Volcano monitoring using SSTV

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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Volcano monitoring using SSTV

Postby BruXy » Mon Mar 02, 2020 3:05 pm

The SSTV found application in other sectors in the past. Perhaps the most notable application is the use of SSTV to monitor the active volcano. U.S. Geological Survey installed in September 1987 sensing camera and FM radio transceiver for observation of volcanic activity on Mount St. Helens.

SSTV was also used for remote medical applications during the eighties, e. g. transfer of radiologic pictures over phone lines and over satellite narrowband communication channels.

Article PDF: Video Surveillance of Active Volcanoes Using Slow-Scan Television
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Re: Volcano monitoring using SSTV

Postby Steve Anderson » Wed Mar 04, 2020 1:23 pm

An interesting article, thanks...

Not being familiar with the camera I guess it had to be enclosed in a weatherproof housing yet able to allow the pan & tilt function.

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Re: Volcano monitoring using SSTV

Postby BruXy » Thu Mar 05, 2020 2:01 am

Looks like, they were using some CCTV camera with remote control for zoom, pan, tilt. The schematics has 74HC943, which is 300 Baud modem:

Full duplex low speed modem It provides a 300 baud bidirectional serial interface for data communication over telephone lines and other narrow bandwidth channels It is Bell 103 compatible The 74VHC943 utilizes advanced silicon-gate CMOS technology Switched capacitor techniques are used to perform analog signal processing MODULATOR SECTION The modulator contains a frequency synthesizer and a sine wave synthesizer It produces a phase coherent frequency shift keyed (FSK) output LINE DRIVER AND HYBRID SECTION The line driver and hybrid are designed to facilitate connection a 600X phone line They can perform two to four wire conversion and drive the line at a maximum of b9 dBm DEMODULATOR SECTION The demodulator incorporates anti-aliasing filters a receive filter limiter discriminator and carrier detect circuit The nine-pole receive filter provides dB of transmitted tone rejection The discriminator is fully balanced for stable operation.
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Re: Volcano monitoring using SSTV

Postby Klaas Robers » Fri Mar 06, 2020 6:45 am

Yes, in 1980 Bell 103, 300 baud duplex, was the standard. I still have one or two of those modems and have used them in those days. However, the newer standard became 1200 / 75 baud. I used that too.

On the photo's I recognised the ROBOT 1200C scan converters. So in fact it was all consumer type of equipment and that is the way to make new systems affordable (cheap).
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