MXPA97005650A - Remote system of audience survey and method for im - Google Patents

Abstract

The present invention relates to an antenna (26) projects a detection zone (28) through a path. A scan receiver (32) is coupled to a computer (34). The receiver searches for a local FM oscillator (LO) signal (22) that can be emitted from within the detection zone. If a LO signal is detected, other LO signals that can be detected in the receiver are ignored until the signal is no longer detectable (90-106). The LO signals detected are ignored if they are detected for less than a minimum duration (100) or if they are detected for more than one maximum duration. The second of two LO signals detected consecutively is ignored if it occurs within a minimum duration from the LO signal previously detected and exhibits the same frequency as the LO signal previously detected

Description

REMOTE HEARING SURVEY SYSTEM AND METHOD FOR THE SAME Technical Field The present invention relates generally to radio frequency (RF) communications. More specifically, the present invention relates to the precise identification from a remote location of the broadcasting stations to which the tuners, used by radios, televisions and the like, are tuned. Background Technique The industry of commercial broadcasting and the businesses that advertise through RF broadcasting media need to know the sizes of audiences that are tuned to particular stations at particular times. This need has been met mainly through the use of audience participation surveys. In other words, individuals are solicited, either directly or indirectly by means of equipment coupled to their tuners, that identify the particular stations to which they can be tuned. The collection of survey data through audience participation has many problems. For example, the accuracy of this data is questionable. People often feel uncomfortable about reliably identifying the broadcast programming they may be experiencing at that time. With respect to the radio, most of the listening occurs in automobiles. However, listeners can not track, in a practical, precise or otherwise, manner about listening trends while driving. As a result, survey data related to car listening are particularly suspect, because they are compiled from memories after the fact occurs. Furthermore, people who agree to participate in such surveys may have different listening tendencies than others, and this factor may polarize the data. The cost represents another problem associated with the collection of data through audience participation surveys. Often, expensive equipment is provided to survey participants to automatically record listening trends. It can improve accuracy, but there is great pressure to keep sample sizes small to minimize the tremendous costs involved. The smaller sample sizes lead to less accurate survey data. Moreover, the use of equipment coupled to the tuner is a totally impractical alternative to survey the radio audience in automobiles due to the installation costs and the reluctance of the audience to allow the unnecessary manipulation of their cars. Furthermore, money is often given to survey participants to compensate them for the inconveniences. Consequently, survey data obtained through audience participation in the collection of survey data lead to costly data of questionable validity. Over the years, attempts have been made to use passive, electronic RF monitoring equipment to remotely identify the stations to which the tuners can be tuned. In general terms, the tuners of the audience use local oscillator signals that are related to the frequencies of the respective stations that are currently tuned. These local oscillator signals are broadcast or otherwise emitted from the tuners as extremely weak signals that can be detected by sensitive monitoring equipment. This remote monitoring technique is desirable because it does not require the cooperation of an audience, and a variety of inaccuracies and costs associated with audience participation are reduced or eliminated. Large sample sizes can be monitored at low cost in relation to audience participation techniques. However, the methodologies and systems of the prior art used to implement the remote monitoring technique have proven to be unsuccessful. The inability of remote monitoring systems of the prior art may be due to, at least in part, to excessive heat in the record of large sample sizes. In general, large sample sizes are desirable because they lead to greater precision. However, when the larger sample sizes include corrupted or otherwise unfairly complicated data, the result can easily be a less accurate survey. Conventional radio remote monitoring systems have failed to adequately address many different situations that lead to corrupt or distorted survey data. For example, when multiple tuners are located close to each other, they may be indistinguishable from each other by the monitoring equipment when tuned to the same station. This distorts the survey data in favor of less popular stations. Moreover, there are no standards about the minimum local oscillator signal strength or frequency accuracy. Conventional monitoring equipment may fail to register some stations due to a weak local oscillator signal on a particular tuner and may count a different station on a different tuner multiple times. In addition, background noise can cause some local oscillator signals at certain frequencies to be more easily detectable than at other frequencies, and this noise can distort ratings in favor of some stations at the expense of other stations. Furthermore, the accuracy of survey data obtained from conventional equipment depends on the skill and concentration of human operators. This human factor still infuses another inaccuracy in the survey data. SUMMARY OF THE INVENTION Accordingly, it is an advantage of the present invention to provide an improved system and method for determining the stations to which the tuners can be tuned. Another advantage of the present invention is that audience survey data is collected without requiring the participation of the audience. Another advantage is that the present invention collects audience survey data without requiring a human operator. Another advantage is that the present invention remotely monitors large sample populations at low cost. Another advantage is that the present invention improves the accuracy of the audience survey data. Another advantage is that the present invention improves the accuracy conventionally obtainable from audience survey data. Another advantage is that the present invention provides a system and a methodology that assign higher priority to obtaining accurate survey data than in obtaining large survey samples. Another advantage is that the present invention automatically ignores detectable and detected data that may otherwise be included in a survey to refrain from introducing unfair polarization into the survey data. The above and other advantages of the present invention are carried out in a form by a remote audience survey method. The method identifies the stations to which the tuners are tuned. The tuners have local oscillator signals emitted from them. The method provides for establishing a detection zone so that the local oscillator signals emitted from the tuners located in this area are detectable by an antenna of a receiver. One of the local oscillator signals is detected in the receiver. Data describing said local oscillator signal is obtained. The data describing other of the local oscillator signals present in the detection zone is ignored while a local oscillator signal is detected in the receiver.

