I’ve written about meteor scatter a few times on this blog. It started with Meteor Scatter — A Burst of Excitement about my first experiences with WSJT’s FSK441 in 2014. A few years later, I examined the differences between FSK441 and the new MSK144 with My Scattered Compilation of Data Points. I also provided a video about meteor scatter and how to work MSK144.

This article covers meteor scatter propagation, WSJT-X MSK144 operation, meteor scatter operating protocols, and required gear.

How Meteor Scatter Works

There are literally tons of meteors entering the Earth’s atmosphere every single day. Meteors are dust trails left by comets. They are tiny, no bigger than a grain of sand. On entry, those grains of sand burn up and, as a result, ionize the E-Layer.

You can catch a glimpse of what’s happening in the image above. The red lines represent the ionization with some meteors more effective than others. The yellow lines represent the transmitted signal, with some reflecting off the ionized meteor trails. Hopefully, it reflects sufficient RF toward the desired receive location.

So that you know, the best time for meteor scatter propagation is in the early morning. There is roughly 3x more propagation at 6 AM than at 6 PM local time. You can see the reason for this in the image below. This is because the Earth’s orbit around the sun moves it into the stream of meteors, with the rotation of the Earth adding to that velocity near dawn versus subtracting from that velocity later in the day.

That’s what’s happening every day. But there’s a bonus during meteor showers. These are the predictable comet trails that have a high concentration of meteors. They happen every year at a set time. You can see the list of major showers in the list below.

MSK144 Making Meteor Scatter QSOs

So that’s the nature of meteors with insight into the best times and days to make contacts. But what does an MSK144 contact look like?

This image shows the WSJT-X Fast Graph display when the mode is set to MSK144. You can see meteor “pings” at 1.7, 3.5, 6.1, and 8.1. The brighter the ping shows up, the stronger the signal. For example, the ones above are +18 and +19 dB at 1.7 seconds and +5 dB at 8.1 seconds. These are the only pings that are decoded, which are displayed in the red box.

Here’s the audio file for the contact sequence displayed above. You can hear each of the pings and readily gauge the differences in amplitude and duration. Note, too, that MSK144 pings are decoded in real-time. It’s not like FT8, where you wait for the entire 15-second transmission before seeing the decode.

So, how do you set up WSJT-X for MSK144 contacts?

Getting on the Air with MSK144

Here are the settings within WSJT-X. By and large, you’ll use the same setting that you would normally use for FT8, rig control, audio, etc. MSK144 QSOs typically use NA Contest Mode to minimize the number of sequences required for a complete QSO.

From the above, you can see the settings for mode, MSK144, and the Decode menu settings. The decode is a pull-down menu for selecting Fast, Normal, or Deep. K1JT suggests selecting the option that works best for your computer; see the % of CPU time at the bottom of the screen and select the option that doesn’t overwhelm the CPU.

The other settings are F Tol to 200 Hz, Rx to 1500 Hz, and T/R to 15 seconds. I also strongly suggest using RRR in your sequence rather than RR73. With WSJT, after you’ve sent RR73, it logs the QSO. But with meteor scatter, it’s unlikely that one transmission of RR73 will actually get through. So you can use RRR as often as needed to get the other station’s confirmation that the QSO is over.

Sample 6 Meter MSK144 QSO

Here’s the screen display for an actual 6 meter MSK144 QSO.

I provide this for insight into the fact that meteor pings can be fickle when transmitting your signal. This QSO took 16 minutes, with lots of silence along the way. It takes patience and, ideally, coordination between stations to help you both continue when it seems all is lost. So that you know, this QSO goes against my recommendation to use contest mode and RRR.

Sample 2 Meter MSK144 QSO

For two meters, even more patience is needed. It’s also recommended that you use the SH setting. This generally stands for Short Hand, dramatically simplifying the messages transmitted, cutting the message to 20 ms versus the standard 72 ms message. That setting is shown below with the Sh checkbox; the blue highlighted messages are the only ones sent with the 20 ms coding.

This mode is often called CMSH for Contest Mode Short Hand. It is typically used on 2 meters and above. It is not standard practice to use it on 6 meters.

