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

Sun Apr 16 18:43:42 UTC 2017

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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