Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
VARA-MFSK16-OFDM Shootout for 60 Meters APRS This Saturday
|
This test will have FOUR copies of UIview running at the same time on my Panasonic CF-51 mobile laptop.? This is a 32-bit dual-core 1.6 GHz CPU with 4 gigs (maximum for a 32-bit system) RAM.? 3 copies will be beaconing APRS posits on the new VARA HF modem, MFSK16 and OFDM -- the latter two generated by two copies of FLdigi.
(All three digi-mode programs present a KISS-type interface that can be used by UIview, instead of a conventional AX.25 packet TNC.) After the dramatic results of the 300 baud AX.25 vs VARA test I made in early January, I am now ready to go with a 3-way comparison test of the new VARA modem -vs- MFSK-16 generated by FLdigi? -vs- OFDM generated by FLdigi. This 3-way shootout will happen enroute from the Lansing, Michigan area to Traverse City, Mi for the annual Cherryland ARC Swap-N-Shop.? I will be departing about 3AM EST Saturday 11 Feb to arrive about 7:00 AM. ? After the hamfest, the return trip will begin around 1-2 PM, depending on what kind of gathering may develop after the hamfest. The tests will be on 60 Meters "Channel 5" at 5.403.5 USB. Full details on the test are on my website at: <> A summary of the previous VARA vs AX.25 test in early January is here on my website: <> ------------------------------------------------------------------------------- Stephen H. Smith??? wa8lmf (at) aol.com Skype:??????? WA8LMF EchoLink:? Node #? 14400? [Think bottom of the 2-meter band] Home Page: -- APRS over FLdigi Modes? -- <> 60-Meter APRS!?? HF NVIS APRS Igate Now Operating <> Flying Digipeater! <> 11 Copies of UIview in Action on One Computer! Live Off-The-Air APRS Activity Maps <> |
|
Stephen,
I am betting on Vara. The previous test you made with Vara was a real accomplishment. The first time I ran Vara on Winlink I was amazed that it could decode stations that I could not physically hear. For years I used a Kantronics KAM for HF packet. I always could hear AX.25 stations that I thought it should decode with no luck. I even made a test with a Behringer UCA202 sound card with the UZ7HO sound modem with only marginally better results. Last year, with the help of John W5PSX, I built a packet station that was originally to be used for VHF. The packet part of the station consisted of a Masters Communications DRA-30 sound card and a Pi 3 computer running Dire Wolf software. This was all mounted in a Bud box. The Vhf location fell through so I thought I would try it on HF 30 meter baud. I was amazed. I am now copying 30 meter AX.25 stations I can't physically hear just like Vara on Winlink. See stations heard directly on APRS.FI for WA5LUY-10. I have UI-View connected to the Pi computer with AGWPE. The only UI-View functionality I have lost is Acks to messages. You might want to give Dire Wolf a try before giving up on AX.25 73 and I will be looking forward to your test results. Wayne WA5LUY |
|
On 2/11/2023 5:20 PM, wa5luy wrote:
Stephen,The test run was a complete fiasco with numerous hardware and software problems. For example, I discovered the FLdigi program's audio detector? on receive is so sensitive that transmitting on one mode would cause the other instance of FLdigi (on receive) to hear the RSID code and auto-switch to to the same mode!??? So I would beacon on MFSK16 -- then the next beacon (from the other copy of FLdigi) would also beacon on MFKS16 instead of OFDM. I think some sort of sneak audio path in the hardware of the computer or interface, or perhaps possibly stray detection of transmitted RF. I did days of testing in my carport before heading out on the trip. ? For the at-home tests, I had a 10dB 50-watt attenuator in the line between the transceiver and the mobile antenna.? Partly to keep the nearby base station receiver from overloading so badly, and partly to hide the severe de-tuning of the mobile whip when parked under the carport canopy, from the transceiver.? (In the interest of keeping the transceiver PA as linear as possible.) Under these conditions there were no problems.? On the road, without out the attenuator with the antenna matched and radiating full power, the problems began. Also, my experiment to have VSPE (Virtual Serial Ports Emulator) allow three applications to share the same serial port for PTT keying worked fine on the desktop pre-test, but came unglued in the real world. It would work for a while, then randomly lockup and stop doing PTT.? ? I suspect this had something to do with the DigiRig interface I used having NO isolation between the computer side and the radio side; i.e. common ground connections, aggravated by automotive electrical noise circulation on the vehicle ground systems. (Again, the home desktop pre-test worked perfectly for days when the the transceiver (Yaesu FT-891) and computer were being powered by clean DC power from a 12 VDC 100AH battery bank being float-charged by a good 20A DC power supply. At the same times,. a second VSPE serial splitter setup sharing a single GPS receiver with 5 destinations (MS MapPoint for navigation, the main two-meters APRS instance of UIview, and three copies of UIview being used for the experiment on 60 meters) would also quit. The normal setup (MapPoint, two UIviews, a GPS monitoring tool "GPS View" and sometimes Delorme Topo NA)? has been absolutely bullet-proof with this setup? in the past for over 100,000 miles of mobile operating. I lost a lot of tine stopping at highway rest areas rebooting the Toughbook and restarting applications in a precise sequence.? On the return trip from the hamfest, I began to suspect the interface and noise/ground loops as the problem. I stopped by the side of route Michigan 115 and switched the interface to my own homebrew totally passive tone-activated self-powered and TOTALLY ISOLATED? interface (that I had been demoing at the hamfest). I lost an hour re-configuring and tweaking multiple applications on the Toughbook; then resumed the drive. ? The GPS splitting and PTT was now bulletproof! But I hadn't noticed that in the meantime the audio tone freqs in both copies of FLdigi had shifted downward 100 Hz, ruining the remainder of the test! I plan to run a proof-of-concept test on a short drive from East Lansing to Grand Rapids (about 70 mi away) sometime next week. Before running a "real" test farther afield enroute to a ham fest in a month or two. All this comes with the territory of mobile radio systems engineering which I have been doing for decades! |
|
Excellent write up and analysis.
toggle quoted message
Show quoted text
Thanks for sharing Dwight n2fmc@... On Feb 12, 2023, at 15:19, WA8LMF via groups.io <wa8lmf@...> wrote: |
wa5luy
to navigate to use esc to dismiss