A more complete understanding of the present invention can be derived by reference to the detailed description and the claims, when considered in relation to the drawings, where similar reference numbers refer to like elements in all the drawings, and: Figure 1 shows a layout diagram of an exemplary environment within which a preferred embodiment of the present invention can operate; Figure 2 shows a block diagram of a remote audience survey system; Figure 3 shows a graph that relates desired signals with noise in a frequency range of interest to the remote audience survey system shown in Figure 2; Figure 4 shows a flow diagram of a process carried out by scanning the receiving portion of the remote audience survey system shown in Figure 2; Figure 5 shows a flow chart of a data recording process carried out by a data record computer portion of the remote audience survey system shown in Figure 2; Figure 6 shows a tuning table that is maintained in a memory structure within the data record computer portion of the remote audience survey system shown in Figure 2; Figure 7 shows an exemplary format of a data record recorded by the data record computer portion of the remote audience survey system shown in Figure 2; Figure 8 shows a flow diagram of a complication cutting process carried out by a complication computer portion of the remote audience survey system shown in Figure 2; Figure 9 shows a flowchart of a compilation process carried out by a compilation computer portion of the remote audience survey system shown in Figure 2; Figure 10 shows a block diagram of a spreadsheet arrangement produced by the compilation computer portion of the remote audience survey system shown in Figure 2. Best Modes for Bringing the Invention to Practice Figure 1 shows a layout diagram of an exemplary environment within which preferred embodiments of the present invention may operate. Figure 1 shows a path 10 in which any number of radio-equipped vehicles 12, such as automobiles, trucks, motorcycles and the like, can travel in any of two directions. The path 10 has an intersection portion 14 and a non-intersection portion 16. The intersection portion 14 resides near an intersection 18 and represents a portion of the path 10 where the vehicles 12 are often stopped, take longer periods of time, and they accumulate or reside close to each other. In the non-intersecting portion 16, the vehicles 12 tend to move and spread among themselves, as compared to the intersecting portion 14. Many of the vehicles 12 include a radio or tuner 20 for receiving commercially transmitted radio signals or other signals, such as conventional signals of AM, FM, television and the like. The presently preferred embodiment of the present invention identifies the FM radio stations to which some of the radios 20 can be tuned. Although this presently preferred embodiment of the present invention is limited to FM stations, the technicians in the It will be appreciated that many aspects of the present invention can be applied successfully to the identification of AM or television stations as well, either alone or in combination with the detection of FM stations. The radios 20 detect broadcasting stations through a well-known demodulation process, which requires the radios 20 to generate local oscillator (LO) signals 22 having frequencies close to the frequencies of the broadcast signals. For FM broadcasting stations, a signal LO 22 oscillates at a frequency of about 10.7 megaHertz over the frequency of the broadcast signal to which a radio 20 is currently tuned. In this way, the frequency of a broadcast signal to which a radio 20 is tuned can be identified by detecting the presence of the signal LO 22 of the tuner and identifying the frequency of the signal LO 22 of the tuner. The signal LO 22 is an extremely weak signal that is emitted from the radio 20 mainly by an antenna 24 of the vehicle. The antenna of the vehicle 24 is coupled to the radio 20 and is intended primarily to receive the broadcast stations. The intensity of the signal LO 22 can vary considerably from vehicle 12 to vehicle 12, and the precise frequency of the signal LO 22 in relation to the frequency of the broadcast signal that is being received in a radius 20 can vary from vehicle to vehicle. The present invention uses an antenna 26 to establish a detection zone 28 within which signals LO 22 emitted from the vehicles 12 can be received. In the presently preferred embodiment of the present invention, the detection zone 28 extends through of road 10 to cover the traffic lanes for both directions. Preferably, the antenna 26 is a directional antenna with a substantially flat response through the frequency band of interest (ie the FM band displaced by 10.7 megaHertz). The directionality of the antenna 26 reduces the ibility of interference from spurious signals emanating from the external detection zone 28. Preferably, a site beside the path 10 at its non-intersecting portion 16 is selected for the antenna 26. By carrying the antenna 26 in proximity with the path 10, and the radii 20 and radio antennas 24 therein, the detection zone 28 is projected so that the signals LO 22 can be received. By selecting a site for the antenna 26 that is adjacent to the non-intersecting portion 16 of the road 10, the vehicles 12 tend to move through the zone 28 and remain separated from each other more than would result from placing the antenna 26 to the side of the intersecting portion 14. This tends to increase the detectable sample population through the system and method of the present invention, as discussed below. Those skilled in the art will appreciate that the detection zone 28 sketched in FIG. 1 represents a zone for the LO signals 22 having an average signal strength. As the intensity of the LO 22 signals varies from vehicle to vehicle, zone 28 may be larger with respect to certain vehicles and smaller compared to others. Moreover, zone 28 can be used in relation to path 10 of any size, either larger or smaller than that sketched in FIG. 1. FIG. 2 shows a block diagram of a remote audience survey system. constructed in accordance with a preferred embodiment of the present invention. The system 30 includes the antenna 26, discussed above, a scanning receiver 32, a data recording computer 34 in data communication with the receiver 32, and a complication computer 36 in data communication with the data recording computer. 34. The receiver 32 and the data recording computer 34 are preferably located near the antenna 26 beside the path 10 (see figure 1). Due to the weak nature of the LO22 signals, the electrical power supplied to both the receiver 32 and the computer 34 is individually conditioned by RF clamping devices (not shown) to reduce interference. In addition, RF shielding (not shown) is used around the receiver 32 and the computer 34 individually, and again around the receiver 32 and the computer 34 collectively. The data communication between the receiver 32 and the computer 34 takes place via an RS-232 data link, and a cable 38 providing this link is fastened and shielded. The antenna 26 is coupled to an attenuator 40 via a coaxial cable 42. Although Figure 2 shows the attenuator 40 as being included in the receiver 32, those skilled in the art will understand that the attenuator 40 may be an individual component located in any point between the antenna 26 and the receiver 32. The receiver 32 represents a scanning receiver. The receiver 32 includes RF conditioning circuits 44, which are fed from the attenuator 40. An output of the RF conditioning circuits 44 is coupled to an IF detector 46. The receiver 32 includes a central processing unit (CPU ) 48 having data lines coupled to the IF detector 46 and a voltage controlled crystal oscillator (VCXO) 50, as well as the cable 38 carrying the above-discussed RS-232 data link to the data recording computer 34. The VCXO 50 is coupled to the IF detector 46, and a memory 52 is coupled to the CPU 48. The memory 52 stores programming instructions defining processes carried out by the CPU 48 and the receiver 32 and stores data used and generated in accordance with these processes. The scanning receiver 32, by itself and dissociated from any processes that it can carry out, represents