OFFICIAL COUPON FOR THE

$40 Mail-In Rebate Offer

Mail your completed form to:
Receive, by mail, a $40 rebate with the purchase of a Panasonic KX-TG2730S cordless phone. Please enter your information online at www.panasonic.com/specialpromos or print legibly and complete all information. No P.O. Box numbers will be accepted. Name Address (No P.O. boxes) City State Zip Date of Purchase
Panasonic Redemption Headquarters, P.O. Box 9321, Bridgeport, NJ 08014
How to claim your $40 Rebate: 1. Purchase a select Panasonic Cordless Phone between May 15, 2005 and July 2, 2005. 2. Return this completed form, including the serial number label, along with a copy of your cash register receipt with the purchase price circled. IMPORTANT: You must sign this form, then cut out and include the original label from the carton, which includes the UPC code, model number and serial number, or your claim cannot be processed. 3. Only handwritten responses will be accepted. No stickers or preprinted address labels. Product must be new and un-used. 4. Offer valid for purchase made from May 15, 2005 through July 2, 2005. All claims must be postmarked within one month of purchase. 5. This offer is only available to the end user and original purchaser. No claims from re-sellers, dealers/distributors, their employees or warehouse facilities, groups, clubs or organizations will be accepted or acknowledged. No P.O. boxes accepted except military APO/FPO (Air/Army Post Office or Fleet Post Office) addresses. 6. Limit one rebate per name, address or household; may not be combined with any other offer or rebate. It is illegal to submit multiple requests for the same individual or family. Fraudulent submissions of multiple requests could result in federal prosecution under the U.S. Mail Fraud Statutes (18 USC, Sections 1341 and 1342). 7. Offer void where taxed, prohibited or restricted by law. Offer good only a) on purchases in the fifty states of the United States and D.C. and b) to current U.S. residents only. Exception for U.S. military personnel overseas. 8. Panasonic Corporation of North America (Panasonic) is not responsible for late, lost or misdirected mail. 9. Claim forms postmarked more than one month after purchase will not be honored. 10. Panasonic rebate checks are ordinarily delivered within 8-14 weeks. Rebate checks are void if not cashed within 90 days of issuance and cannot be reissued. 11. Panasonic reserves the right to audit any claims and to nullify any claims that cannot be substantiated. Panasonic reserves the right to amend the rules of the program or cancel this promotion without prior notice. Visit us on the web at panasonic.com Questions? Go to www.panasonic.com/specialpromos or call 1-800-832-7199 to check or enter info.
For Rebate Status, provide promotional purposes.) E-mail Address

address.

Check here to receive special offers, news and more from Panasonic. Signature ______
Applies to the following models only. Please check the model you purchased: KX-TG2730S

Telecommunications Industry Association

Document Cover Sheet

TR41.3-05-11-009-L
Project Number Document Title

PN-3-0219

Cordless Phone Interference Investigation

By Weili Lin 8-17-05

Source Contact
Starkey Laboratories Name: David Preves Starkey Laboratories 6600 Washington Ave. S Eden Prairie, MN 55344 TR-41.3 X For Incorporation Into TIA Publication For Information Other (describe) Phone: 952-828-9264 Fax: 952-828-6972 Email: dave_preves@starkey.com
Distribution Intended Purpose of Document (Select one)
The document to which this cover statement is attached is submitted to a Formulating Group or sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the provisions of Sections 6.4.16.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of which provisions are hereby incorporated by reference.

Abstract

This investigation was initiated due to a customer complaint regarding interference in hearing aids from cordless phones, which was buzzing and motor boating in nature. Through an initial analysis, it was determined that this was caused by unwanted magnetic emission from the handsets in audio band. In order to gauge the range and magnitude of the interference, the following experiments were conducted.

v1.0 20050426

I Standards
The followings are the existing requirements for the magnetic field strength from a handset and the appropriate acoustic pressure levels: According to FCC part 68.316, the axial field intensity should be more than -22dB relative to 1A/m for an input of -10dBV at 1000Hz. However, there is no correlation between required sound pressure level and magnetic field strength, and no noise floor requirement; TIA/EIA-504 stipulates that the axial field strength should be at least -36dB relative to 1A/m at 1000Hz in order to produce an acoustic output of 80dBSPL at the same frequency measured in an artificial ear; According to Working Group on Hearing Impairment (WGHI): - ETSI ETS or ITU Rec. P.37 indicates that a sound pressure of 80dBSPL at 1000Hz at the ear results in an inductive field of -30 to -17dB relative to 1A/m for the telephone handsets. - UK requires that an inductive field of -40dB relative to 1A/m should be equivalent to 55dBSPL at the microphone input of a hearing aid. As a result, an equivalent sound pressure level of 65 to 78dBSPL will be received at microphone port if such a telephone handset and hearing aid are coupled. - The noise level at the earpiece without inductive input should be less than 45dBSPL at the microphone, which implies an equivalent magnetic noise floor of -50dB relative to 1A/m. - The signal to noise ratio should therefore be at least 20dB (a signal of -30dB rel.1A/m in magnetic field strength, which corresponds to 65dBSPL acoustic input, vs. a magnetic noise of 50dB rel.1A/m) th NSH Hearing Aids Requirements and Guidelines (1997-10-09, 5 edition) section 5.7 requires that an inductive signal of -30dB relative to 1A/m should provide an equivalent acoustic input signal to a hearing device of 55-65dBSPL between 500 and 1000Hz and of 57-67dBSPL between 1000 and 4000Hz. AS a result, a magnetic field of -30dB relative to 1A/m, which corresponds to around 65dBSPL acoustic input to a hearing aid according to the above requirements, will be used as a suitable minimum signal level in the following discussion.

