Abstract:
The present invention relates to a wireless headset configured to communicate with a wireless transceiver over a wireless signal path. The wireless headset includes speakers and a microphone one or more batteries for providing power to the wireless headset; and a connector configurable to receive a bypass cord for bypassing the wireless audio path with a wired signal path. Further embodiments of the wireless headset include speakers and a microphone, Active Noise Reduction (ANR) circuitry; and a connector configurable to receive a bypass cord for bypassing the wireless audio path with a wired signal path. Additional embodiments of the wireless headset include speakers and a microphone and a connector latch for latching a bypass cord to the wireless headset, wherein the bypass cord is configured to bypass the wireless signal path with a wires signal path.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0002]    Aviation headgear is used by professional and private pilots throughout the world. The purpose of this headgear is to enable the pilot to communicate with the ground and with the co-pilot unimpeded by background noise. Most general aviation aircraft were originally built with a hand held microphone and a speaker mounted in the cabin. Over the last thirty years, however, headsets with speakers built into ear cups or pieces and mounted microphones have become the norm. These headsets reduce ambient noise, thus allowing for improved hearing by a user. These headsets also allow for hands free communication by way of the microphone. Typically, such headsets are wired to the aircraft communication system with a cord and jack assembly. These types of headsets are also commonly used in fire trucks and other such emergency vehicles where communication between a crew is required. 
         [0003]    The cord from such wired headsets, however, often may get in the way of a user&#39;s movement, and is frequently responsible for pulling the headset from its most comfortable position on the user&#39;s head. In small aircraft where passengers and crew sit close together, it is common for one person&#39;s movement to cause a pull on his or her own or another person&#39;s headset cord. Often, the plugs on the end of a headset cord become intermittent due to the frequent strain put on them when users accidentally pull on or sit on the cord. In larger aircraft or in emergency vehicles, a cord can interfere with the responsibilities of crew members, so headsets are removed and communication sacrificed while some duties are performed. 
         [0004]    Wireless headsets and related communication systems have been developed to solve the problems created by the cord of the wired headsets. However, existing wireless headsets introduce other problems which often limit their use in noisy environments and environments where communications are critical, such as in an aircraft or emergency vehicle. For example, one limitation of existing wireless headsets is that they typically rely on batteries and will lose power if the batteries are not recharged or replaced. The exclusive use of battery power causes many existing wireless headsets to not use Active Noise Reduction (ANR), as ANR consumes more battery power. ANR, however, provides improved communications and reduces fatigue in noisy environments. In addition, the battery status is often provided with visual indicators such as Light Emitting Diodes which are insufficient to capture the user&#39;s attention when pilot or crew workload is high. 
         [0005]    A further limitation of existing wireless headsets and related communication systems is that the radio or intercom in an aircraft or vehicle must be adapted for wireless headset communications by adding a wireless transceiver in an unobtrusive location. Most existing wireless transceivers provide cords for plugging into a radio or intercom, but the user must come up with a mounting location and method if they want to prevent the transceiver from dangling or shifting about the cabin. In addition, the wireless transceiver requires power and therefore needs custom installation, a power socket, or batteries, which are a potential source of communication failure if the batteries are not recharged or replaced. 
         [0006]    Another limitation of existing wireless headsets and related communication systems is the available license-free RF bandwidth available when multiple wireless headsets are used in an aircraft or vehicle. Passengers and crew often use stereo headsets to listen to music during long trips. Stereo requires an additional audio channel and additional power and RF bandwidth for a wireless headset. Existing stereo wireless transceivers require stereo inputs, and are unable to transmit a single mono input to two stereo outputs when used with a mono source. 
         [0007]    In addition, stereo transceivers running in UHF or higher frequency license-free bands typically incur large delays (&gt; 20 ms) associated with compressing, packetizing, de-packetizing, and decompressing the audio. This causes an unacceptable echo to the user when the radio or intercom provides sidetone, which allows the user to hear their own voice through the headphone. Stereo transceivers in VHF bands using FM stereo are subject to interference from other transmitters. 
       BRIEF SUMMARY 
       [0008]    The principles of the present invention relate to a wireless headset configured to communicate with a wireless transceiver over a wireless signal path. The wireless headset includes at least one speaker, one or more batteries for providing power to the wireless headset; and a connector configurable to receive a bypass cord for bypassing the wireless audio path with a wired signal path. 
         [0009]    Further embodiments of the wireless headset include least one speaker and Active Noise Reduction (ANR) circuitry. 
         [0010]    Additional embodiments of the wireless headset include speakers and a microphone and a connector latch for latching a bypass cord to the headset or handset, wherein the bypass cord is configured to bypass the wireless signal path with a wired signal path. 
         [0011]    Embodiments disclosed herein also relate to a headset or handset including an audio speaker. The headset or handset includes a microprocessor for executing software configured to provide status messages regarding operational parameters of the headset or handset to a user of the headset or handset. The headset or handset performs a method for inserting status messages regarding the operation parameters without interrupting normal communication of the headset or handset. The method comprises determining if there is a pending status message, determining if any normal audio communications are present, in response to determining that normal audio communications are present, not inserting the status message until the normal audio communications are complete, and in response to determining that normal audio communications are not present, inserting the status message into an audio communication. 
         [0012]    Additional embodiments disclose a headset or handset comprising at least one speaker, a microprocessor configured to audibly notify a user of the headset or handset that the headset or handset will experience a power shutdown at a time period after the audio notification, and a user input configured to abort the power shutdown of the headset or handset. 
