Abstract: There is provided an intercom system which realizes high-quality image display and communication with low cost. In the intercom system, front door slave unit 300 having an attached camera and master unit 400 are connected to each other through a two-wire cable, and communication between front door slave unit 300 and master unit 400 is performed with transmission and reception of an image signal. Front door slave unit 300 packetizes a control signal, an image signal, and a sound signal of front door slave unit 300, generates an uplink signal, and transmits the generated uplink signal to master unit 400. Master unit 400 packetizes a control signal and a sound signal of master unit 400, generates a downlink signal, and transmits the generated downlink signal to front door slave unit 300. Front door slave unit 300 and master unit 400 perform transmission of the uplink signal and transmission of the downlink signal in a manner of time division duplex using the two-wire cable.

Abstract: There is provided an intercom system which realizes high-quality image display and communication with low cost. In the intercom system, front door slave unit 300 having an attached camera and master unit 400 are connected to each other through a two-wire cable, and communication between front door slave unit 300 and master unit 400 is performed with transmission and reception of an image signal. Front door slave unit 300 packetizes a control signal, an image signal, and a sound signal of front door slave unit 300, generates an uplink signal, and transmits the generated uplink signal to master unit 400. Master unit 400 packetizes a control signal and a sound signal of master unit 400, generates a downlink signal, and transmits the generated downlink signal to front door slave unit 300. Front door slave unit 300 and master unit 400 perform transmission of the uplink signal and transmission of the downlink signal in a manner of time division duplex using the two-wire cable.

Abstract: In a facsimile apparatus having a magnetic tape recording apparatus for data storage and a buffer memory for data transfer to and from the recording apparatus, with the data being temporarily held in the buffer memory as respective blocks in a set of records, a synchronizing signal is inserted at the start of each recorded block of data, and the synchronizing signals are detected subsequently during playback of the recorded data. During playback, a buffer memory address generating circuit which specifies respective records and intra-record addresses for writing the playback data into the buffer memory, is reset to either the initial address of the current record or the initial address of the succeeding record each time a synchronizing signal is detected, in accordance with the position where the detection occurs within the addresses of the current record. The effects of an error in the playback data can thereby be limited to the data block in which the error occurs, without propogating to subsequent blocks.

Abstract: This invention relates to novel saccharoascorbic acid derivatives and their production. The derivatives are represented by the general formula set forth below, for example, an amido, a thioester or carboxylic ester of saccharoascorbic acid, and their salts.The compounds of the present invention are useful for food additives as antioxidants, an intermediate for the production of dichiral compounds and medicines having antithrombotic activity. ##STR1## wherein Z represents ##STR2## --SR.sub.6 or --OR.sub.7, R.sub.4 and R.sub.5 independently represent hydrogen or a hydrocarbon group of 1 to 24 carbon atoms, or R.sub.4 and R.sub.5 may together form --CH.sub.2 --.sub.n in which n is an integer of 4 to 7, R.sub.6 represents a hydrocarbon group of 1 to 24 carbon atoms, R.sub.7 represents hydrogen or a hydrocarbon group of 1 to 24 carbon atoms, R.sub.1, R.sub.2 and R.sub.3 independently represent hydrogen, an acyl group of 1 to 18 carbon atoms or a hydrocarbon group of 1 to 24 carbon atoms, and .about.