Abstract:
One example discloses a data processing device, comprising: a local oscillator (LO) having an LO frequency output, an LO performance parameter output, and an LO frequency select input; and a degradation detection module, coupled to the LO performance parameter output and to the LO frequency select input, and including an LO frequency select module triggered by the LO performance parameter output. Another example discloses an article of manufacture comprises at least one non-transitory, tangible machine readable storage medium containing executable machine instructions for controlling a data processing device which comprise: monitoring a set of local oscillator (LO) performance parameters; setting an LO degraded state when at least one of the LO performance parameters is not within a predetermined range; and adjusting an LO frequency in response to the LO degraded state.

Description:
Aspects of various example embodiments are directed to systems, methods, apparatuses, devices, articles of manufacture and computer readable mediums involving communication systems. 
     Wireless communication systems in cars can have many embodiments and uses including: car broadcast radios used for infotainment; cellular communication systems; handheld communication units; WLAN; Bluetooth; CAR2CAR; and CAR2X. 
     Certain example communication systems have a dedicated frequency band resulting in electromagnetic fields generated in and around the car. These fields have different strengths and different frequencies depending on the generating equipment. Broadcast radios are connected with a coaxial cable to at least one antenna but may be connected to more than one. These antennas convert the electromagnetic field from different broadcast stations into an electrical signal. In one example, the distance between the car and the broadcast stations can be relative large, perhaps on the order of many kilometers; however, the distance between the car communication antenna and one or more car broadcast antennas can be small, perhaps on the order of a few meters, and the communication systems may generate strong interference towards the broadcast receiver. 
     For example, a car shark fin antenna module may contain cellular communication functionality combined with active broadcast antenna functionality. The communication antennas are positioned in the shark fin together with active circuitry of the broadcast active antenna. More advanced shark fins may also contain the car2car communication antennas and electronics like the transceiver functionality. In one example, the shark fin antenna module includes a multiband antenna for the different cellular bands: GSM 900, GSM 1800 and UMTS; and a separate antenna for car2X communication operating at the 5.9 GHz band, together with a whip antenna for the reception of AM, FM and DAB broadcast. 
     Strong electromagnetic fields from the communication systems in the shark fin or in the car at other frequencies than the broadcast reception frequencies can degrade the performance of various receivers connected to such an antenna module. 
     One example of a communication system is a heterodyne broadcast radio receiver system. Such a system may include an antenna for receiving a first range of radio frequencies (RF), a band selector (BS), having a band pass filter covering a predetermined broadcast band (e.g. an FM band from 87.5 MHz to 108 MHz), a low noise amplifier (LNA), a mixer, a local oscillator and an intermediate frequency (IF) band pass filter. The IF filter includes suitable bandwidth for selecting various broadcast stations, and in one example may be about 250 KHz wide. 
     During one example of the radio receiver&#39;s operation, an FM radio station transmits a first program at a certain channel frequency, for example at 97 MHz in the FM frequency band. Another radio station transmits a second program at another RF frequency, for example at 98 MHz, wherein both the first and second programs have a bandwidth of 220 KHz. To be able to select between the two programs the radio receiver uses an IF selectivity function, perhaps having an output bandwidth of 250 KHz, which is sufficient to include each program&#39;s 220 KHz bandwidth. 
     If the IF selectivity function is implemented at the RF frequency, the band selector (BS) components having a very high quality factors are required. However, if the RF broadcast frequency is down-converted to a lower intermediate frequency (IF), such as 10.7 MHz, lower quality factor components may be used. 
     To convert the broadcast transmitter RF frequency to the IF frequency a mixer can be used together with a local RF oscillator signal generated within the receiver. By varying the local RF oscillator frequency, the receiver can convert (i.e. tune) a range of RF broadcast frequencies to the same (or nearly the same) IF frequency. 
     For example, to convert a 97 MHz broadcast RF frequency to a 10.7 MHz intermediate frequency, the local oscillator frequency can be set at either 107.7 MHz or 86.3 MHz, according to Equations 1 and 2.