         [0013]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
         [0014]    Additional features and advantages will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of the embodiments disclosed herein. The features and advantages of the embodiments disclosed herein may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the embodiments disclosed herein will become more fully apparent from the following description and appended claims, or may be learned by the practice of the embodiments disclosed herein as set forth hereinafter. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0016]      FIG. 1  is a diagram of a wireless headset system with a retractable cord integrated into the wireless transceiver; 
           [0017]      FIG. 2  is a detailed drawing of the latch used by the wireless headset to secure a bypass cord and wireless transceiver; 
           [0018]      FIG. 3  is a detailed drawing of the tether used by the retractable bypass cord to secure the bypass cord and wireless transceiver when the bypass cord is pulled out; 
           [0019]      FIG. 4  is a diagram of a retractable bypass cord for the wireless transceiver supporting a single headset; 
           [0020]      FIG. 5  is a detailed drawing of a wireless transceiver supporting a single wireless headset; 
           [0021]      FIG. 6  is a detailed drawing of a wireless transceiver with integrated intercom functions for use with multiple wireless headsets; 
           [0022]      FIG. 7  is a drawing of a wireless transceiver with cylindrical hole for attaching the transceiver to a plug; 
           [0023]      FIG. 8  is a block diagram of the power management circuits and major components of the wireless headset; 
           [0024]      FIG. 9  shows details of the Digital Stereo Transmitter and Digital Stereo Receiver; 
           [0025]      FIG. 10  shows the format of status message packets; and 
           [0026]      FIG. 11  shows the sequence of steps used to insert status messages without interrupting communications. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The principles of the present invention relate to a wireless headset that may be integrated with a variety of diverse systems, consisting of radios, intercoms and audio selectors. These may provide stereo or mono sound. Some headsets, such as in aircraft or emergency vehicles, need to communicate through VHF radios while other headsets on the same intercom do not. Some headsets in a system may be mission critical, while others in the same system are for entertainment purposes. A wireless headset system may consist of a single headset, or multiple headsets communicating with each other. 
         [0028]    A wireless headset system typically consists of both the wireless headset and a wireless transceiver which converts wired audio signals to wireless. Generally, the wireless transceiver must adapt the wireless headset to the specific operating requirements of a particular audio system. One embodiment of the wireless headset system consists of a single wireless headset design which can be coupled with different wireless transceivers to support a variety of audio installations. 
         [0029]    One such installation may be the pilot of a single-seat acrobatic aircraft who uses his headset to communicate with Air Traffic Control (ATC). In this example, there are no other headsets and no intercom features. A retractable bypass cord is part of the wireless transceiver and is used to plug into the wireless headset should any portion of the wireless system fail. The wireless transceiver must be mounted very securely since the pilot may roll or loop the aircraft. 
         [0030]    Another installation is a six-seat aircraft with a pilot and copilot who both need to talk to ATC. In this example it is desirable for all six seats to have wireless headsets, with the crew talking to ATC and sometimes talking to the passengers, and the passengers listening to stereo music and talking to each other, and sometimes talking to the crew when enabled by the crew. In this case, a wireless transceiver would support all six headsets and include integrated intercom functions with the ability to integrate or segregate headsets groups. However, only the pilot and copilot need the reliability provided by the bypass cord, and if one of them uses the bypass cord the other should be able to continue wireless communications. Explanations of the design differences which enable the invention to be used in these varied applications will be discussed. 
         [0031]    Referring first to  FIG. 1 , a wireless communication system  100  is illustrated. Communication system  100  includes a wireless headset  101  that communicates wirelessly with a wireless transceiver  102  with integrated retractable bypass cord  103 . The wireless transceiver  102  with integrated retractable bypass cord  103  receives electrical audio signal(s) from a radio or intercom  105  through a headphone jack  107  and transmits the audio signal(s) wirelessly to the wireless headset  101 . The wireless transceiver  102  with integrated retractable bypass cord  103  also receives mono voice transmissions from the wireless headset  101  and forwards those to the radio or intercom  105  through a microphone jack  108 . 
         [0032]    As mentioned, the wireless transceiver  102  includes an integrated retractable bypass cord  103  which may be pulled out by the wearer of the wireless headset  101  and plugged into the wireless headset  101  should the batteries powering wireless headset  101  die or any other failure occur with either the wireless headset  101  or wireless transceiver  102  with integrated retractable bypass cord  103 . The retractable bypass cord  103  may be stored in the wireless transceiver  102  using a retracting cord reel  104 . Retractable cord reels such as retractable cord reel  104  are well known in art such as those disclosed in U.S. Pat. No. 6,616,080. The retractable cord reel  104  allows the retractable bypass cord  103  to be withdrawn by simply pulling on it. The retractable cord reel  104  includes a retract button (not illustrated) which allows it to pull the retractable bypass cord  103  back inside when the retract button is pressed by a user. This feature helps ensure that the retractable bypass cord  103  has some slack so that it does not pull on the wireless headset  101  when the retract button is not pressed. 
         [0033]    The connection between the wireless headset  101  and the retractable bypass cord  103  is performed by a novel latching plug and jack architecture as will be described in more detail to follow in relation to  FIG. 2 . Briefly, a 5-conductor plug  110  provides 5 cylindrical conductors stacked along its shaft. A 5-conductor jack with latch  111  provides 5 contacts aligned to connect to the 5 cylindrical conductors in the 5-conductor plug  110  when it is inserted. Thus, the connection is made correctly regardless of the rotational angle of the insertion of the 5-conductor plug  110 . Advantageously, by eliminating the need to rotate the connector correctly, the user can make the connection to the headset without removing the headset from his or her head or looking at the jack before connecting it. 
         [0034]    The wireless transceiver with retractable cord  102  uses a stereo headphone plug  113 , which may be plugged into either a stereo or mono headphone jack  107 . When plugged into a mono headphone jack  107 , one conductor on the plug  113  will be open so that one of the stereo inputs to the wireless transceiver  102  with integrated retractable bypass cord  103  is not driven. The wireless transceiver  102  with integrated retractable bypass cord  103  may also include a stereo/mono switch  112  which, when in the mono position, shorts the left and right audio signals together from the headphone jack  107  so that its mono signal drives both the left and right stereo signal inputs on stereo headphone plug  113 . When the stereo headphone plug  113  is plugged into a stereo headphone jack  107 , the stereo/mono switch  112  is placed in the stereo position, which does not short the right and left stereo inputs together. 
         [0035]    The wireless communication system  100  also includes a tether  106  that is configured to ensure that the plugs from the wireless transceiver  102  with integrated retractable bypass cord  103  are not pulled out of the headphone jack  107  and microphone jack  108  when the user grabs the retractable bypass cord  103  in order to insert the 5-conductor plug  110  into the wireless headset  101 . More detail on the tether  106  will be described below in relation to  FIG. 3 . 
