[amsat-bb] Fwd: Thoughts on ISS packet switch back to 145.825 MHz (long)

Sun Apr 16 23:10:47 UTC 2017

Stefan,

Did you listen to that last pass? There may have been only 10 stations, the
problem is then 8 of them are sending beacons every 30 seconds and have no
intention of making a QSO! This is a longstanding problem on the ISS 2m
digi. I don't agree about your claims on the reliability of the ISS digi; I
have routinely worked it and decoded my digipeated packets to the horizon
with an Arrow and HT, even on 70cm. With little doubt I would consider the
ISS digi one of out most reliable space based transponders, only not
functioning when shut off for more prudent matters aboard the station. The
ISS has a particularly sensitive receive, it will digipeat plenty, as with
most satellites.

As is a common disease among sat ops, people focus more on their transmit
than receive. Take a listen to an FO-29 pass on the weekend, odds are
you'll hear half a dozen stations calling CQ at the exact same spot in the
middle with excessive power, and none of them will make a QSO. Maybe you'll
hear a station crank the power up on AO-7 "because they can't hear
themselves" and knock it into mode A, ruining the pass for most. It IS QRM.
If you are preventing QSOs of people that can hear with blind
transmissions, that is QRM. Knock yourself transmitting beacons in Western
Australia, but over North America you will hear stations, and in any case
you will hear RS0ISS (on the condition that you CAN HEAR. You may assume
you are not creating QRM, but you often are. The ISS is not so different
than SO-50 actually, people blindly transmitting not being able to hear and
sharing a single channel, precluding other QSOs. I seem to recall hearing
you on a pass a few days ago and giving you a call (which I heard myself
clearly) and you didn't hear it. Maybe just a coincidence.

73,
Gabe
NJ7H

On Sun, Apr 16, 2017 at 5:18 PM, Stefan Wagener <wageners at gmail.com> wrote:

