We get quite a few requests from folks to explain how to get started with Amateur Radio Satellites. Requests for information on how to build a computer-controlled ground station for Linear Satellites are also pretty common. I recently got such a request from our CWA class so I decided to put together a session on this topic.
We covered a number of topics and demonstrations during the session including:
How to put together a simple station and work FM EasySats with HTs and a handheld antenna
A recorded demonstration of some contacts using FM EasySats
How-to build a computer-controlled station and work Linear Transponder Satellites
Fixed and Portable Satellite Station Antenna options
A recorded demonstration of some contacts using Linear Satellites
EME or Earth-Moon-Earth contacts involve bouncing signals off the moon to make contacts. EME provides a means to make DX contacts using the VHF and higher bands. There are also some EME Contests including the ARRL EME Contest that provides opportunities to make EME contacts.
Understanding EME Propagation is a project in of itself. The following is a brief overview of some of the (mostly negative) effects involved.
The path loss for EME contacts varies by Band and is in excess of 250 dB on the 2m band. There are some significant “propagation” effects that further impair our ability to make EME contacts. These include:
Faraday Rotation – an effect which results in the polarity of signals being rotated by differing amounts as they pass through the ionosphere on their way to the moon and back
Libration Fading – fading caused by the adding of the multiple wave-fronts that are reflected by the uneven surface of the moon
Path loss variations as the earth to moon distance varies – the moon’s orbit around the earth is somewhat elliptical in shape resulting in a distance variation of approximately 50,000 km during the moon’s monthly orbital cycle. This equates to about a 2 dB variation in total path loss. An average figure for the path loss for 2m EME might be in the range of 252 dB.
Transit Delays – at the speed of light, it takes between 2.4 and 2.7 seconds for our signals to travel from earth to the moon and back.
Noise – the signals returning from the moon are extremely weak and must compete with natural (and man-made) noise sources. The sun and the noise from other stars in our galaxy are significant factors for EME communications on the 2m band.
Doppler shifts – as the earth rotates, the total length of the path to the moon and back is constantly changing and this results in some frequency shift due to doppler effects. Doppler shift changes fairly slowly compared to the time it takes to complete a 2m EME QSO so it is not a major factor for the 2m band.
Moon’s size vs. Antenna Aperture – the moon is a small target (about 0.5 degrees) compared to the radiation pattern of most 2m antenna systems. This means that most of our transmitted power passes by the moon and continues into space.
Taking the moon’s size, an average orbital distance, and an average Libration Fading level into account, one can expect only about 6.5 % of the power that is directed towards the moon to be reflected back towards earth.
EME “Good Guys”
One might look at the challenges associated with making EME contacts and say “why bother”? EME contacts present one of the most challenging and technical forms of Amateur Radio communications. It is this challenge the fascinates most EME’ers including this one. Fortunately, there are some “good-guy” effects that help to put EME communications within reach of most Amateur Radio stations. These include:
WSJT-X and the JT65 Digital Protocol – In the early days of EME communications, one had to rely on CW mode to make contacts. All of the impairments outlined above made these contacts very challenging and the antennas and power levels required put EME communications out of the reach of most Amateurs. Along came Joe Taylor’s digital JT65 protocol which changed all of this. It is now possible to make 2m EME contacts with a single (albeit large) 2m yagi and 200W or so of input power. As a result of these innovations, many more Amateurs have built EME stations and are active on the 2m (and other) bands. Many DXpeditions are now also including EME communications in their operations.
Ground Gain Effects – a horizontally polarized antenna system will experience approximately 6 dB of additional gain when the antenna(s) are pointed approximately parallel to the ground. Ground gain effects made it possible for us to use our single 2m antenna to make our first 2m EME contacts.
MAP65 Adaptive Polarization – Fading resulting from polarity changes due to Faraday Rotation can cause a received signal to fade to nothing over the period of time needed to complete a 2m EME contact. These polarity “lock-out” effects can make contacts take a significant amount of time to complete. Fortunately, a version of the software which implements the JT65 protocol called MAP65 has been created that will automatically detect and adapt to the actual polarity of signals returning from the moon. More on how this is achieved follows below. MAP65 is most useful for making “random” EME contacts during contests. In these situations, a variety of signals will be present in a given band with different polarities, and the MAP65 software can adapt to each one’s polarity and decode as many simultaneous signals as possible.
