONIC EASA-PHONE-AUTO LOGIC BS N AM 10000 N N PANASONIC EASE PHONE KX-TX175-B TP Y CB 3 N N Y PANASONIC KX-T-2420 SF Y AMA 250 Y N PANASONIC KX-T-3155 DV N AMA 114 N Y Y PANASONIC KX-T2315 DL N CB 4 Y Y Y PANASONIC KX-T2315 PO Y AM 50000 Y Y PANASONIC KX-T2355 CG N AMA 1500 N Y PANASONIC KX-T2355 ST Y AM 10000 N N Y PANASONIC KX-T2622 EASAPHONE HL N AMA 462 PANASONIC KX-T3145 OR N AM 50000 N Y PANASONIC KXT 2388 KI N CB 5 N PHONEMATE 3900 NF N CB 7 Y N Y PHONEMATE 3950 GI Y AMA 101 N PHONEMATE 4650 BS N AM 10000 N N RADIO SHACK 209 DUCPHONE 43-617A DS N FM 3000 Y RADIO SHACK 43-384 PS Y CB 5 RADIO SHACK 43-384 DT N CB 3 Y RADIO SHACK 43-625 DUOFONE 202 TP Y CB 4 N Y RADIO SHACK 43.430 PO Y AM 50000 Y N RADIO SHACK DUOPHONE TAD-250 OR N CB 4 Y RADIO SHACK ET 200 LR N CB N SANYO TA S 855 AT N CB 160 N Y SEARS 3293 4761550 SR 3000 KI N FM 3000 N SEARS 34403 DL N AMA 800 Y Y Y SEARS 34505 LV N CB 4 N N SEARS SR-2000 KI N FM 3000 N SOUND DESIGN 7255 AR TP Y CB 3 N N Y SOUNDESIGN 7339 IVY NY Y AMA 100 Y Y SOUTHWESTERN BELL FCC 2555 BE N CB 4 N SOUTHWESTERN BELL FREEDOM PHONE ST Y CB 75 N N Y SOUTHWESTERN BELL FREEDOM PHONE FC 2570 BS N AM 10000 Y N SOUTHWESTERN BELL FT-325 SF N AM 50000 STROMBERG IMAGE 1 AND IMAGE 2 DTMF ST Y FM 51000 N N Y TECHNICO TT-2201 SJ N CB 26 N Y TELEFONICA TXE-1 HISPANO AMERICAN SJ N CB 7 N Y TELEFONICA TXE-1 HISPANO AMERICAN TP N CB 3 N N Y TELKO 221 ST Y CB 4 N N Y THOMAS PP9D NOSTALGIA PHONE FE N AM 50000 Y TIME LIFE (MADE (NONE) IN TAIWAN) DS N AM 5000 Y Y Y TISONIC PT-91 LV Y CB 5 N N ULTRSONIC 019 KC N FM 8000 N UNIDEN TRIMLINE FE N AM 50000 Y UNISONIC (NONE) AL Y AM 5000 N N N UNISONIC (NONE) VB Y CB 30 Y UNISONIC 6434 BM N CB 4 N N Y UNISONIC 9370 PL Y AM 5000 Y Y Y WESTERN ELECTRIC (NONE) DT N AM 438 Y Y WESTERN ELECTRIC (NONE) ROTARY DIAL PHONE DT N AM 438 WESTERN ELECTRIC (NONE) ROTARY DIAL PHONE NF N AMA 1500 Y Y Y WESTERN ELECTRIC AS543M-62587-TE-T PA N AMA 110 N Y WESTERN ELECTRIC CS 2500 DMG 84121 fo=Field Office,fil=filter already installed? ix=Service causing interference power=power of transmiter att=Problem corrected with AT&T Z100-B1? oth=Problem corrected with other filter? fcc=Problem corrected with FCC "bullet-proof" phone? ATTACHMENT 3 FIELD OPERATIONS BUREAU TELEPHONE INTERFERENCE SURVEY TELEPHONES NOT RECEIVING INTERFERENCE off filter make model NF Y AT&T 1316C DL N AT&T 1321 SF N AT&T 1323 NY N AT&T 5200 SF N AT&T 5200 BF