OMDMSF0001Assistive Listenting System for Hard of Hearing

MicroField User Manual Contents Introduction ........................................................................................................................................ 1 MicroField Key Features............................................................................................................... 3 Important Notes About Your MicroField .................................................................................... 4 MicroField Channels ............................................................................................................... 6 Instructions For First-Time Users .......................................................................................... 7 General Functions ......................................................................................................................... 8 Turning the Unit On and Off................................................................................................. 9 Operational Overview - Connections and Controls ........................................................... 10 MicroField’s Display ............................................................................................................. 11 Adjusting Volume ................................................................................................................. 12 Enabling the Automatic Shut-Off Function ...................................................................... 13 Returning to Factory Defaults ............................................................................................ 14 Charging the Batteries ......................................................................................................... 15 Using the Power Supply ....................................................................................................... 16 Replacing the Batteries ........................................................................................................ 17 Applications: 1. Using MicroField for Rebroadcasting .................................................................................. 19 Setting Up The Transmit Channel .......................................................................................19 Important Notes ............................................................................................................... 20 Transmitting to a Phonak MicroLink or MicroEar Receiver .......................................... 22 Transmitting to other 216MHz FM Receivers ................................................................ 23 Setting up MicroField For Use With an External 72MHz Transmitter and Receiver .. 24 Setting up the Receive Channel .......................................................................................... 26 Important Notes ............................................................................................................... 27 Finding a Receive Channel Using Automatic Search ..................................................... 28 Finding a Receive Channel Using Manual Search .......................................................... 29 Storing a Preset Channel ................................................................................................. 30 Selecting a Preset Channel For Use ................................................................................31 Locking Preset Channels .................................................................................................. 32 Using the Infrared (IR) Receiving Cable ......................................................................... 33 2. MicroField as a Receiver ...................................................................................................... 34 Important Notes ................................................................................................................. 35 Using the Headset Jack ..................................................................................................... 36 Using the Optional Speaker .............................................................................................. 37 3. MicroField as a Transmitter ................................................................................................. 38 Using the Auxiliary Input With a Microphone .................................................................. 39 Using the Auxiliary Input With Your TV or Other Device ................................................. 40 Troubleshooting ................................................................................................................................ 41 Compliance Notice............................................................................................................................ 47 Appendix ........................................................................................................................................... 50 This page intentionally blank. 1 Introduction 2 Welcome to the Phonak World of Wireless Communication! Thank you for choosing MicroField! MicroField is a high-quality product from Phonak, a world leader in hearing technology innovation and reliability. MicroField automatically finds audio transmissions (such as from a teacher’s wireless transmitter, a theater sound system, or other facilities providing wireless assistive listening) on any of three frequency bands. Once MicroField finds the transmission, it sends the audio signal to you in one of several ways:
Directly to your hearing aid (when equipped with a Phonak MicroLink or other type 216MHz receiver)
To your personal transmitter and FM receiver
To an earphone or neckloop
To an optional speaker MicroField has been designed to give you the easiest possible way to receive wireless audio trans- missions for personal use and in public facilities. Introduction 3 MicroField Key Features Receives audio on three frequency bands
72-76MHz
216-217MHz
Multiple Infrared (IR) Channe…