Commercially Available Amplifiers for the VHF+ Bands – Modern, solid-state amplifiers have become much for available for the 2m band (and other VHF and higher bands). This has made single-antenna EME on 2m and above much more practical for smaller stations with a single antenna or a small antenna array.
Our 2m EME Goals and Station Design
We began this project by making a list of goals for our 2m EME Station 2.0. Here is that list:
Operation using JT65 and QRA64 digital protocols and possibly CW on the 2m EME band
80th percentile or better station (i.e. we want to be able to work 80% of the JT65 capable 2m EME stations out there)
Operation in EME contests and EME DX’ing; earn a 2m EME DXCC
We have come up with the following station design parameters to meet these goals:
An array of four cross-polarized antennas with an aggregate gain of approximately 23 dBi
The combined gain of the system will be approximately 23 dBi with a 3 dB beamwidth of 12.5°. The XP28 antennas are designed for stacking and have good Gain/Temperature (G/T) characteristics. G/T is a measure of the gain and noise performance of an antenna system. See VE7BQH’s tables for some interesting data on G/T for many commercially available EME and VHF+ antennas.
The antenna system will have separate feeds for the antenna array’s Horizontal (H) and Vertical (V) planes. The Horizontal elements will be oriented parallel to the ground to maximize ground gain when the H plane is used for transmitting (and receive). A pair of 4-port power combiners will be used to combine the H and V polarities of the four antennas into a pair of H and V feedline connections.
M2 Antenna Systems will be supplying a MAP65 Switching and Preamp System that will mount on the tower near the antennas. The MAP65 Housing provides switching and separate receive preamplifiers and feedlines for the H and V polarities of the antennas. Separate H and V receive coax connections bring the Horizontal and Vertical elements of the antennas back to the shack. A third coax connection is provided for Transmit. The transmit feedline can be routed to either the H or the V antenna polarity to help minimize Faraday Rotation related fading at the other end of the contact.
An M2 Antennas S2 Sequencer will provide Tx/Rx sequencing and H/V transmit polarity selection via the MAP65 Switching and Preamp System on the tower. The sequencer is essential to provide safe changeovers between receive and transmit and to protect the preamplifiers and the power amplifier during high power operation.
The signals returning from the moon in an EME system are very, very weak. Because of this, Noise and Dynamic Range performance are critical factors in an EME receive system. In addition, we will need a pair of high-performance, phase-coherent receivers to enable Adaptive Polarization via MAP65.
LinkRF IQ+ Dual Polarity Receive System
We are planning to use a LinkRF IQ+ Dual Channel Receive Converter in our EME system. The Link RF IQ+ features excellent noise and dynamic range performance and its phase-coherent design will support adaptive polarity via MAP65. The IQ+ separately converts both the H and V polarities of the antennas into two separate pairs of I/Q streams.
UADC4 High-Performance 4-Channel A/D Converter
The four channels (two I/Q streams) from the LinkRF IQ+ must be digitized and fed to a Windows PC for decoding. The conventional way to do this is with a 4-channel, 24-bit soundcard. The available computer soundcards add a good bit of noise and therefore limit the overall dynamic range of an EME system. Alex, HB9DRI at LinkRF has come up with the UADC4 – a high-performance 4-channel ADC that is specially designed for software-defined radio. The UADC4 design is based on CERO- IF conversion and is optimized for EME use. The UADC4 should add about 10 – 15 dB of dynamic range improvement over a typical 24-bit PC Soundcard. Alex is currently taking pre-orders for the next run for UADC4 devices. You can contact him at firstname.lastname@example.org for more information.
JT65B Software Block Diagram
Our plans for JT65 software and related components for our EME station are shown above. We are planning on running a combination of Linrad and WSJT software on the same Windows PC to handle JT65B QSOs. There are two configurations that are applicable to our plans:
We are also planning to develop a simple windows application that will read the Moon Tracking data that is generated by WSJT MAP65 and WSJT-X and use it to control the rotator system associated with our EME antennas. More on this to come in a future article.
