Memory organization and output sequencer for a signal processor

A specialized tone receiving apparatus of the type which is connected to a time division multiplexed digital signal bus carrying time division multiplexed pulse code modulated plural digital signal sample sequences corresponding to associated plural independent speech channels, said apparatus comprising:

• input buffer memory means for temporarily storing said bus digital signal sample sequences;
• write sequencer means connected to said memory means and also connected to said digital signal bus for writing said plural digital signal sample sequences into said input buffer memory means, the sequence of samples corresponding to each of said plural independent speech channels being written into said memory means in a first sequential chronological order;
• read sequencer means connected to said memory means for selecting one of said plural independent speech channels and for reading the signal sample sequence corresponding to said selected speech channel from said memory means in a second sequential chronological order opposite said first chronological order;
• and
• digital signal processing means connected to receive said read signal sample sequence for detecting at least one prespecified frequency component within said read signal sample sequence.

A specialized tone receiver of the type which is connected to a digital signal bus carrying a pulse code modulated digital signal sample stream corresponding to a speech channel, said receiver comprising:

• input buffer memory means for temporarily storing said digital signal sample stream;
• write sequencer means connected to said memory means and also connected to receive said digital sample stream for writing said digital signal sample stream into said input buffer memory means in a sequential chronological order;
• read sequencer means connected to said memory means for reading said written digital signal sample stream from said memory means more than once;
• and
• digital signal processing means connected to receive said read digital signal sample streams for detecting a first prespecified frequency component within said read digital signal sample stream the first time said read sequencer means reads said digital signal sample stream and for detecting a second prespecified frequency component within said read digital signal sample stream a subsequent time said read sequencer means reads said digital signal sample stream.

A method of receiving and detecting specialized tones on a digital signal bus carrying a pulse code modulated digital signal sample stream corresponding to a speech channel, said method comprising the steps of:

• temporarily storing said bus digital signal sample stream in an input buffer memory;
• writing said sample stream into said input buffer memory in a first sequential chronological order;
• reading said written sample stream from said input buffer memory in a second sequential chronological order opposite said first chronological order;
• and
• detecting at least one prespecified frequency component within said read sample stream.

A specialized tone receiving method for receiving and detecting specialized tones simultaneously in plural independent time division multiplexed PCM speech channels each carrying a corresponding digital sample sequence, said method comprising the steps of:

• temporarily storing said digital sample sequences carried by said plural speech channels in an input buffer memory.
• writing said digital sample sequences into said memory, including the step of writing each of said sample sequences in a first sequential chronological order;
• selecting one of said speech channels;
• reading the signal sample sequence corresponding to said selected speech channel from said input buffer memory in a second sequential chronological order opposite said first chronological order;
• and
• detecting at least one prespecified frequency component within said read signal sample sequence.

A method for detecting specialized tones in a pulse code modulated digital signal sample stream corresponding to a speech channel, said method including the following steps:

• (a) continually writing portions of said digital signal sample stream into a memory;
• (b) temporarily storing the written portions of said digital signal sample stream in said memory;
• (c) reading a written digital signal sample stream portion from said memory;
• (d) detecting a first prespecified frequency component within said read sample stream portion read by said reading step (c);
• (e) again reading said written digital signal sample stream portion from said memory;
• and
• (f) detecting a second prespecified frequency component different from said first component within said read sample stream portion read by said again reading step (e).