 
 F   intermediate   =|F   broadcast   −F   oscillator |  (Equation 1)
 
 F   intermediate   =|F   oscillator   −F   broadcast |  (Equation 2)
 
     According to an example embodiment, a data processing device, includes: a local oscillator (LO) having an LO frequency output, an LO performance parameter output, and an LO frequency select input; and a degradation detection module, coupled to the LO performance parameter output and to the LO frequency select input, and including an LO frequency select module triggered by the LO performance parameter output. 
     According to another example embodiment, an article of manufacture comprises at least one non-transitory, tangible machine readable storage medium containing executable machine instructions for controlling a data processing device which comprise: monitoring a set of local oscillator (LO) performance parameters; setting an LO degraded state when at least one of the LO performance parameters is not within a predetermined range; and adjusting an LO frequency in response to the LO degraded state. 
     The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future Claim sets. The Figures and Detailed Description that follow also exemplify various example embodiments. 
     Various example embodiments may be more completely understood in consideration of the following Detailed Description in connection with the accompanying Drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an example frequency graph of a set interference signals and corresponding local oscillator degradation. 
         FIG. 2  is an example data processing device. 
         FIG. 3  is an example local oscillator and degradation detection module within the data processing device. 
         FIGS. 4A and 4B  are examples of a high frequency band received by the data processing device. 
         FIG. 5  is an example first set of down-converted channels. 
         FIG. 6  is an example second set of down-converted channels. 
         FIG. 7  is an example set of instructions for operating a data processing device. 
         FIG. 8  is another example of a data processing device. 
     
    
    
     While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that other embodiments, beyond the particular embodiments described, are possible as well. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are covered as well. 
     DETAILED DESCRIPTION 
     Local oscillator systems in various devices and at various frequencies can be degraded by interfering signals that have some sort of a frequency relation with the local oscillator signal (e.g. remote or local signals, in-band or signals, signals generated from a common power supply, etc.). One example of degradation is spurious modulation of a local oscillator&#39;s output signal, causing spurious amplitude variations and/or frequency variations. 
     For example, a cellular system and an FM broadcast radio antenna are often in close proximity within a car. When the cellular communications system, operating according GSM900, would transmit at a frequency of 851.35 MHz, a very strong field in and near the car&#39;s FM broadcast radio antenna is generated. Such a field strength can be on the order of 30 Volts/meters or even higher. Such a strong electromagnetic field may influence the FM broadcast radio reception quality. 
     In one example a broadcast radio signal is decoupled from an interference signal which is somehow related to the local oscillator frequency by: monitoring a set of local oscillator performance parameters; comparing the performance parameters to a calibrated set of performance parameters; and changing the local oscillator frequency in a step-wise manner which still permits a desired channel (e.g. a broadcast radio station) to be processed by other devices and/or presented to a user; 
     Such an embodiment can reduce or practically eliminate electromagnetic and/or direct electrical coupling between an interference signal and the local oscillator, and will likely not introduce audible distortions when combined with an audio concealment algorithm. Such embodiments can be embedded in a car broadcast radio, another kind of receiver, transmitter or transceiver. 
       FIG. 1  is an example frequency graph of a set interference signals  102  and corresponding local oscillator degradation  104 . The measurement shows the results of radio performance degradation due to a strong interference signal. Such audio degradation is in some examples due to interference with a communications device&#39;s local oscillator frequency when there is a harmonic relation between the interfering signal&#39;s frequency and the local oscillator&#39;s frequency. In this example, the broadcast radio&#39;s local oscillator frequency is at 94.6 MHz and if a GSM cellular device would be transmitting at 851.35 MHz, this would equal the 9 th  harmonic of the radio&#39;s local oscillator frequency. 
       FIG. 2  is an example data processing device  200 . The data processing device  200  includes a high frequency stage  202 , a high frequency band input  204 , a high frequency band output  206 , a local oscillator (LO)  208 , an LO frequency output  210 , an LO performance parameter output  212 , an LO frequency select input  214 , a mixer  216 , a degradation detection module  218 , a low frequency stage  220 , a low frequency band input  222 , and a channel output  224 . 
     The data processing device  200  in various example embodiments can be either: a receiver, a transmitter, a transceiver; a radio; a communications device; a phone; a cellular device; a WLAN device; a Bluetooth device; a CAR2CAR device; or a CAR2X device. Other embodiments of the data processing device  200  are also possible. 