II Test Setup A hearing aid coil was used as a probe for measuring the magnetic field around the device under test (DUT). Its sensitivity response is shown in figure 1. An HP 35665A analyzer was used to collect the data in 1/3 octave band. Since most of the magnetic radiation was along the direction perpendicular to the keypads and LCD of the handsets (referred to as the front surface), which is also the orientation pointing toward a callers ear, the measurements were therefore mainly dealt with this component of the magnetic field, which is defined as the axial orientation in FCC part 68.316 and TIA/EIA-504. The measurement distance was 1cm as defined in the aforementioned standards, which was achieved through a spacer as shown in figure 1.

Page 2

-10 -20
Telecoil Output (dB re 1A/m)
-30 -40 -50 -60 -70 -80 -1,000 10,000

Frequency (Hz)

Output Spectrum of a Coil Used As a Magnetic Field Probe

Telecoil

Spacer
FIG 2 Probing Coil and Test Setup
The following cordless phones (except the Siemens phones) were used in this evaluation: - Motorola MA511: 5.8 GHz analog - Uniden EXI4246: 2.4 GHz analog - Panasonic KX-TG5421W: 5.8 GHz digital (FHSS) - Panasonic KX-TG2730S: 2.4 GHz digital (FHSS) - GE 25833GE3-A: 5.8 GHz digital (FHSS) - Siemens E3/P6 and E3/PD: corded analog In order to study the distribution of the magnetic radiation along the surface of the handsets, the following test points were chosen (as shown in figure 3): - Location A: 1.5cm above the speaker - Location B: over the speaker - Location C: 1.5cm below the speaker

Page 3

Location D: over LCD and roughly 3cm below the speaker Location E: over the large button Location F: over the center of keypads

Location B

Location D

Location F

Location A

Location C

Location E
FIG 3 Test Locations for a Cordless Phone
III Results After the signals from the probe coil were collected at various locations of a handset when a dial tone was provided, the results were then corrected by using the probes sensitivity shown in figure 1 to account for its rising response (~6dB per octave). a) Axial Magnetic Field Response The results for all the phones are included in Appendix 1. Figures 4 and 5 show the measured magnetic field strengths at different locations for Motorola MA511 (5.8GHz analog) and Panasonic KX-TG542W (5.8GHz digital), respectively.

The two large spikes between 300 and 500Hz in these figures correspond to the dial tone signal as received by the coil. A marking representing -30dB rel.1A/m at 1000Hz is also shown to indicate the equivalent 65dBSPL acoustic level. As the dark green curve in figure 4 indicated, the response rolls off below 300Hz and above 3300Hz, which represents the bandwidth of the telephone communication.

Page 4

-20 Magnetic Field Strength (dB re 1A/m)

-100 100

1,000 Frequency (Hz) 1.5cm Above Speaker Over Speaker 1.5cm Below Speaker Over LCD 65dBSPL Equivalent

10,000

FIG 4 Axial Magnetic Field Responses for Motorola MA511 at Various Locations
-10 Magnetic Field Strength (dB re 1A/m) -20 -30 -40 -50 -60 -70 -80 -90 -100 100
1,000 Frequency (Hz) Ambient 1.5cm Above Speaker Over Speaker 1.5cm Below Speaker Over LCD

65dBSPL Equivalent

FIG 5 Axial Magnetic Field Responses for Panasonic KX-TG5421W at Various Locations

Page 5

b) Comparisons of Different Cordless Phones Figure 6 shows the magnetic field responses for all cordless phones at different locations.
Magnetic Field Strength (dB re 1A/m)

-90 100

Motorola MA511 Panasonic KX-TG2730S 2.4G

1,000 Frequency (Hz)