Above is a sample QSO on 2 meters. I’m responding to a CQ. It took a long 10 minutes to see the response and then a relatively quick completion with the SH messages shown in brackets.

Sample MSK144 QSY QSO

Another type of MSK144 operation that’s available is a QSY QSO. With this approach, the station calls CQ on the calling frequency and listens on a QSY frequency. When they hear another station, the QSO is completed on the QSY frequency. This is typically only used during contests or other very active times. Here’s an example.

You can see that KG5CCI was calling CQ 250. When I clicked on his CQ, my transmission moved to 50.250 MHz. That was indicated by the QSY message, followed by the rest of the QSO. The lower arrow above shows the checkbox for setting up a QSY CQ. You enter the QSY frequency in the box near the checkbox.

Meteor Scatter Operating Protocol

So there you have the various ways of setting up WSJT-X for meteor scatter. But there’s more! Yes, there’s an operating protocol that began long before WSJT arrived on the scene and has since been expanded.

• Operating Frequencies: 50.260 and 50.265 as well as 144.150 MHz.
• Operating Times: Early Mornings are the Best.
• Transmission Sequence: Pointing East, Transmit First Sequence. Pointing West, Transmit Second Sequence.
• Contest Mode: Often used on 6 meters, CM+SH is used on 2 meters.
• Coordinate Contacts: Ping Jockey, VHF-Chat-Slack, ON4KST. Random contacts are rare.

Useful Meteor Scatter Tools

When you’re transmitting CQs and not hearing anything at all, PSK Reporter can be very helpful. You enter your call sign, select the band, and it will display the stations receiving your signal. You can also find useful information about your signal level and the frequency. It is not restricted to MSK144, as all digital signals can be decoded and displayed. Try it out if you haven’t already used it.

Another helpful meteor scatter tool is the Virgo app. You can see the display below. This example shows the meteor showers in view and suggests the best direction to point your antenna — roughly perpendicular to the meteor shower path. Note that you must enter your grid square to get the correct data and that I’ve selected the sky display of W to E to get it more of a ground map display rather than its automatic sky map display. Plus, I’ve chosen the antenna azimuth indicator rather than the meteor trails. There are lots of options to try.

Meteor Scatter Gear

You’ve probably gleaned that a dipole and 5-watt rig won’t work with this mode. Instead, you’ll need a directional antenna and at least 100 watts on 6 meters, more on 2 meters. High power can be beneficial, and a preamp is typically required on 2 meters.

Interestingly enough, you can have too much antenna directivity for meteor scatter. K1JT recommends 16-degree beamwidth for long paths and 32 degrees for shorter paths. There are also offset azimuth settings to catch the meteor path just right. For example, the WSJT window below shows the direct “Az” of 24 degrees versus the “B” offset heading of 13 degrees when pointing from my grid of EM12 to the station’s grid of EN42. It also shows a recommended elevation. There can also be an “A” offset heading at times.

Get on the Air

That’s a lot to digest. Hopefully, it’s enough information to get you and your antenna pointed in the right direction to make some meteor scatter contacts. Then, watch for the showers and give it a go when the conditions are optimum. The folks on Ping Jockey and other chat rooms can also prove very helpful.

I provide more insight and more words in my meteor scatter video. You may want to check that out as well.

Good luck, and I hope to work you on MSK144.

Meteor Scatter References:

WSJT-X Operating Manual https://physics.princeton.edu//pulsar/k1jt/wsjtx-doc/wsjtx-main-2.5.4.html#_msk144

WSJT References Page – MSK144 Protocol, QEX July/August 2017

https://physics.princeton.edu//pulsar/k1jt/refs.html

VHF Meteor Scatter—An Astronomical Perspective

By Michael Owen, W9IP/2, QST June 1986

MSK144 Update January 2024

The FCC has updated amateur radio regulations to allow 2.8 kHz bandwidth digital modes on the bands below 30 MHz. This means that MSK144 and Q65A can be operated on 10 meters and lower. I’m seeing that the current MSK144 calling frequency is 28.145 MHz.