TV monitor

A TV monitor includes an antenna coupler capable of selectively coupling the TV receiver being monitored to an antenna or an r.f. oscillator. The oscillator is selectively operated to impose an r.f. signal onto the antenna input of the receiver between successive horizontal blanking periods on an active video line. One probe, connected to the horizontal retrace circuit of the receiver monitors the receiver for an "on" or "off" condition. A second probe, connected to the kinescope circuits of the receiver, detects the channel to which the receiver is tuned. A third probe, connected to the vertical retrace circuitry, detects the vertical retrace signal to determine when the r.f. signal is to be imposed onto the receiver's antenna input. By successively stepping the r.f. oscillator through successive frequencies within the bandwidth of individual channels, and by monitoring the kinescope probe for that frequency which compares to that generated, channel identification may be determined. A plurality of individual monitors may be utilized with individual receivers within a household and the data may be collected and stored in a household collector for eventual transmission to a central station.

RELATED APPLICATION 
This application discloses subject matter related to the subject matter 
disclosed in copending application Ser. No. 714,432 filed on even date 
herewith by John R. Thompson and entitled TV Monitor. 
This invention relates to television monitoring, and particularly to 
apparatus for monitoring the status of a plurality of television 
receivers. The invention is particularly useful in "television audience 
measurement" surveys wherein the status and channel identification of a 
plurality of television receivers is monitored to obtain data concerning 
the popularity of television programs. 
Heretofore television audience measurement surveys were often conducted by 
direct contact with television viewers, such as by telephoning them for 
information as to what programs were being viewed at a particular time, or 
by requesting selected persons to maintain diaries in which they recorded 
their viewing habits. Some attempts have been made to automatically 
monitor television receivers to determine the status of each receiver, but 
such apparatus have not been altogether successful due to electrical 
interference with the television receiver. Furthermore, information 
concerning television receiver status which is recorded locally at the 
television receiver must be collected in a manner which does not interfere 
with the ordinary operation of the household in which the set or sets are 
being monitored, and prior electronic techniques have not been altogether 
successful in transmission of data to a central location for collation 
with data from other households. Another problem with prior electronic 
monitoring apparatus has resided in the fact that such apparatus is 
ordinarily quite expensive, so the number of such monitoring apparatus 
must be limited, thereby limiting the scope of the survey. 
The present invention is concerned with television monitoring apparatus 
capable of monitoring a plurality of television receivers to determine 
channel identification and receiver status for purpose of television 
audience measurement surveys. While the present invention will be 
described in connection with the use of the apparatus for television 
audience measurement surveys, it is evident to those skilled in the art 
that the apparatus is equally useful for pay television wherein the sets 
may be monitored for purposes of billing customers for programs subscribed 
on a fee basis. 
It is an object of the present invention to provide a television monitor 
which is inexpensive and which accurately monitors television receivers 
for receiver status and transmits that information to a central station. 
It is another object of the present invention to provide a television 
monitor which does not electrically interfere with the television receiver 
being monitored. 
It is yet another object of the present invention to provide a television 
monitor which is capable of being easily attached to a television set and 
is capable of accurately monitoring the television receiver for receiver 
status. 
In accordance with the present invention, a television monitor includes a 
signal oscillator capable of inserting a radio frequency signal onto the 
antenna leads of the television receiver being monitored, and detectors 
are provided to ascertain channel identification and receiver status and 
for transmitting that information to a central station, such as a central 
computer, for processing with information received from other television 
monitors. 
According to one feature of the present invention, the status of the 
television receiver is monitored at successive intervals (for example, 
each second) and the status information is recorded in the memory of a 
collector unit. Periodically (for example, once each day) that information 
is transmitted to a central station via a suitable communications link, 
for example, telephone lines. At the central station, the information may 
be collated with information received from other television monitors to 
complete the audience measurement survey.

With reference to the drawings, and particularly to FIG. 1, there is 
illustrated a television monitor system in accordance with the presently 
preferred embodiment of the present invention. The system includes a 
household collector illustrated generally at 10 coupled to a plurality of 
individual television monitors illustrated generally at 12 and 14. Each 
television monitor 12, 14 is connected to an individual television 
receiver 16, 18, respectively. Television monitors 12 and 14 are identical 
in configuration, so only the television monitor 12 will be described in 
detail. Monitor 12 includes channel logic 20 connected to a signal channel 
oscillator 22. An antenna coupling 24 is coupled between antenna 26 and 
the television receiver 16. Channel logic 20 and oscillator 22 are also 
connected directly to antenna coupling 24. A pair of probes (not shown) 
are connected via suitable links 28 and 30 to probe signal processor 32 
for input to channel logic 20. The output from channel logic 20 is 
provided to channel data transmitter 34. Each data transmitter 34 
periodically transmits information via communication link 74 to household 
collector 10 where it is received by channel data receiver 36 for input to 
recognition logic 38. Logic 38 provides an output to memory 40 where 
information is stored. A real time clock 42 also provides information to 
memory 40 to identify the time of updating of memory 40. Memory 40 
provides an output to control logic 44 which in turn provides an output to 
household transmitter 46 for transmission to a central station computer 
via channel 48. 
