TELEMETRY SYSTEMS

• US 3,587,077 A
• Filed: 08/21/1968
• Issued: 06/22/1971
• Est. Priority Date: 08/23/1967
• Status: Expired due to Term

• Current Assignee: Kaldor Andrew Ferdinand, Stellema Lammert
• Original Assignee: Kaldor Andrew Ferdinand, Stellema Lammert
• Inventors: KALDOR ANDREW FERDINAND, STELLEMA LAMMERT
• Application Number:
  US04/754,210
• Time in Patent Office: 1,035 Days
• US Class Current: 340/870.07
• CPC Class Codes: H04H 60/43 for identifying broadcast channels
• CPC Class Codes: H04H 60/76 Arrangements characterised by transmission systems other than for broadcast, e.g. the Internet for broadcast H04H20/65
• CPC Class Codes: H04Q 9/12 using combinations of frequencies

Abstract

Telemetry equipment for use in an Audience Survey System for ascertaining at a central control the program channels to which wave signal receivers are tuned at a plurality of remote preselected locations, comprising a single transmission path between the control and remote locations, an interrogation transmitter at the control center, a carrier frequency for transmission from the central control, sources of audio tones, means for grouping two or more of the tones to modulate the carrier, a different grouping of the tones being assigned to be representative of individual wave signal receivers, a transceiver at each remote location for receiving the modulated carrier, means for detecting the modulating tones thereat to initiate transmission of a reply from a respectively remote location which corresponds to the grouping of the modulating tones, means for modulating the reply signal to indicate the program to which the wave signal receiver is tuned at the remote location, and detection means at the central control for deriving from each received reply signal an indication of the tuning of the respective wave signal receiver.

Claims

1. An Audience Survey System comprising a central control and remote signalling units connected with household wave signal receivers tuned to programs, a transmitter at the central control, means for activating the transmitter during a first part of every time slot in a repetitive cycle of time slots to transmit an interrogation signal composed of a carrier modulated to identify in each time slot a respective one of the remote signalling units, means at each remote signalling unit to receive the interrogation signals and to respond thereto with a reply signal during a second part of the respective time slot when that signalling unit corresponds with the modulated identification conveyed by the interrogation signal, a transmitter at each of the remote signalling units,

2. An Audience Survey System according to claim 1, wherein the central control comprises a plurality of audio tone oscillators, gating devices connecting the oscillators to the central control transmitter for modulating the carrier signal, and a cycling generator connected to the gating devices to open successively predetermined groupings of the gating devices whereby an individual group of three audio tones are simultaneously applied to the transmitter in each time slot to prOvide said identification modulation of the carrier.

3. An Audience Survey System according to claim 2, wherein a triple track recording medium is provided at the central control to receive three groups of signals indicating, respectively, the time, identification of the remote station, and the condition signalled from the remote station, whenever a reply signal is received.

4. An Audience Survey System according to claim 1, wherein said circuit is an RC network.