Well, that about covers it as far as our 2m EME goals and station design go. The plan is to break ground for the new EME tower later this week. We’ll continue to post more articles in this series as our project proceeds.
Here are some links to other articles in our series about our EME Station 2.0 project:
There are many reasons to have an accurate time source in your station. Getting the best performance from WSJT-X modes like FT8 requires your computer clock to be synchronized to within a second for example. You can set your clocks accurately using NTP servers on the Internet. This is the most common way that most stations set their clocks.
What if you are portable and don’t have Internet access or what do you do if your Internet connection goes down? One way to solve these problems is to use a GPS controlled NTP time server in your station. We recently installed one from Leo Bodnar in our station.
This device is simple to install. It just requires an Ethernet connection to your network and a GPS antenna. The antenna is included with the unit. The antenna will need to be outdoors with a reasonably clear view of the sky.
GPS Satellite Lock Screen
After a minute or so after it is installed and powered up, the unit will synchronize to the visible GPS satellites in your location and report its coordinates. This indicates that you have a good GPS system lock and that the clock in the unit is accurate to within a microsecond.
NTP Summary Screen
The unit gets its IP either from DHCP or via a fixed IP address that you can program. Once the unit is set, you use its IP address as the NTP server in your software to set your clocks. You would set you NTP server in a program like Dimension 4 to accurately set your computer’s clock for example. You will want to disable your computer’s normal Internet clock setting function to avoid conflicts with Dimension 4. Once this is set up, your computer clock will be synchronized to the GPS system and will be very accurate and you will get the best performance from WSJT-X.
We’ve recently begun experimenting with a WSJT-X derivative for FT8 and other JT Modes. Its called JTDX. The JTDX software is created by Igor Chernikov, UA3DJY, and Arvo Järve ES1JA. The stated purpose for JTDX from the JTDX website is:
The latest release candidate of JTDX supports some interesting additional features beyond WSJT-X including:
Additional FT8 and JT65 decoder options which can provide improved sensitivity
Advanced automatic sequencing and QSO selection features
Decoded messaging filtering features
We’ve been testing JTDX V2.0 release candidates here for about a month now. the JTDX feature additions definitely provide some useful enhancements. The JTDX software is derived from WSJT-X and we’ve been using it here for DX’ing and for weak signal work on 6 meters. It appears to have most of the features of the current version of WSJT-X with the notable exception of support for specific contest exchanges.
JTDX Decoder Options
JTDX adds a number of FT8 decoding options that are useful on crowded bands and in situations when signals are very weak. These features can be selectively enabled to match band and signal conditions as well as the user’s available CPU horsepower. With all features enabled, JTDX seems to decode more signals on a crowded band than WSJT-X.
QSO Partner Decoder Filtering
There is also a QSO partner decoding “filter” option which concentrates the FT8 decoder on a narrow bandwidth around a specific weak signal that you are trying to receive and decode. This feature seems to help to decode very weak signals in a crowded band when they are surrounded by other, stronger callers.
You may have experienced the crowded conditions in the FT8 sub-band on popular bands like 20m.
Typical Stations Decoded Simultaneously on 20m FT8 Sub-band (JTAlert Display)
If you call CQ with Auto Sequence and Call First turned on in WSJT-X, you may find that you don’t have much control over what stations are selected to answer your CQ. It’s also common for the Auto Sequencing in WSJT-X to “get stuck” on a caller that how fails to complete a QSO for whatever reason.
JTDX provides some useful features to prioritize the selection of callers in these situations.
JTDX Auto Sequencing Caller Selection Options
You can see these options on the menu above. Options include choosing a station to answer based upon distance or best Signal To Noise Ratio (SNR), including or excluding stations that you’ve worked before, or including or excluding other stations calling CQ. These features allow JTDX to do a better job selecting a QSO to Auto Respond to when you are calling CQ.
JTDX Auto Sequencing Configuration Options
What about the problem of “stuck” QSOs? JTDX has some useful features that limit the number of tries that the Auto Sequencing algorithm uses before returning to calling CQ or working the next available caller. These features prevent the Auto Sequence algorithm from getting stuck during a contact when your QSO partner fails to respond or decided to work someone else.