         [0036]      FIG. 2  shows detail of a 5-conductor jack with latch  202  that may correspond to the 5-conductor jack with latch  111  of  FIG. 1 . The 5-conductor jack  202  is mounted within a headphone ear cup  201  on one side of the wireless headset such as wireless headset  101 . A spring-steel jack latch  203  is attached to the 5-conductor jack  202  using a nut  204  that also attaches the 5-conductor jack  202  to the headphone ear cup  201 . The spring-steel jack latch  203  is angled such that the insertion of the 5-conductor plug  110  pushes the latch aside momentarily until a latch ring  109 , which may be a simple ring similar to a washer that is placed on the 5-conductor plug  110  and held in place by the plug&#39;s housing, passes by the spring-steel jack latch  203 . The spring-steel jack latch  203  then snaps back to its normal position holding the latch ring  109  and 5-conductor plug  110  securely in place. To remove the 5-conductor plug  110 , the user must bend the spring-steel jack latch  203  out of the way, and then withdraw the 5-conductor plug  110  from the 5-conductor jack with latch  202 . 
         [0037]      FIG. 3  shows detail of a tether  300  that may correspond to the tether  106  of  FIG. 1 . The tether  300  may include a tether cord  301  which may be coupled to the wireless transceiver  102  with integrated retractable bypass cord  103 . The tether  300  may also include a tether clip  302  that is configured to be clipped to a tether washer  304 , or other mechanically secure location. The tether washer  304  advantageously provides an easy way for users to create a secure clip point by unscrewing a nut  303  and placing the tether washer  304  on the headphone or mic jack  306  and then screwing the nut  303  back on again. A washer  305  is included to ensure that the tether washer  304  has enough clearance from a vehicle panel  307  that the tether clip  302  can be easily clipped on. The tether washer  304  may easily be installed in each aircraft or vehicle the user intends to use the wireless headset in. It is also anticipated that in some embodiments, the latch  203  may be attached to the 5-conductor plug  110  and the latch ring  109  may be attached to the jack  202 . 
         [0038]    Turning now to  FIG. 4 , an example embodiment illustrates how the retractable bypass cord  103  may be used in series with a wireless transceiver  401 , which may correspond to wireless transceiver  102  of  FIG. 1 . In this example embodiment, the retractable bypass cord  103  and retracting cord reel  104  are shown as separate from the wireless transceiver  401  to aid in the understanding of the serial nature of the cord connection to the wireless transceiver  401 . However, the retractable bypass cord  103  and retracting cord reel  104  may still be physically integrated within the enclosure of the wireless transceiver  401 , as is illustrated by the wireless transceiver  102  with integrated retractable bypass cord  103  of  FIG. 1 . 
         [0039]    In the case of a serial retractable cord  103 , a user must disconnect the 5-conductor plug  110  from a jack without latch  403  in the wireless transceiver  401  in order to plug it into the 5-conductor jack with latch  111  of the wireless headset  101 . An advantage of placing the serial retractable cord  103  in series with the wireless transceiver  401  instead of in parallel is that the serial retractable cord  103  is used and tested during wireless operation, thus eliminating the need for the user to occasionally test the retractable bypass cord  103  to ensure it will work in an emergency or other bypass situation. 
         [0040]      FIG. 5  illustrates a block diagram of the major functional blocks of an embodiment of a wireless transceiver  102  with integrated retractable bypass cord  103 , and also shows the signal detail for the retractable bypass cord  103 . The retractable bypass cord  103  shown in  FIG. 5  is in series with the wireless transceiver  102 ; however the signals and conductors in the 5-conductor plug  110 , headphone plug  507 , and microphone plug  508  are the same as for a retractable bypass cord  103  in parallel with a wireless transceiver  102 . 
         [0041]    The headphone plug  507  may be plugged into the mono headphone jack  107  of a communications radio, or into the stereo jack from an intercom or other device that provides stereo sound. The stereo/mono switch  112  is used to ensure that both the left and right inputs receive audio signal if headphone plug  507  is plugged into a mono jack or a stereo jack. The tip of the headphone plug  507  is the left speaker  504  input, or the mono input when plugged into a mono jack. The center conductor is the right speaker  503  input. The innermost conductor is the speaker return  505  which provides the DC reference level for the right speaker  503  and left speaker  504  signals. These three headphone signals are carried by the retractable bypass cord  103  to the 5-conductor plug  110  for connection to the wireless headset  101  as illustrated. 
         [0042]    The microphone plug  508  is plugged into the microphone jack  108  of the radio or intercom  105 . The tip of the microphone plug  508  is the Push-To-Talk  506  signal, which is not used by the wireless headset since it is usually provided by a hardwired push-button in the vehicle or on the aircraft&#39;s yoke. The center conductor is the MIC/Power  501  signal which provides power from the radio or intercom  105  to the microphone preamp  815  ( FIG. 8 ) and carries the amplified voice signal from the electret microphone  814  ( FIG. 8 ) to the radio or intercom  105 . The innermost conductor is the MIC Return  502  signal which provides the DC and AC reference level for the microphone preamp  815 . The MIC/Power  501  and MIC Return  502  signals are carried by the retractable bypass cord  103  to the 5-conductor plug  110  for connection to the wireless headset  101  as illustrated. 
         [0043]    An analog receiver  513  receives voice transmissions from the wireless headset  101 , and converts them to electrical signals. The signals are provided to the radio or intercom  105  through the retractable bypass cord  103  and the microphone plug  508  via the MIC/Power  501  and MIC Return  502  signals. The transceiver DC blocking capacitors  509  isolate the analog receiver&#39;s  513  output driver and ground from the DC bias voltage present on the MIC/Power  501  signal, and eliminate ground loop noise on the MIC Return  502  signal. 
         [0044]    A Digital Stereo Transmitter  512  receives left speaker  504  and right speaker  503  mono or stereo electrical audio signals from the radio or intercom  105  through the headphone plug  507 . It then compresses and packetizes the audio signals for wireless transmission to the wireless headset  101  using common digital wireless technology such as Bluetooth. The Digital Stereo Transmitter also receives battery status signals  515  from a battery charger and power distribution module  510 . The battery status signals  515  provide the Digital Stereo Transmitter  512  with battery charge status conditions such as Full, Medium, Low, or Very Low charge. The Digital Stereo Transmitter  512  uses these signals to trigger the insertion of battery status messages into the outgoing audio transmission so that the wearer of the wireless headset  101  is notified that the transceiver battery  511  is low, and notified that he or she should pull out the retractable bypass cord  103  and insert it into the wireless headset  101 .  FIG. 9  and  FIG. 10  discussed below provide more detail on how these audio messages are inserted without interrupting communications with ATC or other source. 
