DAS Installation R.H.F. 21/7/97 **************** Mounting -------- Release bin from packing case by withdrawing flange locaters using obvious finger holes. Lift bin (weight ~40kg) by means of front thumbscrews and handles on rear transport cover. The assembly is normally fully supported in a rack by the front flange. If rear support is considered necessary remove the transport cover and note the position of four large holes provided at the rear of the side panels, and make custom brackets to suit the rack. Because of the weight it may be necessary to remove modules from the bin before installing it in the rack. Begin by loosening the thumbscrews with the aid of a 5mm ball-driver or Allen key, and unscrew them until they clear the internal thread. Do not unscrew them from the front panels. Place the tines of the module extraction tool ("jemmy") under the rim of a bollard on the first module (starting from the left end) and lean it against the bollard on the adjacent module. There is a shallow cusp on the rear of the jemmy to secure its position. Steadily lever out the first module. Repeat until only the N4 module remains. It can be pulled out by hand. When restoring the modules, slide them gently into position until the connectors begin to engage. At this stage firm pressure will make a little progress but is rarely sufficient to seat them properly. Wind the module into position by progressively tightening the thumbscrews until the front panel is tight against the mounting rails. The module order is N2 N3 N2 N3 D3 N4. If possible leave the transport cover in place while installing the bin in the rack. After removing it immediately replace the screws in the bin as they are part of the construction! Be careful to start the screws in their original threads as they are tapered self-tappers and it is easy to cross-thread them in the aluminium bin rails. Do not replace modules while these screws are absent. About 1" of clear space should be left above and below the assembly to allow efficient ventilation. Most modules draw air in through the front panel fans and exhaust through their side panels, but the N4 Power Supply module relies on convection from below. Power ----- A mains cord with IEC format plug is required. If the power supply has been strapped for 115V the IEC socket will be so labelled. The default setting is 240V. Time & Frequency References --------------------------- a) Full system (N2 modules present, IF signal inputs) ''''''''''''''' Connect clean (integrated phase noise < -70dBC) 5MHz CW at +5 to +13dBm to 5MHz REF. The input is terminated by 50 Ohms. While the DAS will lock to lower levels sampling noise begins to rise below +5dBm. Levels in excess of +16dBm may cause damage. Connect a 1PPS TTL pulse to SYNC INPUT. This signal MUST MAINTAIN TRUE TTL LEVELS INTO A 50 OHM TERMINATION. IE. 0 < Vmin < 0.8V AND 2.0V < Vmax < 3V. To ease the strain on common "50 Ohm" drivers the internal 50 Ohm termination has been returned to 0.8V rather than ground. Leave BLANK IN and CLK IN connectors empty. Put CLK and SYNC jumpers JP13..JP20 in the INTERN (lower) position. b) Partial system (N2s absent, digital data inputs) ''''''''''''''''' Signal Inputs ------------- a) Full system (N2 modules present, IF signal inputs) ''''''''''''''' Connect broadband (DC-1GHz) or <= 64MHz bandlimited IF signals in the range DC-192MHz to IF CH1 and IF CH2. Input levels are -41 to -29dBm/MHz for broadband inputs or -24 to -12 dBm for pre-filtered inputs. Use semi-rigid cable (preferably) or filled-braid semiflexible coax and torque all connectors. These measures are essential to prevent breakthrough from 32MHz data and clock signals, especially in the presence of digital correlators. The HIGH/LOW NIBBLE IN/OUT connector pairs should be joined together by the cables provided. b) Partial system (N2s absent, digital data inputs) ''''''''''''''''' Computer Control Interface -------------------------- a) DAS as element of a Data Set Bus (RS-485 in and out) ''''''''''''''''''''''''''''''''''''''''''''''''''''''' Link the DAS into the chain using the two DATASET RS485 connectors. If the DAS is the last element on the DSB place a terminator in one of them. The connector format is described in [1] para. 1.1 . Move 'Ser.Input' jumpers JP3..JP6 to RS-485. Set the allocated Data Set Address using 'Dataset Adr' jumpers JP8..JP12 (OFF ==> 0, ON ==> 1, ADR0 is LSB). b) DAS as head element of a Data Set Bus (RS-232 in; RS-485 out) ''''''''''''''''''''''''''''''''''''''''''''''''''''''' Connect an RS-232 line to DATASET RS232 and use either of the DATASET RS485 connectors to connect the DSB to the next element in the chain. The connector formats are described in [1] para. 1.1 . Move 'Ser.Input' jumpers JP3..JP6 to RS-232. Set the allocated Data Set Address using 'Dataset Adr' jumpers JP8..JP12 (OFF ==> 0, ON ==> 1, ADR0 is LSB). c) DAS as stand-alone RS-232 device ''''''''''''''''''''''''''''''''''' Configure as for b) above, but leave both DATASET RS485 connectors empty. Leave all 'Dataset Adr' jumpers JP8..JP12 OFF, ie. DSA = 0. Other Jumpers ''''''''''''' 'Channel Addr' Jumpers JP1 and JP2 should be OFF (==> 0) and ON (==> 1) respectively. Move 'Baudrate' jumper JP7 to select a signalling rate of 38400bd or 4800bd as required. S2 Output --------- For most S2 modes connect the S2 C1 cable to S2 RECORDER OUT. In certain cases plug the S2 C1 cable into S2 AUX and plug the short "mode converter" cable from S2 AUX into the S2 RECORDER OUT socket. See [2] for details. Correlator Outputs ------------------ a) Multibeam Correlator ''''''''''''''''''''''' Connect the 128MHz and 32MHz outputs to the corresponding clock inputs in the correlator block. Connect a data cable from CORR OUT CH1/CH2 to the correlator input. Cable details are in [1] para 1.9 . b)AT Correlator via Delay Unit '''''''''''''''''''''''''''''' c)AT Correlator direct '''''''''''''''''''''' Analog Monitor Outputs ---------------------- It is probably desirable to cable these to a patch panel accessible from the front of the rack. References ---------- [1] "LBA DAS Backplane Connectors and Jumpers" [2] "LBA DAS to S2 Interface"