Directed CQ – CQ DX
JTDX also has the ability to enforce “directed CQ’ing”. Directed CQ’ing is when you call, for example, “CQ DX” and get responses from callers in your country. JTDX Auto Sequencing can be configured to ignore such callers and only work DX stations that answer your CQ. Directed CQ’s can also be applied to specific regions of the world (CQ AS for example) as well.
Decoded Message Filtering Options
Finally, you may have experienced a flood of decoded messages on a busy band. It is almost impossible to read and process all of the information a large number of decoded messages in the 15 seconds available. JTDX has some good filtering options to selectively hide decoded messages to enable the operator to focus on messages from stations that they are looking for. The image above shows a very simple application of this capability to limit the decoded message display to only CQ messages. More complex rules are possible via configuration in the Filters tab.
There is a learning curve with JTDX and it takes a little time to learn to use all of the new features. There is a basic getting started guide that helps to get JTDX setup and configured at your station and some useful FAQ documents to help you learn about some of the JTDX features. The best source of information on the more advanced features is the JTDX groups.io group.
I don’t think that JTDX is a replacement for WSJT-X. We run both here and they both work well. JTDX has some important advantages in crowded band situations and is my tool of choice for working DX with FT8. I also like the more sensitive decoder in JTDX for weak signal FT8 work on the 6m band. WSJT-X is a better tool for contests as it contains support for specific contest exchanges via FT8 – a feature which JTDX does not yet support. WSJT-X also supports important modes like MSK144 for Meteor Scatter QSOs.
If you are new to FT8, I’d suggest you begin with WSJT-X and use it to learn the basics of the FT8 protocol and how to operate using FT8. You can find a Video Introduction to WSJT-X and FT8 here on our blog to help you get started and get on the air with FT8 using WSJT-X.
The Nashua Area Radio Society recently held a Tech Night on WSJT-X: FT8, WSPR, MSK144, and More. This Tech Night was recorded and provides a good starting point for folks who want to understand what the WSJT-X software can do, how to use it, and how to integrate it into their station.
August 2018 Tech Night – WSJT-X: FT8, WSPR, MSK144, and More
The video from our Tech Night includes lots of information about how to get started as well as some recorded demonstrations of FT8 and Meteor Scatter contacts.
Topics Cover During WSJT-X Tech Night
Our Tech Night also covered tools like PSKreporter and JTAlert that can be used with WSJT-X. Finally, we spent some time on using WSPR to evaluate your station’s performance and how you can use the software to do more “exotic” QSOs such as Meteor Scatter on 6m.
Nashua Area Radio Society members have access to our full library of over 30 Tech Night Video on a wide range of topics for both beginning and advanced Hams. You can see the list of what is available on the Nashua Area Radio Society Tech Night page.
Better support for North American VHF Contests with improved handling of grids and /R rover call sign designators
Six-character locators and call sign suffix support for portable operators focused on EU VHF contesting
Support for ARRL Field Day exchanges
Support for ARRL RTTY Roundup exchanges
Support for call signs up to 11 characters to support non-standard and compound call signs
The new version extends the length of the messages used for FT8 and MSK144 from 75/72 bits to 77 bits to enable the above features. As a result, there are compatibility issues between the v1.x releases of WSJT-X and v2.0 when FT8 and MSK144 modes are used. More detail about the new features and changes can be found here.
It is expected that the Meteor Scatter community (MSK144 mode users) will rapidly move to WSJT-X V2.0 so no backward compatibility features are provided for MSK144.
The transition for FT8 mode users is a much bigger problem. As a result, it is suggested that users test the new mode on alternative frequencies on the 20m band at 14.078 MHz and on the 40m band at 7.078 Mhz.
WSJT-X 2.0 FT8 Compatibility and Contest Options
The Advanced Tab in the WSJT-X v2.0 settings provides some options to help with compatibility between v1.x and V2.0. One must choose whether to transmit using the shorter v1.x or the v2.0 messages. If you are operating in the above mention “2.0” frequency areas on 20m or 40m, it’s a good idea to transmit using the 2.0 message format (check always generate 77-bit messages).