         [0045]    The battery charger and power distribution module  510  charges the transceiver battery  511  using the power input from the MIC/Power  501  signal, which come from the radio or intercom  105 , or from a dedicated power supply which provides power using a jack compatible with the microphone plug  508 . Battery charging circuitry, which is well known in the art, is used to ensure that the battery charger and power distribution module  510  does not overcharge the battery  511 . The battery charger and power distribution module  510  draws as much current as the transceiver battery  511  needs to charge quickly and safely, or the maximum current the power supply or MIC/Power  501  provides, whichever is smaller. MIC/Power  501  from the radio or intercom  105  typically provides 12V through a 1K ohm resistor, limiting the current to about 6 mA usable at 6V. The battery charger and power distribution module  510  uses a 6V zener diode as a voltage reference for a voltage regulator to set the voltage drop from the MIC/Power  501  so that the maximum possible current is drawn from MIC/Power  501  without drawing so much current that the MIC/Power  501  voltage drops below the  6 V needed to supplement the transceiver battery  511 . Typically, 6 mA is enough to supplement the transceiver battery  511  and lengthen the operating time of a battery powered transceiver, but is not enough to charge the transceiver battery  511  while the wireless transceiver  102  with integrated retractable bypass cord  103  is in use. When connected to a higher current MIC/Power  501  source such as a power supply, the battery charger and power distribution module  510  may draw sufficient current to quickly and safely charge the transceiver battery  511 . 
         [0046]    The battery charger and power distribution module  510  detects the presence of voltage on MIC/Power  501  and uses that power to power up the battery charger and power distribution module  510  circuits. Then, if the battery charger and power distribution module  510  detects sufficient voltage from the transceiver battery  511 , it powers up the digital stereo transmitter  512  and analog receiver  513  by enabling current flow between the transceiver battery  511  and the transceiver power  514  using a relay or solid state device such as a transistor (not illustrated). Thus, the wireless transceiver  102  with integrated retractable bypass cord  103  typically does not need a power switch and will automatically power up whenever voltage is present on MIC/Power  501  and sufficient voltage is present from the transceiver battery  511 . In addition to providing transceiver battery status  515  to the digital stereo transmitter  512 , the battery charger and power distribution module  510  also drive LEDs (not illustrated) that provide visual status of transceiver battery  511  power. 
         [0047]    Referring now to  FIG. 6 , a wireless transceiver/intercom  601  which may provide intercom features using wireless headsets  101  in an aircraft or vehicle without an installed intercom is illustrated. Wired intercoms are well known in the art and at a minimum provide headsets with the ability to talk to each other. Wired intercoms also provide the ability to mute all microphones except the microphone associated with a currently pressed push-to-talk button. This ensures that radio transmissions come only from the voice intending to transmit. Like many radios, advanced wired intercoms can also provide mono or stereo background music or other entertainment audio which is muted when someone speaks. Advanced wired intercoms also provide the ability to use a cell phone with one or more headsets. Advanced wired intercoms further provide a feature for segregating the headsets into groups, so that members of each group can only hear other members of their group. Aircraft wired intercoms often have three group settings called “Pilot Isolate”, “Crew”, and “All”. The “Pilot Isolate” setting isolates the pilot and the VHF radio into one group, while letting everyone else in the second group talk to each other. The “Crew” setting creates two groups where one group consists of the crew and VHF radio and the second group consists of the passengers. The “All” setting puts everyone and the VHF radio in the same group. 
         [0048]    Within the wireless transceiver/intercom  601  there may be an intercom  602  which incorporates the features of advanced wired intercoms such as background audio and grouping modes. The background music is provided by an external music player  603 , which may be a DVD or MP3 player. Wired intercom technology is well known and is incorporated by replacing the microphone inputs from a typical wired intercom with Mono Rx Modules  609 ,  610 ,  612 ,  613 ,  614 , and  615 . Also, the headphone outputs of a typical wired intercom are replaced by Stereo TX Modules  608  and  611 , which in some embodiments may provide stereo audio broadcast to the “Crew” group (Group A) and the “Passenger” group (Group B). 
         [0049]    When the “Crew” mode of segregation is chosen, Mono Rx Modules  609  and  610  are microphone inputs from the “Crew” group (Group A) and Mono Rx Modules  612 ,  613 ,  614 , and  615  are microphone inputs from the “Passenger” group (Group B). Also, when “Crew” mode is chosen Stereo TX Module A1&amp;A2  608  provides broadcast transmission to the pilot (A1) and copilot (A2) wireless headsets. By using a broadcast transmission for Group A, and another broadcast transmission for Group B, all headsets are able to hear everyone in their respective groups and RF bandwidth requirements are minimized, making it possible to support all headsets with high fidelity stereo audio with the limited bandwidth available in license-free RF bands. On the other hand, when “All” mode is chosen, all headsets are integrated into a single group and Stereo Tx Module A1&amp;A2  608  and Stereo Tx Module Group B  611  are provided with the same audio by intercom  602  so that everyone hears the same thing. 
         [0050]    The wireless transceiver/intercom  601  may also contain a single retractable bypass cord  103  for use by the pilots (A1) wireless headset  101 . Since multiple wireless headsets  101  are supported by the single wireless transceiver/intercom  601 , the wireless transceiver/intercom  601  uses a parallel retractable bypass cord  103  instead of a serial retractable bypass cord, so that the integrated intercom  602  can continue to perform normally for all headsets when the parallel retractable bypass cord is used by the pilot. A Wireless Mic Disconnect  604  ensures that when the pilot plugs the parallel retractable bypass cord  103  into his or her wireless headset  101 , the MIC/Power  501  signal into the radio or intercom  105  is not driven by both the wired MIC/Power signal  501  from the parallel retractable bypass cord  103  and the A1 Rx Mic Signal  617  from Mono Rx Module A1  609 . 
