Hi!
A lot of satellite work tonight, starting with a LilacSat-2 pass, then a couple of AO-85 passes, and wrapping up with an SO-50 pass approaching midnight (0700 UTC). Fun stuff, and a lot to scribble about...
The LilacSat-2 pass around 0130 UTC this evening was a nice and high (almost 49 degrees maximum elevation) pass. One slight problem - the repeater was off. Regardless of that issue, I listened to the pass with my SDRplay receiver and Elk log periodic, copying the transmissions using the HDSDR software on my 8-inch tablet. This also let me prepare for the AO-85 pass a few minutes later, the first of two AO-85 passes tonight.
My first AO-85 pass tonight, starting around 0150 UTC, went up the center of the continental USA. As I expected, there was a lot of activity on the new satellite. Glenn AA5PK was my first AO-85 QSO this evening, and I logged 8 more QSOs over the next 10 minutes I was in the footprint. I was using my Icom IC-2820H 2m/70cm mobile radio for the uplink, at 15 or 50 watts transmitter power (I could not get through with the 5-watt low power setting during this pass). My SDRplay receiver along with HDSDR on an 8-inch Windows 10 tablet for the downlink. I made an RF recording of the pass using the SDRplay at 200 kHz IF bandwidth, hoping I could sneak it through the Fox telemetry software and upload some data packets after the pass. The telemetry program appeared to accept my RF recording, even though it was at 200 kHz and the software was designed to accept 192 kHz RF recordings from a FUNcube Dongle Pro+. Although the RF recording played in the program, no data packets were decoded. The SDRplay did a good job hearing the satellite; I think a little better than the FUNcube Dongle Pro+. I had to twist my Elk log periodic almost constantly throughout this pass. It was a nice pass to work, with a maximum elevation out here at 37 degrees.
The later AO-85 pass around 0330 UTC wasn't as high in the western sky, at a maximum elevation for me at just over 24 degrees. This turned out to be the first pass I tried one of my Chinese-made HTs, seeing if I could work this satellite full-duplex. I actually set up two stations in my driveway for this pass - Wouxun KG-UV9D and Elk log periodic I used to talk through the satellite; and the FUNcube Dongle Pro+ and AMSAT-UK (Winkler) VHF crossed dipole, connected to my 8-inch Windows 10 tablet and HDSDR to write an RF recording of this pass that I could use with the Fox telemetry software for a data upload after the pass.
Even though the KG-UV9D can tune in 2.5 kHz steps, I stuck with 5 kHz steps for the uplink tuning. Being able to tune in 2.5 kHz steps did not appear to help me work AO-85. With the sharper receive filtering in the KG-UV9D, I set my downlink frequency at 145.9825 for the first minute or so of the pass, and then moved it down to 145.980 for the next several minutes. Near the end of the pass, I had to put the HT on 145.9775 MHz to hear the downlink without the voices sounding off-frequency.
It seemed like I had to twist my Elk more often this pass. I also saw and heard the fading on my SDR receive setup during the pass. A few minutes into the pass, I was able to make my only QSO during this pass, a quick QSO with Tom KA6SIP in northern California. The best part of this QSO, besides being the first AO-85 QSO I made using a 5-watt HT... I was able to complete this QSO full-duplex with the KG-UV9D! I could hear in the receiver when I pushed the PTT, but unlike using this HT on SO-50, there was no receiver desense as I transmitted to AO-85 on 70cm! This is a very good sign, and I hope to repeat this using a couple of my other Chinese- made dual-band HTs on upcoming AO-85 passes (Wouxun KG-UV8D, AnyTone TERMN-8R). I was not able to get through AO-85 with the HT early or late in the pass, but near the midpoint when the satellite was around 20 degrees elevation or higher. I'll see if this is something that will be an issue going forward, or if the commissioning process will lead to some tweaks on the AO-85 uplink receiver, to make it a little more sensitive to lower- power uplink signals.
After this pass, I took my HDSDR RF recording and played it in the Fox telemetry software on my 8-inch Windows 10 tablet. I successfully copied, and uploaded, 4 data packets from the 0330 UTC pass! This is one more than the number of packets I received during two passes last night. Since I used the FUNcube Dongle Pro+ as my SDR receiver, I knew HDSDR's RF recordings - at the dongle's maximum input bandwidth of 192 kHz - would work fine with the Fox telemetry software. Not a bad way to wrap up the second of the two AO-85 passes - a full-duplex QSO on that HT, and helping AMSAT with some data uploaded to the telemetry server.
To wrap up the evening, I worked an SO-50 pass from the back yard around 0625 UTC. A very nice late-evening pass, using the KG-UV9D as my uplink radio and the SDRplay receiver with my 8-inch Windows 10 tablet and HDSDR as my receiver. Only a few stations on, including Tom WA0POD, Tom KA6SIP, and Frank K6FW - all who were on the 0330 UTC AO-85 pass a few hours earlier.
A few observations, in no particular order...