a conventional scanner. Although numerous commercially available scouts may suitably serve the present invention, the presently preferred embodiment uses a model AR3000A receiver, available from Ace Communications of Fishers, Indiana, United States. Figure 3 shows a graph that relates the desired signals with the noise in the frequency range of interest to the remote audience survey system 30 (ie, the FM band displaced by 10.7 megaHertz). Those skilled in the art will appreciate that the graph sketched in Figure 3 illustrates a hypothetical situation, and that the signal amplitude versus frequency image experienced by system 30 (see Figure 2) will vary from instant to instant and from place to place. . However, the background noise, in the lower half of the frequency range, is usually considerably higher than the background noise in the upper half of the frequency range. This phenomenon is a result, at least in part, of the fact that the lower half of the LO signal frequency range resides in the FM band where a considerable amount of RF energy is present. On the other hand, the upper half of the LO signal frequency range resides on the highest possible FM broadcast signal at 100 megaHertz, where significantly less RF energy is present. In particular, FM signals are broadcasted in the United States and other countries at frequencies in tenths in megaHertz in the range of 88 to 108 megaHertz, such as 88.1, 88. 3, 88.5 megaHertz, and so on up to 107.9 megaHertz. "Of course, different frequencies of approximately one hundred possible frequencies of FM broadcasting stations are used in different geographical areas, and no area has FM stations authorized to radiotransmit to all or even a majority of the possible frequencies in tenths of a million megaHertz. to prevent interference. Figure 3 outlines the energy of the local FM broadcasting stations as concentrated mainly on the peaks 23, which have such a large amplitude that they are not fully illustrated in the graph. These peaks are centered on frequencies of tenths of megaHertz. The LO22 signals typically have a much lower signal strength than the FM broadcast station signals. Figure 3 outlines a constant amplitude for LO 22 signals of various frequencies. However, for the reasons discussed above, this constant amplitude represents an average, and the individual LO22 signals may have amplitudes above or below those indicated. In fact, for many radios 20 (see Figure 1), LO22 signals may exhibit an amplitude less than the background noise level. Since LO signals are displaced from FM broadcast signals by 10.7 megaHertz, LO signals are output at a tenth megaHertz frequency, in the range of 98.8 to 118.6 megaHertz, such as 98.8, 99.0, 99.2 megaHertz and so on. successively, up to 118.6 megaHertz. Since signals LO 22 are broadcast at frequencies in tenth megahertz pairs and FM stations transmit signals 23 at frequencies of tenths of a million megahertz, many signals LO 22 can still be distinguished from broadcast FM signals 23. However, when the frequency of a signal LO 22 and an FM signal 23 are very close to each other, as shown at 22 'and 23' in Figure 3, the signal LO 22 may be difficult to detect or otherwise distinguish from background noise compared to other LO22 signals that do not experience the same interference. The attenuator 40 (see Figure 2) serves to compensate for the detection of the louder signal LO 22, such as the signal LO 22 ', with the detection of other LO22 less noisy signals. Without such compensation, a smaller percentage of the louder LO 22 'signals would be detected by the system 30 (see Figure 2) compared to the percentage of the other LO 22 signals detected by the system 30. This lower percentage would introduce an inaccuracy in the system. the audience surveys provided by the system 30. As is conventional, the receiver 32 detects signals that have an amplitude that exceeds a sensitivity parameter. The sensitivity parameter defines the signal of the lowest amplitude that receiver 32 can detect, and is indicated by the letter ^ S ^ in figure 3. The highest background noise level at a LO signal frequency is indicated by the letter ^ N ^ in figure 3. This level can be determined empirically at each site where an antenna 26 (see figures 1-2) is located. The attenuator 40 supplies a magnitude of attenuation corresponding to N / S. In this way, any signal, including any signal LO 22, having an amplitude less than N will pass undetected by the receiver 32. Examining Figure 3, those skilled in the art will appreciate that this configuration of the receiver 32 causes many signals What can otherwise be detected by the receiver 32 is ignored. However, it prevents an unfair polarization towards stations corresponding to the frequencies of such LO signals 22. With reference back to FIG. 2, the data recording computer 34 includes a CPU 54 which is coupled to at least one memory 56, a timer 58, and a disk drive 60. The memory 56 stores programming instructions defining processes carried out by the CPU 54 and the data recording computer 34 and stores the data used and generated in accordance with these processes. The timer 58 helps the CPU 54 maintain a clock that tracks the current date and time. Disk drive 60 is used for non-volatile data storage, preferably in a removable medium such as a floppy disk. Of course, nothing prevents the data recording computer 34 from including additional features, such as a keyboard, a screen, a modem, and the like (not shown). In fact, in the presently preferred embodiment of the present invention, a conventional portable personal computer serves as a data recording computer 34. The data recorded by the data recording computer 34 is communicated to the compilation computer 36 via a link data 62. In the preferred embodiment, the data link 62 is provided by physically carrying disks of the data recording computer 34 to the compilation computer 36. However, nothing prevents the implementation of more automated links, such as links established through a modem and a cell phone. In the preferred embodiment, the recorded data is subsequently kept separate from the data compiled by the compilation computer. This allows a variety of compilation formats to be adapted to the same data. The compilation computer 36 includes a CPU 64, which is coupled to at least one memory 66, a disk drive 68, a keyboard and a screen 70, and a printer 72. The memory 66 stores programming instructions that define carried-over processes performed by the CPU 64 and the compilation computer 36 and stores data used and generated according to these processes. The disk unit 68 is used for non-volatile data storage and for obtaining data from the data recording computer 34 via diskettes. The printer 72 is used to form paper reports of the surveyed data. Of course, nothing prevents the compilation computer 36 from including additional features, such as a hard disk drive, a modem, a pointer (mouse), and the like (not shown). In the presently preferred embodiment of the present invention, a conventional personal computer serves as a compilation computer 36. Figure 4 shows a flow diagram of a browser process 74 carried out by the scanning receiver 32 (see FIG. 2). ). In general terms, the browser process 74 causes the receiver 32 to act as a slave under the control of the data recording computer 34 (see figure 2). The receiver 32 simply responds to the instructions presented thereto from the data recording computer 34 by the data link 38 (see figure 2). The method 74 is carried out in accordance with software programming instructions stored in the memory 52 of the receiver 32 in a manner well known to those skilled in the art. The procedure 74 performs a task 76 to output data describing the results obtained at a frequency to which the receiver 32 is currently tuned. This data is outputted by the data link 38, from which they are received. by a data recording computer 34 and processed in a manner discussed below. The particular data output in the task 76 generally describes whether a signal has been detected at the frequency to which the receiver 32 is currently tuned! The detection information can be communicated through or accompanied by data indicating the intensity of