Tag Archives: FLDIGI

GPS time sync for digital modes

Following Bas’ (PE4BAS) recommendation, I obtained a USB GPS receiver to sync time for portable digital operations when cell data service is unavailable.

I purchased this device for $13.96:

USB GPS receiver

The Amazon listing is:

Diymall Vk-172 vk 172 Gmouse G-mouse Usb Gps Dongle Glonass Ublox Support Windows 10/8/7/vista/XP Raspberry PI B+ 3 Vehicle Aviation Tracker

It was primed into my hands in the usual two days. Following Bas’ recommendation I downloaded and installed a Windows GPS time sync application by IZ2BKT called BktTimeSync.

The laptop I’m using it with is running Windows Xp/SP3. I plugged in the GPS receiver and within a couple of minutes the LED in it began to flash green indicating that it was receiving GPS signals. I started the BktTimeSync app, set the serial port to COM8 (which is where my laptop assigned the GPS receiver) and the software found the GPS and updated the clock on the PC. I had intentionally set the time on the PC back a few minutes to verify that the application worked properly. It also found my location, as indicated by the coordinates:

BktTimeSync Application

The BktTimeSync application continued to receive updates and update the clock but it became non-responsive to inputs from the UI and the only way I could close the application was to terminate the process tree in the Windows Task Manager. I did a bunch of testing with it (starting without the GPS plugged in, not syncing on startup, syncing on startup but manually syncing as opposed to automatic, etc.) Without fail it would receive updates and update the clock but then sit at about 50% CPU utilization and not respond to the UI.

IZ2BKT has a forum for questions and I found an old thread with a person asking questions about the same GPS receiver that I was using. I added some information to the thread and Iz2BKT promptly replied. His response was that there appears to be a problem with the serial comms with the GPS. Given that there are a fair number of variables at play here not the least of which include the variance in implementation of serial comms with a multitude of devices and an old OS I was just happy that it worked at all. There don’t appear to be a plethora of Windows applications available to simply read a USB GPS receiver and update the system clock.

The BktTimeSync doesn’t need to run all the time. For my needs one sync is enough as I doubt my PC clock drifts at all in the time that I may operate. This is a good solution for my time sync needs when operating portable digital and thanks to Bas for  suggesting it.

USB GPS receiver


KX2 Digital modes configuration examples

I spent a lot of time working on digital mode configurations with my KX2 this weekend. I got involved in a thread on the Elecraft mailing list regarding FT8 configuration using a SignaLink USB. Even though I had a functioning configuration using a USB soundcard I pulled out my SignaLink USB, the jumper board, and cables in order to put that configuration together for use with my KX2 as well. I got it going for both WSJT-X and Fldigi. One thing led to another and as I was putting together a little document with notes for myself I decided to polish it up a bit and post it.

Here it is:

KX2 Digital Mode Configuration Examples.pdf

It’s hosted in my lutherie domain so don’t worry about the download source.

Understand that there are more than a couple of variables involved in setting this up. Your situation and\or needs may well differ from mine. It’s not an exhaustive document, there are other bits for you to sort out, but it may be useful to get you started. As I said, I was preparing a simple document for myself to keep track of my configurations and it sort of took on a life of its own. I’m early into my experience with these modes and the KX2. Also, I only have a KX2 with which to test but I’m pretty sure that all of this works the same for a KX3. If you find this useful, great. If not, so be it. As they say, YMMV.



Ps – If you find any errors please let me know and I will correct them and re-post.

PSK31 with the Elecraft KX2

One of the items on my seeming endless list of things to do in Amateur Radio has been to sort out a portable digital station. Other than a little WSPRing now and again I’ve only operated with any other digital mode (PSK31) once, just to try it out. That was three years ago with a Signalink USB and my IC-718. I’ve not touched it since however with my growing interest in portable operations I’ve wanted to add digital capability, especially when operating QRP. The portable digital station made its way to the top of the list with the recent acquisition of my KX2.

Even before the radio arrived I began to research digital operations with it. Obviously one way to do it is with the built-in functionality to both decode and send via the key, digital modes like PSK31 and RTTY. While this is a very nice feature and is clearly the lowest profile as it doesn’t require any additional hardware or software I wanted to have the ability to use a keyboard and perhaps a little large display than the scrolling one-line in the KX2.

