[amsat-bb] BY70-1 Observations

Paul Stoetzer n8hm at arrl.net
Wed Jan 4 15:04:07 UTC 2017


Good observations, John.

It's a tricky satellite at times, but still fun to play around with.
It's certainly a shame that it'll have such a short lifetime due to
the partial launch failure.

I have also sent an email requesting it's addition to LoTW.

Just a general FYI about new satellites and LoTW: The name of the
satellite is not able to be changed once it is added to the TQSL
configuration file. After a satellite is made available to the amateur
community, I have advised the ARRL to hold off on adding satellites to
the configuration file until an OSCAR number is issued or we are
certain that no OSCAR number will be requested and/or granted. I did
ask about BY70-1 with no response, so I consider that such a request
is unlikely at this point.

73,

Paul, N8HM

On Wed, Jan 4, 2017 at 1:39 AM, John Papay <john at papays.com> wrote:
> I had a chance to run some tests on BY70-1
> this evening from my Arizona Station since there
> was no one on the pass.  It was only a 15 degree pass
> for me but the satellite did very well.
>
> BY70-1 is much stronger than SO-50.  The morning passes
> are around 500KM and the evening passes are only 250KM.
> But the signal is quite strong on both.  If you are having
> trouble hearing SO-50, try BY70-1.  You should hear it much
> better.
>
> At first I thought the sensitivity might not be very good, but
> upon further testing it was possible to hold the satellite
> at 1 watt provided that you were on the right polarity at
> the moment.  I was changing between horizontal and vertical
> frequently.  The wrong polarity produced noise, but a switch to
> the opposite polarity yielded a full quieting signal consistently.
>
> Many have experienced dropout when attempting to talk through the
> satellite.  Sometimes it is due to the many signals present on
> the input frequency including those that are not coming from
> satellite users.  It's the same situation on SO-50.  But there
> are also dropouts that occur when there is no one else on the
> input.
>
> It seems that if you are fairly wide in deviation, certain
> speech will cause the satellite to stop transmitting.  This
> may be a receiver bandwidth issue or perhaps the PL
> decoder responding to voice frequencies etc.  At any rate
> I think the dropouts are due to the PL decoder not decoding
> the PL tone for the above reasons.
>
> BY70-1 seems to be less sensitive to dropouts if you use narrow
> band FM on the transmit.  I found very little difference in the
> repeated audio level when using wide or narrow.  So there is
> signal processing in play which keeps the audio output level
> constant.  AO-85 audio levels do change quite a bit between
> wideband and narrow.  So do use narrow FM on this bird for
> best results.
>
> The signal processing also apparently causes a significant
> delay in the repeated audio.  It can cause some discomfort
> but keep the rx level low so you are able to ignore the delay
> and converse normally.  Audio quality is quite good.
>
> Some have thought there is some sort of VOX on the bird
> but a dead carrier seems to hold the transmitter keyed with
> no audio present.  Again, the PL Decoder is likely responsible
> for the dropouts.
>
> Be sure to download the latest keps from Celestrak or apace-track.
> The keps on the amsat site may not always be current.  The orbit is
> changing daily so get the new keps every 24 hours.  The catalog
> number is 41909. http://celestrak.com/NORAD/elements/tle-new.txt
> The amsat nasa.all file can be edited with Wordpad and the new
> keps can replace the ones in the file if different.  Set your PL
> to 67Hz just like SO-50.
>
> doppler.sqf:
> BY70-1,436200,145920,FM,FM,NOR,0,0,FM Voice
> BY70-1,436200,145920,FM,FMN,NOR,0,0,Narrow FM Voice
> The coordinated frequencies seen to be close enough.
>
> I have asked KX9X to facilitate adding BY70-1 to the list of
> satellites in LOTW.
>
> Don't be reluctant to try this satellite.  You will find
> it much easier to access than SO-50 or AO-85.  It does have
> a short window but you can hear it down low if you don't
> have any obstructions.
>
> 73,
> John K8YSE/7
>
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