7912: Difference between revisions

The '''Tektronix 7912''' was a series of high-speed digitizers that take one [[7000-series_plug-ins#Vertical plug-ins|7000-series vertical plug-in]] and one [[7000-series_plug-ins#Horizontal plug-ins|7000-series horizontal plug-in]].   

The signal from the vertical plug-in deflects a writing beam through [[distributed deflection plates]]. The electrons hit a small flat rectangular solid state target, conceptually similar to the image sensor in a digital camera. The resolution of the target is 512×512, giving 512 points in the time domain and 9-bit linear quantization of the input voltage.

With a [[7B92]] sweeping the whole X-axis in 5 ns, and the 7912 capturing 512 samples in that sweep, the 7912 performs the function of a 100 GSample/s A/D converter.

The '''R7912''', introduced in September 1973 (Ref.1), achieved a bandwidth of 500 MHz with a [[7A19]] vertical amplifier plug-in. It was also possible, like in the [[7904]] scope,  to access the CRT deflection plates directly through a [[7A21N]] plug-in and achieve a bandwidth of 1 GHz, albeit at reduced sensitivity (4 V/Div) and loss of triggering and readout functions. Some customers further modified the stock 7912 to increase bandwidth up to 3 GHz in special applications (see literature links below).

The reading beam operates differently depending on the output mode. In TV mode, the reading beam scans the target in a horizontal format similar to that used in conventional television systems, and a video output compatible with TV monitors is generated. In Digital mode, the reading beam scans the target vertically, in 512 discrete steps for each of 512 horizontal positions. Waveforms are converted to digital, stored in memory, and can be read by a computer.

The R7912 used the [[7000 series readout system]] writing readout characters onto the storage target, which would become part of the output signal in the NON STORE mode.

From the '''7912AD''' (1978) on, the instrument had a standard [[GPIB interface]]. The 7912AD has 500 MHz bandwidth.  It was succeeded by the 750 MHz 7912HB in 1987 (using a [[7A29P]] amplifier).  

For the 7912AD and 7912HB, special GPIB-controllable plug-in modules with a 'P' suffix, meaning Programmable, were available, e.g. [[7A16P]], [[7A29P]] and [[7B90P]].