         [0051]    The Wireless Mic Disconnect  604  senses that the retractable bypass cord  103  has been plugged into the wireless headset  101  by detecting the current being drawn from the MIC/Power  501  signal by the preamp  815  ( FIG. 8 ) in the wireless headset  101 . The current drawn by the preamp  815  causes a small voltage drop across a low ohm resistor  606 , which is in series with the MIC/Power  501  from the retractable bypass cord  103 . The small voltage drop is detected by a comparator  605 , which then discontinues driving the coil of a Mic Disconnect Relay  607 , thus disconnecting the output of Mono Rx Module A1  609  from the MIC/Power  501  signal input to intercom  602 . Accordingly, the MIC/Power  501  signal from the retractable bypass cord  103  becomes the only signal to drive the microphone input of the intercom  602  and radio or intercom  105  when the retractable bypass cord  103  is plugged into a wireless headset  101 . It is important that when the Mic Disconnect Relay  607  is in an un-powered state that it disconnect Mono Rx Module Al from the MIC/Power  501  signal to prevent interference with the wired signal from the retractable bypass cord  103 . 
         [0052]      FIG. 7  illustrates a wireless transceiver enclosure  701  designed for compatibility with the physical placement of a wide variety of headphone jacks  107  and microphone jacks  108  ( FIG. 1 ). In vehicles such as aircraft or fire trucks, the headphone jacks  107  and microphone jacks  108  are intended to work with headphones which have long cords and small plugs. Thus, the headphone jacks  107  and microphone jacks  108  in such vehicles are typically not designed for use with a small box such as a wireless transceiver. Consequently, the spacing between the headphone jacks  107  and the microphone jacks  108  is not consistent and often protrusions such as knobs or buttons are in close proximity to the jacks since the jacks are often mounted on a control panel of the vehicle. These protrusions may not interfere with plugging a cord into the jack, but often they do interfere with placing a wireless transceiver close against the jack. An undesirable solution is to place the wireless transceiver on a long enough cord to get the wireless transceiver away from the jacks where physical space is tight. This method defeats some advantages of a cordless solution, and unless the wireless transceiver is securely mounted, there is high likelihood that the wireless transceiver will dangle or shift about the cabin and get in the way. It is desirable that a portable wireless transceiver would avoid special mounting or installation requirements when possible, and provide maximum compatibility with existing headphone jacks  107  and microphone jacks  108 . 
         [0053]    As illustrated in  FIG. 7 , the wireless transceiver enclosure  701  includes a plug holding cylinder  702  to hold the wireless transceiver enclosure  701  securely to the headphone plug  507  so that the wireless transceiver enclosure  701  is mounted as closely to the headphone jack  107  as possible and does not shift about the vehicle cabin. The plug holding cylinder  702  is lined with rubber to provide enough friction and pressure on the headphone plug  507  to grip the headphone plug  507  securely even when the wireless transceiver enclosure  701  is used in an acrobatic aircraft. An alternative to using a rubber-lined cylinder would be to use a clamp or other method which adjusts the size of the plug holding cylinder  702 . The plug holding cylinder  702  is placed at the very end of the wireless transceiver enclosure  701  so that the wireless transceiver enclosure  701  overhangs on only one side of the headphone plug  507 , thus minimizing the possibility that a knob or button or other protrusion in the panel will prevent the wireless transceiver enclosure  701  and headphone plug  507  from inserting into the headphone jack  107  at some rotational angle. The microphone plug  508  is able to move freely on the microphone cord  703  in order to plug into a jack with unknown spacing with respect to the headphone jack. 
         [0054]    This mounting method may also work by mounting the wireless transceiver enclosure  701  to the microphone plug  508  instead of the headphone plug  507 , and letting the headphone plug  507  move freely on a cord. The headphone plug  507  is preferable since it is larger in diameter and can hold more weight than the microphone plug  508 . No tether or latch is required if the wireless transceiver enclosure  701  is light weight, such as a wireless transceiver enclosure  701  that does not house a retractable bypass cord  103 . A heavier wireless transceiver enclosure  701 , especially one with the retractable bypass cord  103  may require a tether  106  as shown in  FIG. 3 , or a spring-steel jack latch  203  combined with a latch ring  109  on the headphone plug  507 . 
         [0055]    The vehicle may have so many knobs or other protrusions around the headphone jack  107  or microphone jack  108  that the wireless transceiver enclosure  701  cannot be mounted on the headphone plug  507 . In such case, the headphone plug  507  may be removed from the plug holding cylinder  702 , which may cause the wireless transceiver enclosure to dangle from its headphone cord  704  and microphone cord  703 , which are typically just slightly longer than the length of the headphone plug  507  from tip to cord. When the headphone plug is removed from the plug holding cylinder  702 , the wireless transceiver enclosure  701 , though dangling, may still be used without mounting in some vehicles, and with mounting in others such as acrobatic aircraft. Hook and loop fasteners, such as Velcro may be used as a temporary mounting method. A Tether Cord  301  as shown in  FIG. 3  may also be used in locations when it is acceptable for the wireless transceiver enclosure  701  to dangle. 
         [0056]    Turning now to  FIG. 8 , a block diagram of the power management circuits and major components of the wireless headset  101  is illustrated. A Digital Stereo Receiver  806  receives wireless audio transmissions from the wireless transceiver  102  with retractable bypass cord  103 . After decompressing the packetized audio transmissions and converting them back to analog using common digital wireless audio technology, the Digital Stereo Receiver  806  drives the Left Speaker  503  and Right Speaker  504  with the original audio signal from the radio or intercom  105 . 
         [0057]    The Digital Stereo Receiver  806  also receives battery status signals  817 ,  818 ,  819 , and  820  from a battery charger and status unit  801 . The battery status signals  817 ,  818 ,  819 , and  820  provide the Digital Stereo Receiver  806  with battery charge status conditions of Full, Medium, Low, or Very Low charge. The Digital Stereo Receiver  806  uses these signals to trigger the insertion of battery status messages into the outgoing audio driver. These messages notify the wearer of the wireless headset  101  in advance if the headset battery  802  is about to die so that he or she has time to pull out the retractable bypass cord  103  and insert it into the wireless headset  101 .  FIG. 9  and  FIG. 10  to follow provide more detail on how these audio messages are inserted without interrupting communications with ATC or another destination. 
         [0058]    The Left SPKR Assembly  821  and Right SPKR assembly  822  each contain a driver  827  and  828  respectively that is driven directly by the Digital Stereo Receiver  806  or the retractable bypass cord  103  Left Speaker  504  and Right Speaker  503 . The Left SPKR Assembly  821  and Right SPKR assembly  822  also each contain an anti-noise driver  825  and  826  respectively driven by the Active Noise Reduction (ANR) unit  805 . The ANR unit  805  generates an anti-noise signal in order to cancel out any noise present in the Left and Right speaker assemblies  821  and  822 . The Left SPKR Assembly  821  and Right SPKR assembly  822  each may further contain a microphone  829  and  830  for feeding a noise-plus-audio signal back to the ANR unit  805 , which the ANR unit  805  uses to create the anti-noise signal. 