     The high frequency stage  202  receives a data channel at a high frequency from the high frequency band input  204 . In one example, the data channel at the high frequency is within an FM radio band, and the data channel includes a set of data channels (e.g. multiple broadcast stations). The high frequency band input  204  is herein defined as the interface between the received high frequency data channel and an antenna  230 . 
     The high frequency stage  202  may also include various RF band select (BS) filters and a low noise amplifier (LNA) as shown in  FIG. 2 . In one example, at least one of the RF band select filters has a center frequency of 98 MHz and a bandwidth (i.e. 21 MHz) covering the complete FM band, from 87 MHz to 108 MHz, and shown and later discussed in  FIGS. 4A and 4B . 
     The mixer  216  receives the high frequency data channel from the high frequency stage  202  and the LO frequency output  210  from the LO  208 . Using the LO  208  output frequency, the mixer  216  coverts the high frequency data channels to a set of low frequency data channels and presents them to the low frequency band input  222  of the low frequency stage  220 . In one example, high RF frequency data channels are converted to low intermediate frequency (IF) data channels (e.g. +/−0 Hz), such as when the data processing device  200  is a data receiver. Note that in other example embodiments, the data processing device  200  can be a transmitter or transceiver function. 
     The low frequency stage  220  includes an IF band-pass filter  226 , a channel select filter  228  and an ADC. Any selected data channel from the set of high frequency data channels must, in one example, be within the IF band-pass filter  226  pass-band so as to be later presented at the low frequency stage  220  output  224  for later processing. For example, a 3 MHz wide IF band-pass filter  226  is wide enough to select multiple broadcast stations within an FM band.  FIGS. 5 and 6  show such an example IF pass-band, and are discussed below. 
     The degradation detection module  218  receives a set of performance parameters from the LO  208  over the LO performance parameter output, and upon detection of a degraded LO condition (i.e. the device  200  is in an LO degraded state), sends a command over the LO frequency select input  214  to change the LO  208  frequency. The LO degraded state is entered when one or more signals on the LO performance parameter output is not within a predetermined range. 
     The degradation detection module  218  ensures that any selected high frequency data channel from the high frequency stage  202  are still confined (e.g. still fall within) the IF band-pass filter&#39;s  226  pass-band, and thus can be further processed by the low frequency stage  220  and any subsequent circuitry. If a particular change in the LO  208  frequency would cause one or more of the selected high frequency data channels to fall outside of the IF band-pass filter&#39;s  226  pass-band, the degradation detection module  218  will select a different LO  208  frequency. Example routines for detecting and remediating LO  208  signal degradation are discussed in  FIG. 3 . 
     Once the LO  208  is not degraded, additional processing may include digitizing a set of the high frequency data channels with an analogue to digital converter (ADC) and selecting one of the channels using a narrower bandwidth channel select filter  228 . For example, if the high frequency data channels include 12 FM band radio stations, the degradation detection module  218  can select just one of the FM band radio stations, using the narrower bandwidth channel select filter  228 , for further base-band processing and presentation to a user. 
       FIG. 3  is an example local oscillator  208  and degradation detection module  218  within the data processing device  200 . In this example the degradation detection module  218  includes a frequency lock detect (LD) module  302 , an amplitude detect (AD) module  304 , an LO frequency select module  306 , and a digital channel select module  308 . 
     The LO  208  includes a reference frequency (XTAL)  310 , a phase detector  312  low-pass filter  314 , a voltage controlled oscillator (VCO)  316 , a divider  318 , and a buffer amplifier  320 . 
     The local oscillator output frequency  210  is stabilized in a feedback system that consists of comparing the reference frequency  310  with the divided  318  frequency of the VCO  316 . The local oscillator&#39;s  208  VCO  316  signal is also buffered and amplified  320  and then presented at the output  210  which is sent to the mixer  216 . 
     Whenever at least one of the LO performance parameter output  212  signals are not within their predetermined range, an LO  208  degraded state is indicated and the degradation detection module  218  commands the LO frequency select module  306  to tune the LO  208  to a new LO frequency. Some specific example routines for detecting and remediating LO  208  signal degradation are now discussed. 