> Thanks Mike,
>
> Again, you don't seem to get the point. Based on your setup, TNC, software
> etc you will NOT be able to decode every single packet and based on your
> setup and the ISS position the ISS digipeater will not re-transmit. It's
> the nature of the beast. No, you are not creating QRM if the ISS does not
> repeat your packet. Listen to the path of the ISS and you will hear that
> 50% of the time the radio is silent. It does not TX since there are no
> valid packets. Where is the QRM? There is none other than in you local
> environment where nobody cares. Don't discourage those that are trying to
> make it work. If you want a case, point out the stations and callsigns that
> create QRM and are not listenting/responding!
>
> Just check out the last pass over the US. You will find 10 stations,
> that's a station a minute with room to spare. This is NOT SO-50!
>
> 73, Stefan, VE4NSA
>
>
>
> On Sun, Apr 16, 2017 at 5:05 PM, Mike Diehl <diehl.mike.a at gmail.com>
> wrote:
>
>> Stefan,
>>
>> I think you're taking Gabe's comment too literal. The point he's trying
>> to make is that many stations just keep on transmitting when they can't
>> hear anything.
>>
>> We can use that amateur radio on ISS as an experiment as an excuse but
>> that doesn't really fly. APRS is beyond an experiment as it is a well
>> established form of using APRS via satellite, nothing new here.
>>
>> Furthermore, what is the point of trying repeatedly to transmit if you
>> can't decode? It is the golden rule for a reason and it applies everywhere,
>> satellite or terrestrial. If you can't hear it you can't work it, bottom
>> line. Until you can decode packets you're just creating QRM.
>>
>> 73,
>>
>> Mike Diehl
>> AI6GS
>>
>> > On Apr 16, 2017, at 2:46 PM, Stefan Wagener <wageners at gmail.com> wrote:
>> >
>> > Hi Gabe,
>> >
>> > With all respect I very much disagree. The amateur radio equipment on
>> the
>> > ISS is an experiment! Sometimes it works and sometimes it doesn't.
>> Based on
>> > your location, equipment and ISS position you will* NOT* decode every
>> > packet, and yes that includes your own packets. So folks will be trying
>> > again and that's okay. *They don't become a source of QRM* on the ISS
>> since
>> > the ISS will only re-transmit if its a good packet. They are exercising
>> > their license privileges to work through the ISS and for many having
>> that
>> > first digipeat after many tries is their success story and we welcome
>> that.
>> >
>> > 73, Stefan, VE4NSA
>> >
>> >
>> >
>> > On Sun, Apr 16, 2017 at 1:43 PM, Gabriel Zeifman <
>> gabrielzeifman at gmail.com>
>> > wrote:
>> >
>> >> I think the golden rule of working all sats applies to ISS as well: if
>> you
>> >> can't hear (or decode), don't transmit! It's easy to become a source
>> of QRM
>> >> if you keep transmitting in the blind when you can't hear.
>> >>
>> >> 73,
>> >> Gabe
>> >> NJ7H
>> >>
>> >>> On Apr 16, 2017, at 1:28 PM, Robert Bruninga <bruninga at usna.edu>
>> wrote:
>> >>>
>> >>> I agree completely.  ISS digipeting should be for LIVE operators.  Or
>> for
>> >>> LIVE things.... (a student experimental ocean going buoy for
>> example)...
>> >>>
>> >>> NOT for non-moving-fixed egos...
>> >>>
>> >>> Bob, WB4APR
>> >>>
>> >>> -----Original Message-----
>> >>> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of
>> Patrick
>> >>> STODDARD (WD9EWK/VA7EWK)
>> >>> Sent: Saturday, April 15, 2017 7:51 PM
>> >>> To: amsat-bb at amsat.org
>> >>> Subject: [amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz
>> >>> (long)
>> >>>
>> >>> Hi!
>> >>>
>> >>> Earlier today, I tweeted a quick comment about what I saw on the ISS
>> >>> 145.825 MHz digipeater just after 1900 UTC this afternoon. Since
>> tweets
>> >>> are limited in length, I'm posting a longer message here...
>> >>>
>> >>> In the past few weeks, once word got out that a replacement for the
>> >> failed
>> >>> Ericsson VHF HT on the ISS was being sent up to the station, many were
>> >>> anxiously looking forward to seeing the ISS digipeater move from
>> 437.550
>> >>> MHz back to 145.825 MHz, where it had been until the old radio's
>> failure
>> >>> in mid-October 2016. I understood that many would welcome this change,
>> >> but
>> >>> I was not jumping up and down with excitement. Unfortunately, after
>> >> seeing
>> >>> the activity on the ISS digipeater in the past day or so since the
>> >>> replacement VHF radio was put on 145.825 MHz, my worries have been
>> >>> confirmed.
>> >>>
>> >>> For many, the move to 437.550 MHz meant many stations that could
>> easily
>> >>> work 145.825 MHz would have to change. Whether it was a different
>> antenna
>> >>> for the 70cm band or dealing with Doppler with the 437.550 MHz
>> frequency,
>> >>> almost all of the unattended stations that had been present on the
>> >> 145.825
>> >>> MHz frequency were gone. If you wanted to use the ISS digipeater to
>> work
>> >>> other stations, this was a great opportunity. Many stations using
>> >>> APRS-ready HTs and mobile transceivers were showing up, using a group
>> of
>> >>> memory channels to compensate for Doppler, and were making contacts.
>> Some
>> >>> fixed stations, including those already capable of satellite
>> operating,
>> >>> were also showing up. Even on the busier passes, the
>> >>> 437.550 MHz always seemed to be clear of the clutter from the
>> unattended
>> >>> stations that previously inhabited 145.825 MHz.
>> >>>
>> >>> Fast forward to yesterday (Friday, 14 April). The ISS digipeater
>> switched