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E l e c t r o n i c s Inc October 14, 2003 To: Timothy Johnson American Telecommunications Certification Body Inc. From : Leon Kogan JMR Electronics Inc. Applicant : Listen Technologies Corporation FCC ID: OMDMSF0001 Dear Mr. Johnson: Below you will find the information that was requested in your letter on September 11, 2003. All items concur with the numbered questions in your letter. 1) FRN Number for Listen Technologies Corporation is: 0009694597 2) Internal photographs , as you suggested, are uploaded independently to ATCB website. 3) The label and photo showing label location are uploaded. 4) Test configuration photographs , as requested by FCC, are uploaded independently to ATCB website 5) Both receivers, 72 MHz and 216 MHz, had been tested per Part 15 Verification requirements. Please see pages 47-50 (sections 8.3 and 8.4).of the Test Report. 6) ) The complete transmitter circuit operates from a regulated 3.3 VDC source. There are three stages of the transmitter; VCO, buffer and final amplifier. The final amplifier operates in a saturated mode at 8 milliamps collector current. RF power fed to the loop antenna is 0 dBm. 7) The test procedure measures radiated power and verifies it to be within minimum and maximum limits. 8,10) This is a typo. DRG Horn Antenna was calibrated by Liberty Lab on 10/18/2002. Certificate Number: 2002101718. 9) The measurements are corrected, as you suggested. Please see revised Test Report. 11) When the AUX IN input is used, RF output power is increased 6 dB. All tests were performed with a connection to AUX IN resulting in the high power mode. 12) Maximum transmission range in the low power mode is less than 10 feet and is typically used at a range of 3 feet. Microfield transmits to a hearing aid that has an internal 216 MHz receiver. When the AUX IN is connected the range is 20 feet maximum. In this case the Microfield unit may be placed next to a television and the user is across the room. 20400 Plummer Street Chatsworth, CA 91311 Tel (818) 993-4801 Fax (818) 993-9173 Internet; www.jmr.com Confidential Page 2 10/14/2003 13) Output power is constant regardless of audio or RF input level. Received RF signals are demodulated to recover the audio signal. FM transmission produces no RF output power change with varying modulation level. Microfield is not a transponder. It is similar to a repeater. 14) The plots generated by Microsoft Excel are removed from the Test Report. 16) Occupied bandwidth measurements were identical to those used in a previous application as requested by FCC. Bessel functions are the standard practice used for accurate FM deviation measurements. Reference: Agilent(HP) Application Note 150-1. 15,18,19) Modulation levels are identical for all channels. The Phonak receiver can accept a maximum of +/- 8 kHz peak deviation. The modulation limiting threshold is set to meet this requirement. 17) The deviation was corrected to 8.016 kHz, as measured with 4 kHz sinewave. Please see page 34 of the Report. Designation of emission is changed appropriately: 24K0F3E (see revised page 58 of the Report). 20) This is re-calculated spurious emissions limit at EUT, not at a distance of 3 meters. 21,22) The page 35 of the User’s Manual is deleted. I hope these answers are sufficient. If there are any further questions, please feel free to email me or call me back . Sincerely, Leon Kogan Technical Director JMR Electronics [email protected] <mailto:[email protected]> Phone: (818) 739-1122 Fax: (818) 727-2215 20400 Plummer Street Chatsworth, CA 91311 Tel (818) 993-4801 Fax (818) 993-9173 Internet; www.jmr.com

E l e c t r o n i c s Inc November 6, 2003 To: Timothy Johnson American Telecommunications Certification Body Inc. From : Leon Kogan JMR Electronics Inc. Applicant : Listen Technologies Corporation FCC ID: OMDMSF0001 Dear Mr. Johnson: Below you will find the information that was requested in your letter on October 31, 2003. All items concur with the numbered questions in your letter. 1) and 2) All receivers have been re-tested per Part 15.109 Verification requirements. using ANSI C63.4 test methods Please see pages 42-54 (sections 8.3, 8.4, 8.5).of the Revised Test Report. 3) The Tune up Procedure is revised to provide more details. The EUT was properly tuned up prior to testing. The revised Tune Up Procedure is uploaded to ATCB web. 4) The ERP calculations in section 5.0 are corrected as you suggested. Please see revised Test Report. 5) Radiated emissions were monitored from the EUT in horizontal polarization with the scanning antenna repeatedly moving from 1 to 4 meters in elevation while the turntable rotated through a 360 degree arc. This procedure was then repeated in vertical polarization to confirm the strongest signals and polarization orientation. Only strongest signals are recorded. 6) Please see corrected User’s manual uploaded to ATCB website. 7) The Tx limit is corrected. Please see pages 46 of the Revised Test Report. 8) The Microfield 216 MHz transmitter circuit incorporates a low-pass audio filter just prior to the FM modulator. It is therefore not possible to modulate at a greater bandwidth than the frequency response plots indicate. The filter utilized is an active low-pass type with a 12 dB/octave roll off characteristic. The program material will have no effect on maximum modulation bandwidth.. Frequency response can not be accurately measured at 20% of maximum deviation due to low signal to noise ratio. 20% would be acceptable for a wideband transmitter such as used in FM broadcast. Sincerely, Leon Kogan Technical Director JMR Electronics [email protected] <mailto:[email protected]> Phone: (818) 739-1122 Fax: (818) 727-2215 20400 Plummer Street Chatsworth, CA 91311 Tel (818) 993-4801 Fax (818) 993-9173 Internet; www.jmr.com

