How close of a pass do I need to pick up ISS SSTV?

[dragon48]

I got excited when I saw the news:

ISS SSTV Scheduled for October 3-5, 2023

UPDATE: Event to be Rescheduled. R4UAB reports that from October 3, 2023 to October 5, 2023 images will be transmitted from the International Space Station via the SSTV protocol as part of the “Abo…

amsat-uk.org

So, I dusted off my AOR 3000a and fired up MMSSTV. Nothing was close to me until recently, when I got a pass as close as 207 miles, but I didn't pick up anything at all. I'm just going to keep the entire setup running until the end of the scheduled broadcasts. I don't have a great antenna. I'm just using this which is mounted vertically outside on my patio:

https://www.amazon.com/gp/product/B07X2LK2NL

I have picked up OK images with a normal telescoping antenna in similar urban scenarios, but I don't know how close the passes were.

With my setup, how close of a pass do I need to pickup a signal good enough to decode?

 

[popnokick]

The distance to the ISS doesn't matter as much as the elevation above the horizon, and whether your line of sight in that direction is clear (not blocked by buildings, mountains, etc.) In the pass description data that equates to the "highest point altitude" and is shown in degrees above the horizon for the pass. With the type of antenna you are using you'll want passes that are at least 15-20 degrees above the horizon for some portion, and preferably ascending to higher. So why don't you hear the SSTV on every pass that meets that criteria? Because the broadcasts are not always taking place when you're in the ISS footprint.

 

[ind224]

As long as you can hear it with good audio quality it should decode just fine. I would expect any pass at least 30* (elevation) to work a better antenna will impove that as well.
If I had a telescoping to BNC antenna thats what I would use over the mag mount, no coax loss. I tried the last two passes we just had and didn't hear anything. They should announce where they're going to be operating it when they're going to be over the United States or over Europe and Russia because they do that a lot of times with the school contacts works remote and it's not actually when it's going over for a local listener

 

[dragon48]

As long as you can hear it with good audio quality it should decode just fine. I would expect any pass at least 30* (elevation) to work a better antenna will impove that as well.
If I had a telescoping to BNC antenna thats what I would use over the mag mount, no coax loss. I tried the last two passes we just had and didn't hear anything. They should announce where they're going to be operating it when they're going to be over the United States or over Europe and Russia because they do that a lot of times with the school contacts works remote and it's not actually when it's going over for a local listener

I was ready for reception the last time they broadcast, as the ISS almost hit me on the head on one of the passes, but they had transmitter problems at the time. 😞

Tonight's pass looks like the best prospect for me.

Start	Max altitude	End	Visible passes
Date, Local time	Az	Local time	Az	El	Local time	Az	Mag	Info
4-Oct 20:20	NW 322°	20:25	NE 56°	64°	20:30	SE 133°	-2.2

When I buy a house one day and have more control and freedom, I'll get some proper antenna setups.

 

[jwt873]

When the ISS is transmitting SSTV, I don't bother with pass times/data.. I just connect my radio to my computer running SSTV decoding software. The software I use (MMSTV) saves each image it decodes.

I leave everything on continuously. I check on it from time to time to see what I received.

Edit.. I just set everything up.. Hope I get something

 

[dragon48]

When the ISS is transmitting SSTV, I don't bother with pass times/data.. I just connect my radio to my computer running SSTV decoding software. The software I use (MMSTV) saves each image it decodes.

I leave everything on continuously. I check on it from time to time to see what I received.

That's exactly what I'm doing now - but am also looking at pass times. Good luck yourself.

 

[jwt873]

And.... According to this site: --> International Space Station we just had good pass. Nothing heard.

Normally they transmit continuously during the event, but I guess not this time.

 

[dragon48]

The ISS was not transmitting anything during the last pass over my area. While my patio setup was picking up nothing, I was outside with a handheld. I was away from buildings, in an area with perfect marine band reception. I had my handheld plugged directly into a digital recorder. The pass got as close as 77 miles away from me, just east over the ocean, yet I picked up nothing but static the entire time. I had the recording going from a good 15 minutes before the ISS approached, until after it was well over South America.

 

[jwt873]

Same here.. I've copied the ISS on a couple of other occasions. It's easy to hear. But this time there were no signals. They weren't transmitting.

I did some digging and see that on the Russian ISS page, they state that "the time and date may change". С борта МКС с 03 октября 2023 года по 05 октября 2023 года будет организована передача изображений по протоколу SSTV | R4UAB

So I guess the event might occur sometime in the future. There is no mention of when.

 

[ind224]

At least two South American amatuers posted good captures to the ARISS archives and then it was reported the radio had an issue so the test was aborted.

 

[dragon48]

At least two South American amatuers posted good captures to the ARISS archives and then it was reported the radio had an issue so the test was aborted.

Appreciate the intel. The main Amsat-UK page never updated the schedule or mentioned the problem. I like to keep abreast of ISS broadcast news. What is your source?

 

[ind224]

ARISS-SSTV images

Welcome to the ARISS SSTV gallery Info is all over the place. Work and life had me in the dark until the 4th and then scrambling to get to Heavens Above to confirm a good pass before UTC time runs out.

 

[dragon48]

ARISS-SSTV images

Welcome to the ARISS SSTV gallery Info is all over the place. Work and life had me in the dark until the 4th and then scrambling to get to Heavens Above to confirm a good pass before UTC time runs out.

Ty - Too bad. Last night's pass would have been perfect for me - nothing very tall between my 20 and the area over the Atlantic Ocean where ISS made a close pass at a good angle. I was in a perfect spot with my handheld to get a good image. Hope I get a good pass next time.

 

[dragon48]

Though it more appropriate to ask my reception question here, rather than the new thread, as it is on point with my OP. Today, at 15:37 UTC in Boynton Beach, Florida, I picked up the attached. I'm surprised I was able to get this much decoded, as the ISS was pretty far away (all relative, I understand ) during the pass. I don't remember the exact distance, but while looking at my ISS Spotter iPhone app while the radio was receiving the transmission, I don't think the ISS ever got closer than 600 miles to my 20. It was, however, within a direct line of sight, mostly paralleling my location as it was travelling south over the Atlantic Ocean.


Here is the pass data pasted with my local time showing - showing the 10° starting and ending angles, and the 20° highest angle.


11:32:50 10° WNW 11:35:22 20° SW 11:37:53 10° S

Back to my core reception question. I'm never going to pick up a terrestrial FM radio signal from 600 miles away. So, can somebody please explain how the propagation works from the ISS while it's 240-260 miles above the surface of the earth?

 

[wtp]

no hills, no mountains, no trees, no buildings, just great direct reception.

 

[dickie757]

no hills, no mountains, no trees, no buildings, just great direct reception.

And no curvature of the Earth.

Of course I cant find it now, but there is a site that will calculate distances to the horizon based on location, and maybe height, too.

 

[K5MPH]

You need a better antenna than the one you are using now........

 

[ind224]

Antennas and height can make all the difference. I have a 2045 and a Diamond discone up about 35' for elevations over 10* and a BC780XLT to a StationMaster up about 25' for lower than 10*. With my zip code in N2YO I can show reception as low as 3*. First pass w recent test I had excellent results showing a maximum of 12° elevation