Abstract:
A method of enhancing the viewing of information in digital video format in a media device is provided. Digital video information is read from a memory and converted with a controller into a television signal. The television signal is low pass filtered with a filtering unit in a wireless communication unit of the media device. A wireless communication signal is generated with an oscillator in the wireless communication unit and the signal is divided in a divider with a predefined factor to obtain an RF frequency signal which is further multiplied with a multiplier in the wireless communication unit by the television signal, thus obtaining a multiplied television signal in an RF output connector in the wireless communication unit of the media device.

Description:
FIELD  
       [0001]     The invention relates to media devices configured to store information in video format, such as movies, and a method of enhancing the viewing of the movies.  
       BACKGROUND  
       [0002]     Modern terminal equipment offers users many services in addition to being conventional phones. The equipment can be used as a versatile media device for viewing multimedia presentations, multimedia messages, audio and video information, such as music and movies. The same also applies to personal computers and portable personal digital assistants (PDA). The memory capacity of these devices has increased and is expected to increase even more in the near future. Users may load various digital media to the devices and access the media later. For example, it will be possible to load movies in DVD (Digital Versatile Disk) format into the media devices for future viewing.  
         [0003]     One problem associated with these media devices is that the display of the devices is typically small. The small size is due to the portability of the devices. Typical terminal equipment and PDAs are intended to be handheld devices and their size is usually smaller than the size of a conventional shirt pocket. The small display makes viewing movies less enjoyable as users are used to view movies from a large TV screen. A typical diagonal size for a TV screen may be from 14″ to 60″ whereas the typical size of a media terminal is 3.5″.  
         [0004]     In many situations a user of a media device may be in a place where a television set is available. The user may be in a hotel room equipped with a television set, for example. It would be advantageous if the television set could be used for viewing movies stored in a media device. However, currently media devices do not have a coaxial television signal output. Media devices, such as terminal equipment, PDAs or laptop personal computers, are usually equipped with a short range wireless connection, such as Wireless Local Area Network (WLAN) connection, or a Low power radio frequency (LPRF) connections, such as Bluetooth. These connections offer short range radio based communications with relatively low power consumption. Designing a specific television output, such as a SCART connector output, for these media devices would increase the cost and the size of the devices.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0005]     An object of the invention is to provide an improved solution for enhancing viewing of information in digital video format. According to an aspect of the invention, there is provided a media device, comprising: a memory to store information in a digital video format; a controller operationally connected to the memory; a wireless communication unit operationally connected to the controller; the controller being configured to read digital video information from the memory, and convert the digital video information into a television signal; the wireless communication unit comprising a filtering unit to low pass filter the television signal; an oscillator to generate a wireless communication signal; a divider to divide the wireless communication signal with a predefined factor to obtain an RF frequency signal, a multiplier to multiply the television signal with the RF frequency signal; and an RF output connector to output the multiplied television signal.  
         [0006]     According to another aspect of the invention, there is provided a method of enhancing the viewing of information in digital video format in a media device, the method comprising: storing information in a digital video format in a memory; reading digital video information from the memory; converting the digital video information into a television signal with a controller; low pass filtering the television signal with a filtering unit in a wireless communication unit of the media device; generating a wireless communication signal with an oscillator in the wireless communication unit; dividing the wireless communication signal with a predefined factor with a divider in the wireless communication unit to obtain an RF frequency signal; multiplying the television signal with the RF frequency signal by a multiplier in the wireless communication unit, thus obtaining a multiplied television signal in an RF output connector in the wireless communication unit of the media device.  
         [0007]     The invention provides several advantages. In an embodiment of the invention, an existing wireless connection transceiver of the media device is utilized in realizing video output in television format. This enables the user of the device to watch movies stored in the media device using a nearby television set. The realization of the device of this embodiment does not increase the size of the device, as the number of new required components is small.  
         [0008]     In an embodiment of the invention, the television output is realized utilizing a WLAN transmitter unit of the media device. In another embodiment of the invention, the television output is realized utilizing a Bluetooth transmitter unit of the media device. In both of these embodiments, no extra radio frequency module is needed in the media device. By making small modifications to the WLAN or Bluetooth units and equipping the device with an additional connector it is possible to connect a television set to the media device and view movies stored in the device from the television, for example.  
         [0009]     The connection between the media device and a television may be realized with a coaxial antenna cable or with a wireless connection. 
     
    
     LIST OF DRAWINGS  
       [0010]     In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which  
         [0011]      FIGS. 1A  to  1 C illustrate embodiments of the invention;  
         [0012]      FIG. 2  illustrates an example of a media device;  
         [0013]      FIG. 3  illustrates an embodiment of the invention with a flowchart;  
         [0014]      FIG. 4  illustrates another example of a media device;  
         [0015]      FIG. 5  illustrates VSB modulation;  
         [0016]      FIGS. 6A and 6B  illustrate embodiments of transmitter sections of a transceiver unit,  
         [0017]      FIGS. 7 and 8  illustrate yet other embodiments of a transmitter section of a transceiver unit. 