     In a first example, the frequency lock detect (LD) module  302 , in the degradation detection module  218 , monitors the LO frequency monitoring signal  322 , on the LO performance parameter output  212 , and sets the LO unlocked state when a frequency on the LO frequency output  210  is not locked to a frequency from the LO frequency reference  310  circuit. 
     In a second example, the amplitude detect (AD) module  304 , in the degradation detection module  218 , monitors the LO amplitude monitoring signal  324 , on the LO performance parameter output  212 , and sets an LO amplitude invalid state when an amplitude on the LO amplitude monitoring output  324  is not within a predetermined range. 
     Since there is often some small intrinsic amplitude modulation that is generated by imperfections within the local oscillator  208 , the LO degraded state is not set by the degradation detection module  218  until the amplitude variation exceeds a predetermined threshold. In one example, the threshold level is programmable and can be set for example 10% above the LO&#39;s  208  intrinsic amplitude modulation. The threshold level can be set during testing and tuning to maximize reliable operation of the data processing device  200  (e.g. a radio broadcast receiver). In a certain example embodiments the threshold can be set based on a known isolation level between multiple antennas packaged together in a same antenna unit. The isolation between the antennas can be used to define the interference power. An external interference source strength/power exceeding the isolation level then defines an unacceptable degradation which sets the LO degraded state and triggers the degradation detection module  218  to change the LO  208  frequency. 
     In response to such LO performance parameter out of tolerance conditions, the degradation detection module  218  then commands the LO frequency select module  306  to send a new frequency select signal to the LO frequency select input  214  of the LO  208 . The LO frequency select input  214  is connected to the divider  318  and thus can adjust the VCO  316  frequency sent to the phase detector  312 , which in turn alters the output frequency of the VCO  316  presented on the LO output  210 . 
     The LO  208  frequency can be adjusted in a variety of ways. For example, by adjusting (e.g. increasing, decreasing, stepping, jumping to a pre-set, etc.) the local oscillator  208  frequency until the LO degradation is below a predetermined threshold. Then verifying that all selected high frequency data channels are still within the IF band-pass filter&#39;s  226  pass-band. If not, then iterating the adjusting and verifying until all of the selected high frequency data channels are within the IF band-pass filter&#39;s  226  pass-band. 
     In another example, F_local_oscillator is the current oscillator frequency that is degraded. Then setting F_local_oscillator_new=F_local_oscillator+STEP, where STEP=minimal possible frequency step, usually 1 channel, for example 250 KHz for an FM band radio station channel. If |F_local_oscillator_new−F_broadcast|&gt;IF pass band, then F_local_oscillator_new=F_local_oscillator−2×STEP. This last step occurs if up-converting the selected channel by one STEP would place is outside of the IF selection filter band, thereby requiring that the selected channel be down-converted by at least two steps, thereby placing the LO frequency at least one STEP below its original frequency. 
       FIGS. 4A and 4B  are an example set of high frequency channels  402  received by the data processing device  200 . The set of high frequency channels  402 , in this example, represent twelve FM band radio station channels having frequencies ranging from 97 MHz to 100 MHz, and labeled as channels A through L. Channel E is highlighted to indicate that channel E has been selected for further processing by the low frequency stage  220  and any subsequent base-band circuits. 
       FIG. 5  is an example first set of down-converted channels  502 . The first set of down-converted channels  502  represent the set of high frequency channels  402  which have been down-converted by the mixer  216  to within a 3 MHz bandwidth of the band-pass filter  226  in the low frequency stage  220 . Channel E originally had an RF frequency of 98 MHz which after mixing with a 96 MHz LO  208  frequency is converted to an intermediate frequency of 2 MHz. 
       FIG. 6  is an example second set of down-converted channels  602 . The second set of down-converted channels  602  is generated if the degradation detection module  218  determines that the LO  208  at 96 MHz is degraded. In response to the detected degradation, the degradation detection module  218  commands the LO  208  to change the LO frequency to 94.5 MHz. 
     Such a lower LO  208  frequency converts one spectral lobe of Channel E to a higher intermediate frequency of 3.5 MHz (i.e. 98 MHz-94.5 MHz=3.5 MHz). In this example, 94.5 MHz is the lowest LO  208  frequency allowable if Channel E has been selected, since a lower LO  208  frequency would place Channel E outside of the band-pass filter&#39;s  226  pass-band. 