The new version of WSJT-X can decode both the shorter v1.x and the longer v2.0 messages simultaneously. The decoding will be faster on slower computers if you check the Decode only 77-bit messages option when operating in the v2.0 frequency ranges.
If you want to try the new v2.0 FT8 mode in one of the supported contests, you’ll want to check the appropriate Special operating activity option. If you are not operating in one of these contests, you’ll want to select None.
All you need to do to try the new version is to download and install it and configure the FT8 options. I’ve been running WSJT-X v2.0 rc1 in the 20m band in the 14.078 MHz sub-band this morning and have made about 20 contacts using the new format. The v2.0 software is working well.
There are some additional enhancements which will be included in WSJT-X v2.0. Here’s some information on these features from the WSJT-X v2.0 Quick Start Guide –
WSJT-X 2.0 has several other new features and capabilities. The WSPR decoder has better sensitivity by about 1 dB. Color highlighting of decoded messages provides worked-before status for callsigns, grid locators, and DXCC entities on a “by band” basis. Color highlighting can also identify stations that have (or have not) uploaded their logs to Logbook of the World (LoTW) within the past year. The necessary information from LoTW can be easily downloaded from the ARRL website.
Currently, several additional release candidates are planned for WSJT-X v2.0 as follows:
September 17, 2018: -rc1 Expires October 31, 2018
October 15, 2018: -rc2 Expires November 30, 2018
November 12, 2018: -rc3 Expires December 31, 2018
December 10, 2018: GA Full release of WSJT-X 2.0
Note that the release candidates will expire about 2 weeks after each new version becomes available. Also, its required that anyone who runs the Beta (release candidate) software agrees to report any bugs that they find.
We are looking forward to trying the new FT8 in the next digital contest which allows it.
I have been operating using the FT8 digital mode on the 6m band using our remote operating gateway quite a bit this summer. The SDR-based remote operating gateway in our station allows us to operate our station from other rooms in our home as well as from outside our QTH via the Internet. When I’m at home, I have computers set up with outboard monitors to create an operating setup for FT8 digital contacts on the 6m and other bands. The photo above shows this setup. Having the extra screen space and multiple laptops enables control of our station, making and logging QSOs, and checking propagation via Reverse Beacon Networks as we operate.
Flex-6700 SmartSDR and WSJT-X Weak Signal Digital Software
This laptop runs the WSJT-X software (left windows above) which conducts QSOs in FT8 and other weak signal modes and the JTAlert Software (lower right windows above) which interfaces WSJT-X to the DXLab logging suite. JTAlert displays all callsigns decoded by WSJT-X and compares them to my log to determine which potential contacts are new DXCC’s, Grids, States, etc. JTAlert adds contacts to my logs in DXLab when a QSO is completed using WSJT-X.
DXLab Suite Logging and Rotator Control Software
The windows laptop also runs the DXLab logging suite. DXLab handles logging of QSOs, the one-click pointing of our antennas based upon the callsign being worked, and uploading contacts to LoTW, eQSL, and ClubLog for confirming contacts.
Reverse Beacon Network and Station Monitoring Computer
I like to use the second computer to monitor the propagation and strength of my FT8 signal while operating.
PSKReporter RBN Monitoring on 6m
I use two tools to assess propagation conditions while I am operating. The first is PSKReporter which is a Reverse Beacon Network (RBN) tool that is enabled by WSJT-X and most other digital mode software programs. Each time WSJT-X decodes a station’s transmission, it reports the decoded callsign along with location and signal strength information to the PSKReporter website. This website then uses this information to display all of the stations that hear my and other’s transmissions in real-time. The RBN information is used to determine where a given band is open and as a tool to determine how much transmit power is needed to provide acceptable signal strength at stations that I am trying to work.
DXMaps Propagation Report on 6m
The DXMaps website shows a real-time map view of contacts being made on the 10m and higher bands. This second tool provides a real-time view of band conditions and opening on bands like 6m which have somewhat unpredictable propagation characteristics.