     
    
     DESCRIPTION OF EMBODIMENTS  
       [0018]     With reference to  FIG. 1A , examine an example of a device of an embodiment of the invention. The media device  100  comprises a memory unit  102 , which is configured to store video in digital format. One such format may be MPEG4 format used in DVDs. The memory unit may be realized with a hard disk, memory chips, a card reader, an external USB (Universal Serial Bus) memory device or another corresponding device. The device further comprises a controller  104  configured to control the operation of the device. In an embodiment, the controller is configured to read video information from the memory unit and convert the information from MPEG4 format to a format suitable for an analog television. Formats supported by an analog television include PAL, NTSC and SECAM, for example. These formats and the required conversions are well known to one skilled in the art. The control processor forwards the converted signal to a wireless transceiver unit  106 , which is in this example a WLAN or a Bluetooth transceiver with a television transmitter. The control processor controls the wireless transceiver unit to process the converted signal further so that the signal is suitable for a television set. In the wireless transceiver unit  106 , the signal is filtered and modulated into a suitable television channel. The processed signal is taken to a coaxial connector  108 .  
         [0019]      FIG. 1B  illustrates an embodiment where the media device  100  is connected to a television set  110  with a coaxial cable  112 . The coaxial cable is connected to the coaxial connector  108  of the media device  100  and to an RF input  114  of the television set  110 . The television set  110  sees the media device  100  as a normal VCR (Video Cassette Recorder).  
         [0020]      FIG. 1C  illustrates an embodiment where an antenna  116  is connected to the coaxial connector  108  of the media device  100 . In this embodiment, the media device transmits the signal wirelessly into the antenna  118  of the television set  110 .  
         [0021]      FIG. 2  illustrates a more detailed example of the media device  100 . The media device  100  comprises a controller  104  configured to control the operation of the device. The controller is typically implemented with one or more general or signal processors and suitable software. The controller may also be implemented with discrete components such as ASICs (Application Specific Integrated Circuits), for example.  
         [0022]     The media device  100  may comprise a hardware interface  200  connected to the controller  104 . The hardware interface provides the media device with an interface to outside systems. The interface may be implemented with a USB port, Firewire port, USB memory reader or any other interface type suitable for transferring data between electronic devices.  
         [0023]     The media device  100  comprises a memory unit  102  which is configured to store video in digital formats. The suitable information source may be connected to the hardware interface  200  of the media device. The control processor may read information from the source and store it in the memory. As stated in connection with  FIG. 1 , the memory unit may be realized with a hard disk, one or more internal memory chips, a card reader such as a MultiMediaCard (MMC) reader, a USB (Universal Serial Bus) memory or another corresponding device.  
         [0024]     The media device  100  comprises a user interface  202  with which the user of the device interacts with the device. The user interface  202  may comprise different components. Typically, the user interface includes a display  204 , a keyboard  206 , a microphone  208  and a speaker  210 . The display  204  may be a color or a black and white display. The keyboard  206  may be a QWERTY keyboard as in personal computers, a phone type numeric keyboard, a separate keyboard or a keyboard integrated with the display as a touch sensitive display.  
         [0025]     The media device  100  may further comprise a cellular transceiver unit  212 . The unit may be a GSM or a WCDMA transceiver unit, for example. The cellular transceiver unit  212  enables the media device to act as a mobile phone.  
         [0026]     In addition, the media device  100  further comprises a short range wireless transceiver unit  106 . Examples of such units are Wireless Local Area Network (WLAN) transceiver or a low power radio frequency (LPRF) transceiver, such as a Bluetooth transceiver.  
         [0027]     With reference to FIGS.  2  to  5 , study an example of an embodiment of the invention.  FIG. 3  shows a flowchart illustrating an embodiment of the invention.  FIG. 4  illustrates an example of a section of the media device. The example of  FIG. 4  shows the memory  102 , the controller  104  and the transmitter section  106  of a WLAN 802.11b transceiver unit.  
         [0028]     In step  300 , a movie in an MPEG4 format is stored in the memory  102  of a media device. At a later stage, the user of a media device may wish to view the movie stored in the memory  102  of the user&#39;s media device and utilize an external television set as a display for the media device. After receiving a command from the user, the controller  104  of the media device starts reading the movie file from the memory in step  302 .  
