I have been playing around with the weak-signal propagation mode WSPR for about a year now. Most of my WSPR initial work was in receiving and reporting Spots from WSPR transmitters. Now I wanted to do some HF antenna testing but it was in a rough RF reception environment. So instead of receiving and reporting WSPR packets, I decided to use a WSPR Transmitter and to analyze resulting Spots reported by monitoring Stations. That allows me to see how other stations are receiving my signal, as I change or modify antennas. I think using a single transmitter on my end, and many receivers is better than the alternative for me anyway. It gives me control of the most important signal factors.

Antenna Testing with WSPR

It seems like WSPR is a natural for HF antenna testing and evaluation/comparison. I have heard some say that it is NOT a good vehicle for antenna testing because of the way HF propagation changes and varies over time. It IS true that you could not perform evaluation of a single antenna over many weeks or months without considering this variable. There are some things to keep in mind when using WSPR for testing of antennas:

1. HF Propagation changes, so you must run tests over relatively short periods of time and watch for significant events (like Solar Storms) that could change signal propagation on a Band or Bands.
2. Remember that you do NOT know what is on the receiving end of the link, unless you coordinate with the receiving Station. But there are many stations that are monitoring consistently with fixed antenna configurations.
3. If running tests over several days, test at the same time of day or as close as possible for each run.
4. For best results, find some Stations that appear to always be monitoring, and seem to be able to pickup your signals on a daily basis. There are may out there.
5. If you are using a particular Receive Station and you want to make sure they are using a consistent antenna on some Band, just ask them. Most people using WSPR would be thrilled to hear that you are using their WSPR reports to improve your Station/antennas

Selecting a WSPR Transmitter

You can use most modern HF radios with WSJT-X software as your WSPR transmitter. There are some drawbacks. Many HF Transceivers only go down to 5 watts. While this is acceptable, it is overkill. Most testing on WSPR is done with 10s or hundreds of milliwatts. If you do not use GPS for timing, some other means of time synchronization will be required. For my field testing, I selected a nice portable WSPR Transmitter from Zachtek. There are many transmitters out there to choose from. The one I am using can be found here. A picture is provided below. Help is also readily available on the Zachtek forum, if you run into any trouble.

This unit uses just 5V DC which you can provide from any USB charger. It does REQUIRE GPS and an antenna is provided. GPS is used for both timing ad location calculation, so it is not optional. I have found that placing the included GPS antenna on a ground plane (mine is about 10 X 10 inches) gives me adequate signal, even inside my house with metal-backed roof insulation. The Zachtek Desktop unit can transmit on any HF Band or a combination of Bands. For my current testing, I transmit on 15, 20, and 80 meters during each 10 minute time period.

Observing WSPR reports for your Transmissions

All stations that receive WSPR packets can report their signal reports to a universal database. You can find this database online and have permanent access to all WSPR Spots ever reported. There is also an incredible WSPR front-end by VK7JJ which can be found at WSPR.ROCKS This provides an interface for extracting and sorting of WSPR Spots from the universal database. Here is a screenshot of my WSPR reports after a few hours. I was using 200 mW from the Zachtek Transmitter and the antenna was an 80 meter broadband dipole. Here is a screenshot of the map vies for my transmissions at the WSPR.Rocks Site:

Table-oriented lists are also available at WSPR.ROCKS and they can be easily imported into any spreadsheet or data analysis software.

Initial Results

When I start a WSPR session, I am always shocked at the locations where my low-power WSPR transmissions are being received. This transmitter is well designed for protection even from poorly-matched antennas. Antenna tuners are not really needed unless there is some terribly high-SWR case that is being used.

I have now found several WSPR monitoring stations that can receive my signals on a daily basis. I am just in the process of creating some test scenarios for evaluation. If you like working with HF antennas and you aren’t using WSPR, why not? It takes little of no investment if you already have HF radio equipment. If you give this a try, please let me know how it works out for you. There is much to be learned here!

73,

Tom, KG3V

I’ve quit Twitter/X, and am now part of the Fediverse. There are quite a few radio amateurs in the Fediverse, and if you’d like to follow me there, you can follow @kb6nu@mastodon.radio. Mastodon.radio is a space for radio amateurs and SWLs, but it’s not the only radio-focused Fediverse server. It connects with the servers listed on fediverse.radio, including mastodon.hams.social, a server here in the U.S.

