Wireless microphone for use with an in-car video system

BACKGROUND OF THE INVENTION

[0001] This invention is related generally to surveillance systems, and more particularly to a wireless microphone for use with an in-car video system.

[0002] Vehicle-mounted surveillance systems, also termed in-car video systems, are seeing increased use in the security industry and law enforcement community as an effective means to provide an indisputable video and audio record of encounters involving officers and citizens. In these systems, a video camera is typically mounted on the police car's dashboard or windshield and is generally arranged to have a field of view of the area to the immediate front of the car. The field of view approximately corresponds to what an officer would see when seated in the car's front seat.

[0003] The video camera is operably coupled to a recording device, such as a video cassette recorder (“VCR”), mounted in the police car, often in the trunk. A videotape recording may be started manually by the officer, or in some systems, the videotaping is started automatically when, for example, the officer activates the police car's emergency systems (such as overhead lights and/or sirens), or when a vehicle speed-measuring radar unit is operated.

[0004] In some in-car video systems, the VCR may start recording when the officer activates the wireless microphone. Security schemes may also be used where the VCR starts recording only when it receives a predetermined code at a certain RF frequency from the wireless microphone. Inadvertent triggering from stray RF signals is thus avoided. A visual indicator to verify that a videotape recording is being made may be displayed on an indicating device mounted on the car (such as a light in the car's front grill or windshield) that can be seen by the officer at a distance (for example, when the officer is located in the proximity of a stopped car).

[0005] In-car video systems serve to enhance prosecution of traffic, DWI/DUI and controlled dangerous substances offenses (to name just a few) by contributing detailed graphical and auditory evidence in a time-sequential manner that is inherently unbiased and objective. Such evidence is a valuable adjunct to eyewitness and officer testimony. In addition, as with other quality-improvement initiatives where conduct is surveyed and recorded, in-car video system usage has been shown to assist in the maintenance of high professional standards among law enforcement personnel. Police-community relations have improved and citizen complaints of police misconduct have lessened in many jurisdictions where in-car video systems are used, often as a result of the inherently high-quality evidence provided by such systems. Videos taken with in-car video systems are also valuable training aids to law enforcement personnel.

[0006] Videotape evidence is protected (and the evidentiary chain of custody readily established) because the video cassette recorder and video recording medium (i.e., videotape) are typically “locked”, often both mechanically and electronically, within a tamperproof security enclosure in the car that is only accessible by law enforcement command personnel. In addition, the in-car systems are configured to prevent erasure or over-recording of a recorded encounter to ensure the integrity of the videotaped evidence. In-car video systems may superimpose time and date stamps on the recorded video image as a further enhancement to the evidentiary strength of the videotape.

[0007] In-car video systems generally employ a wireless microphone carried on the person of a law enforcement officer to record an audio soundtrack that accompanies the visual scene captured on videotape. The audio soundtrack is an extremely valuable complement to the recorded video because it acts as a transcript of the what was said, by whom and when. In some cases, the audio soundtrack is more valuable as evidence than the visual record because issues pertaining to consent, admissions, and state-of-mind of the suspect and/or officer (to cite just a few examples) may be resolved more effectively by the audio record. In some systems, additional wired microphones may be deployed in other locations within the car, such as the rear-seat passenger area, to record sounds and conversations emanating from those locations.

[0008] While current in-car video systems perform very well in many applications, there have been instances where officers have inadvertently failed to turn on the wireless microphone during an encounter or traffic stop even though the videotaping may be properly activated. Thus, a valuable piece of the evidentiary record is lost. Additionally, while car-mounted visual recording status indicators are very satisfactory in most situations, there may be times when the car-mounted indicator is out of the line of sight of the officer, or is obscured by weather conditions. Lost or damaged wireless microphones may also present a logistical challenge to some departments since each wireless microphone must be matched to a particular in-car video system in some systems in order to enable secure transmission from the wireless microphone.

SUMMARY OF THE INVENTION

[0009] An in-car video system and method is provided where a wireless microphone is configured with bidirectional RF communications capability. In response to a received RF activation signal, the wireless microphone is automatically switched on to capture (and transmit back to the in-car video system) an audio soundtrack that accompanies the visual images captured by the car-mounted video camera. A wireless microphone controller mounted in the car transmits the RF activation signal to the wireless microphone. The wireless microphone controller is arranged to transmit the RF activation signal when the VCR starts recording.

[0010] In an illustrative embodiment of the invention, the wireless microphone receives information, including a confirmation that the VCR is recording, from an RF information signal received from the wireless microphone controller mounted in the car. The wireless microphone displays the information to the officer on a display screen. The wireless microphone sounds an audible alert when it receives the RF activation or information signals. The wireless microphone controller is arranged to send an RF deactivation signal to the wireless microphone when the VCR stops recording.