         [0029]     In step  302 , the controller  100  converts the digital video information of the movie file into a television signal. In an analog PAL television system, the signal is modulated using vestigial sideband modulation (VSB).  FIG. 5  illustrates VSB modulation. The signal comprises the luminance component of the video signal  500 , color information  502  and audio  504  as a separate component. The coding of color information depends upon the system used. There exist three main methods, PAL, NTSC, SECAM (Phase Alternating Line, National Television Standards Committee, Sequentiel Couleur avec Mémoire). The conversion of a MPEG4 to a television signal can be performed according to the methods known to one skilled in the art. After the conversion two signals  400 ,  402  are at the output of the controller  104 . The signals are I- and Q-components of the television signal, if quadrature modulation is used in transmitter section  106 .  
         [0030]     In step  306 , the components are converted into an analogue form in converters  404 ,  406 .  
         [0031]     In step  308 , the analogue components are taken to the wireless transceiver unit  106  and to low pass filters  408 ,  410 . The low pass filters  408 ,  410  may be adjustable. The controller  104  provides a control signal  412  which selects the filter characteristics to be used. When the input signals  400 ,  402  of the wireless transceiver unit  106  are to be transmitted using the wireless system supported by the unit, such as WLAN, the control signal  412  directs the low pass filter to use a corner frequency which is suitable for a WLAN signal having a 22-MHz bandwidth. When the input signals  400 ,  402  of the wireless transceiver unit  106  are to be transmitted as a television signal using an RF connector, the control signal  412  directs the low pass filter to use a corner frequency suitable for a television signal having a 8 MHz bandwidth.  
         [0032]     When the input signals  400 ,  402  of the wireless transceiver unit  106  are to be transmitted using the wireless system supported by the unit, such as WLAN, the filtered signals are taken into a mixer  412 , where the signals are mixed into a suitable WLAN frequency. In WLAN, the center frequencies are between 2412 to 2472 MHz with step of 5 MHz.  
         [0033]     In an embodiment, the media device comprises an RF circuit  414  generating a reference frequency of 1 MHz. The reference frequency is taken into a phase locked loop  416 , which controls a voltage controlled oscillator  418 . In an embodiment, the tuning range of the oscillator is from 2412 to 2472 MHz. In another embodiment, the tuning range of the oscillator is from 2365 to 2493 MHz. The tuning is controlled on the basis of the desired WLAN frequency. The WLAN output signal of the oscillator  418  is taken to the mixer  412 . The output signal of the mixer  412  is taken to a wireless output  426 , where the signal is transmitted.  
         [0034]     In step  310 , the filtered signals are taken into a mixer  420  where the signals are mixed into an RF frequency suitable for television. Table 1 illustrates an example of the relationship between TV channels and carrier center frequencies.  
                                     TABLE 1                       Channel Number   MHz   *4                                36   591.25   2365       37   599.25   2397       38   607.25   2429       39   615.25   2461       40   623.25   2493                  
 
         [0035]     The filtered signals are mixed in the mixer  420  with a signal originating from the oscillator  418 . The output signal of the oscillator  418  is first supplied to a divider  422  where signal is divided by four. The result of the division is supplied to the mixer  420 .  
         [0036]     In Table 1, the first column shows TV channels numbers and the second column the corresponding frequencies. The third column shows the frequency value when the TV channel frequency is multiplied by four.  
         [0037]     Thus, in the embodiment where the tuning range of the oscillator is from 2412 to 2472 MHz, TV channels  38  and  39  can be obtained.  
         [0038]     In another embodiment where the tuning range of the oscillator is from 2365 to 2493, TV channels  36  to  40  can be obtained.  
         [0039]     In an embodiment, the media device comprises an RF circuit  414  generating a reference frequency of 5 MHz. In such a case TV channel  37  can be obtained in mixer  420 .  
         [0040]     In step  312 , the mixed TV signal is taken to an RF connector  424 . The signal may be delivered to a television set using a coaxial cable connected to the RF connector.  
         [0041]     The media device may also comprise other components, such as switches, filters and amplifiers, as one skilled in the art is aware.  
         [0042]      FIG. 6A  illustrates an embodiment where the wireless transceiver unit  106  comprises low pass filters  600 ,  602  to the I and Q components of WLAN signals  604 ,  606  and low pass filters  608 ,  610  to the I and Q components  612 ,  614  of television signals. Thus, the low pass filters do not need to be adjustable. Otherwise, the embodiment is similar to the embodiment of  FIG. 4 .  
         [0043]      FIG. 6B  illustrates an embodiment where television signal is not divided into I and Q components. Thus, the wireless transceiver unit  106  comprises a low pass filter  618  for the television signal  616 . From the filter  618 , the filtered signal is taken to mixer  620 , where the signal is mixed as in the previous examples.  