any signal so detected. Other data may also be provided, but need not be, such as data describing the frequency to which the receiver 32 is currently tuned, attenuation factors and / or types of signals, such as AM, FM and the like. After task 76, an interrogation task 78 determines whether a new tuning command has been received from the data recording computer 34 via the data link 38. A tuning command instructs the receiver 32 to tune to a particular frequency, and may include other data components, such as bandwidth to be used in signal detection, attenuation factors to be applied to any received signals, types, such as AM or FM signals to be detected, and the like. If a new tuning command has not been received, task 78 routes the program control back to task 76. Process 74 remains in a loop that includes tasks 76 and 78 until a new tuning command is received. The receiver 32 remains tuned to a frequency, and a data stream is supplied by the receiver 32 via the data link 38. This data stream tracks any signal detected at the tuned frequency. If the task 78 detects a new tuning command, a task 80 programs the receiver 32 in response to the new tuning command. In particular, the detector IF 46 and the VCXO 50 (see figure 2) are programmed to carry out the new command. The program control may remain in task 80 until sufficient time has elapsed to allow the acquisition of any signal that may be present in the newly commanded frequency. When such time has elapsed, the program control returns to task 76 to output a stream of data describing the results according to the new tuning command. The program control remains in the turns described above consisting of tasks 76, 78 and 80 indefinitely. A human operator can interrupt the process 74, for example by removing energy from the receiver 32, when the data recording operations are complete for a given location. Figure 5 shows a flow chart of a data recording process 82 carried out by the data recording computer 34. In general terms, the data recording process 82 controls the operation of the scan receiver 32 and records data supplied by the receiver 32. The method 82 is carried out according to software programming instructions stored in the memory 56 (see figure 2) of the computer 34 in a manner well known to those skilled in the art. The procedure 82 performs a task 84 to send another tuning command over the data link 38 to the receiver 32. As discussed above, this command includes data identifying a frequency at which it is ordered to tune the receiver 32 together with others. tuning parameters, such as signal type, attenuation and bandwidth. The particular frequency to be sent during the task 84 can be obtained by consulting a tuning table 86, an exemplary block diagram of which is shown in Figure 6. The table 86 can be formed into a memory structure stored in the memory 56 (see figure 2). With reference to Figure 6, Table 86 includes a list of LO signal frequencies. As discussed above, these frequencies are tenth megaHertz frequencies in the range of 98.8 to 118.6 megaHertz. However, table 86 is constructed to include only LO signals corresponding to those FM stations that are to be included in a hearing survey prepared by system 30. Typically, all FM stations reasonably detectable by typical radios 20 (see figure 1) in the detection zone 28 (see figure 1) are included in a hearing survey. Any stations not reasonably detectable in zone 28 are omitted from table 86 and the audience survey. Stations are not listed twice in table 86. In addition, table 86 may include descriptive data in association with each LO signal frequency. Such descriptive data may include an FM station frequency corresponding to the frequency of the LO signal, which is 10.7 megaHertz less than the frequency of the LO signal, and the call letters of the station or any other description. With reference to Figures 5 and 6, task 84 can move a pointer (not shown) to a next record in table 86 to determine what frequency LO to send to receiver 32. In this way, the next frequency tuned by receiver 32 is the next frequency listed in table 86. Of course, when the pointer reaches the end of table 86, it can return to the beginning of table 86. Referring back to figure 5 , the task 84 may select other data required by the tuning command from the constants stored in the memory 56 (see figure 2). In the preferred embodiment, a type parameter is set to command the reception of an FM signal, and an attenuator parameter is set to command that there is no attenuation. In the preferred embodiment, the attenuation is carried out via the attenuator 40 because more precise attenuation can be obtained. However, other embodiments may carry out the attenuation function within the receiver 32 via software programming. In the preferred embodiment, a bandwidth parameter is set to order a bandwidth of less than 18 kiloHertz, and more preferably around 12 kiloHertz. This bandwidth represents a desirable compromise between obtaining inaccurate data and missing calls, where a call represents the detection of a radio station to which a radio 20 is tuned (see Figure 1). Larger bandwidths lead to inaccurate data because the FM 23 broadcast signals (see Figure 3) can be confused with LO 22 signals in the lower half of the frequency band of the LO signal. Lower bandwidth leads to missing calls, because the precise frequencies of signals LO 22 vary from radius 20 to radius 20. After task 84, process 82 performs a task 88 to obtain data transmitted to the computer. data record 34 from receiver 32. Task 88 may desirably include a waiting period to allow receiver 32 to adjust its tuning to a newly programmed frequency and lock any signal that may be present at this new frequency. However, any wait is typically no greater than a small fraction of a second. Once such data has been received, an interrogation task 90 is carried out to evaluate the data of the receiver 32 to determine if an LO signal 22 has been detected. In making this determination, the task 90 can desirably evaluate a parameter of signal strength to ensure that any received LO signal 22 displays an amplitude above a predetermined minimum to reduce the possibility of confusion of a spurious signal with a legitimate call. If no signal is detected, or if there is no signal of sufficient amplitude present, the program control goes into a loop back to the task 84, where the receiver 32 is ordered to tune to a new frequency. Process 82 remains in a scan loop that includes tasks 84, 88 and 90 until a LO signal 22 is detected. In other words, the process 82 causes the receiver 32 to scan the LO signal frequencies corresponding to FM stations by being included in an audience survey until such an LO 22 signal is detected. When task 90 decides that it has detected a legitimate signal LO 22, the process 82 performs a task 92. Task 92 is not part of the exploration loop discussed above. A new tuning command is not sent to the receiver 32, and the receiver 32 remains tuned to the frequency at which the LO 22 signal was detected. Any other signal LO 22 that could possibly be detectable by the receiver 32 at this point in time it is ignored. Task 92 initiates a call register 94 in memory 56 of data recording computer 34. Figure 7 shows a block diagram of exemplary format for call recording 94. With reference to figures 5 and 7, task 92 Write data to the register 94 which describes a unique serial number for the call, the frequency of the radio station detected by the call, various descriptive data, such as the call letters of the station, the LO frequency, and the like, the current date and current time. The current time identifies the start time of the call. These data represent parameters that identify the particular LO signal that is currently being detected in the receiver 32. Referring again to Figure 5, after task 92, a task 96 obtains additional data from the receiver 32. The task 96 performs substantially the same function as the task 88, discussed above. After task 96, an interrogation task 98 examines the data obtained in task 96 to determine whether the signal LO 22 that is being detected by the receiver 32 has disappeared by falling below predetermined limits. If the signal LO 22 has not