Patent GB-898607-A (GB)
Title: Improvements in or relating to methods of and apparatus for monitoring the use of radio receivers
IPC: H04H60/31
Filed: 1958-09-18
Abstract: 898,607. Radio receiving apparatus. NIELSEN CO., A.C. Sept. 18, 1958 [June 9, 1958], No. 29955/58. Class 40(5). In a system for providing, at a central station, a record which indicates on a minuteby-minute basis the numbers of radio receivers in a sample which are tuned to receive particular radio transmissions, there is provided in association with each receiver an attachment 21 which delivers an output corresponding to the tuning condition of the receiver, the outputs of all the attachments 21 being taken over telephone lines to a central office where in each minute, the number of receivers tuned to each radio transmission is totalled and a corresponding record printed. In the arrangement illustrated a record is provided of the number of receivers tuned to each of four particular stations A, B, C, D; in addition the total number of receivers operative and an indication of the time of the recording are simultaneously recorded. Hence each receiver attachment may provide one of five different possible D.C. output-voltage levels; four corresponding to the four radio stations and the fifth corresponding to reception of some further unidentified transmission. These D.C. outputs are applied through telephone exchange 23 to the central office where they enter a classifier unit 26. Under the control of a sequence controller 41 which is initiated once per minute from a timer 42 the classifier unit 26 samples in turn the signals it receives over the telephone lines once each minute and supplies corresponding outputs to the various "accumulators" 30-39. An output is supplied to accumulators 30 and 35 whenever the sampled incoming signal indicates that the corresponding receiver is operative; furthermore if the incoming signal indicates that one of the four stations A, B, C or D is being received an output is supplied to the corresponding ones of each of the groups of accumulators 31-34 and 36-39. These accumulators comprise stepping switches which consequently are advanced in accordance with the total number of receivers in the sample operative or tuned to receive the appropriate transmission as the case may be. After the sampling by unit 26 has been completed, the totals accumulated in units 30-34 are applied to a printer 40 whereafter a "print order" is delivered thereto from the sequence controller and a record of the contents of these accumulators is printed. In addition, for one minute of each quarter hour, the timer alters the operation of the sequence controller so that after the contents of accumulators 30-34 have been recorded those of accumulators 35-39, representing 15-minute totals are printed. Alter the contents of the accumulators have been recorded the accumulators are reset and a further cycle of operation commences at the beginning of the next minute period as determined by the timer 42. There are also applied to the printer members signifying the minute of the quarter hour and the quarter hour of the day so that a record of the time correspcnding to each record is associated with it. The system also provides an indication of whether the programme radiated from each of stations A, B, C and D is the same as that transmitted by a corresponding national network (shown also as A, B, C, D). The network programmes which are supplied to the central office are compared with the outputs of receivers 48, 49, 50, 51 tuned respectively to stations A, B, C, D, in the programme analyzer 44. The pairs of inputs are sampled in turn and an output is sent to the printer which indicates whether or not the two received signals are the same. If the signals are the same for at least 10 minutes in each quarter hour the printer prints a "9" at the end of the 15-minute period after the contents of all the accumulators have been printed; otherwise a "1" is printed. Once per day, in the small hours of the morning, the timer alters the operation of the system to cause the unit 26 to send interrogating signals in turn to each of the receiver attachments 21. If these are operating correctly they reply with an appropriate sequence of signals (i.e. in turn those corresponding to reception of stations A, B, C, D and unidentified reception). Should any of these signals be incorrectly sent, a self-holding relay is actuated to short-circuit the appropriate telephone line and prevent signals being received from that attachment for the following 24 hours. Also the total number of attachments 21 which are operating correctly is stored in accumulator 30; at the end of the test period this number is printed. Immediately before the commencement of the next test period the self-holding relays operative are  released. Specification 873,626 is referred to.