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Tape Address Detection Circuitry

IP.com Disclosure Number: IPCOM000074017D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Schaefer, WC: AUTHOR [+2]

Abstract

This address error detection system improves the reliability of contemporary systems by several orders of magnitude. The subsystem consists of a tone burst generator which writes address marks on a tape and a tone burst detector which reads these marks. The tone burst generator, not shown, delivers alternating short and long bursts of 500 Hz which are recorded on one track of a magnetic tape by a tape recorder. This tape contains two tracks: one track contains audio messages which are voice waves from a microphone: the other contains the alternately short and long tone bursts which occur between the audio messages on the first track. These tone bursts are used to count the number of audio messages on the first track. During normal play operation, the tone bursts are 500 Hz.

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Tape Address Detection Circuitry

This address error detection system improves the reliability of contemporary systems by several orders of magnitude. The subsystem consists of a tone burst generator which writes address marks on a tape and a tone burst detector which reads these marks. The tone burst generator, not shown, delivers alternating short and long bursts of 500 Hz which are recorded on one track of a magnetic tape by a tape recorder. This tape contains two tracks: one track contains audio messages which are voice waves from a microphone: the other contains the alternately short and long tone bursts which occur between the audio messages on the first track. These tone bursts are used to count the number of audio messages on the first track. During normal play operation, the tone bursts are 500 Hz. During fast playback operation, the tone burst frequency coming off the tape increases to 13 KHz.

The tone burst detector serves to detect the burst coming from the second track through read head 10 connected to input terminals 12. Amplifier and limiter stage 14 serves to amplify the read back signal and square it up. These square- wave pulses then enter a 165 ms stairstep generator 16, a 55 ms generator 18 and absence detector 20. The output voltage of 165 ms stairstep generator 16 builds up relatively slowly in a stairstep fashion and trips a connected Schmitt trigger 22 when 100 ms of tone burst has been received. The output of 55 ms stairstep generator 18 builds up relatively fast in a stairstep fashion and trips Schmitt trigger 24 when 40 ms of tone burst has been received. A 50 ms single- shot circuit 26 delivers an up level output for 50 ms eve...