disappeared, the program control returns to the task 96 to obtain additional data from the receiver 32. In this way, once a signal LO 22 has been detected, the process 82 remains in a loop consisting of in tasks 96 and 98 until signal LO 22 is no longer detected by receiver 32. When task 98 determines that signal LO 22 has disappeared, an interrogation task 100 determines whether the newly detected call lasted for at least one Minimum allowed call duration. In the preferred embodiment, this minimum allowable call duration is about one second. This determination can be made by comparing the current time with the time stored in the previous call record in task 92. If the call duration was less than the minimum allowed, a task 102 clears the call record 94 (see figure 7) started previously in task 92, and the program control goes into turn back to task 84 to cause receiver 32 to scan the next detectable LO 22 signal. This brief call will be ignored in the audience survey. Such brief calls may be the result of spurious signals, momentary specular reflections, radio station changes on radios 20, and the like. Such events do not represent legitimate calls and may distort the audience survey data. When the task 100 determines that the call duration exceeded the minimum allowed, a task 104 completes the call record 94 (see figure 7). In particular, task 104 adds the current time to call register 94 together with data describing the peak signal strength detected during the call. The day time recorded in the call record 94 for the end of the call when it was taken with the time recorded for the start of the call describes the duration of the call. After task 104, a task 106 writes the call record 94 to a file that is now or subsequently will be written to the disk unit 60 (see figure 2) on a removable disk. In this way, task 106 causes the call register 94 to be registered in a substantially permanent and non-volatile medium. After the task 106, the program control goes into turn back to the task 84, where the receiver 32 is ordered to scan another signal LO 22. In this way, the process 82 remains in an indefinite loop. The LO signal frequency band is scanned for an LO 22 signal. When such a signal is detected, other LO signals are ignored until the detected LO 22 signal is no longer detectable at the receiver 22. The ignoring of the others LO signals while a LO signal is detectable prevents a particular type of distortion in the audience survey data. Thus, a situation in which multiple radios are tuned to a common station within the detection zone is prevented from distorting the audience survey data. Although ignoring the other LO signals that are otherwise detectable reduces the population of shows, reduces the recorded calls for all stations included in the survey in proportion to the actual number of radios 20 tuned to those stations. As a result, no unfair polarization is introduced into the survey data. On the other hand, if other detectable LO signals were recorded while more than one LO signal could be detected, disproportionately fewer calls would be recorded for popular stations. Such an unfair result would occur due to the difficulty of determining when more than one radio 20 in the detection zone 28 is tuned to the same station., and it is feasible that the most popular stations have multiple calls simultaneously in the detection zone 28. In the preferred embodiment of the present invention, the receiver 32 continuously carries out the process 74 (see figure 4) and the computer data record 34 continuously carries out processes 82 in any given place for any period of time. In a duration of 48-96 hours, typically thousands of calls are recorded. Of course, those skilled in the art will appreciate that the number of registered calls depends on the amount of traffic in the location and other factors. A diskette in which these calls have been registered is then transported to the compilation computer 36 (see figure 2), which can be located at any convenient place, whether or not it is near the detection zone 28 (see figure 1). The antenna 26, the receiver 32 and the data recording computer 34 can then continue to record data in the same place, be moved to a different place to register calls in the different place, or simply be inactive. Those skilled in the art will appreciate that no human operator is required for the operation of the receiver 32 or the data recording computer 34 or for the interpretation of the data received. This provides a benefit of precision because the results do not depend on the skill and concentration of an operator. It also provides a cost benefit because high salaries for experienced operators can be eliminated along with the provision of a comfortable environment near a monitoring site within which a human operator could work. Figure 8 shows a flow diagram of a compilation cut process 108 that is carried out by the compilation computer 36. In general terms, the compilation cut process cuts certain call records 94 from the contents in the file Call register 94 registered as explained above. The process 108 cuts the call records 94 that possibly describe illegitimate calls that could distort the survey data. The procedure 108 is carried out according to software programming instructions stored in the memory 66 (see figure 2) of the computer 36 in a manner well known to those skilled in the art. The procedure 108 iteratively examines each recorded call record 94 (see figure 7) in a loop that will be described later. The procedure 108 performs a task 110 to obtain the next call record 94 of the file. Next, an interrogation task 112 determines whether the inter-call duration, which elapses between the end of the previously examined call and the start of the call currently examined, is less than a predetermined minimum duration. In the preferred embodiment, this minimum duration is set to around eight seconds for normal city traffic speeds. However, this minimum duration can be adjusted up or down to accommodate slower or faster traffic. If this inter-call duration is less than a minimum duration, then there is a possibility that an illegitimate call has been recorded. If so, an interrogation task 114 is carried out to examine the recorded signal frequencies for this call register and the previous call register. If these frequencies are the same, then the call is treated as an illegitimate call, and the program control proceeds back to task 110 to examine the next call record 94 of the file. The data recorded in the call log will simply be ignored. Tasks 112 and 114 jointly test a situation in which two consecutive calls are recorded for the same station within the minimum duration. In some cases, this situation can represent two legitimate calls. Nevertheless, in other cases, it may result from a single radio 20 whose signal LO 22 was momentarily interrupted. Such an interruption ?, for example, can be the result of a low level signal that can only be detected in the first place or from a vehicle 12 passing between the radio transmitter 20 of the signal LO and the antenna 26 (see figure 1) . In the case of a momentary interruption, the recording of two calls for a single radio would distort audience survey data in favor of stations where the occurrence would be more feasible, such as stations whose LO frequencies reside in the lower half of the band. of frequencies LO where there is more noise or for stations that are more popular. If the inter-call duration is not less than the minimum duration or the inter-call duration is less than the minimum duration but the calls are for different frequencies, the program control proceeds to task 116. Task 116 compares the recorded duration in the call register 94 that is being examined with a maximum, predetermined, allowed time period. In the preferred embodiment, this maximum allowed time period is set to around 10 minutes. If the call record indicates a duration greater than this maximum, the call is considered to be illegitimate, and the program control returns to task 110 to examine the next call record 94. The data included in this call record 94 will be ignored . The vehicles 12 must normally pass through a detection zone 28 in a matter of a few seconds.