[0011] In another illustrative embodiment of the invention, the wireless microphone and wireless microphone controller are arranged in a docking configuration where a security code is exchanged between them during a synchronization process. When the wireless microphone is subsequently un-docked from the microphone controller, the security code is used to provide secure RF transmission back to the microphone controller using the code exchanged during the synchronization process. In a preferred embodiment of the invention, the code exchanged during synchronization comprises the frequency spreading code used in the inherently-secure, digital spread spectrum (“DSS”) RF transmission stream utilized by the wireless microphone at a nominal frequency of 900 MHz. The wireless microphone controller uses the code to de-spread the received RF transmission to construct an information stream representing the audio captured by the wireless microphone.

[0012] Advantageously, the invention ensures that a complete evidentiary record is established, including the audio soundtrack, without requiring the officer to remember to turn on the wireless microphone during an encounter or traffic stop (which can very often be highly stressful situations). By utilizing the bi-directional communications capabilities of the present inventive arrangement, the wireless microphone may be activated automatically, for example, when the VCR starts recording upon activation of the car's emergency lights. Information displayed on a screen incorporated into the wireless microphone (including, for example, a VCR recording confirmation) and audible alerts provide the officer with valuable in-car video system status even when the visual indicators mounted on the patrol car are out of sight or otherwise obscured.

[0013] In addition, the docking and synchronization arrangement of the present invention advantageously reduces the administrative burden on police department when managing in-car video equipment. Unlike conventional in-car systems where a specific microphone must be matched to a specific video system in the patrol car (to ensure that the transmitter and receiver use the same security code), the inventive synchronization process allows any wireless microphone in the equipment pool to work with any in-car video equipped vehicle in the department's fleet.

BRIEF DESCRIPTION OF THE DRAWING

P-0014[0014]FIG. 1 is a simplified functional block diagram of an illustrative arrangement of the present invention depicting an in-car video surveillance system (including a windshield mounted camera and trunk-mounted VCR), a car-mounted wireless microphone controller, and wireless microphone equipped with bidirectional RF communications capability;

P-0015[0015]FIG. 2 is a simplified functional block diagram of the wireless microphone of FIG. 1;

P-0016[0016]FIG. 3 is a simplified functional block diagram of the wireless microphone controller of FIG. 1;

P-0017[0017]FIG. 4 is a pictorial representation of an illustrative embodiment of a wireless microphone equipped with bi-directional RF communications capability, in accordance with the invention;

P-0018[0018]FIG. 5 is a pictorial representation of a wireless microphone inserted into a duty belt holster, in accordance with the invention;

P-0019[0019]FIG. 6 is a side pictorial view of the belt holster shown in FIG. 5 depicting a hinged retainer clip;

P-0020[0020]FIG. 7 shows a side view of the belt holster with wireless microphone inserted therein;

P-0021[0021]FIG. 8 shows a front pictorial representation of the wireless microphone inserted in the wireless microphone controller in a docking configuration, in accordance with the invention;

P-0022[0022]FIG. 9 is a side pictorial view of the wireless microphone controller depicting the docking feature of the wireless microphone and controller, in accordance with the invention; and

P-0023[0023]FIG. 10 is a flowchart illustrating a method of operating an in-car video system with the wireless microphone and wireless microphone controller of the present invention.

DETAILED DESCRIPTION

P-0024[0024] Referring to FIG. 1, there is depicted a simplified functional block diagram of an illustrative arrangement of the present invention depicting an in-car video surveillance system <b>110</b> (including a windshield mounted camera <b>150</b> and trunk-mounted VCR <b>120</b>), a car-mounted wireless microphone controller <b>300</b>, and wireless microphone <b>100</b> equipped with bidirectional RF communications capability. Vehicle <b>175</b> is depicted in FIG. 1 as a police cruiser with emergency lightbar <b>180</b>, however it is emphasized that the features and benefits of the present invention may be equally applicable to a wide variety of vehicle types, and further that the invention is not limited to law enforcement applications. Applications of the invention to the security and the transportation industries may be readily made, for example. Therefore, the term “officer” in the description that follows should be understood to refer to the user or operator of the inventive in-car video system in non-law enforcement applications.

P-0025[0025] VCR <b>120</b>, as shown in FIG. 1, is typically located in secure enclosure contained in the trunk of the car. The enclosure is generally quite rugged, both to provide deterrents against tampering or improper access to the videotape, and also to protect the tape in the event that the vehicle <b>175</b> is involved in a crash. The enclosure may also be environmentally controlled to keep the VCR <b>120</b> and videotape within acceptable operating conditions. VCR is operably coupled to wireless microphone controller <b>300</b> by bus <b>125</b>, as shown in FIG. 1. It is noted that VCR <b>120</b> is merely representative of any of a number of recording devices that are arranged to record video and audio, either as a single device or a combination of devices. Such recording devices include those that record on tape as well as those that use other media, such magnetic media (including disk-drives and cartridge drives), electronic media (including volatile and non-volatile memory), and optical media (including optically writeable disks).