American Telecommunications Certification Body Inc. 6731 Whittier Ave, McLean, VA 22101 September 11, 2003 RE: Listen Technologies Corporation FCC ID: OMDMSF0001 After a review of the submitted information, I have a few comments on the above referenced Application. 1) Please provide a FRN Number for Listen Technologies Corporation. Note that the FRN number is different than the applicants grantee code. This is now required for all Grantees - (reference MD Docket No. 00- 205). To obtain an FRN online, visit the FCC's Web site at www.fcc.gov and click the Commission Registration System (CORES) link. For further assistance, please either refer to the FAQ at this same link; contact the CORES helpdesk at [email protected]; or call the CORES helpdesk toll-free number: 1-877- 480-3201. 2) Internal photographs must show both the top and bottom views of all boards containing any RF circuitry. Please provide additional photographs as necessary. Given the nature of the device containing several antennas, it would be suggested to provide labeling on the photographs that shows which antennas are for which portion of the device (72 MHz RX, 216 MHz RX, 216 MHz TX, etc.). 3) Please provide a labeling exhibit that shows the following: a) example label for this device (this should include information specified by 95.1017) b) photograph or drawing showing label location 4) Please provide a separate exhibit for the test configuration photographs. The FCC requires this to be submitted as a stand alone exhibit. 5) Please verify that the 72 and 216 MHz receivers have been tested to comply with Part 15 Verification requirements. 6) Please provide both the DC voltage & current applied into the several elements of the final radio frequency amplifying device for normal operation over the power range. 7) The tune up procedure provided appears incomplete, especially relative to power output level adjustments. Please correct. 8) Some of the equipment given in section 4.0 appears to be out of calibration. Please explain. 9) The RF power and spurious radiated measurements made in sections 5.0 & 8.0 of the report mentions using the substitution method. However, the equation used for calculating the final value mentions the use of an antenna factor (AF). Note that the antenna factor is NOT the correct factor to use in this equation (i.e. The factor used was 10.95, while the gain of many Biologs around 200 MHz is around 5 dBi in this range; the horn antenna gain @ 1.3 GHz is typically around 9 dBi). The equation expects the actual gain in dBi. Please explain and/or correct the measurements as necessary. Note that this may actually decrease the power measured even further. 10) The measurement antenna during radiated tests should have been checked for both Horizontal and Vertical polarities. Please explain if this was performed. 11) The users manual mentions, "when you plug a device into the AUX IN, the transmission range of the internal transmitter is increased". How does this feature affect the output power? Has this mode been tested? Was this mode used for final testing since it is likely worse case? 12) The power measurements are much lower than one would typical expect. What is the expected transmission distance for the various output levels (see question 9)? Can you provide an explanation for this device having such a low power measurement. 13) How does variation of the input signal amplitude affect the radiated output power level? (i.e. how is the power output limited and the input drive level controlled)? 14) The plots in section 7.1 do not appear to match the tabular data results. Please explain. 15) The plots provided in section 7.1.2-7.1.4 should be provide for a slightly larger span (approx 50 kHz), relative to the unmodulated carrier level, and also must be provided for both standard and extra band channels (width) modes for comparison to the limits of 95.635(c). z Page 2September 11, 2003 16) I am not familiar with the method used for the occupied bandwidth. Typically BW measurements are provided using a spectrum analyzer power measurement feature to measure the 99% Occupied BW, or for certain types of emissions the 20 dB bandwidth may suffice. The 99% is the portion of the spectrum which contains 99% of the emitted energy (.5% of the remaining is above and .5% is below the occupied BW) while typically using a RBW setting of >= 1% and VBW > RBW. The occupied bandwidth measured should be less than the authorized bandwidth. Note that occupied bandwidth measurements should be consistent with the necessary bandwidth calculations but less that the authorized bandwidth. 17) Please explain the derivation of the 9420 Hz deviation used in the Necessary Bandwidth calculation. This does not appear to be obtained from the deviation threshold testing. 18) Please provide a calculation of the necessary bandwidth for both the standard and extra band channels (width) modes. 19) Please provide a modulation limiting data for both the standard and extra band channels (width) modes. It is uncertain which was used for the data provided. 20) Please explain the derivation of the -23.6 dBm level in section 8.0 of the report. Typically the limit for 43 + 10 log P = -13 dBm. 21) Page 35 of the users manual mentions that this device has been certified to comply with the Class B computing device limits. Note that this application is only requested certification to Part 95. It is assumed that the digital device and receivers have been tested under a verification. Please explain and/or correct the users manual as necessary. 22) Page 35 of the users manual mentions that the cables used must be shielded. Note that according to the users manual shielded cables were not used for power, mic, or speaker connections. Please explain. Timothy R. Johnson Examining Engineer mailto: [email protected] The items indicated above must be submitted before processing can continue on the above referenced application. Failure to provide the requested inform…

