Multi frequency receiver

Claim 2

A multi-frequency receiver for receiving, validating and transmitting valid signals wherein a valid signal comprises a tone of a first group and a tone of a second group both within voice frequency range, comprising means for rejecting tones of lower than a predetermined minimum amplitude, means for separating tones into said first and second groups, means for amplifying said tones and for further separating said tones into selected specific tones within each group, control means receptive of tones from said first and second group of at least predetermined minimum amplitude, means responsive to tones received from both said groups for comparing the amplitude of the received tones to amplitude standards, means responsive to a tone in each group greater than said standards for actuating a timing sequence, individual latch means for each group actuated to start said timing sequence and responsive to both said tones continuing at above said amplitude standard for a predetermined period for maintaining said timing sequence in effect, means responsive to the end of said timing sequence for emitting an accept signal, said memory means responsive to said accept signal for enabling the storage of said received tones, and further means operative to translate received tones into a binary decimal code.

Claim 3

A receiver as claimed in claim 1, wherein said latch means comprises a four input, two gate latch network for each of said groups.

Claim 4

A receiver as claimEd in claim 1, wherein all said tone separating means and said tone rejecting means comprise active filter networks.

Claim 5

A receiver as claimed in claim 1, wherein said further separating means comprise a plurality of filter circuits, each tuned to pass tones of a specific frequency, a pair of operational amplifiers serially connected in each of said filter circuits, and means for tuning each of said amplifiers for frequencies on each side of said specific frequency to approximate a flat peak response band.

Claim 6

A multi-frequency receiver for receiving individual tones of multi-frequency signals, wherein each of said tones comprises one or more signals in either a high or a low frequency group within the voice frequency range, the invention comprising: a plurality of combined filtering and amplifying stages for passing only a selected signals for each group within said range, a plurality of frequency selective stages with a separate active filter for each frequency selected, means commonly connected to the filters of each group and responsive to a frequency signal transmitted through a filter of each group for comparing said signals against amplitude standards, means responsive to both said signals exceeding said standards for initiating a timing sequence, means responsive to failure of continuation of either signal to exceed said standard after less than a full timing sequence for resetting said initiating means, and memory means for each signal frequency maintained in a disabled state by the resetting of said timing sequence.

Claim 7

A multi-frequency receiver for receiving individual tones of multi-frequency signals, wherein each of said tones comprises one or more signals in either a high or a low frequency group within the voice frequency range, the invention comprising: a plurality of combined filtering and amplifying stages for passing only a selected signals for each group within said range, a plurality of frequency selective stages with a separate active filter for each frequency selected, means commonly connected to the filters of each group and responsive to a frequency signal transmitted through a filter of each group for comparing said signals against amplitude standards, means responsive to both said signals exceeding said standards for initiating a timing sequence, means responsive to failure of continuation of either signal to exceed said standard after less than a full timing sequence for resetting said initiating means, and memory means for each signal frequency maintained in a disabled state by the resetting of said timing sequence.

Claim 8

A receiver as claimed in claim 5, wherein said initiating means comprises a gate circuit for each of said frequency groups, amplitude comparing means for each of said groups, said resetting means responsive to said amplitude comparing means sensing a signal of less than a predetermined amplitude in either of said groups for resetting said initiating means.

Claim 9

A receiver as claimed in claim 6, wherein said resetting means comprises an inverter latch network for each of said groups.

Claim 10

A receiver for a multi-frequency telecommunications signals comprising a plurality of cascaded stages of which there is a first stage including means for amplifying a frequency signal input and for rejecting all frequencies below a first minimum frequency, a second stage comprising a high and a low band pass filter network for passing frequency signals within the pass bands of the two filter networks, a third stage comprising a limiter circuit for each filter network for developing a square wave form for each frequency signal received; a plurality of selective band pass filter networks comprising the fourth stage of said network, said last-mentioned networks including means for passing only signals above a predetermined minimum amplitude level, a fifth stage comprising means for testing passed signals against an amplitude comparison standard, amplifier means responsive only to signals of higher amplitude than said standard for causing the initiation of a timing sequence, means for monitoring the continuance of said passed signals at higher amplitude than said standard for a predetermined time interval comprising said sequence, said monitoring means responsive to the discontinuance of at least one of said signals for terminating said timing sequence, means responsive to the normal ending of said timing interval for emitting an enabling signal, a memory stage for receiving frequency signals from said amplifier means, and means responsive to the termination of said sequence for disabling said memory stage from receiving said signals for storage.

Claim 11

A receiver for a multi-frequency telecommunications signals comprising a plurality of cascaded stages of which there is a first stage including means for amplifying a frequency signal input and for rejecting all frequencies below a first minimum frequency, a second stage comprising a high and a low band pass filter network for passing frequency signals within the pass bands of the two filter networks, a third stage comprising a limiter circuit for each filter network for developing a square wave form for each frequency signal received; a plurality of selective band pass filter networks comprising the fourth stage of said network, said last-mentioned networks including means for passing only signals above a predetermined minimum amplitude level, a fifth stage comprising means for testing passed signals against an amplitude comparison standard, amplifier means responsive only to signals of higher amplitude than said standard for causing the initiation of a timing sequence, means for monitoring the continuance of said passed signals at higher amplitude than said standard for a predetermined time interval comprising said sequence, said monitoring means responsive to the discontinuance of at least one of said signals for terminating said timing sequence, means responsive to the normal ending of said timing interval for emitting an enabling signal, a memory stage for receiving frequency signals from said amplifier means, and means responsive to the termination of said sequence for disabling said memory stage from receiving said signals for storage.