Digital - N4MI Ham Radio

ZUMSpot and openSPOT 3

I have been casually using DMR, D-STAR and YSF (Yaesu System Fusion) modes for a couple of years, using a ZUMSpot. The ZUMSpot is a small board that sits on a Raspberry Pi Zero W. It incorporates a Multimode Digital Voice Modem (MMDVM) and a 10mW UHF transceiver that operates YSF, DMR, YSF2DMR, D-Star, P25 and NXDN modes. The ZUMSpot uses Pi-Star digital voice software. Pi-Star is a custom, pre-configured SD Card image for the Raspbperry Pi, with configuration and operation performed through a web browser. The Amateur Radio Notes website has an excellent tutorial on setting up and configuring Pi-Star. While the Pi-Star configuration appears daunting at first, it is easy to set up by following the tutorial. There are also several videos on YouTube with instructions for configuring Pi-Star.

A few days ago, I was attempting to update the Pi-Star software and the ZumSpot firmware, but kept seeing errors during the firmware update. After several attempts to update the firmware, the ZumSpot wasn’t operating properly*, so I decided to purchase an openSPOT 3, which is made by SharkRF in Estonia.

The openSPOT3 is a battery powered, portable, standalone digital radio internet gateway (aka hotspot). The openSPOT 3 is also configured through a web interface, but the interface and steps for configuration are different than Pi-Star’s. The openSPOT 3 user manual is a web page that is updated frequently when there are firmware updates or features added to the device. Having learned the basics of DMR, D-STAR, and YSF with the ZUMSpot, I found configuration of the OPENSpot 3 to be fairly easy.

* After I had the openSPOT 3 up and running for a few days, I decided to attempt the ZUMSpot firmware upgrade again. It turns out I had missed a step in my earlier attempts, and this time the update was successful. So now I have two MMDVMs!

Both the ZUMSpot and OpenSPOT 3 are excellent MMDVMs. Both are capable of operating the most popular digital voice modes using a DMR, D-STAR or C4FM radio. Also, they both require a wi-fi connection and are configured through a web interface. The openSPOT 3 is great for portable operations since it has a built-in battery and the configuration web page works very well on a mobile phone web browser. Since the ZUMSpot is based on a Raspberry Pi Zero W, it could also be used portable with a USB power bank. The openSPOT 3 costs a bit more more than the ZUMSpot. There are also many other MMDVMs on the market, including inexpensive generic boards and kits available on Amazon and eBay. Digital voice modes with MMDVMs are a great way to talk to hams from all over the world using a VHF/UHF digital radio and an Internet connection.

The Pi-Star configuration panel is used to enter all of the necessary settings for the MMDVM to operate properly.

The Pi-Star Dashboard displays a call log and the current status of the MMDVM.

The Pi-Star Administration panel displays some additional status information, and options to change some of the settings for the digital mode currently in use.

The openSPOT 3 has a “Quick Setup” page to configure the openSPOT3 with the transceiver and connect to the preferred network.

The openSPOT 3 status page and call log – you can see information about the openSPOT3’s current status, and listen to call audio on this page.

ZUMSpot in D_STAR mode with Kenwood TH-D74

Both the ZUMSpot and openSPOT 3 can be configured to send your station location via an APRS server

New VUCC and WAS Award Milestones Reached!

Due to work obligations, I haven’t had much time to spend on the radio, or to update this blog. Since my last update, QSOs with several stations have been confirmed in Logbook of the World, allowing me to reach a achieve a couple of new awards.

I recently received a LoTW confirmation for a QSO on 6 meters that took place in July. This confirmation was number 300 on 6 meters, and an endorsement for the 50 MHz VUCC Award.

It took a while, but I finally confirmed 300 grids!

Also, on November 28th, I had a FT8 QSO on 12 meters with a station in Alaska, which gave me my 50th state for the Worked All States Award on 12 meters. I still need to work Alaska on 10 meters for a 5 Band WAS, so hopefully the band conditions will continue to improve!

Alaska on 12 meters, finally! Now hoping for 10 meters!

I am getting close to WAS on all HF bands!

Morning DX on 40m and 15m

It has been a while since I’ve found time to add a post, or to spend much time on the radio. On this Saturday morning, I decided to get up a little earlier than usual to check the band conditions for DX. I found some good DX to the west, in the Pacific and Asiatic Russia on 40 meters, as well as to the east in Europe and the Mediterranean on 15 meters. The propagation on both bands was very good, but there were lots of stations so breaking through the QRM made some contacts challenging. I only worked one new country on 15 meters, but it was lots of fun to see the variety of locations active on the bands.

New DXCC on 20 Meters – Hong Kong

I haven’t been on the radio much over the past week, but this morning I had some time and found that 20 and 30 meters were open to the Far East. It took a bunch of tries, but I was able to complete a FT8 QSO on 20 meters with VR2XRW in Hong Kong. That’s a new DXCC entity for me, and he confirmed the QSO on Logbook of the World in just a few minutes! The new DXCC entities are becoming fewer and further between, and it’s always special to work a new one!

A few good FT8 and FT4 QSOs on 20 and 30 meters

VR2XRW confirmed our QSO on Logtbook of the World within minutes!

N1ADM’s DXCC Account Status as of August 15th, 2020

Accurate Time for Digital Modes by GPS

Accurate computer time is absolutely essential for successful QSOs using digital modes such as FT8, FT4 and JS8. While millisecond accuracy is not necessary, if the computer clock is off by more than a second, you are likely to experience problems. It is very easy to check the accuracy of your computer’s clock by using the website time.is.

A check of my computer’s clock on time.is showed that it was 0.3 seconds behind. This is well within specs for digital modes.

Recent versions of Windows will frequently update the clock through time servers, but the updates are not usually as frequent or accurate as I would like. There are also several applications that will connect to Internet time servers to periodically update the computer clock. Some examples are Meinburg NTP, BktimeSynch, Dimension 4, and NetTime. I have Dimension 4 loaded on my shack computer.

Dimension 4 periodically updates the computer clock using a low level internet protocol, called SNTP, to connect with special purpose Internet Time Servers.

But what if you don’t have Internet access, due to an outage or working in the field? Fortunately, there are computer applications that will synchronize your clock using GPS signals. To do this, you need the software and a GPS receiver for the computer.

For my computer, I use a GlobalSat BU-353-S4 USB GPS Receiver and NMEATime2 software for GPS-PC time synchronization. The GPS receiver cost me $34, and it also cost me $20 to register the software.

The GPS receiver connects to a USB port on the computer as a serial device. I have the receiver in a windowsill near the computer.

On my computer, the GPS receiver is the Prolific USB-to-Serial Comm Port (COM4).

After the GPS receiver, I installed the NMEATime2 software. It was very easy to set up the software to work with the GPS receiver. Once installed, the software runs in the background to keep the computer clock updated. There is an icon in the system tray that shows the current status.

The green satellite icon in the system tray indicates that NMEATime2 has a good GPS signal lock and the application is disciplining the computer clock.

A right click on the tray icon and selecting “Show Panel” will bring up the software control panel with menus for settings and four tabs: Status, GPS Status, Loop Status, and NMEA Output. For my purposes, the Status panel and GPS Status panel contain the most important information.