[amsat-bb] Saturday evening @ WD9EWK - two AO-85 passes...

Sun Oct 11 14:17:20 UTC 2015

Hi!

Because I had to be awake for a 5am/1200 UTC conference call with my office
this morning, I only worked two passes last (Saturday) evening. Both were
AO-85 passes, with different radios for each of the passes. It is amazing
that we have access to this satellite's FM transponder, so soon after its
launch.

The first pass I attempted was around 0215 UTC. This pass was an overhead
pass, so I took advantage of that to try another one of my Chinese-made
dual-band HTs (Wouxun KG-UV8D) with this U/V FM satellite. The KG-UV8D was
connected to my Elk log periodic. I had my SDRplay receiver out in the yard
for this pass, connected to the VHF crossed dipole sold by AMSAT-UK, with
HDSDR running on my 8-inch Windows 10 tablet to make an RF recording of
this pass. After the pass, I would play the RF recording from HDSDR into
the FoxTelem software, so the telemetry I captured would be uploaded to the
AMSAT server.

I had previously written a lot about the KG-UV8D in a thread on the QRZ.com
satellite forum last year. I had tested it against the Fox-1A engineering
model at two events in 2014, and it was able to work the transponder on the
engineering model without suffering from receiver desense when transmitting
on 70cm. I was working the transponder at the low-power setting (1W), and
would move the HT around to shield the radio from the model, all in attempts
to simulate working an actual satellite in orbit. Not hearing any desense,
I was hopeful this HT would be one that could work Fox-1A (now AO-85) full-
duplex. The answer...

YES

There are issues with the KG-UV8D's receiver, where you'll occasionally
hear what might be more static coming through on the receiver. The noise
level increases, even when receiving a stronger signal like from a local
2m or 70cm repeater, or other non-amateur transmitters. I had to be more
diligent in orienting my Elk log periodic, so I could hear the AO-85
downlink clearly. When I was able to get through the transponder, I could
clearly hear my voice in the earpiece I plugged into the HT. I also heard
myself in the RF recording written by HDSDR on my tablet. It helped that
I changed both the receive and transmit VFOs to use narrow FM, instead of
"wide" FM. My transmitted audio seemed better, when I heard myself on the
RF recording from HDSDR, and I could hear the downlink better on the HT
during the pass. I worked K8YSE/7 here in the Phoenix area and KO6TZ in
southern California just before the satellite was directly over my head.
This is in line with my previous test with the KG-UV9D, where lower power
levels were not sufficient to get through AO-85 until the satellite was
up from the horizon a bit.

For the uplink, I was able to get through using 435.165 MHz for my two
QSOs with the KG-UV8D. Downlink... I started on 145.9825 MHz, then tuned
down to 145.980 MHz, and later I tuned down to 145.9775 MHz. Just like I
saw when I used my KG-UV9D Friday evening, the sharper receive filters in
the Chinese-made radios made using the smaller tuning step (2.5 kHz)
useful.

After this pass, I played the HDSDR RF recording into FoxTelem, and
uploaded 9 packets to the AMSAT server. Had I used the Elk with the SDR
setup, I am sure I would have collected many more packets from that pass.

The second pass I worked, around 0400 UTC, was a shallow pass. AO-85 was
only up to a maximum elevation of just over 11 degrees. I used only my
Icom IC-2820H for this pass. I had used the IC-2820H as the uplink radio
for a pass I worked Friday evening with my SDRplay receiver and HDSDR
handling the downlink, but wanted to try the mobile radio by itself this
time. it had no problems hearing the downlink, once AO-85 rose above the
nearby mountains and houses.

I started the radio on 435.160 MHz for the uplink (with 67.0 Hz tone
activated for this VFO), and 145.980 MHz for the downlink. Both with
narrow FM, a suggestion that had been tweeted earlier by Peter 2E0SQL. I
was not able to get through using 435.160 MHz, but was able to when I
tuned my uplink to 435.165 MHz. Later in the pass, I could get through
when transmitting on 435.170 and 435.175 MHz. I had to use 15W, and at
times 50W, to get through. The pass was too shallow for me to get through
at 5W. Around the midpoint of the pass, possibly just after that, I had
to tune my receive VFO down to 145.975 MHz to hear the rest of the pass.
I mostly heard stations in California, along with W7JPI in southern
Arizona and WQ3U in Oregon, and logging a total of 5 QSOs (working all I
heard, except for WQ3U).

The later pass was more orderly, probably a function of the footprint
covering more of the Pacific Ocean. All stations allowed time for others
to make (or complete) their calls. Fading is still an issue, and we all
experienced the fades while trying to complete QSOs.

Some observations...

Now that I have a KG-UV9D HT, I probably won't use the KG-UV8D much. The
KG-UV9D's receiver is probably the best receiver for satellite work from
any of the Chinese-made HTs I have tried. The KG-UV8D *is* capable of full-
duplex operation on AO-85, something that I had been told last year would
not be possible with this radio (and before we had a U/V FM satellite to
test radios against).

While working the earlier pass with the HT, I kept an eye on HDSDR on my
tablet. Once again, with AO-85's downlink, the AFC function tracked the
downlink from start to finish. I would not have had to make any manual
adjustments to the downlink frequency, had I used the SDR setup as my
downlink receiver.

After installing a virtual audio cable on my laptop, I was able to feed
the RF recording I made with HDSDR into the FoxTelem software. I think this
is how I will send telemetry to the AMSAT server, unless I have an occasion
to use the FUNcube Dongle Pro+ and FoxTelem to send telemetry to the
server automatically. When I am able to work the passes, I will use the
SDRplay, which appears to work a little better for working satellites, and
in making a RF recording that FoxTelem is able to extract more data packets
from.

As I have been doing recently, I uploaded files related to last night's
AO-85 passes to my Dropbox space. You can get to that using this link:

http://dropbox.wd9ewk.net/

(press F5 if the folder/file listing doesn't appear immediately)

I have only one RF recording from last night, since I didn't use an SDR
receive setup for the later pass. I have MP3 files from each pass, to show
what I heard on the KG-UV8D and IC-2820H as I worked each pass. Photos
and screengrabs, too.

Thanks again to AMSAT for allowing us to use the FM transponder on AO-85 so
soon after the launch! I have a few radios, and combinations of radios, I
want to try with this U/V FM satellite. I have used different setups for
each AO-85 pass I have worked, and hope to continue this for a while. This
effort may take a pause while I attend the upcoming AMSAT Symposium, but I
will certainly continue this after the Symposium.

73!

Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
Twitter: @WD9EWK