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American Telecommunications Certification Body Inc. 6731 Whittier Ave, McLean, VA 22101 October 31, 2003 RE: Listen Technologies Corporation FCC ID: OMDMSF0001 After a review of the submitted information, I have a few comments on the above referenced Application. 1) We do not understand the information for the 72 and 216 MHz receivers given in section 8.3 and 8.4 of the report. Note that RX emissions are actually measurements of the fields strength and are NOT performed using the substitution method. The methods specified by ANSI C63.4 and part 15 should be used. The limits given in 15.109 do not appear to have been used. The data should be presented such that the results, correction factors, corrected results, and limits are given in the table. It appears that the measurements and possibly the ground floor shown at the higher frequencies exceed the limits of 15.109. Please correct/explain as necessary. 2) The data given on page 49 of 59 does not appear relevant to the Part 15 emissions. Emissions should be shown by correcting for the measurement system according to methods given in ANSI C63.4. Substitution methods are not applicable here since limits are given in field strength given at a particular distance. 3) Your previous response to item 7) does not appear to address the question completely. The EUT was expected to be tuned up following the maximum levels given in the alignment procedure (tune-up procedure) prior to testing. However the tune up procedure appears incomplete (levels are not filled in for various items). Please provide a tune up procedure that has all levels filled in. Also a confirmation that the device was tuned up prior to testing to the maximum levels per this procedure needs to be provided. 4) The calculations given in section 5.0 for the power appear to be EIRP, not ERP calculations. Typically, the ERP would include EIRP - 2.14 dB. Please comment/correct this section of the report. 5) Radiated power, spurious and Receiver emissions should have been performed with the receive antenna positioned both Horizontal and Vertical in attempt to obtain the worse case readings. However all data provided appears for one polarity only. Please confirm this was performed or provide additional data. 6) Compliance information still needs to be in the users manual. From the information provided in your last response, page 35 of the users manual should not be removed. Instead the phrase "computing device" should be adjusted to "digital device". Please provide a corrected Users Manual. Additionally, please adjust the shielded cables phrase to list exactly which cables need to be shielded, or if they were all unshielded, please remove this sentence from the compliance statements. 7) We are unsure of your response regarding previous question 20. Spurious emissions of the TX must meet the limit of -13 dBm which is done using a substitution method and this limit of -13 dBm is the limit at the TX port using a substitution method. All receiver/idle mode spurious emissions must meet Part 15 and done using the methods of ANSI C63.4 (see items 1 & 2 above) and should not be done using a substitution method. --- Continued on Next Page --- z Page 2October 31, 2003 8) It is uncertain that the use of 4 kHz maximum modulation frequency is acceptable since the frequency response plot provided has such a slow rolloff (likely due to linear units ploted vs. log units for x axis). Note that 4 or 5 kHz is acceptable if the device only passes voice. However the aux input appears to be for multiple uses (theaters, TV, DVD, Music, etc), and uses of this device may also pass music. Devices that are capable of transmitting music are many times considered by the FCC to have a maximum modulation frequency as 15 kHz. To help determine the appropriate maximum frequency capable by this device, please provide the following information: a) Adjust the plot for audio deviation frequency to include units, a grid, and also to plot the frequency using a log axis. This will help to determine the proper rolloff frequency to use for this device. b) Please provide information regarding how the reference level is established for the frequency response plots. This is typically performed using a level of 20% of maximum deviation at 1 kHz. c) The results may change the reported necessary bandwidth calculation. Timothy R. Johnson Examining Engineer mailto: [email protected] The items indicated above must be submitted before processing can continue on the above referenced application. Failure to provide the requested information may result in application termination. Correspondence should be considered part of the permanent submission and may be viewed from the Internet after a Grant of Equipment Authorization is issued. Please do not respond to this correspondence using the email reply button. In order for your response to be processed expeditiously, you must submit your documents through the AmericanTCB.com website. Also, please note that partial responses increase processing time and should not be submitted. Any questions about the content of this correspondence should be directed to the sender.

