Slow Scan TV
Android SSTV Apps and Links
These are the two Slow-Scan TV apps I have used to transfer images via audio between two Android cell-phones.
Apparently there's also:
- Getting Started with MMSSTV for Windows
- QSSTV for Linux - in your REPO [apt install ... worked for me]
- Fldigi also does SSTV
- There are Ham Radio Live Distros ...
What SSTV is Currently Happening
As it's audio, not digital, and meant for sending images over HF, 'the internet' says it's technically a bit of a waste of bandwidth over FM, and digital modes are more efficient, but have a go when the screeching won't bother everyone. There also seem to be simplex VHF frequencies for SSTV. The ISS Slow Scan TV (SSTV) frequency is 145.800 MHz FM.
” The ISS puts out a strong signal on 145.800 MHz FM and a 2m handheld with a 1/4 wave antenna will be enough to receive it. The FM transmission uses 5 kHz deviation which is standard in much of the world. In IARU Region 1 (British Isles, Europe, Africa) FM equipment is usually set by default to the narrower 2.5 kHz deviation. ”
Suggestion ...
Perhaps a simple way to begin would be to
- install this Robot36 - SSTV Image Decoder SSTV Decoding app,
- decode a couple of SSTV samples
- Exercise over simplex, a quiet repeater, receive ISS SSTV (ARISS), field uses, ...
” An ARISS Slow Scan TV (SSTV) event is scheduled from the International Space Station (ISS) for late December. The event celebrates the 20th anniversary of ARISS. The event is scheduled for Dec 24 and to continue through Dec 31. Dates may change due to ISS operational adjustments.
”
UPDATE: I participated and enjoyed it while learning.
VHF/UHF Bands (from SigID Wiki)
| Band |
Freq. (MHz) |
Mode |
Notes |
| 2m |
145.625 |
NFM |
Australia |
| 2m |
145.800 |
NFM |
ISS Downlink Call: RS0ISS |
| 70cm |
433.775 |
NFM |
Australia |
Some considerations ...
These are just an ad-hoc collection
- avoid transmitting on calling channels
- avoiding weak signal and satellite uplink ranges
- avoiding channels being monitored by several expecting voice not screech
- do announce beforehand
- prefer simplex, or unused repeater, or VHF repeater SSTV nets
- A low Necessary Bandwidth of N-SSTV allows it to fit into narrow bandwidth digital mode slots that conventional SSTV doesn't.
- Duty Cycle (except Narrow-SSTV)
- SSTV IS FULL DUTY CYCLE, so reduced audio in should help prevent overheating. And Pauses. And thermal protection.
- Remember........... SSTV IS FULL DUTY CYCLE, so if your rig runs 100 watts on ssb, then cut audio back to about 50 watts with computer volume control.
- Remember: SSTV and DMR have a 100% duty-cycle, so run at reduced power with the ALC at its minimum
- But Narrow-SSTV is lower duty cycle, and is suitable over voice transceivers.
SSTV and Satellites Links Collection
some maybe related maybe not links below...
The following frequencies are currently used for Amateur Radio ISS contacts (QSOs):
Voice and SSTV Downlink: 145.80 (Worldwide)
Voice Uplink: 144.49 for ITU Regions 2 and 3 (The Americas, and the Pacific and Southern Asia)
Voice Uplink: 145.20 for ITU Region 1 (Europe, Russia and Africa)
VHF Packet Uplink and Downlink: 145.825 (Worldwide)
UHF Packet Uplink and Downlink: 437.550
VHF/UHF Repeater Uplink: 145.99 (PL 67 Hz)
VHF/UHF Repeater Downlink: 437.80
2 metres: (FM)
145.500 MHz 2m Band SSTV Call Freq.
145.600 MHz 2m Band SSTV Call Freq.
144.550 MHz SSB SSTV Call Freq.
145.500 MHz 2m is not SSTV calling frequency, that is for voice. It’s 144.500 according to RSGB band plans. Made me look like a right idiot when I was sending SSTV out on the FM calling frequency.
Source
145.5 MHz is recommended in several places, but I would avoid VHF calling frequencies that may be monitored, as the long duration audio warble may be a bit much in that case, generally, I guess.