[amsat-bb] R: Re: ISS SSTV frequency

Mon Nov 30 21:29:34 UTC 2020

All,

We CANNOT move the ARISS SSTV frequency to 145.825.  This is being used for other satellites employing APRS and we would interfere with their operation.

Prior to their being an ARISS station on ISS, we conducted an extensive, international effort to ensure ARISS had a clear downlink on 2 meters.  We worked with all IARU regions and concluded that the best world-wide downlink frequency for Human would be 145.80 MHz.  At the time (1997) the United States had terrestrial APRS on 145.79.  In the USA we worked with the APRS community in a collaborative fashion to QSY APRS terrestrial from 145.79 to 144.39 (where it is today).  This was a HUGE effort and required many digipeaters, several on snow covered mountains, to be modified or replaced.  Donations were collected.  And AMSAT-NA and TAPR worked together to make it happen. 

Again, please note that IARU region 1 agreed with this downlink frequency for human spaceflight many years ago so we could have one common downlink.  I am very sorry you are experiencing this.  I think this will take local coordination to resolve this.  Similar to what we did for terrestrial APRS.  Trying to move ARISS around in the very small OSCAR 2 meter sub-band (145.8-146) is virtually unworkable, given the many 2 meter satellites that are employing this band.  

I hope this helps explain things from an ARISS perspective.  Back in the day, I was given the unenviable task of working these frequency coordination issues for human spaceflight.  To be clear, we are much better today than some of the issues we were experiencing in the past.  And changing things around will probably make it worse for ARISS and other users in the satellite community.    

73,  Frank Bauer, KA3HDO
Chair, ARISS-International

-----Original Message-----
From: ik5jrz at tin.it <ik5jrz at tin.it> 
Sent: Monday, November 30, 2020 2:36 PM
To: fabrizio.carrai at gmail.com; amsat-bb at amsat.org
Subject: [amsat-bb] R: Re: ISS SSTV frequency

Thanks for answer,
The repeater is R7a (Monte Secchieta), it's not only an Italian problem unfortunately, I have read many complaints in other areas as well. I don't question the correct spacing between frequencies, but I'm afraid it's only on actual paper. I don't want to doubt that the repeater is working correctly, but I think that if the ISS transmitted at 145.825, since when it transmits in SSTV APRS is disabled, the problem would be solved. The video demonstrates the proximity between the frequencies even if I admit to being in the high area and to receive the repeater very well.
https://www.youtube.com/watch?v=nsoSjh54a3A&ab_channel=IK5JRZThanks again.
Carlo IK5JRZ.

----Messaggio originale----
Da: amsat-bb at amsat.org
Data: 30-nov-2020 12.51
A: "Pedro Converso"<pconver at gmail.com>
Cc: "AMSAT BB"<amsat-bb at amsat.org>
Ogg: Re: [amsat-bb] ISS SSTV frequency

According to the band plan reported on the ARI web site, the space communication band is protected starting at 145.794 Mhz, i.e. 6 Khz below
145.800 Mhz. The R7a is indeed at 145.7875 Mhz with a bandwidth of 12 Khz there shouldn't be any interference (in theory). Have you checked which repeater is in your (our) zone ?

Ciao
Fabrizio IU5GEZ

Il giorno dom 29 nov 2020 alle ore 23:11 Pedro Converso via AMSAT-BB < amsat-bb at amsat.org> ha scritto:

> This situation doesn't happen in IARU R2, as 145.790-145.800 is a 
> protection segment.
>
> In IARU R1, there is no such a protection, suggest request change thru 
> your IARU Rep.
>
>
> On 11/29/20, John Brier via AMSAT-BB <amsat-bb at amsat.org> wrote:
> > What repeater are you referring to exactly?
> >
> > 73, John Brier KG4AKV
> >
> > On Sun, Nov 29, 2020, 16:51 ik5jrz--- via AMSAT-BB 
> > <amsat-bb at amsat.org>
> > wrote:
> >
> >>  Hello,
> >> I am very interesting to know how many peoples in the world have 
> >> my, and not only mine..problem for receive ISS SSTV on 145.800. The 
> >> problem is the repeater (7a) at 145.787.5 and ISS , for doppler 
> >> naturally go down
> >> 145.800
> >> and its impossible to receive well if someone talk on repeater.
> >> Thanks for attention.
> >> Carlo IK5JRZ.
> >> _______________________________________________
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> _______________________________________________
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--
*Fabrizio*
_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
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