When a call record indicates a call duration greater than the maximum time allowed, the receiver 32 probably detected something other than a radius 20. For example, a source of interference noise may have entered the neighborhood. Such call data distorts audience survey data, typically in favor of stations whose LO signals oscillate in the frequency band of FM broadcasting signal. When the task 118 determines that the call record 94 indicates a call duration less than the maximum allowed, the call may be considered legitimate for the time being, and the program control proceeds to an interrogation task 120. The task 120 may examine data in the call log to determine if something unusual is indicated. For example, task 120 may examine the strength of the call signal to determine if an unusually high signal was received. Alternatively, task 120 may examine the duration of the call to determine if an unusually long call was recorded, although the call duration may be less than the maximum allowed. Such events, and perhaps others, by themselves do not indicate deficient data, but may indicate deficient data if they occur in several different 94 call records. Accordingly, when such events are detected, a task 124 activates a flag associated with the call register 94 for further consideration.

After task 124 or when task 120 is unable to find questionable data in call register 94, process 108 performs a task 126. Task 126 stores call register 94 in a compilation file. Next, an interrogation task 128 determines whether the call register 94 was the last call register 94 to be examined for cutting. If it is not the last call register 94, the program control returns to task 110 to examine the next call record 94. The process 108 remains on this loop until all the call records 94 have been examined. Potentially polarizing data they are automatically cut off from the remaining 94 call records. When all the call records 94 have been examined, the program control proceeds to a compilation process 130. Of course, those skilled in the art will appreciate that the program control does not need to automatically proceed to the process 130, and that the process 130 can be described by a computer program totally different from the process 108. Figure 9 shows a flow chart of the compilation process 130 that can be carried out by the compilation computer 36. In general terms, the compilation process 130 infuses data of the compilation file produced by the cutting process 108 (see figure 8) in a spreadsheet arrangement, an example of which is illustrated by figure 10. The procedure 130 is carried out according to programming instructions of software stored in the memory 66 (see Figure 2) of the computer 36 in a manner well known to those skilled in the art. The process 130 performs a task 132 to obtain cell definitions for a spreadsheet 134, an example of which is sketched in Fig. 10. The spreadsheet 134 is divided into cells 136 arranged in rows and columns. Various types of data may be included in each cell 136. In the preferred embodiment, a column is provided for each hour of a day and a row is provided for each radio station to be included in a hearing survey. Task 132 defines these rows and columns. However, those skilled in the art will appreciate that the row and column definitions of the spreadsheet are flexible and can change from application to application. For example, additional columns can be added to sketch blocks of several hours. With reference of new account to figure 9, after task 132, a task 138 processes the compilation file to accumulate the data contained therein, or at least portions thereof, in spreadsheet 134 (see figure 10). Task 138 determines the number of calls recorded for each station during each hour of the day and any other factors that may be considered valuable for the particular report that is being generated. Next, a task 140 calculates the cell percentages for each cell 136 in the spreadsheet array 134. The percentages are calculated with respect to the total number of calls recorded for each column in spreadsheet 134 and provide standardized data for comparison from hour to hour. After task 140, a loop is instigated to examine the various cells 136 and columns of spreadsheet 134. In the preferred embodiment, all cells in a column are examined before examining cells in another column. In this manner, a task 142 identifies the next column of the spreadsheet to be examined, and a task 144 identifies the next cell within the column currently identified to be examined. After task 144 identifies a subject cell 136, a series of determinations is made to put a flag of data that could potentially be bad. Any number of determinations can be made. For example, an interrogation task 146 can determine if an excessive number of flags has been registered for the subject cell 136. Such flags were set in the cutting process 108 (see figure 8) in task 124. If a number is found excessive, a task 148 may add a descriptive flag to the subject cell 136. After task 148 or when task 146 is unable to find an excessive number of flags, an interrogation task 150 may determine if an excessive change of flag is reported. percentage for the cell from the previous hour. An excessive change in the percentage of market share between two consecutive hours may indicate bad data. In this way, when this situation is detected, a flag 152 may add a descriptive flag to the subject cell 136. After task 152 or when task 150 is unable to find an excessive change in percentage of market share in consecutive hours , an interrogation task 154 may determine if an excessive percentage change is reported for the cell from a corresponding cell for a corresponding geographic location in a spreadsheet 134 for a previous month or week. A spreadsheet 134 for a previous month or week can be obtained from memory 66 or from disk unit 68 (see figure 2). Again, such excessive change in market share