Together, these tools help to determine where to point antennas and what stations we can work on the 6m band.
The second laptop also runs Teamviewer remote control software. This provides access to the antenna switching controls, SWR and power monitoring equipment, station electrical power, and amplifier controls in our shack. These tools are important elements in safely operating and controlling our station when we are not in the same room as the radios and other equipment we are using.
2018 has been a summer 6m E-Skip (Es) season to remember. The Es openings have been strong this year and they are continuing into the second half of July. We are enjoying almost daily openings to Europe and the western USA from here in New England. For fun, I’ve plotted my 6m Grids worked and confirmed to date using WG7J’s GridMapper site.
We got started a little late with 6m Es operations this year but the conditions have really helped our Grids, DXCC’s, and States totals worked on 6m. My totals are currently standing at:
6m DXCC’s – 55 worked
6m US States – 48 of 50 (only AK and HI still needed)
6m Grids – 357 worked
A great deal of this progress has been made in 2018. Here are my 6m worked totals since the beginning of the year:
6m DXCC’s – 48 worked
6m US States – 46 worked (All but AK and HI)
6m Grids – 312 worked
AB1OC Europe 6m Grids
The new FT8 and MSK144 modes has made more difficult 6m contacts much easier. This is especially true for DX contacts into Europe and Africa.
AB1OC Americas 6m Grids
At this point, we have worked most of the grids in the eastern half of the US. There are still some “rare” ones that are needed and a contact with Delaware is still needed for my last state on 6m in the continental USA. Alaska and Hawaii will be a challenge on 6m and I may need to use JT65 and EME propagation to work these states on 6m.
With some work on QSL’ing, the recent 6m activity will add significant progress to several of my operating awards. The new 6m DXCC’s worked recently should enable breaking the 2,000 band point level on my DXCC Challenge Award.
If you are interested in trying 6m operations or perhaps you are a new Technician Licensee or are looking for something new to try, don’t forget about the Magic Band (6m). The availability of FT8 mode has really enhanced the activity on 6m. Give it a try!
Portable Satellite Station With Additions For Digital and Packet
We’ve recently upgraded our Portable Satellite Station 2.0 to add digital and packet capabilities. The upgrade was pretty simple – we added a SignaLink USB Soundcard and a Windows Laptop PC. Most of the software for packet and digital Amateur Radio communications is written for the Windows OS so using a separate laptop running Windows 10 was the simplest way to go. Another benefit of the second laptop was added screen space to use when doing packet communications via satellites and the International Space Station (ISS).
The video above was made during the reception of an SSTV image from the ISS during a pass over the United States. The video gives a good idea of what its like to receive SSTV from the space station.
Another SSTV Image From The ISS
We were able to receive several different images from the ISS during the period that it was transmitting SSTV worldwide.
A Third SSTV Image From The ISS
It was pretty easy to capture the SSTV transmissions from the ISS with our Portable Satellite Station 2.0 setup. The signals were strong and I would imagine that the SSTV transmission could have also been received with a simple portable satellite setup with a hand-held yagi antenna.
We hope that the ISS will send SSTV images again in the near future. It was fun receiving them.
I’ve been pretty active on the 6m band the past few years. As you can see from the image above, we’ve worked most of the grid squares in the eastern third of the United States on 6m. I use a mix of modes on 6m including SSB Phone, CW, JT65, FT8, and MSK144. The addition of the MSK144 mode for Meteor Scatter contacts has been a lot of fun and has added some new grid squares to my total.
Orionid Meteor Shower Forecast
One of the fall Meteor Showers, the Orionids, occurred not too long ago and I decided to focus on MSK144 during the Orionids to see how many grid squares I could work. The shower mast most active over a 3-day period (Friday, Saturday, and Sunday).
The video above shows an example of an MSK144 Meteor Scatter QSO using WSJT-X.
6m MSK144 QSOs During Orionids
So I bet you may be wondering how many 6m QSOs and grid squares was I able to work during the Orionids? I made a total of 23 Meteor Scatter QSOs using MSK144 during the 2017 Orionids. The image above shows the 16 grids that were worked using MSK144 during the three-day period. A few of these grids were new for me on 6m.