P-0026[0026] A remote VCR control head <b>135</b> is located in vehicle <b>175</b> near the driver and is operably coupled to VCR <b>120</b> via bus <b>137</b> to allow the VCR to be conveniently controlled by the officer from within the vehicle. VCR control head <b>135</b> may be arranged with typical controls such as “POWER”, “RECORD”, “STOP”, “REWIND”, “PLAY”, and “FORWARD” buttons which operate the VCR <b>120</b> accordingly.

P-0027[0027] Camera <b>150</b> may be selected from the wide variety of available cameras. Preferably, camera <b>150</b> is a compact camera (to reduce the likelihood of obstructing the officer's view out the windshield) with color capabilities such as a solid-state CCD (“charge-coupled device”) camera that can operate in low-light environments. Camera <b>150</b> may be optionally configured with digital and/or optical zoom capabilities. Camera <b>150</b>, in this illustrative arrangement, is mounted to the windshield of vehicle <b>175</b>, however other mounting locations may be used in other applications. Camera <b>150</b> is operably coupled to VCR <b>120</b> via bus <b>155</b>.

P-0028[0028] Wireless microphone <b>100</b> is depicted in FIG. 1 to be located outside of vehicle <b>175</b>. Such location is merely illustrative as wireless microphone <b>100</b> is most often carried on the person of the officer, and thus, may be located both inside and outside of the vehicle <b>175</b> at any given time. Wireless microphone <b>100</b>, in accordance with the invention, is equipped with bidirectional RF communications capabilities. That is, wireless microphone <b>100</b> is configured to transmit an RF data signal (over wireless path <b>105</b> in FIG. 1) and receive RF signals (over wireless path <b>107</b>), including information and controls signals as described more fully below. A bi-directional RF communications stream <b>112</b> is thus formed by the combination of wireless path <b>105</b> and wireless path <b>107</b>.

P-0029[0029] Wireless microphone controller <b>300</b>, like VCR <b>120</b> and camera <b>150</b>, is mounted in vehicle <b>175</b>. While shown as a discrete unit in FIG. 1, in some applications of the invention it may be desirable to incorporate the features and functions of wireless microphone controller <b>300</b> into other equipment mounted in the vehicle, including equipment that is typically part of the in-car video system (such as a video monitor which is not shown in FIG. 1). Alternatively, wireless microphone controller functionality may be incorporated into other equipment such as radios and other communications equipment that is typically installed in law enforcement patrol vehicles.

P-0030[0030] Referring now to FIG. 2, there is depicted a simplified functional block diagram of the wireless microphone <b>100</b>. As indicated in FIG. 2, wireless microphone is bi-directional as that term is defined above. Accordingly, radio transceiver <b>260</b> comprises both an RF transmitter <b>262</b> and RF receiver <b>264</b>. RF transmitter <b>262</b> may be selected to use any number of conventional radio transmission methodologies. However, in many applications, a secure transmission stream is desirable. Thus, in this illustrative arrangement, an FCC Rules Part 15 compliant spread spectrum transmission technique is utilized in the 902-928 MHz band. Both frequency hopping and direct sequence spreading methods (i.e., coding schemes) may be used.

P-0031[0031] While spread spectrum RF modulation is well known, briefly, spread spectrum systems use two modulation processes—a conventional form of modulation (which may be digital or analog) to impress data onto the transmission stream, and RF carrier modulation by the spreading code causing the RF carrier spread over a large bandwidth. Spread spectrum modulation advantageously provides excellent resistance to interference and unwanted detection by unauthorized personnel because non-spread signals are rejected by the spread spectrum receiver while other radio receivers (without the spreading code) are unable to recover the data signal from the RF transmission stream.

P-0032[0032] Antenna <b>270</b> is coupled to radio transceiver <b>260</b>, as shown in FIG. 2. Both external and internal antennae may be used as required by the specific applications.

P-0033[0033] Radio transceiver <b>260</b> is coupled to controller <b>210</b> via bus <b>214</b>. Controller <b>210</b> may be arranged from discrete circuits, general purpose integrated circuits, and application-specific integrated circuits (“ASICs”). In this illustrative arrangement, controller <b>210</b> is an ASIC that includes the spread spectrum engine and performs all the usual control and monitoring functions necessary to implement a bidirectional wireless microphone.

P-0034[0034] Controller <b>210</b> sends an information signal via bus <b>212</b> to LCD display <b>220</b>. While an LC (“liquid crystal”) display is shown in FIG. 2, other displays including light emitting diode (“LED”) arrays and other conventional display technologies may also be used in some applications. LCD display <b>220</b> is arranged to display status information relating the in-car video system <b>110</b> (FIG. 1), as well as status information relation to the wireless microphone <b>100</b>. FIG. 2 shows several illustrative status indicators, including the word “REC” plus a round icon to indicate that VCR <b>120</b> (FIG. 1) is recording. A battery icon is also displayed to indicate the current battery level of wireless microphone <b>100</b> (where a higher battery charge would correspond to a larger percentage of the battery icon being displayed in black on LCD display <b>220</b>). However, these status indicators are merely exemplary, and other indicators may be selected.