With reference to FIG. 2, the details of television monitor 12 may be 
readily explained. Lead 28 is connected to a nonshielded electrostatic 
probe (not shown) which may consist simply of a wire connected directly to 
the horizontal retrace circuitry of the television receiver 16. A shielded 
electrostatic probe is connected to lead 30 and is wrapped around the 
luminance leads of the kinescope circuits of the television receiver. A 
shielded magnetic probe, which consists of a toroidal or split core 
transformer, is connected via lead 80 to the vertical retrace circuitry of 
the receiver. The probe connected to the horizontal retrace circuitry via 
lead 28 is connected to voltage detector 50 to detect the voltage level of 
the horizontal retrace circuitry of the receiver. The output of voltage 
detector 50 is connected to an input of status logic 52 to determine the 
"on/off" status of the television receiver. Thus, if the voltage appearing 
on the probe connected to the horizontal retrace circuitry is below a 
predetermined level established by voltage detector 50, the status of the 
set is determined to be "off", and that information is transferred to 
logic 52 for transmission to data transmitter 54. If, however, the 
receiver is determined to be in an "on" condition, logic 52 conditions 
gate 56 for operation. The probe connected to the vertical retrace 
circuitry is connected to voltage detector 82 to detect the vertical 
retrace signal so that gate 56, connected to voltage detector 82, will 
operate only when the vertical retrace signal resets the kinescope to the 
upper portion of the video screen. Hence, gate 56 will operate oscillator 
58 at a time within the top two or three lines on the video screen. At 
that time, radio frequency oscillator 58 supplies a radio frequency signal 
within the frequency band of one channel capable of being received by 
receiver 16 to antenna coupling 24. At the same time, gate 56 operates 
coupling 24 to disconnect antenna 26 from receiver 16 and to connect 
oscillator 58 to receiver 16. 
It is important to note that the decoupling of antenna 26 from receiver 16 
and the injection of the r.f. signal onto the antenna input of the 
receiver occurs only during the upper few lines of the video sweep, 
thereby assuring that such interruptions are not within the main portion 
of the picture, nor annoying to the viewer. Following the injection of the 
r.f. signal, gate 56 operates coupler 24 to reconnect the antenna to the 
receiver for normal operation. 
The radio frequency signal inserted by oscillator 58 onto the antenna leads 
of receiver 16 is inserted into the receiver circuitry. If the receiver is 
tuned to that channel corresponding to the frequency generated by 
oscillator 58, the luminance probe connected to lead 30 will detect a 
signal which will be amplified by automatic gain control amplifier 60 for 
insertion into the vertical signal logic 62. 
Assuming the set was tuned to that channel corresponding to the radio 
frequency inserted by oscillator 58, logic 62 forwards a channel signal 
identification to compare circuit 64 which compares the received signal 
from logic 62 with that generated by oscillator 58. If a comparison is 
made (which it will be made in the event that the oscillator did insert a 
radio frequency signal corresponding to the channel to which the set was 
tuned), compare circuit 64 provides an output on lead 66 to data 
transmitter 54 indicative that the set was tuned to the particular 
channel. 
If, however, the receiver was not tuned to the frequency established by a 
radio frequency oscillator 58, that fact is determined by a non-comparison 
by compare circuit 64, in which event an output is provided to step 
control 68 to control oscillator 58 to provide a different radio frequency 
signal during the next iteration between two horizontal blanking periods. 
At the same time, reset counter 70 is advanced one count for purposes to 
be hereinafter explained. Thus, assuming the set was not tuned to that 
channel corresponding to the signal provided by oscillator 58, during the 
next monitor cycle (upon a vertical retrace to the upper portion of the 
video) a different signal frequency is inserted into the television 
receiver via the antenna leads for comparison by compare circuit 64. The 
process continues until a comparison is found between a signal detected by 
the luminance probe and that inserted by oscillator 58. At which point, 
compare circuit 64 provides information as to channel identification to 
data transmitter 54. Lead 66 is also connected to the reset portion of 
counter 70 to reset the count in counter 70 to zero. 
Counter 70 is preferably a counter capable of advancing to an adequate 
count in excess of the number of channels capable of being received by the 
television receiver. For example, counter 70 may be capable of advancing 
to a count of 24, which is in excess of the number of television channels 
capable of being received in any particular community. In the event that 
counter 70 advances to its full count without being reset, such 
information is provided to data transmitter 54 to indicate a malfunction 
with the television monitor. It should be evident that a normal operation, 
reset counter 70 should never advance to its full count, but instead wll 
be reset to zero each time a comparison is made as to channel 
identification. 