     In other example embodiments, Channel E can be mixed with frequencies within the range of 94.5 MHz to 97.5 MHz, just as long as Channel E is converted to a frequency which still falls within the band-pass filter&#39;s  226  pass-band. 
     Note that the second set of down-converted channels  602  includes a second set of twelve RF channel frequencies ranging from 95.25 MHz to 98.25 MHz, and labeled as channels T through E This second set of twelve RF channel frequencies includes channels A through E from the first set of down-converted channels  502 , and channels T through Z of the second set of RF channel frequencies down-converted to the intermediate frequencies and filtered. 
       FIG. 7  is an example set of instructions for operating a data processing device  200 . 
     The instructions  700  begin in block  702 , by monitoring a set of local oscillator (LO) performance parameters. In block  704 , setting an LO degraded state when at least one of the LO performance parameters is not within a predetermined range. Then in block  706  adjusting an LO frequency in response to the LO degraded state. 
     The instructions can be augmented with one or more of the following additional instructions blocks, presented in no particular order. 
     In block  708 , wherein monitoring includes monitoring an LO frequency; and wherein setting includes setting an LO frequency unlocked state when the LO frequency is not locked to an LO reference frequency. 
     In block  710 , wherein monitoring includes monitoring an LO amplitude; and wherein setting includes setting an LO amplitude invalid state when the LO amplitude is not within a predetermined range. 
     In block  712 , wherein adjusting includes at least one of: increasing, decreasing, stepping, and jumping to a pre-set frequency. 
     In block  714 , wherein the LO degraded state is set in response to at least one of: an interference signal external to the data processing device; an interference signal internal to the data processing device; a power supply signal; a broadcast radio signal; or a cellular phone signal. 
     In block  716 , further including, receiving a set of high frequency data channels; receiving specific data channel selection from the set of channels; down-converting the high frequency data channels to intermediate frequencies (IF); filtering the intermediate frequency data channels to within an IF pass-band; and wherein adjusting includes, adjusting the local oscillator frequency until at least one of the LO performance parameters is within the predetermined range; checking if the specific data channel is within the IF pass-band; and repeating the adjusting and checking until the specific data channel is within the IF pass-band. 
     These instructions have been presented in one example order of execution, however, other orderings, such as discussed with respect to  FIGS. 2-6 , are also possible. Also, those skilled in the art will recognize that while one example set of instructions/method has been discussed, the material in this specification can be combined in a variety of ways to yield other examples as well, and are to be understood within a context provided by this detailed description. 
       FIG. 8  is another example  800  of a data processing device. The diagram  800  shows an input/output data  802  interface with an electronic apparatus  804 . The electronic apparatus  804  includes a processor  806 , a storage device  808 , and a machine-readable storage medium  810 . The machine-readable storage medium  810  includes instructions  812  which control how the processor  806  receives input data  802  and transforms the input data into output data  802 , using data within the storage device  808 . Example instructions  812  stored in the machine-readable storage medium  810  are discussed elsewhere in this specification. The machine-readable storage medium in an alternate example embodiment is a computer-readable storage medium. 
     The processor (such as a central processing unit, CPU, microprocessor, application-specific integrated circuit (ASIC), etc.) controls the overall operation of the storage device (such as random access memory (RAM) for temporary data storage, read only memory (ROM) for permanent data storage, firmware, flash memory, external and internal hard-disk drives, and the like). The processor device communicates with the storage device and non-transient machine-readable storage medium using a bus and performs operations and tasks that implement one or more blocks stored in the machine-readable storage medium. The machine-readable storage medium in an alternate example embodiment is a computer-readable storage medium. 
     Example embodiments of the material discussed in this specification can be implemented in whole or in part through network, computer, or data based devices and/or services. These may include cloud, internet, intranet, mobile, desktop, processor, look-up table, microcontroller, consumer equipment, infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided. 
     In this specification, example embodiments have been presented in terms of a selected set of details. However, a person of ordinary skill in the art would understand that many other example embodiments may be practiced which include a different selected set of these details. It is intended that the following claims cover all possible example embodiments.