During the 0330 UTC AO-85 pass, there was a 45-second period where the downlink simply disappeared. Nothing was heard from the satellite. I could clearly see this on my RF recording with my FUNcube dongle and HDSDR, and a local friend of mine (Brad KG7NXH) also observed this at his station in another part of the Phoenix area. When the downlink transmitter came back on, it appeared that the downlink frequency ramped up to the nominal 145.980 MHz frequency - just like I saw when the voice announcements were transmitted on the passes Thursday evening. I tweeted screengrabs from my RF recording in HDSDR the moments when the downlink shut off and then restarted:
https://twitter.com/WD9EWK/status/652715204287946752
This is also visible in the RF recording I made from this pass. KG7NXH posted his screengrabs in a thread on the QRZ.com satellite forum:
https://forums.qrz.com/index.php?threads/ao-85.496019/#post-3621413
It seems like my SDRplay receiver is more sensitive than the FUNcube Dongle Pro+ on these passes. I wish the Fox telemetry software had a little bit of a "fudge factor" in the WAV files it can process. Since the SDRplay's smallest bandwidth is 200 kHz, 8 kHz more than the FUNcube dongle's maximum 192 kHz bandwidth, I wonder if there is a way that the Fox telemetry software could be tweaked to accept WAV files at either 192 or 200 kHz RF bandwidth. This wouldn't mean the Fox software could directly work with the SDRplay receiver, but certainly opens up the SDRplay as an option for working the passes and having a usable RF recording that can be processed by the Fox telemetry software. Now if I could use the SDRplay and the Fox software to copy and upload data packets in real time during passes...
Even though the KG-UV9D and probably a few other Chinese-made dual-band HTs can't work SO-50 full-duplex, they are probably going to be viable options for a dual-band HT capable of full-duplex operation on AO-85 and other Fox-1 U/V satellites. For many who have Icom IC-W32As that would suffer from receiver desense on V/U satellites including SO-50, it is time to dust them off - these should also be good for full-duplex operation on the Fox-1 satellites, free of any receiver desense. The time has come to prove - or, hopefully, disprove - statements about these HTs and their ability to work Fox-1 satellites full-duplex. :-)
For all of the passes I worked and monitored this evening, I have uploaded my audio and RF recordings, along with photos and screengrabs, to my Dropbox space. You can get to those files at:
Press F5 if the Dropbox page doesn't immediately appear in your browser window. This is easier than pasting the long string of gibberish that makes up a link to a public Dropbox folder. All of my files from this evening are in folders with name starting with 20151010.
It is approaching the 48-hour mark since the launch of AO-85. Being able to actually use this satellite, so soon after the launch, is hopefully a sign that the satellite is in good working order. I know that AMSAT personnel are still checking over the telemetry being downloaded from the satellite and uploaded to the AMSAT telemetry server. I hope the 45 seconds of silence heard this evening was a one-off incident. Add in the LilacSat-2 pass I heard early this evening, to the SO-50 pass just before midnight, it has been another fun day to work satellites. :-)
Good night, and 73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
Hi Patrick
Interesting observation about the Chinese handhelds being able to work full duplex on AO-85 (U/V) but not on SO-50 (V/U)
I saw some testing figures for harmonic output which suggested some radios use a single low pass with a cut-off just above 70cm, but the 2m transmitter uses the same filter. This meant the 3rd harmonic from 2m was very high and fell in the 70cm band de-sensing the radio.
What you have proved (hopefully) is that there are no outputs from the 70cm transmitter which interfere with the 2m receiver and that the receiver front end is not de-sensed when transmitting up to AO-85.
Nice.....
Thanks
David
-----Original Message----- From: Patrick STODDARD (WD9EWK/VA7EWK) [email protected] To: amsat-bb [email protected] Sent: Sat, 10 Oct 2015 9:34 Subject: [amsat-bb] Friday evening - LilacSat-2, AO-85 (yes!!!), and SO-50...
Hi!
Even though the KG-UV9D and probably a few other Chinese-made dual-band HTs can't work SO-50 full-duplex, they are probably going to be viable options for a dual-band HT capable of full-duplex operation on AO-85 and other Fox-1 U/V satellites.
Hi David!
I think that could be the case. Radios like these Chinese-made HTs, and later versions of the Icom IC-W32A sold over here (and possibly others - I will try to dig up my Alinco DJ-G7T that is in a box or bin in my garage), all of these suffer from the same desense issues with the V/U satellites like SO-50 and others. With the need to make Doppler adjustments on the AO-85 uplink, along with slight adjustments on the downlink to deal with the sharper receive filtering in the Chinese-made radios, this should open up more options for those wanting to work this satellite full-duplex using a single radio.
Burns W2BFJ and I spent some time working the Fox-1A engineering model's transponder last year at the ARRL Centennial Convention. I had the KG-UV8D, Wouxun's predecessor to the KG-UV9D I used last night, and Burns had his Kenwood TH-D72A. I had the squelch wide open on my radio, and moved the HT around while trying to shield the HT's antenna, in an attempt to simulate the downlink signals from this satellite in orbit. I had an earpiece plugged into the KG-UV8D's speaker jack, and Burns and I chatted as I walked around the convention's main hall, and even a little ways outside the hall. This is why I have had confidence that these radios could handle full-duplex operation on this satellite.
Now we need to figure out how to be heard with the 5-watt HTs through more of a pass, including the shallow passes... hopefully the commissioning process will allow AMSAT to make adjustments so this can happen.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
On Sat, Oct 10, 2015 at 1:08 PM, David G0MRF [email protected] wrote:
Hi Patrick
Interesting observation about the Chinese handhelds being able to work full duplex on AO-85 (U/V) but not on SO-50 (V/U)
I saw some testing figures for harmonic output which suggested some radios use a single low pass with a cut-off just above 70cm, but the 2m transmitter uses the same filter. This meant the 3rd harmonic from 2m was very high and fell in the 70cm band de-sensing the radio.
What you have proved (hopefully) is that there are no outputs from the 70cm transmitter which interfere with the 2m receiver and that the receiver front end is not de-sensed when transmitting up to AO-85.
Nice.....
Thanks
David
-
David G0MRF -
Patrick STODDARD (WD9EWK/VA7EWK)