percentage between two consecutive months or weeks may indicate bad data. If an excessive change is detected, a task 156 may add a descriptive flag to the subject cell 136. After a task 156 or when task 154 is unable to find an excessive change in market share percentage from a previous month or week , an interrogation task 158 determines whether the subject cell 136 represents the last cell 136 to be examined in the concerned column of the spreadsheet 134. If this is not the case, the program control goes back to the task 144 to examine the next cell in the column. If the last cell 136 in the column has been examined, an interrogation task 160 determines whether the total number of calls recorded in the column is greater than a predetermined minimum number. If less than the minimum number is detected, the sample population of call records is in danger of being unable to constitute a statistically significant sample size. This situation can occur when a large number of call records 94 has been cut through process 108 (see figure 8), or when vehicle traffic has been low. If this situation is detected, a task 162 may add a descriptive flag to the column in question of the spreadsheet 134. After task 162 or when task 160 determines that the number of calls is greater than the minimum, an interrogation task 164 determines whether the column in question is the last column in spreadsheet 134. If other columns remain to be evaluated, the control program spirals back to task 142 to examine the rest of spreadsheet 134. When the entire sheet calculation 134 has been evaluated, process 130 proceeds to a task 166 to continue processing spreadsheet 134. Task 166 may include external data in spreadsheet arrangement 134. Such external data, for example, may represent car account numbers for the monitored place. The car account numbers represent the total number of cars that pass through a particular point. Since the system and method of the present invention do not record all of the vehicles 12 (see Figure 1) that pass through the detection zone 28 for the numerous reasons discussed above, such car account numbers can be multiplied by numbers of percentage to give an indication of the total number of vehicles 12 that listen to particular stations during particular hours in the monitored place. Alternatively, such external data may represent population or traffic data for the area, such as a city or the like, where the detection zone 28 is located. Such population data, when included in the spreadsheet 134 multiplying by the percentage data, provide a common denominator that allows spreadsheets 134 to be compared to each other for different areas and compiled together into statistics for additional areas. large formed by a conglomerate of smaller areas. After task 166, a task 168 stores the spreadsheet 134 on a non-volatile storage medium, and an optional task 170 can be carried out to print the spreadsheet arrangement or at least portions of it, in a format of particular report, and leaves the process 130. The cells and columns with flag, as discussed above in relation to tasks 146-162, can be examined by a human operator in terms of judgment calls as to whether they indicate or not bad data. If an operator decides that erroneous or bad data is indicated, the process 130 can be repeated by adjusting the cell definitions in the worksheet in task 132 to omit particular days or hours of the compilation. If insufficient data is obtained, additional data can be collected in the same place, as discussed above in relation to figures 1-7. In sum, the present invention provides an improved system and method for determining the stations to which the tuners can be tuned. Audience survey data is collected without requiring the participation of the audience or constant monitoring by a trained human operator. The system and methodology of the present invention place higher priority on obtaining accurate survey data than on obtaining large survey samples. Accordingly, the present invention automatically ignores detectable and / or detected data that might otherwise have been included in a survey in order to prevent the introduction of undue biases in the survey data. Notwithstanding the foregoing, due to the automated data collection technique of the present invention, large sample populations can still be monitored at low cost. The improved accuracy in the audience survey data is obtained through signal and data processing. Improved accuracy in audience survey data is obtained because screening zones can be established in any number of different locations, and audience survey data from these locations can be combined after weighing the survey results with external data, such as population or other data. The present invention has been described above with reference to preferred embodiments. However, those skilled in the art will recognize that changes and modifications can be made to these preferred embodiments without departing from the scope of the present invention. For example, the receiver of the present invention need not be a scanning receiver but may be a spectrum analyzer or multiple receivers tuned to different stations and operated in parallel. Moreover, those skilled in the art can distribute the processing functions described herein between a receiver, a data recording computer, and a compilation computer in a manner different from that indicated herein, or the technicians in the art. they may combine functions that are indicated herein as carried out in or by different components of the system. Furthermore, those skilled in the art will appreciate that the present invention will be adapted to a wide variation in the specific tasks and ordering of the specific tasks used to achieve the processes described herein. These and other changes and modifications that are obvious to those skilled in the art are intended to be included within the scope of the present invention.