P-0035[0035] Wireless microphone <b>100</b> includes an analog microphone module <b>225</b>. Analog microphone module <b>225</b> is operably coupled to controller <b>210</b> via bus <b>231</b>. Analog microphone module <b>225</b> includes an internal microphone <b>227</b> and an interface <b>229</b> for an external microphone which include corded microphones such as lavaliere microphones. The signal from the external microphone is received at interface <b>229</b> on line <b>280</b>, as shown in FIG. 2.

P-0036[0036] In some applications of the invention, it may be desirable to use only an internal microphone or external microphone, but not both. However, an internal microphone provides a back-up in case the external microphone fails, for example, by an electrical break in the cord or damage to the external microphone element itself. Omni-directional condenser microphones may often provide the best performance in many applications and may be used for both internal and external microphones.

P-0037[0037] An analog sound signal corresponding to the audio captured by the microphone module <b>225</b> is sent to the controller <b>210</b> on bus <b>231</b>. Controller <b>210</b> performs an audio encoding function to convert the analog sound signal received from microphone module <b>225</b> into a digital signal. In some applications, a discrete, dedicated audio codec (i.e., digital-analog coder/decoder) may be preferred.

P-0038[0038] Wireless microphone <b>100</b> includes battery <b>247</b>. In this illustrative arrangement of the invention, battery <b>247</b> comprises a rechargeable battery pack, however non-rechargeable (i.e., single use or disposable) batteries may be also be used. Nickel-cadmium (“Ni—CAD”), nickel-metal hydride (“NiMH”) and lithium Ion (“LiOn”) are all suitable rechargeable battery types, although LiOn provides the highest performance (longest discharge time with quickest recharge time and greatest number of discharge/charge cycles) in most applications. LiOn batteries may be particularly well suited to applications, including the present inventive application, where a reliable power source is needed. LiOn batteries do not suffer from the so-called “memory effect” which limits the of charge capacity of other battery types when they are discharged repeatedly and then recharged before they have fully drained.

P-0039[0039] Audible alert generator <b>230</b> is operably coupled to controller <b>210</b> with bus <b>276</b>. Audible alert generator <b>230</b> is a device, such as tone generator, buzzer or ringer, that is used to direct the officer's attention to the LCD display <b>220</b> or otherwise indicate to the officer that an action has occurred. For example, the audible alert generator <b>230</b> may sound to indicate a low battery level in wireless microphone <b>100</b>, or that the wireless microphone <b>100</b> is out of radio range with the in-car video system <b>110</b> (FIG. 1), or to provide a confirmation to the officer that VCR <b>120</b> is recording. Audible alert generator <b>230</b> may be configured to sound distinctive tones that correspond to the various alerts. LCD display <b>220</b> may be arranged to display a visual alert corresponding to the audible alert, such as a flashing battery icon or the term “BAT” in the case of low battery level, “NO SIGNAL” in the case of an out of range condition, or “REC” in the case of record confirmation.

P-0040[0040] Power switch <b>242</b> is disposed between battery <b>247</b> and controller <b>210</b> with bus <b>272</b> and bus <b>245</b>, respectively. Power switch <b>242</b> is user-operable to switch battery power on and off to wireless microphone <b>100</b>.

P-0041[0041] Talk switch <b>235</b> is a user-operable switch that switches wireless microphone <b>100</b> into transmit mode (i.e., “talk” mode) where audio captured by microphone module <b>225</b> is digitized by controller <b>210</b> and transmitted by radio transceiver <b>260</b> to the wireless microphone controller <b>300</b>. As described in more detail below, talk switch <b>235</b> is used by the officer to switch wireless microphone <b>100</b> into “talk” mode, but it may be arranged so that it is not usable as a means to switch the wireless microphone out of “talk mode” (i.e., back into a standby mode of operation) when VCR <b>120</b> (FIG. 1) is recording.

P-0042[0042] A docking connector <b>205</b> is provided in wireless microphone <b>100</b> as shown in FIG. 2. Docking connector <b>205</b> is arranged to provide a interface with wireless microphone controller <b>300</b> to enable the docking and synchronization features (described more fully below) using synchronization port <b>294</b>. Docking connector <b>205</b> also includes a battery charger port <b>292</b> that allows current to flow on bus <b>296</b> to battery <b>247</b> from an external battery charger (such as battery charger <b>392</b> depicted in FIG. 3).