         [0059]    ANR circuits are well known in the art as demonstrated by U.S. Pat. No. 5,675,658. Although noise canceling may be performed electronically with a single driver instead of acoustically using two drivers, an advantage of using a separate driver in each speaker assembly for noise canceling is that if the ANR circuits fail, normal audio is still heard from the Left Driver  827  and Right Driver  828 , which have no active electronics between them and the radio or intercom  105  when the retractable bypass cable  103  is used. Optionally, instead of using two drivers in the Left Speaker Assembly  821  and Right Speaker Assembly  822 , each speaker assembly may use a dual voice-coil driver where one voice coil is driven by the audio signal and the other voice coil is driven by the anti-noise signal. Like the dual driver approach, the dual voice-coil approach also carries the advantage of eliminating active electronics from the audio signal path when the retractable bypass cord  103  is used. The dual voice-coil approach reduces weight associated with a second driver. 
         [0060]    When the retractable bypass cord  103  is not plugged into the 5-conductor jack with latch  111 , an Analog Transmitter  809  transmits voice from an Electret Microphone  814  to the wireless transceiver  102  with retractable bypass cord  103  or another wireless transceiver. An analog transmitter is used in some embodiments instead of digital because voice only requires 3 KHz of bandwidth, thus the RF bandwidth requirements are small and the digital logic associated with packetized transmissions consume more power and incur more audio delay than a simple analog transmission. The Analog Transmitter  809  will typically have a user selectable Channel ID so that it transmits on the frequency expected by the Wireless Transceiver  102  with retractable bypass cord  103 . The Analog Transmitter  809  receives a voice signal  831  and a Tx On/Off signal  832  from a VOX  810 , which provides squelch control so that the Analog Transmitter  809  is not transmitting when the user is not speaking, thus conserving power. The VOX  810  receives voice signal  831  from a preamp  815  through DC blocking capacitors  811 . The preamp  815  is powered by the Tx/Rx PWR  813  through a current limiting resistor  812  when wireless transmissions are used. When the retractable bypass cord  103  is used, the preamp  815  is powered by the MIC/Power  501  through a low ohm resistor  808 . 
         [0061]    The battery charger and status unit  801  charges the headset battery  802  using the power input from the MIC/Power  501  signal, which comes from the radio or intercom  105  when the retractable bypass cord  103  is plugged in, or from a power supply which provides power using a plug compatible with the 5-conductor jack with latch  111 . Battery charging circuitry, which is well known in the art, is used to ensure that the battery charger and status unit  801  does not overcharge the battery  802 . The battery charger and status unit  801  draws as much current as the headset battery  802  needs to charge quickly and safely, or the maximum current the power supply or MIC/Power  501  provides, whichever is smaller. MIC/Power  501  from a radio or intercom  105  typically provides 12V through a 1K ohm resistor, limiting the current to about 6 mA usable at 6V. 
         [0062]    The battery charger and status unit  801  typically uses a 6V zener diode as a voltage reference for a voltage regulator to set the voltage drop from the MIC/Power  501  so that the maximum possible current is drawn from MIC/Power  501  without drawing so much current that the MIC/Power  501  voltage drops below the 6V needed to supplement the headset battery  802  or power the preamp  815 . Six mA is typically enough to supplement the headset battery  802  and lengthen the operating time of a battery powered headset, but not enough to charge the headset battery  802  while the ANR unit  805 , Digital Stereo Receiver  806 , VOX  810 , Analog Transmitter  809 , and Preamp  815  are in use. When connected to a higher current MIC/Power  501  source such as a power supply, the battery charger and status unit  801  may draw sufficient current to quickly and safely charge the headset battery  802 . In addition to providing headset battery status signals  817 ,  818 ,  819 , and  820  to the Digital Stereo Receiver  806 , the battery charger and status unit  801  also drives LEDs (not illustrated) that provide visual status of headset battery  802  power. 
         [0063]    A Power Distribution unit  803  enables and disables headset power  823  to ANR unit  805  through the ANR PWR  824  bus, and also enables or disables headset power  823  to the Digital Stereo Receiver  806 , Analog Transmitter  809 , VOX  810 , and Preamp  815  through the TX/RX PWR  813  bus. The Power Distribution unit  803  intelligently provides power based on a number of monitored conditions including battery status, audio inactivity, presence of the retractable bypass cord  103 , and a user&#39;s request for power on or off via momentary Power Button  804 . 
         [0064]    The presence of the retractable bypass cord  103  is detected when the PWR Present signal  816  is asserted due to DC current being sensed on the MIC/Power  501  signal of the retractable bypass cord  103 . The PWR Present signal  816  is asserted when current drawn by the preamp  815  causes a small voltage drop across a low ohm resistor  808 , which is in series with the MIC/Power  501  from the retractable bypass cord  103 . The small voltage drop is detected by a comparator  807  which then asserts the PWR Present signal  816 . 
         [0065]    The presence of the retractable bypass cord  103  as provided by PWR Present signal  816  causes Power Distribution unit  803  to disable headset power  823  to the Digital Stereo Receiver  806 , Analog Transmitter  809 , VOX  810 , and preamp  815 , by disabling the Tx/Rx PWR power bus  813 . ANR Power  824  is provided even when the retractable bypass cord  103  is connected if battery status signals Full  817  or Medium  818  are asserted. When battery status Very Low  820  is asserted, both ANR PWR  824  and Tx/Rx PWR  813  are disabled to prevent damaging the headset battery  802 . When battery status Low  819  is asserted, ANR PWR  824  is enabled when PWR Present  816  is asserted, and is disabled when PWR Present  816  is de-asserted. 
         [0066]    The momentary Power Button  804  may be pressed by a user to power up the wireless headset  101  when power is off, and is also pressed to turn off the wireless headset  101  when power is on, except when after the Shutdown Warning  918  ( FIG. 9 ) flag is asserted. When the momentary Power Button  804  is pressed and battery status Very Low  820  is asserted, power is enabled momentarily to allow the user to see the battery status LED&#39;s or hear a battery status message, and then shut off again automatically after a few seconds to prevent damage to the headset battery  802 . 