N AT&T 5400 ST N AT&T 5600 PA N AT&T 60921 CG N AT&T 700 ST N AT&T 730 PA N AT&T ANS MACHINE PA N AT&T AS5 THA-60921-MT-E DL N AT&T CS8702A DL Y AT&T NE-229A OR N AT&T OLD DIAL STYLE BF Y AT&T TRIMLINE BM N BELL SOUTH 665 CORDLESS PHONE HU N BELL SOUTH HAE-701 OR N BELL SYSTEM TRIMLINE AL N COBRA AN-8519 DT N COBRA ST-410 SD N CODE A PHONE 8100 AL N CONAIR CORP XS2400 LV N CONAIR CORPORATE AMERICA BS N DAK INDUSTRIES DAL-4000 AX NF Y DAK INDUSTRIES DK 4000 AX CG N GANDALF COMDIAL AL N GENERAL ELECTRIC 2-9051LRB KC N GENERAL ELECTRIC 2-9800B BM N GTE (UNKNOWN) ST N GTE 980 SLIMLINE PS N ITT 183499-236 FE N ITT 500D AN N ITT RJ11C AL N LENNOX SOUND PH-319 HL N UNKNOWN (CHINA) FCC #: GEZ 364-16521 TE-E HL N NORTHERN TELECOM SYMPHONY 1000 DV N NW BELL FAVORITE PLUS DHT6CJ-14584-TE BS N PANASONIC EASE PHONE-ONE LINE HU N PANASONIC GASA-PHONE DV N PANASONIC KX-T-3120 HL N PANASONIC KXT-2355 KC N PHONEMATE 4300 ST N RADIO SHACK 43-368A FE N RADIO SHACK 43-500 FE N RADIO SHACK 43-5018 DV N RADIO SHACK 43-621 OR N SEARS 329 34451750 DT N SEARS 34413 GI N SEARS HAC 3466 ST N SEARS SR 3000 SERIES SF N SHARP UX-172 SF N SOUND DESIGN AM/FM CLOCK RADIO PHONE AL N SPECTRA PHONE TL-4 DT N STC TELECORP INC SOUNDDESIGN 7255 ST N TELECONCEPTS (NONE) NF N WESTERN ELECTRIC (UNKNOWN) BM N WESTERN ELECTRIC (UNKNOWN) DL N WESTERN ELECTRIC (UNKNOWN) KC Y WESTERN ELECTRIC (UNKNOWN) LA N WESTERN ELECTRIC "LA OLYMPIC PHONE" PA N WESTERN ELECTRIC 2554 BMPG-82103 BS N WESTERN ELECTRIC RB 1311 (ROTARY) NF Y WESTERN ELECTRIC TRIMLINE #CS 2224A NF N WESTERN ELECTRIC TRIMLINE PHONE ATTACHMENT 4 FIELD OPERATIONS BUREAU TELEPHONE INTERFERENCE SURVEY OTHER FILTERS TESTED K-COM RF-1 1 K COM RF1 3 RADIO SHACK-SNAPON 1 TCE 1 TCE536 2 TCE TP12 4 TEC RF1400 2 TII 931-W1 2 The filters listed here deserve further study. During the project, FOB found that these filters eliminated interference when tried in individual cases. However, because FOB did not use any of these filters in a sufficient number of cases, we cannot conclude whether any of them would be effective in eliminating interference most of the time. ATTACHMENT 5 FCC BULLET PROOF PHONE Manufacturer Make Address Pro Distributors Western Electric 2811 74th Street, Desk Model Lubbock, TX Touch Tone 1-800 (658-2027) TCE Labs Rural Route 9 Box 243D New Branufels, TX 78133 (800-KILL-TVI) Note: All phones were refurbished, internally modified commercial units.