         [0044]      FIG. 6A  may also be used to illustrate an embodiment where wireless transceiver unit  106  supports Bluetooth transmission. In this embodiment, the signals  604 ,  606  coming from the controller  104  are Bluetooth signals. The low pass filters  600 ,  602  have a corner frequency which is suitable for a Bluetooth signal having a 1-MHz bandwidth. Otherwise, the operation of the embodiment is similar to the above examples.  
         [0045]      FIG. 7  illustrates an embodiment where intermediate frequency (IF) is utilized. Only the transmitter section of the wireless transceiver unit is shown. This embodiment provides better overall filtering with the cost of a slightly more complicated design.  
         [0046]     The input signals  700 ,  702  to the wireless transceiver unit  106  are the digitized I and Q components from the controller  104 . The components are taken to low pass filters  408 ,  410 . The low pass filters  408 ,  410  may be adjustable. The controller  104  provides a control signal  412  which selects the filter characteristics to be used. When the input signals  400 ,  402  of the wireless transceiver unit  106  are to be transmitted using WLAN, the control signal  412  directs the low pass filter to use a corner frequency which is suitable for a WLAN signal. When the input signals  700 ,  702  of the wireless transceiver unit  106  are to be transmitted as a television signal using RF connector, the control signal  412  directs the low pass filter to use a corner frequency suitable for a television signal.  
         [0047]     When the input signals  700 ,  702  of the wireless transceiver unit  106  are to be transmitted using WLAN, the filtered signals are taken into a mixer  412  where the signals are mixed into a suitable WLAN frequency.  
         [0048]     The media device comprises an RF circuit  704  generating a reference frequency of 0.2 MHz. The reference frequency is taken into a phase locked loop  706 , which controls a voltage controlled oscillator  708 . In this embodiment, the tuning range of the oscillator is from 2211.4 to 2472 MHz. The tuning is controlled on the basis of the desired WLAN frequency. The output signal of the oscillator  708  is taken to the mixer  412 . The output signal of the mixer  412  is taken to a wireless output  426 , where the signal is transmitted.  
         [0049]     When the input signals  700 ,  702  of the wireless transceiver unit  106  are TV signals the signals are taken into a mixer  710  where the signals are mixed into an RF frequency suitable for television. The filtered signals are mixed in the mixer  710  with an IF signal, which is a sinusoidal local injection signal  712 . IF frequency is selected so that it matches the used VCO tuning range The output signal of the mixer  710  is filtered in the IF filter  714 . The filtered signal is taken further to a mixer  716 , where the signal is mixed with a signal obtained from the oscillator  708  via the divider  718  where the oscillator output signal is divided by four.  
         [0050]     The output signal of the mixer  716  is taken to an RF filter  720  and to the RF connector  424 . In this embodiment, TV channels  36  to  40  can be obtained.  
         [0051]      FIG. 8  illustrates an embodiment where transmitter section  106  of a WLAN 802.11a transceiver unit is utilized. In the embodiment of  FIG. 4 , a WLAN 802.11b was utilized. The frequency area of 802.11a is 5.150 to 5.727 GHz. In WLAN 802.11b, the frequency is about half of 802.11a, or 2.400 to 2.483 GHz. Thus, in the example of  FIG. 8 , the output signal of the oscillator  418  is about twice the frequency of  FIG. 4 . The output signal of the oscillator  418  is taken to a divider  800 , which divides the oscillator signal by eight instead of four as in  FIG. 4 . Thus the television signal can be mixed to correct frequencies. In this embodiment, TV channels that can be obtained are related to the selected VCO tuning range. The channels, which are directly supported with 802.11 a European frequency band, are TV channel numbers from 43 to 51.  
         [0052]     The above described embodiments analog television transmission. However, the invention can be used also in connection with digital television transmission.  FIGS. 3 and 4  may also be used to illustrate en embodiment where digital television transmission is utilized. The  FIGS. 3 and 4  have been described above and the description applies also in this embodiment with the exception of step  304  of  FIG. 3 , where the incoming video format is converted to a corresponding digital television format, which is defined in the selected digital television standard. The conversion is performed in the controller  104  of  FIG. 4 . In the DVB-T standard, the video signal is packed with a MPEG4 coding. The actual analog television transmission of the DVB (Digital Video Broadcast) signal is based on OFDMA modulation. There are several methods defined in DVB standards that support terrestrial transmission standard T, cable television transmission standard C, satellite television standard S and handheld device standard H. The OFDMA modulation is multicarrier modulation, where one television channel is constructed with several subcarriers. The required OFDMA modulation is performed in step  304 . The method to generate OFDMA modulation is known to one skilled in the art.  
         [0053]     Even though the invention is described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but it can be modified in several ways within the scope of the appended claims.