Data transmitter 54 receives information from reset counter 70, compare 
circuit 64 and status logic 52. This information will indicate malfunction 
of the apparatus from reset counter 70, receiver status (that is whether 
the receiver is on or off) from logic 52, and channel identification from 
compare circuit 54. A free-running oscillator 72 provides periodic pulses 
to data transmitter 54. For example, oscillator 52 may provide pulses each 
second to data transmitter 54 thereby initiating transmission of data via 
communication link 74. Address circuitry 76 is also connected to data 
transmitter 54 to provide data concerning the identification of the 
particular television receiver being monitored. 
With reference to FIG. 1, the data from each of the television monitors 12 
and 14 transmitted via communication link 74 is received by channel data 
receiver 36 for processing by logic 38. Information concerning receiver 
status and identification of the receiver is forwarded to memory 40 and 
stored therein. At the same time, real time clock 42 provides the time of 
day for storage in memory 40. The data from memory 40 is forwarded back to 
control logic 44 for insertion into recognition logic 48, so that upon 
subsequent reception of the same information from each receiver, the 
memory is not updated with repetitive information. Instead, when a change 
in status occurs (e.g., change in channel reception or on/off status of 
the receiver), data concerning the new status is inserted into the memory 
40. Thus, memory 40 contains data concerning the time period that each 
receiver was tuned to each channel. 
Periodically, and preferably during a period of late night and early 
morning hours, the central station connected to communication channel 48 
by a suitable telephone link automatically dials the telephone number of 
the household to gain access to the memory 40 through household 
transmitter 46, logic 44 and logic 38. At that time, the data within 
memory 40 is read out of necessary through logic 44 and is transmitted via 
communication channel 48 to the central station for collating with other 
data from other household receivers. 
The transmission link 74 between channel data transmitters 34 and channel 
data receiver 36 may be any suitable communication link, such as radio 
frequency transmission at low power or power line transmission. It is 
preferred that all transmitters 34 within a particular household be tuned 
to the same carrier frequency to avoid interference between households so 
that data from one particular household is not collected by the household 
collector of another household. While a small risk exists that data from 
two or more television monitors within a particular household may be 
transmitted at precisely the same time, it is preferred that each 
oscillator 72 within transmitter 34 be adjusted to a slight variance from 
one second oscillation so that coincident transmission will occur only in 
a small percentage of cases. Further, data transmitters 54 of each 
television monitor are preferably adjusted to confine data transmission to 
less than 100 milliseconds so that the chance of overlap of data 
transmission from two or more television monitors is minimized. In those 
few cases where transmission from two or more television monitors occurs 
at precisely the same time, the information received by data receiver 36 
in the household collector will not be recognized by recognition logic 38, 
so that data will be discarded, but new data will be received from each 
television receiver approximately one second later. 
FIG. 3 illustrates a television receiver monitor for situations where a 
household may have only one television receiver to be monitored. The 
system illustrated in FIG. 3 is basically similar to that illustrated in 
FIG. 1, except that data transmitter 34 and data receiver 36 have been 
eliminated, as has communication channel 74. Thus, the apparatus 
illustrated in FIG. 3 is connected to a single set and provides channel 
data and set status directly to a central station. 
One feature of the present invention resides in the fact that antenna 
coupling 24 switches the antenna input to receiver 16 between the 
television antenna 26 and the signal oscillator 22. This prevents spurious 
rebroadcast of signals from oscillator 22 by way of antenna 26, and 
permits accurate identification and insertion of signal frequencies within 
the frequency of each channel to be received directly onto the antenna 
leads of the television receiver. Further, in the event of malfunction of 
the apparatus, the home owner may disconnect the television monitor by 
merely reconnecting the antenna 26 directly to the antenna leads of 
receiver 16. 
The apparatus according to the present invention is useful for television 
monitoring for the purposes of audience measurement surveys, fare 
collection, etc., and is simple and efficient in operation. The apparatus 
is relatively inexpensive, thereby permitting the production of a great 
number of monitor units to increase the number of monitored receivers for 
audience measurement purposes. In this regard, a plurality of individual 
television monitors 12, 14, may be provided in any particular household, 
apartment house, etc., each connected to a single household collector 10 
which receives and collects the data from each television monitor. By 
providing a unique address for each television monitor, information may be 
collated concerning the programs received by each receiver. This 
information will be particularly valuable in connection with demographic 
studies wherein particular sets are ordinarily viewed by particular 
people, such as childern, adults, etc. Thus, a television receiver located 
in the living room or family room of a home would be most likely viewed by 
the entire family, whereas television receivers located in children's 
rooms might more likely be viewed by the children. 
This invention is not to be limited by the embodiments shown in the 
drawings and described in the description, which are given by way of 
example and not of limitation, but only in accordance with the scope of 
the appended claims.