P-0043[0043] Referring now to FIG. 3, there is depicted a simplified functional block diagram of the microphone controller <b>300</b> arranged in accordance with the invention. Microphone controller <b>300</b> performs as the functional interface with wireless microphone <b>100</b> to the in-car video system <b>110</b>. Microphone controller <b>300</b> is arranged to share the bidirectional RF communications stream <b>112</b> with wireless microphone <b>100</b>, and is thus equipped with a radio transceiver <b>360</b> which may be similar in form and function to the radio transceiver <b>260</b> in FIG. 2. As wireless microphone controller <b>300</b> is an interface between the RF domain (with wireless microphone <b>100</b>) and the wired domain (with VCR <b>120</b>), it may also be termed an audio “base station” in the in-car video system <b>110</b>

P-0044[0044] Wireless transceiver <b>360</b> includes an RF transmitter <b>362</b> and RF receiver <b>364</b>, as shown in FIG. 3. The RF transmitter <b>362</b> is used to send RF activation and RF deactivation signals to the wireless microphone <b>100</b> (to switch it between standby and “talk” modes), as described in greater detail below. RF transmitter <b>362</b> and RF receiver <b>364</b> are selected to be functionally complementary to RF transmitter <b>262</b> and RF receiver <b>264</b> (FIG. 2) in wireless microphone <b>100</b>. Therefore, in the illustrative embodiment of the invention depicted in FIG. 3, a spread spectrum transceiver operating at a nominal frequency of 900 MHz is used in wireless microphone controller <b>300</b>.

P-0045[0045] An antenna <b>370</b> is coupled to wireless transceiver <b>360</b>, as shown in FIG. 3. Because the bidirectional RF communications stream <b>112</b> may be imbalanced (i.e., wireless microphone <b>100</b> transmits relatively more data over wireless link <b>105</b> to wireless microphone controller <b>300</b> than it receives over wireless link <b>107</b>), it may be advantageous to configure antenna <b>370</b> externally to wireless microphone controller <b>300</b> to present a strong signal to RF receiver <b>364</b>. However, an internally-configured antenna may also be used.

P-0046[0046] Radio transceiver <b>360</b> is operably coupled to controller <b>310</b> via bidirectional bus <b>314</b>. Controller <b>310</b> may be similar in form and operation to controller <b>210</b> shown in FIG. 2. Controller <b>310</b> includes an audio codec and spread spectrum engine to take the signal from radio transceiver <b>360</b> on bus <b>314</b>, de-spread the signal to remove the effects of the spreading code and recover the digital information from the received RF signal. Controller <b>310</b> additionally decodes the digital information into a corresponding analog signal which is provided to the external interface (“I/F”) <b>330</b> on bi-directional bus <b>332</b>, as shown in FIG. 3. As with controller <b>210</b>, a discrete audio codec may be preferred in some applications of the invention. The analog signal is presented to the VCR <b>120</b> via a connection in the external I/F <b>330</b> depicted by line <b>344</b>. It is noted that some signal conditioning, such as voltage rectification, and signal phase and amplitude adjustments, may be required in some applications which may be performed by conventional circuits (not shown in FIG. 3).

P-0047[0047] External I/F <b>330</b> provides inputs and outputs to and from wireless microphone controller <b>300</b> to devices in the in-car video system <b>110</b> that are external to the wireless microphone controller. Specifically, as depicted in FIG. 3, DC power (typically <b>12</b>V from the electrical system of vehicle <b>175</b>) is received on line <b>340</b>. Ground is provided on line <b>342</b>. The VCR line-level output signal is provided on line <b>344</b>. A signal indicative that the VCR <b>110</b> is recording is received on line <b>346</b>.

P-0048[0048] A command signal to switch the VCR <b>120</b> to record mode is output on line <b>348</b>. If the VCR <b>120</b> is not already recording, the wireless microphone controller <b>300</b> sends the command signal to start the recording when the officer activates the talk switch <b>235</b> and the RF transmission stream from wireless microphone <b>100</b> is received by the wireless microphone controller. Thus, the officer is able to remotely activate the in-car video system <b>120</b> manually by actuating a single switch (i.e., talk switch <b>235</b>).

P-0049[0049] Controller <b>310</b> is operably coupled to indicator LED <b>380</b> on bus <b>334</b>. Controller <b>310</b>, in response to the indicative signal received from VCR <b>120</b> on line <b>346</b>, sends a signal to a visual recording status indicator <b>382</b>. While an LED is depicted in this illustrative arrangement, other indicator devices may be used including lasers, and incandescent or fluorescent sources. Recording status indicator <b>382</b> is operated to provide a visual indication that the VCR <b>120</b> is recording at the wireless microphone controller <b>300</b> which is mounted inside vehicle <b>175</b>.

P-0050[0050] A power and/or charging indicator <b>384</b> is also provided. Indicator <b>384</b> may be similar in form and function to indicator <b>382</b> and provides a visual indicator at the wireless microphone controller <b>300</b> that it is powered-on, and as described below, may be arranged (alone or in combination with the power-on status function) provide the charging status of the wireless microphone <b>100</b> when it is docked with the wireless microphone controller in accordance with the invention. The charging status is displayed on indicator <b>384</b> in response to a charging status signal received on bus <b>396</b> from battery charger <b>392</b>, as shown in FIG. 3.

P-0051[0051] A docking connector <b>390</b> is included in wireless microphone controller <b>300</b> to provide a physical interface to wireless microphone <b>100</b> when it is docked to implement the synchronization feature of the invention. As noted above, a battery charger <b>392</b> is coupled to the docked wireless microphone <b>100</b> through the docking connector <b>390</b> which also includes a synchronization port <b>394</b>.

