Robot 400

The first of the Robot models to incorporate digital techniques and
solid state memories, the 400 represented a major step forward at the
time of its introduction and was possibly their most successful model.

The most noticeable difference between using digital memories to the
previously used display method of phosphor or silicon storage tubes,
is the permanent retention of the received picture in the memory
without fading after a few minutes (whilst the power remains switched
on of course). Flicker-free received pictures with the slow downward
scan of the replacing frame, and the ability to preview transmit
pictures on the fast-scan receiver/monitor were also new experiences.

The features exhibited by the model 400 are generally the expected
norm for modern scan converters:

* Standard 8 second 128 line by 128 pixel transmit and receive, black
and white only with a 16 level grey scale.

* Fast-scan video input 1 volt peak-to-peak into 75 ohms.

* Fast-scan video output 1.4 volt peak-to-peak into 75 ohms.

* SSTV input 20mV to IV into 10k. Signal-to-Noise ratio for noise free
picture 6dB.

* SSTV output 2V peak-to-peak maximum into 1k, adjustable by rear
panel control.

* Snatch controls for brightness and contrast to enable picture level
to be set prior to transmission or storage.

* Receive controls for adjusting contrast and brightness whilst
viewing picture, or is, prior to memory storage.

* "Hold" facility to allow retention of a received frame without it
being updated a by further incoming SSTV.

* Width control to allow reception of pictures from countries using 50
or 60Hz supplies.

* Internal grey scale generator for receiver adjustment or transmission.

Robot 400C

The 400C is actually an upgrade unit for the model 400 giving the
added features of full colour transceive, automatic fine tuning of the
received picture, three picture memories and the capability of
interfacing to the model a 800 for colour graphics.

The upgraded specifications are:

* Transmit speed selectable from: 120 lines at 8 or 12 seconds, or 240
lines at 24 or 36 seconds B&W, 120 lines at 12 or 24 seconds, or 240
lines at 36 or 72 seconds colour.

* Automatic speed tracking of the received picture, allowing reception
of the standard SSTV formats without independent selection.

* Automatic fine tuning within the range +/- 150Hz.

* Three independently selectable memories for storing received or
snatched pictures. The memories can be simultaneously selected to give a
composite picture of all three.