         [0067]    The ANR PWR  824  and Tx/Rx PWR  813  are shutoff automatically by power distribution unit  803  when the Inactive  833  signal is asserted. This feature saves battery power by assuming that a user forgot to power off the wireless headset  101  when finished using it. This assumption is based on the absence of any audible signal received by the Digital Stereo Receiver  806  for a user selected period of  10  or  20  minutes. Approximately twenty seconds before asserting the Inactive  833  signal, the Digital Stereo Receiver  806  audibly notifies the user that he or she must press the Power Button  804  in order to maintain power, which is a safeguard in case the inactivity assumption is false. 
         [0068]    Referring now to  FIG. 9 , details of a Digital Stereo Transmitter and Digital Stereo Receiver, such as those previously disclosed, will be described. A wireless audio processor, such as the XInC2, which is a commercially available product of Eleven Engineering, having offices at 10150-100 street, suite 900 Edmonton, Alberta, Canada, T5J OP6, is used as the Transmitter Processor  901  and Receiver Processor  910  and provides hardware support for up to eight separate software threads which each run in parallel in real time without interrupts from the other threads. This parallel processing architecture simplifies many of the operations discussed below, which are implemented as stand-alone threads. 
         [0069]    A stereo A-to-D Converter  902  may be implemented using a Cirrus Logic CS5341, which is commercially available from Cirrus Logic, Inc., having offices at 2901 Via Fortuna, Austin, Tex., 78746, USA, to convert the analog Left Speaker  504  and Right Speaker  503  to digital signals for processing by a Transmitter Processor  901 . The Transmitter Processor  901  uses one thread as the Stereo Compressor  903  or “codec”, another thread as the Packetizer  904 , and another thread for Transmitter Baseband Control  905 . These functions are well known in the field of digital wireless audio. Another thread functions as the Transmitter Message Inserter (MSG)  907  which inserts Complete Packetized Messages  1006  ( FIG. 10 ) into the outgoing audio stream without interrupting communications by monitoring the status of a Transmit Sound Detected  922  flag provided by the Stereo Compressor  903  thread. 
         [0070]    The Stereo Compressor  903  thread compresses the audio amplitude as part of a compression algorithm and sets the Transmit Sound Detected  922  flag according to the audio amplitude, similar to a squelch circuit. When Battery Status  515  indicates that the Transceiver Battery  511  is Low or Very Low, the appropriate message to a user is retrieved from Transmitter EPROM or other persistent memory  908  by Transmitter Message Inserter  907  and provided to Transmitter Baseband Control  905  for transmission using the sequence shown in  FIG. 11 , which avoids interrupting communications originating from the Left Speaker  504  and Right Speaker  503  inputs. 
         [0071]    The Transmitter Baseband Control  905  handles configuration of the Transmitter RF Module  906 , data transfer, and provides error handling of dropped packets. The Transmitter Baseband Control  905  configures the Transmitter RF Module  906  to only link up with a Receiver RF Module with the same ID  909  as the Transmitter RF Module  906  has. Three dip switches (not illustrated) are set by the user to select the ID  909  in order to pair the transmitter to the same ID as the wireless headset  101 . 
         [0072]    The Receiver Processor  910  in the Digital Stereo Receiver  806  may be the same processor used for the Transmitter Processor  901 , and performs both similar functions and inverse functions. The Receiver Processor  910  uses one thread as the Receiver Baseband Control  912 , another thread as the Depacketizer  913 , and another thread for the Stereo Decompressor  914 . Another thread functions as the Receiver Message Inserter  919 , which inserts Complete Packetized Messages  1006  into the outgoing audio stream without interrupting communications by monitoring the status of a Receive Sound Detected  922  flag provided by the Decompressor thread  914 . 
         [0073]    The Decompressor  914  thread decompresses the audio amplitude as part of the decompression algorithm and sets the Receive Sound Detected  922  flag according to the audio amplitude, similar to a squelch circuit. Decompressed digital audio from the Decompressor  914  is sent to a stereo D-to-A Converter  915  implemented with a Cirrus Logic CS4341, which is commercially available from Cirrus Logic, Inc., having offices at 2901 Via Fortuna, Austin, Tex., 78746, USA, which converts the digital audio back to analog. The right and left analog audio is then amplified by dual Amps  920  and driven onto the Left Speaker  504  and Right Speaker  503  signals which drive the Left Driver  827  and Right Driver  828 . When battery status Low  819  or Very Low  820  are asserted, or the Shutdown Warning  918  flag is asserted by the Inactivity Timer  916 , the appropriate message for the user is retrieved from Receiver EPROM  917  by the Receiver Message Inserter  919  thread and provided to the Depacketizer  913  using the sequence shown in  FIG. 1   1 , which avoids interrupting communications originating from the Receiver RF Module  911  input. 
         [0074]    The Inactivity Timer  916  resets to zero whenever the Receive Sound Detected  923  flag is asserted by the Decompress  914  thread. The Inactivity Timer  916  is programmable via a dip switch (not illustrated) to time for  10  or  20  minutes or some other desirable time. Approximately twenty seconds before the Inactivity Timer  916  reaches its termination count, it asserts the Shutdown Warning  918  flag to cause a warning message to be sent to the user by the Receiver Message Inserter  919  thread, which tells the user to press the power button  804  to abort the shut down. The Inactivity Timer  916  senses the Button Pushed  834  signal and resets to zero if Button Pushed  834  is asserted while the Shutdown Warning  918  flag is asserted, thus aborting the power shutdown. The Receiver Message Inserter  919  thread also monitors whether the Receiver Baseband Control  912  has linked up with the Digital Stereo Transmitter  512  in a wireless transceiver, and inserts messages regarding link status into the outgoing audio stream until link up is complete. 
         [0075]    Both the wireless transceiver  102  with retractable bypass cord  103  and the wireless headset  101  monitor the receive audio path and insert warning and status messages into the receive audio stream without interrupting communications. The receive audio path is the path from the radio or intercom  105  to the wireless headset  101 . The transmit audio path from the wireless headset  101  to the radio or intercom is not monitored directly, but is still monitored as a result of a sidetone feature provided by the radio or intercom  105 , which provides feedback of the microphones back into the headsets. Thus, status and warning messages are inserted without interrupting communications in either the receive audio path or the transmit audio path, even though the receive audio path is the only path being directly monitored. 