Photos of the EUT EUT: MSF0001 with AC-DC A41208D Power Adapter Front View EUT: MSF0001 FM Transmitter/Receiver Front View EUT: MSF0001 FM Transmitter/Receiver Bottom View EUT: MSF0001 FM , Power Adapter Front View

Internal photos EUT: MSF0001 FM Transmitter/Receiver Solder side view without cover EUT: MSF0001 FM Transmitter/Receiver PCB Component side view EUT: MSF0001 FM Transmitter/Receiver Transmitter Antenna (216 MHz) EUT: MSF0001 FM Transmitter/Receiver Receiver Antenna (72 MHz and 216 MHz) Daughter PCB side 1 EUT: MSF0001 FM Transmitter/Receiver Receiver Antenna (72 MHz and 216 MHz) Daughter PCB side 2

1 Listen Technologies Microfield Theory of Operation M. Simon 6-30-03 Scope This document describes the operation of the Microfield product at a circuit and component level. This theory of operation is to be used as an aid to the engineer or technician in troubleshooting the Microfield product. One should refer to the Microfield block diagram and schematic while reading this document. The schematic is organized as functional blocks with a description in the title block. General Microfield is designed to transmit audio to Phonak in-ear and behind-the-ear hearing aids. These hearing aids utilize 216 MHz FM receivers. The Microfield unit transmits on Phonak 216 MHz channels in addition to Listen and other manufacturer’s channels. Microfield derives audio from either a built-in 72 MHz, 216 MHz or IR (infrared) receiver. Audio may also come from an external microphone or auxiliary input. An external speaker produces the same audio that is transmitted to the hearing aid. A microprocessor controls all internal functions including battery charging and monitoring. The user may program the Microfield unit with preset transmit and receive frequencies. CPU Section The CPU performs many functions during Microfield operation. These include battery charging and monitoring, driving the LCD, controlling the transmit and receive PLL frequency synthesizers, reading and writing to EEPROM, controlling RF squelch, detecting front panel switch actions and controlling DC power to various circuits as needed. U9 is the CPU and runs at 1 MHz (Y1) clock speed. U5 is an EEPROM which stores information such as self calibration data(battery and squelch) , channel presets and volume settings. Self calibration is initiated by shorting jumper J1 while turning unit on. This process establishes accurate analog-to-digital conversion for battery monitoring and determines squelch and RF meter baseline values. 2 Receiver Section U16 is an FM receiver circuit that contains IF amplification, FM demodulation, RSSI generation and RF mixing. U16 functions as either a 72 MHz, 216 MHz or IR receiver. IR frequencies range between 95 kHz to 3.8 MHz. U18 up-converts these frequencies to the 48.095 to 51.8 MHz range. U13 is a programmable phase locked loop (PLL) synthesizer that stabilizes the VCO (Q11) to the appropriate local oscillator (L.O.) frequency. The 72 MHz receiver operates with the L.O. set to 10.7 MHz below the receive frequency. The 216 MHz receiver operates with the L.O. set to 10.7 MHz above the receive frequency. The IR receiver operates with the L.O. set 10.7 MHz above the receive frequency. F1 and F3 are 110 kHz bandwidth 10.7 MHz ceramic IF filters that provide channel-to- channel selectivity. L9, C97, R101 and C99 form a phase shift network that is part of the internal FM demodulator. C97 fine tunes the circuit for lowest audio distortion and maximum audio amplitude. The RSSI (receive signal strength indicator) signal at TP7 