P-0052[0052] When the two synchronization ports <b>294</b> (FIG. 2) and <b>394</b> are coupled during docking, a synchronization path is established between wireless microphone <b>100</b> and wireless microphone controller <b>300</b>. A spreading code may then be selected and shared. For example, in this illustrative arrangement of the invention, a new spreading code is selected and shared between wireless microphone <b>100</b> and wireless microphone controller <b>300</b> during each docking event. That is, each time the wireless microphone <b>100</b> is docked with wireless microphone controller <b>300</b>, controllers <b>210</b> and <b>310</b> select and share a spreading code.

P-0053[0053] In the case of frequency hopping, a pseudo-random list of channels is generated and the center frequency of the RF carrier is altered according to the list. In direct sequence, the phase of the RF carrier is shifted by a binary sequence that is generated in a pseudo-random manner. In both cases, the random-like properties used by the spreading method is termed pseudo-noise (“PN”) sequences or codes. Thus, the PN code is duplicated and synchronized at the transmitter and receiver during docking. Later, when the wireless microphone <b>100</b> is un-docked from the wireless microphone controller <b>300</b>, the RF receiver <b>364</b> in wireless microphone controller <b>300</b>, using the same spreading sequence to follow the transmitter, moves from channel to channel (in a frequency hopping scheme) or follows the same binary sequence (in a direct sequence scheme) in lock-step with the RF transmitter <b>262</b> in wireless microphone <b>100</b>.

P-0054[0054] In a similar manner, the RF receiver <b>264</b> in wireless microphone <b>100</b> locks with the RF transmitter <b>362</b> in wireless microphone controller <b>300</b> as both receiver and transmitter follow the same spreading sequence. Non-spread signals that do not bear the shared PN code are rejected by the RF receiver <b>264</b> in wireless microphone <b>100</b> to ensure that it is not inadvertently activated by an undesired or stray RF signal.

P-0055[0055]FIG. 4 is a pictorial representation of an illustrative embodiment of a wireless microphone <b>100</b> equipped with bidirectional RF communications capability, in accordance with the invention. Wireless microphone <b>100</b> in this illustrative embodiment is configured as a compact unit (slightly larger than a typical pager) that is well suited to be comfortably worn on the body of an officer, for example, clipped to the officer's duty or gun belt. Accordingly, a belt clip (not shown in FIG. 4) may be integrated with the external housing <b>101</b> of the wireless microphone, or as shown in FIGS. <b>5</b>-<b>7</b>, wireless microphone <b>100</b> may be removably inserted into a fitted “holster” <b>520</b> which is equipped with a moveable spring-type belt clip <b>625</b> (FIGS. 6 and 7).

P-0056[0056] Advantageously, the holster <b>520</b> allows an officer to reserve a space for the wireless microphone <b>100</b> on his or her typically crowded duty belt. The holster <b>520</b> may be semi-permanently attached to the belt with clip <b>625</b> (FIGS. 6 and 7) and the wireless microphone <b>100</b> may be slipped in and out as required to dock or recharge it. As shown in FIGS. 6 and 7 a small contoured lip <b>630</b> extends from the rear of the holster <b>520</b> to engage a corresponding contour on the wireless microphone <b>100</b> to keep it securely contained. A small amount of elastic deflection on the lip <b>630</b> thus occurs during insertion and withdrawal of the wireless microphone <b>100</b>.

P-0057[0057] Returning back to FIG. 4, an external lavaliere microphone <b>410</b> and clothing clip <b>412</b> is shown being coupled to the external microphone interface <b>229</b> (FIG. 2). As described above, the external microphone <b>410</b> may be used in a complementary or “back-up” microphone to an internal microphone <b>227</b> (FIG. 2) that is arranged to pick up audio through a small aperture <b>427</b> in housing <b>01</b>, as shown in FIG. 4. Audible alert generator <b>230</b> (FIG. 2) is located behind a grill <b>430</b> which may comprise an array of small apertures in housing <b>101</b>.

P-0058[0058] Talk switch <b>235</b> and power switch <b>242</b> (FIG. 2) are externally disposed on housing <b>101</b> as shown in FIG. 4. LCD display <b>220</b> (FIG. 2) is located on wireless microphone <b>100</b> in an area that provides for ready viewing. It is emphasized that the location of the various elements and the physical design of the housing <b>101</b> depicted in FIG. 4 are merely illustrative, and that invention contemplates that a wide variety of designs and arrangements of such elements may be readily tailored to the specific requirements of each application. For example, it may be desirable in some applications of the invention to orient the LCD display <b>220</b> to the top face of wireless microphone <b>100</b> (and thus be co-planar with the external microphone interface <b>229</b> shown in FIG. 4).