Uniden EXI4246 2.4G GE 25833GE3-A Panasonic KX-TG5421W 65dBSPL Equivalent

(a) Over the Speaker

(b) 1.5cm Below the Speaker
-30 Magnetic Field Strength (dB re 1A/m)
Motorola MA511 Panasonic KX-TG2730S 2.4G Uniden EXI4246 2.4G GE 25833GE3-A Panasonic KX-TG5421W 65dBSPL Equivalent
(c) 3cm Below the Speaker and Over the LCD FIG 6

(d) Over the Main Button

Axial Magnetic Field Responses for Cordless Phones at Various Locations
It can be seen from figure 6(a), the magnetic field strengths measured over the speakers were similar for all the phones. However, as soon as the test points were below the speakers, all the digital cordless phones showed much worse magnetic radiations. As shown in figure 6(c), over the LCD (about 3cm below the speaker), the magnetic radiations from three digital cordless phones were either higher than or within 15dB from -30dB rel.1A/m (65dBSPL equivalent acoustic output) above 1000Hz, while the magnetic outputs from two analog phones were nearly 40dB below the same mark (-70dB rel.1A/m ).
It can also be observed that there are comb filter type of noise spectrums above 1000Hz for all there digital phones as shown in figure 6(b)-(d), which may have contributed to the motor boating sounding.

Page 6

c) Signal To Noise If the dial tone is used to represent a suitable signal level during a phone conversation, and the highest output above 1000Hz is defined as the noise floor, it can be seen that all the analog phones showed much better results in terms of signal to noise ratio as well. As shown in figure 6(c), at location D (over the LCD, roughly 3cm below the speaker), the signal to noise ratios for all the digital phones were on the order of 15dB, while more than 40dB signal to noise were achieved for the analog phones. d) Side Radiation In order to understand the strength of the magnetic field from the side of a handset, additional measurements were taken by placing the probe coil next to the edge of the phone with its center axis parallel to the front surface of the handset. The recorded magnetic signals at three locations were overlaid with those at axial orientation (shown in figure 7). The side radiations were much less than their axial counterparts at locations over the speaker and LCD, but were equivalent to the axial component near the buttons.

-10 Magnetic Field Strength (dB re 1A/m)

-80 100

1,000 Frequency (Hz) Over Speaker Over Button (Side) Over LCD Over Button Over Speaker (Side) 65dBSPL Equivalent Over LCD (Side)
Axial and Side Magnetic Field Responses for Panasonic KX-TG2730S at Various Locations
e) Volume Setting The previous measurements were performed under the default volume setting for each phone. By turning down the phone volume, the dial tone signal was reduced as expected; however, the magnetic radiations stayed the same as shown in figure 8.

Page 7

1,000 Frequency (Hz) Over Speaker Over LCD (Lower Volume) 65dBSPL Equivalent Over LCD Over Button (Lower Volume) Over Speaker (Lower Volume) Over Button
Axial Magnetic Field Responses for Panasonic KX-TG2730S at Different Volume Settings
f) Effect of Dial Tone By disconnecting the phone line, the field measurements were repeated without the dial tones. It can be observed that the radiations were only slightly better than those with the dial tones (figure 9).
-10 -20 -30 -40 -50 -60 -70 -80 -90 -Ambient #1 Over LCD 1.5cm Below Speaker
1,000 Frequency (Hz) 1.5cm Above Speaker Over Speaker Ambient #2 1.5cm Above Speaker Over LCD 65dBSPL Equivalent
10,000 1.5cm Below Speaker Over Speaker
Axial Magnetic Field Responses for Panasonic KX-TG5421W With and Without Dial Tones

Page 8

IV Conclusions
All three digital cordless phones generated unacceptable magnet radiations in audio band, while two analog phones were still very quiet; The undesirable magnetic radiations were independent of the volume settings and dial tones; If the magnetic radiation is below -60dB rel.1A/m above 1000Hz over the LCD, and the signal to noise ratio (defined in III(c)) is more than 30dB at the same location, it will be deemed acceptable; Further evaluations may involve phones with different digital technology (such as DSSS), hearing aid telecoil in-situ pickup, audio signal recording, and the detection of radial axis component. Appendix 1 Telephone Axial Magnetic Field Responses
1,000 Frequency (Hz) Over Speaker (E3/P6) Over Speaker (E3/PD) 65dBSPL Equivalent
FIG A1.1 Axial Magnetic Field Responses for Siemens Corded Phones

Page 9

FIG A1.2 Axial Magnetic Field Responses for Uniden EXI4246 at Various Locations

Page 10

1.5cm Above Speaker Over Speaker 1.5cm Below Speaker & Over LCD Over Button
FIG A1.3 Axial Magnetic Field Responses for GE 25833GE3-A at Various Locations

Page 11

FIG A1.3 Axial Magnetic Field Responses for Panasonic KX-TG2730S at Various Locations

Page 12