is used to mute the receiver audio when no signal is present. It is also used for searching for an active channel and setting the receive RF level meter on the LCD. The RSSI signal connects to a microprocessor input which is an internal analog-to-digital converter. The RSSI is a DC level ranging from 200mV to 2.5 V and is proportional to RF signal strength. The RSSI also functional during IR reception. U15-B is primarily a receiver de-emphasis (low-pass) filter but also equalizes audio gain between 72 MHz, IR, and 216 MHz operation. Q10, Q11, Q18 and U13 form a PLL frequency synthesizer circuit. Q11 is a VCO for 72 MHz and IR. Q8 is a VCO for 216 MHz. Q10 is an RF buffer amplifier. The output of Q10 is split to two paths. One is to U16 to provide a local oscillator signal. The other is to the input of the PLL synthesizer U13. D7 and D8 are varactor diodes which control the VCO frequency by varying the DC bias voltage across these diodes. Pin 2 of U13 is a phase error signal that precisely controls the VCO frequency so that it is locked to the programmed frequency and stabilized by the 4 MHz reference crystal oscillator. The CPU selects either the 72 MHz/IR VCO or the 216 MHz VCO. The CPU loads U13 via three serial interface lines(U13 pins 11,12,13). 3 Receiver Antennas The receiver uses two small loop antennas. One is tuned to the 72 MHz band and the other is tuned to 216 MHz. Variable capacitors tune the Each loop antenna is followed by a low noise amplifier (U20 and U21). The CPU switches power to the low noise amplifiers so that they are active only when receiving a channel in that band. IR Section The IR receiver uses an external sensor to detect the optical IR signal. The sensor uses a PIN photodiode detector (D1) which is connected to a low noise amplifier (Q11). Operational amplifier U1 provides additional amplification. The signal at the output of the sensor will be between 95 kHz and 3.8 MHz depending on IR transmitter channel. The signal at this point is very small and can not be observed on an oscilloscope unless the sensor is extremely close to the IR transmitter. The Microfield unit provides 3.3 volts to the sensor circuit via the ring contact of the IR connector. The signal is carried via the tip connection. The IR signal is up-converted to the range of 48.095 – 51.8 MHz by the diode mixer U18. Q19 is a crystal oscillator that generates a 48 MHz local oscillator for the mixer. L14 and L12 form a band pass filter for the up-converter frequencies. U10 amplifies the signal while C131 and L15 match the signal to the receiver input. D12 is a PIN diode that acts as a switch to open the IR circuit when it is not used so that the 72 MHz signal can flow to the receiver input. The receiver (U16) down-converts the signal to 10.7 MHz, amplifies and performs FM demodulation. U15-B amplifies and filters the IR audio signal. Audio Section Q20 is a audio mute switch(squelch) that is controlled by the CPU. The switch is on when either the IR, 72 MHz or 216 MHz RSSI level is low. When Q20 is on the a…

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Bill of Materials for 2003-6-17 MicroField Anrenna Boar Parts listing for basic Board rd ManufacturerCase - PAD\60MIL - PAD\60MIL Voltronics Corporation - JZ-200 Voltronics Corporation - JZ-030

Bill of Materials f 2/6/2003 SCH-MicroField Fron for basic Board for MicroField Front Panel Display nt Panel.sch ManufacturerCase MolexHEADER-24PIN-2MM DigiKey WM18211-ND Single Row Low profile Machined pin b…

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