P-0059[0059]FIGS. 8 and 9 show front and side pictorial representations of the docking feature of the wireless microphone <b>100</b> and wireless microphone controller <b>300</b>, in accordance with the invention. Referring to FIG. 8, the wireless microphone controller <b>300</b> may be physically embodied as shown with an area arranged to receive the wireless microphone <b>100</b>. The receiving area is sized to be close fitting to the wireless microphone <b>100</b> and further includes the docking connector <b>390</b> (FIG. 3) disposed along the lower interior surface so that the corresponding docking connector <b>205</b> on wireless microphone <b>100</b> mechanically and electrically engage when the units are docked.

P-0060[0060] It is emphasized that the specific locations of the connectors is merely illustrative, and that other arrangements may be used. For example, while a downward insertion action is shown in FIG. 9 to accomplish docking via a connector on the bottom surface of the wireless microphone <b>100</b>, it may be desired in some applications to provide an configuration where the wireless microphone is coupled on a side or top surface. In addition, the male/female engagement roles may be reversed so that the wireless microphone <b>100</b> is arranged with a receiving space that accepts the insertion of an appropriately configured microphone controller docking interface.

P-0061[0061]FIGS. 8 and 9 show an exterior antenna <b>835</b>. As noted above, the use of an exterior antenna is optional depending on the requirements of the application. FIG. 8 also shows the indicator LED <b>380</b> shown in FIG. 3 and described in the accompanying text. The power indicator <b>384</b>, as noted above, indicates that the wireless microphone controller <b>300</b> is powered up. However, it may also be desirable to have a visual indicator of the charging status of battery <b>247</b> (FIG. 2) when the wireless microphone <b>100</b> is docked. The battery charger <b>392</b> (FIG. 3) includes circuitry that can sense the current take-up and/or voltage of the battery <b>247</b> and sends an appropriate signal to indicator <b>380</b>. For example, a color coding scheme may be used to indicate that the battery is charging, charging is near completion, and that the battery is fully charged, where red, amber, and green indicators are used, respectively. This same circuitry may also be used to regulate the current provided to the battery <b>247</b> by the charger <b>392</b> to ensure that the battery <b>247</b> is not overcharged.

P-0062[0062]FIG. 10 is a flowchart illustrating an exemplary method of operating the in-car video system <b>110</b> with the wireless microphone <b>100</b> and wireless microphone controller <b>300</b> of the present invention. The method starts at block <b>1010</b>. At block <b>1020</b>, an officer is issued a wireless microphone <b>100</b> from a pool of microphones that may be kept in charging stands as indicated in block <b>1030</b> to keep the battery <b>247</b> fresh. As described above, the present invention allows the officer to take any microphone from the pool without concern about matching the transmitter to the in-car receiver to enable secure communications.

P-0063[0063] As shown in block <b>1040</b>, the officer prepares vehicle <b>175</b> for duty, which typically includes a check of major systems including emergency systems such as lights and siren, as well as powering on communications equipment such as radio and mobile data communications. At this time, the in-car video system <b>110</b> is powered-on and the power indicator <b>384</b> (FIG. 8) is activated to indicate to the officer that the wireless microphone controller <b>300</b> is powered up and ready for docking to implement the synchronization process.

P-0064[0064] The officer switches the wireless microphone <b>100</b> on using switch <b>242</b> (FIG. 2) as indicated in block <b>1050</b>. LCD display <b>220</b> (FIG. 2) displays a battery icon to indicate the level of battery charge of battery <b>247</b> (FIG. 2). In addition, the wireless microphone may be optionally arranged to perform a self-diagnostic at power-up and display an indicator to the officer such as “READY TO DOCK”. An audible alert may also be generated by audible alert generator <b>230</b> (FIG. 2) to indicate proper operation.

P-0065[0065] The wireless microphone <b>100</b> is next docked with wireless microphone controller <b>300</b> in block <b>1060</b> of FIG. 10. Upon docking, an alert tone is generated by audible alert generator <b>230</b> in wireless microphone <b>100</b> to indicate to the officer that the synchronization process has been effected. A corresponding visual alert may be optionally displayed on LCD display <b>220</b> on the wireless microphone. In addition, the power indicator <b>384</b> (FIGS. 3 and 8) may be arranged to confirm the status of battery <b>247</b> as described above in the text accompanying FIG. 8.

P-0066[0066] The inventive method continues at block <b>1070</b> with the synchronization process where the spreading code is selected and shared between wireless microphone <b>100</b> and wireless microphone controller <b>300</b>. The length of the synchronization process may vary according the specific spreading methodology and controllers selected, however, typically the synchronization is completed within several seconds. At block <b>1080</b>, the wireless microphone <b>100</b> may sound an audible alert using audible alert generator <b>230</b> to indicate that the synchronization process was successful. Similarly, the LCD display <b>220</b> may be arranged to provide a visual indicator to the officer that the synchronization is performed (e.g., by setting indicator <b>384</b> to intermittently flash during the synchronization process). Indicator <b>384</b> may use another pattern (e.g., going from flash to steady) to indicate that wireless microphone <b>100</b> is in a ready condition for use (i.e., is in standby mode), as shown in block <b>1090</b> in FIG. 10.