         [0076]    The wireless transceiver  102  with retractable bypass cord  103  may insert the following voice messages into its outgoing stereo transmission without interrupting communications:
       1) “Transceiver battery is low. Please use bypass cord.”   2) “Transceiver battery is very low. Wireless is shutting down. Please use bypass cord now.”       
 
         [0079]    The wireless headset  101  may insert the following voice messages into the outgoing audio stream without interrupting communications:
       1) “Headset battery low. Please use bypass cord to maintain noise canceling.”   2) “Headset battery is very low. Wireless is shutting down. Please use bypass cord now.”   3) “Headset inactivity timeout. Please press the power button to abort shut down.”   4) “The headset is linked to a wireless transceiver”.   5) “No wireless transceiver found. Please check transceiver batteries and connection to a powered microphone jack.”       
 
         [0085]      FIG. 10  shows the format of status message packets. As illustrated, each Message Packet  1005  consists of fields including a Start-of-Packet  1001 , a Header  1002 , a Message Fragment  1003 , and an End-of-Packet  1004 . The Header  1002  field contains information distinguishing Message Packets  1005  from configuration and linking packets and other packets associated with digital wireless transfer. The Message Fragment  1003  field contains compressed digital audio which is ready for decompression by the Stereo Decompressor  914 . In order to minimize the delay associated with normal digital wireless audio transmission, Message Fragments  1003  and packet sizes are kept small, containing less than a complete English word. A Complete Packetized Message  1006  requires many Message Packets  1005 . 
         [0086]    Referring now to  FIG. 1   1 , a sequence of steps used to insert status messages into the audio stream without interrupting communications in accordance with one embodiment of the present invention is illustrated. Note that the sequence of  FIG. 11  is only one of several possible ways to insert status messages into the audio stream without interrupting communications and should not therefore be used to limit the appended claims. 
         [0087]    Initially, the Message Inserter  907  or  919  thread determines in Pending Message Decision Block  1007  if there is a pending status message. If there is no pending message (NO in decision block  1007 ), then the Message Inserter  907  or  919  thread continues to monitor for a pending message. When it is determined that a status message needs to be sent to a headset user (YES in decision block  1007 ), the Message Inserter  907  or  919  thread proceeds to Initialize MSG Packet Pointer  1008 , which is an address pointer used by the Message Inserter  907  or  919  thread to keep track of which packet is sent next. The Message Inserter  907  or  919  thread will then Wait 2 Seconds  1009  and determine in the Sound Detected Flag Decision Block  1010  if the Sound Detected Flag is detected to see if any communications audio is in progress which should not be interrupted. The Sound Detected Flag is also shown in  FIG. 9  as Transmit Sound Detected  922  and Receive Sound Detected  923 . 
         [0088]    If the Sound Detected Flag is set (Yes in decision block  1010 ), the Message Inserter  907  or  919  thread loops back to again Initialize MSG Packet Pointer  1008 . If the Sound Detected Flag is cleared (NO in decision block  1010 ), a Message Packet is Inserted  1011  and is sent out to Transmitter Baseband Control  905  by the Transmit Message Inserter  907  or provided to the Decompressor  914  thread by the Receiver Message Inserter  919 . The Message Inserter  907  or  919  thread will then Increment Packet Pointer  1012  and then determine in the Last MSG Packet Decision Block  1013  if the Last MSG Packet is Sent as indicated by the packet pointer being greater than the last packet in the Complete Packetized Message  1006 . 
         [0089]    If the last Message Packet  1005  in the Complete Packetized Message  1006  has not been sent (NO in decision block  1013 ), the Message Inserter  907  or  919  thread will loop back to check the Sound Detected Flag  1010  in case any communications from the radio or intercom  105  or the Electret Microphone  814  have come in which would cause the message to be aborted in favor of communications. If the last Message Packet  1005  in the Complete Packetized Message  1006  has been sent (Yes in decision block  1013 ), the Message Inserter  907  or  919  thread is done and goes back to the Pending Message Decision Block  1007 . 
         [0090]    Total delay from the A-to-D Converter  902  through the Digital Stereo Transmitter  512  through the Digital Stereo Receiver  806  and finally the D-to-A Converter  915  is kept under  20  ms in order to minimize echo. Echo results if the round-trip delay is long enough to be audible because of the sidetone provided by the radio or intercom  105 . Sidetone is a feature which feeds the microphone audio back to the headset so that the user can hear himself or herself speak, which provides the user with confidence that others can hear them. Echo due to sidetone can be caused by delay in the path from the Electret Microphone  814  to the Radio or Intercom  105 , or by delay in the path from the Radio or Intercom  105  to the Left Driver  827  and Right Driver  828 . 
         [0091]    Due to the fixed overhead of non-payload fields associated with packets such as the Header  1002  field, higher throughput is provided by larger payload fields, such as the Message Fragment  1003  field. Unfortunately, large payload fields also cause larger delays which result in echo due to sidetone. The throughput provided does not change linearly with payload size due to the fixed overhead, so the penalty for decreasing the delay from 40 ms to 20 ms is much more than twice the number of packets. Since there is a limited amount of RF bandwidth available in license-free bands, and because there may be multiple wireless headsets in a single cockpit all sharing the same license-free RF band using frequency hopping, it is critical to balance the tradeoff between sidetone echo caused by larger packet sizes, and higher RF bandwidth efficiency which results from larger packet sizes. Traditional digital wireless audio systems which provide full-duplex communications use digital technology in both directions. A novel approach to solving this problem in the wireless headset  101  is to eliminate delay between the microphone and the wireless transceiver by using analog transmission in a different RF band than that used by the Digital Stereo Transmitter  512  and Digital Stereo Receiver  806 . Thus the digital delays are only incurred in one direction of the full-duplex communication path. 
         [0092]    Although the present invention has been described above with respect to a wireless headset, this is for illustration only and should not be used to limit the scope of the appended claims. It is also anticipated that the principles of the present invention may apply to any wired or wireless headset or handset. A headset or a handset is defined to at least include any communication device that has an audio speaker that may be placed against a user&#39;s ear. Examples include, but are not limited to, wireless and wired headsets, cellular telephones, walkie/talkies, other hand held communication devices, or radios. In particular, the status message insertion method described above could be applied to any handset or headset that includes a microprocessor configured to insert status messages without interrupting normal communication. 
         [0093]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.