>> >>> to 145.825 MHz in time for afternoon/evening passes over Europe
>> (around
>> >>> 1330-1400 UTC). Lots of stations showed up, based on looking at the
>> >>> ariss.net web site. The same thing started to happen here in North
>> >>> America, later in the day. The passes I worked last night were not
>> bad,
>> >>> but there were more stations on one pass that went over much of the
>> >>> continental USA than I'd typically see on 437.550 MHz.
>> >>>
>> >>> By midday today (1900 UTC), it seemed like many more stations were on
>> the
>> >>> frequency. I saw 11 other call signs on a pass just after that time
>> this
>> >>> afternoon. At best, there may have been 4 or 5 other operators at
>> their
>> >>> keyboards or keypads, looking to make contacts.
>> >>> The others were just squawking away, not answering APRS messages sent
>> to
>> >>> them. By the time the ISS footprint was reaching the east coast, the
>> >>> frequency was congested. Lots of position beacons were coming through,
>> >> but
>> >>> not much of anything else. This is not new; Clayton W5PFG wrote about
>> >> this
>> >>> about a year ago, here on the AMSAT-BB list:
>> >>>
>> >>> http://amsat.org/pipermail/amsat-bb/2016-April/058200.html
>> >>>
>> >>> For the two passes I worked this afternoon, around 1900 and 2035 UTC,
>> I
>> >>> made two QSOs on the earlier pass, and one on the later pass. A shame,
>> >>> considering there were so many other call signs on the earlier pass,
>> and
>> >>> even some rare spots - stations in DM44 in northern Arizona and CM86
>> in
>> >>> Santa Cruz CA were seen.
>> >>>
>> >>> It is interesting that hams want to have their stations squawk on
>> >>> 145.825 MHz when nobody is at the keyboard. It could be doing it
>> 24/7, no
>> >>> matter if the ISS is in view or not. Would anyone think of setting up
>> >>> their satellite station to automatically transmit their call sign and
>> >>> location every 15/30/60 seconds to SO-50, unattended? I think not!
>> That
>> >>> could be a violation of the regulations, and would definitely be poor
>> >> form
>> >>> by that operator.
>> >>>
>> >>> Bob Bruninga WB4APR has a couple of documents with recommendations for
>> >>> beacon intervals when working the ISS digipeater. One mentioned a
>> >> 5-minute
>> >>> interval for unattended stations:
>> >>>
>> >>> http://www.aprs.org/iss-aprs/iss-tx.txt
>> >>>
>> >>> Another document recommends that unattended stations should be in
>> >> "receive
>> >>> ONLY mode." (emphasis is Bob's):
>> >>>
>> >>> http://www.aprs.org/iss-aprs/utiquet.txt
>> >>>
>> >>> I agree with the latter. If your station is unattended, why have it
>> >>> transmit at all?! It may be different for less-populated parts of the
>> >>> world, where gateway stations may transmit and then receive their
>> beacons
>> >>> from the ISS, which will show up on ariss.net and other sites. For
>> >> Europe,
>> >>> and definitely North America, the gateways really don't need to
>> transmit
>> >>> if they are unattended. There should be activity on most passes, maybe
>> >>> even late into the night, to know 145.825 MHz on the ISS is up and
>> >>> running.
>> >>>
>> >>> Please don't misunderstand me... I think it is great for hams to set
>> up
>> >>> gateway stations listening on 145.825 MHz for the space-borne APRS
>> >>> activity (ISS, NO-84, even NO-44 when it gets enough power to transmit
>> >>> complete packets). But these stations, like other stations that aren't
>> >>> operating as gateways yet transmit automatically, shouldn't
>> contribute to
>> >>> the congestion on the frequency.
>> >>>
>> >>> I know I am in the minority on the ISS digipeater moving back to
>> >>> 145.825 MHz. Between the unattended stations clogging up the frequency
>> >> and
>> >>> some local interference I hear on 145.825 MHz around my house, having
>> the
>> >>> ISS on 437.550 MHz was fun! I worked it from home, and on some of my
>> road
>> >>> trips in the past 5+ months. Even for some of my last NPOTA
>> activations
>> >> at
>> >>> the end of 2016. I'll continue to work the ISS digipeater, almost
>> >>> exclusively with my APRS-ready HTs (TH-D72A, or TH-D74A), looking to
>> make
>> >>> QSOs by exchanging APRS messages with other stations. If you can work
>> >>> packet from your station, and we are in the same footprints, I hope to
>> >>> hear you (and see you on my screen) soon. Like W5PFG mentioned a year
>> >> ago,
>> >>> let's get more stations on 145.825 MHz making QSOs...
>> >>>
>> >>> 73!
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> Patrick WD9EWK/VA7EWK
>> >>> http://www.wd9ewk.net/
>> >>> Twitter: @WD9EWK
>> >>> _______________________________________________
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>> official
>> >>> views of AMSAT-NA.
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>> >>> _______________________________________________
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>> >> _______________________________________________
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>> >> to all interested persons worldwide without requiring membership.
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>> > _______________________________________________
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>> > to all interested persons worldwide without requiring membership.
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>> of AMSAT-NA.
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>> program!
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>
>