Mastodon seems to have a much higher signal-to-noise ratio than Twitter. Here’s a few links I found and things I learned on Mastodon last night:

K8CX Ham Gallery. K8CX has an interesting collection of photos from Dayton, DX sound clips, and a QSL card museum. I’ve submitted a couple photos of me and the ICQ Podcast crew at Dayton 2024.

M17 Users mailing list. The  home page for this mailing list says, “The primary assumption of this mailing list is that M17 is (in June, 2024) in usable (enough) form for actual deployment and use in amateur radio.” They believe that all the pieces are there now.  Typically, to use M17, you’ll have to be “somewhat of an experimenter” to work around the inevitable glitches in using M17, but in the opinion of this list founder, “all the pieces are there now”.

44-foot doublet. Last night, there was some discussion of portable antennas, mainly the 44-ft. doublet antenna. This is the antenna that L. B. Cebik describes on the web page, “1 Wire, 7 Bands, 2 Directions, or The 44′ Doublet as a 40-10 Meter Antenna.” There’s a similar antenna out there called the NorCal Doublet. The NorCal Doublet uses ribbon cable as the feedline to reduce weight. These two antennas look like they’d be worth experimenting with.

See you in the Fediverse!

Months of research prove the notion compressed data over ARQ modem techniques is anything, but effective encryption.

The post “Effective encryption” effectively debunked appeared first on Ham Radio . Magnum Experimentum.

NO-84 (PSAT) was launched in 2015 and although it’s been in orbit for some time, you will find a lot of people have only used the APRS Digipeater which is also a payload on the satellite, however, the main payload is a PSK Transponder.

Uplink is on the 10m PSK frequency of 28.120 USB and it downlinks on 435.350 FM (PSK31), the satellite builders recommend using up to 75w into an omnidirectional antenna on 10m.

Antennas

In my own experience of using NO-84, I was using a 10m dipole which worked reasonably well, but I found the best antenna for myself was a 10m GP this was easy to build with a small fibreglass fishing rod, wire and a dipole centre I made one for less than £10 (Bargain!)

I found with this setup I was able to activate the transponder with as little as 10w, however, of course, increasing the power made sure that NO-84 could hear my signal a lot more.

Software

Transmitting

Of course, with this satellite doppler is a consideration and although you can use a standard PSK31 application for transmitting and receive you’ll see your signal has the Doppler curve on it, however, K0SM has produced a simple application called DopplerPSK

Setting this up is simple, you download the application which is Java and launch it and then set some parameters. In Station -> Edit Station Information you specify your location like you would with any other tracking application. You then select the satellite you want to use by going to Satellite -> Choose Satellite and select NO-84.

It’s worth noting you’ll need to manually update the TLEs, these are stored in the /tle/ subdirectory. I’d recommend using the https://www.amsat.org/tle/current/nasabare.txt once you have updated the TLEs relaunch the application.

Select the output soundcard by clicking on Audio Device in the menu and selecting the correct one, remember this is the audio going to your radio.

On the main screen of DopplerPSK you’ll notice you have some tracking information and boxes update the MyCall with your own callsign and press update. Notice below that there are prepopulated text inputs and radio buttons to represent the one that has been selected for now use CQ.

Its generally recommended you transmit the whole time NO-84 is passing over. The other station will be on a different frequency to yourself, update their callsign in DXCall and the exchange and hit the Update button, again then select the message you want to send till the contacts complete. Then go back to CQ or reply to someone else if their calling CQ, this method seems to work well.

The above screenshot is DopperPSKs main screen.

The above image shows FL-Digi decoding multiple signals, in this case, 2E0SQL and the satellite’s beacon.

Receiving

To decode the signals, I personally recommend using a PSK application that supports multi decoding, for instance, FL-Digi, you can watch all the stations on the passband and your own and carry out your contact with ease.

Remember that if NO-84 doesn’t hear a PSK31 signal on 28.120 the transponder will not turn on unless it is sending its beacon signal.

Final Thoughts

Hopefully, this gives you some idea how to setup DopplerPSK to complete a NO-84 PSK QSO. It’s worth keeping in mind that activity can be low, so do not be scared to ask for prearranged contact.

Useful Links

• DopplerPSK – http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
• 1/4 Wave Ground Plane Antenna Calculator – https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

Downloads

• DopplerPSK-Quick-Start-Guide
• DopplerPSK version 0.2

The post Using the NO-84 (PSAT) PSK Transponder appeared first on 2M0SQL.