Hughes Aircraft Company

Multilink Group

James W Henderson

Guy B Coleman

Jacob M Sacks

Jack Sacks

A multiplexer for compressing two television programs into the bandwidth normally required for a single television signal is disclosed wherein vertically adjacent lines in the odd and even field of each frame are summed and differenced in pairs having the same color subcarrier phase. 'Line pair signals' respectively comprising the sum and difference of each line pair are then formed after the difference signal is time compressed without an overall increase in bandwdth. The line pair signals for each frame of one program are alternately transmitted with the line pair signals of a frame from the second program. The line pair signals of a video frame are fewer in number and longer in duration than NTSC field lines. Timing is such that one frame of both programs is transmitted during the time allotted to the transmission of one frame under the NTSC standard. The lines from odd fields of each program are reconstructed after transmission by adding the appropriate difference signals and sum signals. The lines from even fields are reconstructed by differencing the sum signals and the difference signals.

Method and apparatus for multiplexing television signals

Operating at real-time data rates, the disclosed hardware network generates a signal which closely approximates the Mth-largest of a set of R input data signals. The operational basis of this network is a comparison (121-127) between the input data (101-107) and a monotonically-scanning reference function (110). At that point (140, 150, 160) when the lower (R-M+1) of the inputs have been equaled by an increasing reference, the reference has become the same as the Mth-largest and is used (119b, 165, 170, 175) as the filter output. Analogous operation is achieved with a decreasing reference. When the number R of inputs is odd and M is made equal to ((R+1)/2), the network becomes a real-time median filter.

Real-time ordinal-value filter utilizing reference-function comparison

Operating at real-time data rates, the disclosed hardware apparatus determine which one of a set of R input data signals is the Mth-largest. Mutual comparisons between the data values themselves provides the basis for the mechanized determination schemes. After every data signal is pair-wise compared (112-167) with every other data signal, each subset of results (C12-C17, C12-C27, C13-C37, C14-C47, C15-C57, C16-C67), consistng of the outcome of the comparisons between a given data signal and all other data signals, is tested (210-260) to determine whether the results indicate that (M-1) of the other data signals are greater than the given signal. That data signal whose result set satisfies this (M-1) condition is the Mth-largest and is used (270, 280) as the network output (285). For data that is serially-presented (490,400) a network simplification makes set-testing possible after only one data value, that most-recently-presented, is compared (412-417) to all other (R-1) signals of the set. The simplification entails reducing the number of comparators utilized, while employing storage elements (512-567) to preserve for set-testing purposes the appropriate ones of the results of comparisons made prior to the presentation of the most-recent serial data element. When the number R of inputs is odd and M is made equal to (R+1)/2, the networks become real-time median filters.

Real-time ordinal-value filters utilizing complete intra-data comparisons

Operating at real-time data rates, hardware logic networks (FIGS. 3-6) receive onto a data-channel array (390 in FIG. 3) a set of unordered input data values and iteratively pair-wise transpose the set members until their positional order on the array coincides with the order the members would assume if their magnitudes were arranged according to sequential ordinal rank. Pair-wise comparisons between the data values themselves provide the basis for the mechanized pair-wise transposition schemes. Within each network, a key building block for performing both the pair comparisons and member transpositions is a Number Pair Orderer (NPO) (FIG. 2). Each NPO compares (210) two data elements and passes the smaller to one of its outputs (240), while passing the larger to the other of its outputs (260). Individual NPO's are arranged into two groups (311-315 and 321-325), each of which operates iteratively upon pairs of substantially all of the data values. The data-channel array, mechanized in a recirculatory configuration, carries the data back and forth between the two NPO groups. By making the pairs ordered by one NPO group mutually offset from the pairs ordered by the other group, a pair-to-pair transfer of unordered data elements to array positions beyond adjacent channels is accomplished. The recirculatory pair-wise ordering action is complete when the data has passed through the alternate NPO groups a sufficient number of times to enable a maximally-unordered set to be transposed into proper sequence. The networks become real-time median filters when configured to receive an odd number R of inputs and the ((R+1)/2)nd-largest member of the final ordered set is selected as the overall network output.

Growing community of inventors

Woodland Hills, CA, United States of America

James W Henderson