Claims (16)

1. A remote audience survey method for identifying radio stations to which tuners are tuned, said tuners having local oscillator signals emitted therefrom, and said method comprising the steps of: establishing a detection zone so that said local signals of oscillator emitted therein by tuners tuned to different said radio stations are detectable by an antenna of a receiver; detecting one of said local oscillator signals in said receiver; obtaining data describing said signal from said local oscillator signals; and ignoring data describing other such local oscillator signals emitted from within said detection zone while said local oscillator signal is detected in said receiver.

2. A remote audience survey method, as defined in claim 1, wherein: said set-up step is configured such that local oscillator signals emitted in said detection zone to any of a plurality of local oscillator frequencies are detectable, wherein a noise level in said detection zone for the loudest of said plurality of local oscillator frequencies is greater than the noise levels in others of said plurality of local oscillator frequencies; said method further comprising the step of configuring said receiver to detect local oscillator signals having an intensity greater than a predetermined minimum signal strength at any of said local oscillator frequencies; and said method further comprising the step of preventing calls corresponding to local oscillator signals having said intensity less than said minimum signal strength at a local oscillator frequency different from the noisiest one from corrupting said survey results.

3. A remote audience survey method, as defined in claim 1, wherein: said detection step is configured to detect only a local oscillator signal at one time; said method further comprising the step of determining when said local oscillator signal is not already detected in said receiver; and said method further comprising the step of repeating said detection step after said local oscillator signal is no longer detected in said receiver.

4. A remote audience survey method, as defined in claim 1, wherein said obtaining step is configured to ignore calls associated with durations less than a predetermined minimum time period.

5. A remote audience survey method, as defined in claim 1, wherein: said set-up step is configured such that said local oscillator signals emitted in said detection zone from tuners tuned to different stations of said radio stations are detectable through said antenna; and said method further comprising the step of ignoring data describing other detectable local oscillator signals emitted from within said detection zone while said detection step is being carried out to detect a local oscillator signal.

6. A remote audience survey method, as defined in claim 1, wherein said obtaining step comprises the step of recording data identifying a duration during which a local oscillator signal is detected in said receiver, and said method further comprises the steps of: comparing said duration with a predetermined period of time; and ignoring said data describing said signal from said local oscillator signals when said comparison step indicates that said duration exceeds said predetermined time period.

7. A remote audience survey method for identifying radio stations to which tuners are tuned, said tuners having local oscillator signals emitted therefrom, and said method comprising the steps of: establishing a detection zone so that local signals of oscillator emitted in it are detectable by an antenna of a receiver; detect local oscillator signals in said receiver; obtaining data describing said local oscillator signals, said data being divided into calls, where each call corresponds to a single local oscillator signal detected, and where said calls transmit local oscillator frequency data and timing data configured so that it can determine a duration between consecutive calls; generate, in response to said step of obtaining, survey results that respond only to a portion of said calls; and preventing one of two consecutive calls from corrupting said survey results when said two consecutive calls have substantially equivalent local oscillator frequencies and occur for a predetermined duration with each other.

8. A remote audience survey method, as defined in claim 7, wherein: said set-up step is configured so that the local oscillator signals emitted in said detection zone at any frequency of a plurality of local frequencies of oscillator are detectable, wherein a noise level in said detection zone for a louder frequency of said plurality of local oscillator frequencies is greater than noise levels to others of said plurality of local oscillator frequencies; said method further comprising the step of configuring said receiver to detect local oscillator signals having an intensity greater than a predetermined minimum signal strength at any of said local oscillator frequencies; and said method further comprising the step of preventing calls corresponding to local oscillator signals having an intensity less than said minimum signal strength to a frequency other than said louder oscillator local frequency from corrupting said survey results.

9. A remote audience survey method, as defined in claim 7, wherein: said detection step is configured to detect only a local oscillator signal at a time; said method further comprising the step of determining when said local oscillator signal is no longer detected in said receiver; and said method further comprising the step of repeating said detection step after said local oscillator signal is no longer detected in said receiver.

10. A remote audience survey method, as defined in claim 7, wherein: said call timing data is further configured so that a duration in which said local oscillator signals are detected in said receiver can be determined; said obtaining step is configured to ignore calls associated with detecting durations less than a predetermined minimum period of time.

11. A remote audience survey method, as defined in claim 7, wherein: said set-up step is configured such that said local oscillator signals emitted in said detection zone from tuners tuned to different from said stations of radio are detectable through said antenna; said method further comprising the step of ignoring data describing other detectable local oscillator signals emitted from within said detection zone while said detection step is being carried out to detect a local oscillator signal.

12. A remote audience survey method for identifying radio stations to which tuners are tuned, said tuners having local oscillator signals output from them, and said method comprising the steps of: establishing a detection zone so that local signals of oscillator emitted therein at any frequency of a plurality of local oscillator frequencies are detectable by an antenna of a receiver, wherein a noise level in said detection zone for a louder frequency of said plurality of local oscillator frequencies is greater that the noise levels at other frequencies of said plurality of local oscillator frequencies; configuring a receiver to detect local oscillator signals having an intensity greater than a predetermined minimum signal strength at any of said local oscillator frequencies; detect local oscillator signals in said receiver; obtaining data describing said local oscillator signals, said data being divided into calls, where each call corresponds to a single local oscillator signal detected; generate, in response to said obtaining step, survey results that respond to only a portion of said calls; and preventing calls that correspond to local oscillator signals having an intensity less than said minimum signal strength at a frequency other than said louder oscillator local frequency from corrupting said survey results.

13. A remote audience survey method, as defined in claim 12, wherein said tuners are tuned to any of a plurality of tenth non-megaHertz frequencies in the range of 88.1-107.9 megaHertz, and said detection step comprises the step of tuning said receiver to detect a plurality of frequencies in tenth megaHertz in a local oscillator frequency range of 98.8-118.6 megaHertz.

14. A remote audience survey method, as defined in claim 12, wherein: said detection step is configured to detect only one local oscillator signal at a time so that otherwise detectable local oscillator signals are ignored that occur simultaneously with said local oscillator signal; said method further comprising the step of determining when said local oscillator signal is no longer detected in said receiver; and said method further comprising the step of repeating said detection step after said local oscillator signal is no longer detected in said receiver.

15. A remote audience survey method, as defined in claim 12, wherein said obtaining step comprises the steps of: transmitting timing data describing durations during which said local oscillator signals are detected in said receiver; ignore calls associated with durations less than a predetermined minimum period of time.

16. A remote audience survey method, as defined in claim 12, further comprising the step of ignoring data describing other detectable local oscillator signals emitted from within said detection zone while said detection step is being carried out. out to detect a local oscillator signal.