Sstv Black And White

Slow Scan


Louis I Hutton, K1YZZ . 2235 SE 62ND Si Bellevue Washington 98004

For a two year period (1967-1968) i was gran till permission by the FCC to conduct experimental tests with other amateurs authorized for SSTV transmissions on the Hi bands. This is a relatively new mode of communication and has only recently been made available for general amateur use. The interested amateur will soon find that he must construct his own SSTV equipment in order to enjoy this new mode of communication. The first item necessary for SSTV reception is a monitor Details on the construction of an economical monitor may be found in 73 Magazine for July 1967. Once the budding SSTV enthusiast has completed construction of his monitor, he wonders how can he test it? What is needed is some type of signal generator that would generate the various signals required to check out the monitor. Signals of this type are generated by a SSTV Camera1, or a SSTV Flying Spot Scanner2. In either case a lot of equipment

~n.M;v circuit boards That comprise the gen orator

! \ I ,t*>i Sran V lit icon hi I lie Slow-Scan TV ( amer.i/ 7.1 Mjjtti/inc.

2+ "A NUvw-Scjiih Idevision Picture tienetfttur," Manu/ine. < )<?'(.. h7.

Generator with Panadaptor.

Generator with Panadaptor.

is involved in generating a test signal The unit described in this article has been developed to provide SSTV test signals.

Circuit Description

The SSTV Signal Generator provides selectable test signals of the Sync, Black and White frequencies, a variable Grey Scale signal, a vertical Bar pattern and a variable hot-Bar pattern. The sync signals are stabilized by synchronization with the 60 Hz power line frequency.

The transistors 0' and Q2 are used to shape the 60 Hz power line frequency sine wave into a square wave so that it will stabilize the horizontal frequency miltivibra-lor (Q3 and 04) al 15 Hz. The 8 second per-cycle vertical oscillator (Q5 and Q6) is frequency stabilized by inter-connecting the horizontal oscillator ihrough the 1N-648 diode and the .047 coupling capacitor. Sync pulses are taken from the collectors of Q4 and Q6, combined and fed to the sync amplifier QIO and modulator QI1. The vertical syne pulse is 30 ms long and the

Sstv Monitor
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