Diversity switch for digital transmission

Claim 2

Diversity apparatus comprising: means for transmitting a plurality of identical digital bit streams, route diversity means for transmitting a plurality of bit streams on diverse transmission paths, each of said paths having independently varying transmission times, means for receiving said plurality of bit streams differing in arrival times of corresponding bits, a plurality of storage means, means for storing said plurality of bit streams bit-by-bit in corresponding ones of said plurality of storage means, means for simultaneously removing from storage corresponding bits of said plurality of bit streams under control of a timing signal, said signal being continuously determined by the varying arrival times of the bits of a selected one of said bit streams, a utilization circuit, and means for selectively connecting one of said plurality of bit streams to said utilization circuit.

Claim 3

Diversity apparatus as claimed in claim 1 wherein each of said plurality of storage means is an elastic store having individual write-in and readout control and wherein an identical timing signal controls the readout of said each elastic store.

Claim 4

Diversity apparatus as claimed in claim 2 wherein at any one time one of said plurality of bit streams is an active bit stream selectively connected to said utilization circuit and said identical timing signal is extracted from said active bit stream.

Claim 5

Diversity apparatus as claimed in claim 3 wherein said idle bit stream is written into an idle elastic store having an occupancy determined by the delay between the write-in and readout of each cell therein and wherein the occupancy of said idle elastic store is periodically increased under control of an error signal, said error signal existing when said active and said idle bit streams read out of their respective stores are out of synchronization.

Claim 6

In a digital signal receiver receiving two signals carrying identical digital information, diversity apparatus comprising: a utilization circuit, a diversity switch for selecting one of said two signals and connecting said one signal to said utilization circuit exclusive of the other of said two signals, a first elastic store, means for writing said other signal into said first store at its received rate, extracting means for deriving a timing signal from said one signal, means for reading said other signal from said first store upon demand of said timing signal, comparison means for detecting a timing difFerence between said one signal and said other signal being read out and producing an error signal during the occurrence of said difference, and first stepping means under control of said error signal for delaying the reading of said other signal whereby said other signal is synchronized with said one signal.

Claim 7

In a digital signal receiver receiving two signals carrying identical digital information, diversity apparatus comprising: a utilization circuit, a diversity switch for selecting one of said two signals and connecting said one signal to said utilization circuit exclusive of the other of said two signals, a first elastic store, means for writing said other signal into said first store at its received rate, extracting means for deriving a timing signal from said one signal, means for reading said other signal from said first store upon demand of said timing signal, comparison means for detecting a timing difFerence between said one signal and said other signal being read out and producing an error signal during the occurrence of said difference, and first stepping means under control of said error signal for delaying the reading of said other signal whereby said other signal is synchronized with said one signal.

Claim 8

Diversity apparatus as claimed in claim 5 wherein said apparatus includes a second elastic store into which said one signal is written and wherein the readout of said first and second elastic stores occurs upon demand of said timing signal and wherein said first stepping means alters the relative occupancy between said first and second elastic stores.

Claim 9

Apparatus as claimed in claim 6 wherein said stepping means causes the readout from said first elastic store to fail to read during a single time slot.

Claim 10

Apparatus as claimed in claim 7 wherein said apparatus includes a phase comparator for sampling the occupancy of said second elastic store and producing an indication when occupancy exists below or above a preselected threshold and auxiliary stepping means for increasing said occupancy of said second elastic store upon the occurrence of said indication.

Claim 11

Apparatus as claimed in claim 5 further including an inhibit circuit for preventing the operation of said first stepping means in the event that said two signals are inadequate for service.