P-0067[0067] Moving next to block <b>1100</b>, once the officer has confirmed proper operating condition of the wireless microphone <b>100</b> via the audible and/or visual indicators, the officer may test the operation of the wireless microphone by removing it from the wireless microphone controller <b>300</b> and briefly triggering the talk switch <b>235</b> (FIG. 2) to ensure that the VCR <b>120</b> starts recording. A visual confirmation that the VCR is recording is displayed on LCD display <b>220</b> and the record indicator <b>382</b> (FIG. 3) on wireless microphone controller should also confirm that VCR <b>120</b> is recording. Once the test is concluded, the officer affixes the wireless microphone <b>100</b> to an article of clothing, or places the wireless microphone in the holster <b>520</b> that is clipped to the officer's duty belt. If an external microphone is used, then the external microphone is plugged into the external microphone interface <b>229</b> and then clipped to the officer's clothing such as tie or lapel, as shown in blocks <b>1120</b> and <b>1130</b> in FIG. 10.

P-0068[0068] The inventive method moves to block <b>1140</b> where the wireless microphone <b>100</b> is powered on, but in standby mode awaiting either manual or automatic activation at the appropriate time. Should the officer manually activate the wireless microphone <b>100</b> by actuating the talk switch <b>235</b> (FIG. 2), as shown in decision block <b>1150</b>, the transmitted RF signal is received at the wireless microphone controller which triggers the issuance of command signal <b>348</b> (FIG. 3) to start VCR <b>120</b> (FIG. 1) recording, as shown in block <b>1170</b>. VCR <b>120</b> records the audio soundtrack captured and transmitted by the wireless microphone <b>100</b> at block <b>1180</b> in a spread spectrum RF transmission stream. VCR <b>120</b> will simultaneously record the images captured by camera <b>150</b> (FIG. 1), thus creating an evidentiary record, including video and accompanying audio soundtrack, as shown in block <b>1190</b>. At block <b>1210</b>, the wireless microphone controller <b>300</b> transmits a confirmation to the wireless microphone <b>100</b> that the VCR is recording. The wireless microphone <b>100</b> displays the confirmation on the LCD display <b>220</b> (FIG. 2) and may sound an audible alert using audible alert generator <b>230</b> (FIG. 2) as an additional record confirmation.

P-0069[0069] If at decision block <b>1150</b>, a manual activation has not occurred, then other in-car video system activations are evaluated at decision block <b>1310</b>. For example, with in-car video systems that are configured to automatically activate when the vehicle's emergency systems are switched on, the officer may switch on the overhead lights <b>180</b> (FIG. 1) in vehicle <b>175</b> to initiate a traffic stop, or during an emergency situation or citizen encounter. VCR <b>120</b> will then record the images captured by camera <b>150</b> (FIG. 1). The VCR recording indicative signal is received on line <b>346</b> by wireless microphone controller <b>300</b> when the VCR begins recording as indicated in block <b>1320</b> in FIG. 10. At block <b>1330</b>, the wireless microphone controller <b>300</b> sends the RF activation signal to the wireless microphone <b>100</b> to automatically switch it from standby mode to “talk” mode where audio is captured by the microphone and then transmitted back to the wireless microphone controller <b>300</b> in a spread spectrum RF transmission stream, as shown in block <b>1350</b>. As with the manual activation described above, wireless microphone controller <b>300</b> transmits a VCR record confirmation to wireless microphone <b>100</b>.

P-0070[0070] At the end of the encounter, traffic stop or emergency condition, as shown in block <b>1220</b> the officer deactivates the in-car video system <b>110</b> using the “STOP” or “POWER” switches on the VCR control head <b>135</b>. Once the in-car video system <b>110</b> is deactivated by the VCR control head <b>135</b>, VCR <b>120</b> stops recording and the wireless microphone controller <b>300</b> sends an RF deactivation signal to wireless microphone <b>100</b> to switch it from “talk” mode to standby mode, as shown in block <b>1230</b>. It is noted that this illustrative embodiment of the invention is arranged to allow wireless microphone <b>100</b> deactivation solely via an affirmative press of the “STOP” or “POWER” switches on VCR control head <b>135</b>. Accordingly, and as described above in the text accompanying FIG. 2, the user-operable talk switch <b>235</b> (FIGS. 2 and 4) on wireless microphone <b>100</b> is used only to switch wireless microphone <b>100</b> to “talk” mode, but not from “talk” mode to standby mode. This arrangement advantageously ensures that the audio soundtrack is fully continuous with the video being recorded and no audio drop outs occur if the talk switch <b>235</b> on the wireless microphone is actuated (for example, by contact during some physical interaction between an officer and a suspect).

P-0071[0071] As shown in FIG. 10, the inventive method may repeat at block <b>1235</b> or the officer may power down the in-car video system <b>110</b> as shown in block <b>1265</b> when going out of service. The method ends at block <b>1280</b>.

P-0072[0072] Other features of the invention are contained in the claims that follow.