The first approach that I thought I’d try was that of an Android tablet. We have a 7″ Samsung Galaxy 4 tablet that lies about largely unused in light of other devices. It’s certainly appealing due to its size, that being just a wee bit larger than the radio itself. I did a bit of research on this option and quickly found the DroidPSK app which is developed by Wolphi Solutions who also has have developed a simple tablet\smartphone to radio interface. A few more minutes research found that DroidPSK also can be used with a Signalink USB. The only downsides to this approach are that I’d need to carry a powered USB hub and I’d rather have a reasonable hardware keyboard as opposed to the soft keyboard of an Android app. The plus side was that I already own both the Signalink USB and a few powered USB hubs so other than the small fee for the app and some cables I was largely set. A nicer keyboard was kind of a sticking point though. The only time that I operated PSK31 I quickly found that I really wasn’t all that enamored with macro exchanges. I wanted to have an actual QSO, not just regurgitate canned messages. QSOs actually do occur in PSK31 but in order to facilitate this a half-decent keyboard was going to be a necessity. I realize that small USB and Bluetooth keyboards are available but that’s yet another piece of hardware to cart along and they are small, so I continued my research.

This past week, as I was sitting in my office eating my lunch and perusing QRZ.com I came upon a post by K5ACL entitled, “JT Modes & the Elecraft KX3, a how-to guide!” The post contained a video in which he described the use of a USB soundcard to interface to his KX3 in order to operate digital modes. Within minutes of watching the video I checked Amazon for the device, found it and ordered it, and as is typical, Amazon Primed it into my hands in two days. In between watching the video and ordering the USB soundcard, another dormant piece of hardware came to mind. We have an old Windows XP laptop that was purchased for the kids sometime ago, well before the days of smartphones and Android tablets. It’s small enough to be very portable and has a reasonable keyboard. With the addition of the USB soundcard it will make a nice platform for a portable digital station.

The USB soundcard that I purchased is a Sabrent. It gets very good reviews on Amazon and so for $6.49 it was worth a try. I plugged it into the XP machine and it had no issues. I quickly tested the input and output to make sure that it was working correctly prior to connecting it to the radio. When I purchased the KX2 in anticipation of digital operation I spent a few extra dollars to get their I\O cables, (E980229) Transmit Audio Cable and the (E980230) Receive Audio Cable. They are nicely done, with a right angle connector on one end and shrink-wrap colored labels that match their intended connections. The USB soundcard jacks are colored green for speaker\headphone (audio output from the PC) and red for the mic (audio input from the radio.) These match nicely with the labels on the Elecraft cables. The red plugs into the “phone” jack on the radio (audio output from the radio to the mic on the PC) and the green plugs into the “mic” jack on the radio (audio input to the radio from the speaker\headphone output.) The KX2 USB interface cable is used for radio control so you’ll need two USB ports.

KX2 PSK31 cables

Aside from the cable interface I set the KX2 to the “Data A” mode and dialed the power back to 5W as recommended by Elecraft.

Turning to the software, it seems as if the most popular PSK31 software is Fldigi, by W1HKJ, so I downloaded and installed that on the old laptop. If you are new to Fldigi, K4REF has a bunch of very nice videos on his YouTube channel that are very helpful.

The configuration of the software for my station is as follows. First, use the KX2 utility application to determine which com port is used by the KX2 cable to connect to the radio. In my case it was com7. Once that is complete shut the KX2 utility application down so that it frees the port for use by Fldigi.

KX2 com port

There are a lot of options in Fldigi. The most important ones to get right are the radio controls and the soundcard interface. When you first start Fldigi it will run a wizard which will step you through the settings. For my PC and the USB soundcard the configuration was a follows:

USB soundcard config

It’s possible that this may be different for your computer depending upon the sound devices in your PC. In XP you can check the audio devices by going to the Control Panel, double-clicking “Sound and Audio Devices” clicking the “Audio” tab, and then clicking the drop-downs for Default Device in both Sound playback and Sound recording. When I plugged in the USB soundcard they both defaulted to “USB Audio Device.”

There are several options for control of the radio. I chose to use Hamlib. My configuration was as follows:

Radio interface config

There wasn’t a selection in the rig list for KX2 so I chose the KX3 as they are likely the same for the purposes of rig interface for PSK31 operation. Set “Device” to the com port that the KX2 is on, in my case it was COM7.

Next I set the mode to USB and BPSK31:

Mode config

And finally I entered the Operator settings (Configure\UI\Operator):

Fldigi operator config

As soon as the soundcard settings were complete signals started to appear on the waterfall and be decoded. In order to check my transmission I picked a clear spot on the waterfall and transmitted a test message to check the soundcard levels and adjust the mic gain on the radio to the 4-5 bars of ALC as recommended by Elecraft.

After a quick check of the macros, I looked for someone calling CQ. One of the first signals that I found on 20m was that of VY2PLH. This is a special callsign for lighthouse activations on Prince Edward Island. In this case the operator, Bernie, VE9BGC was operating at Point Prim Lighthouse. According to their site, Point Prim Lighthouse was built in 1845 and is the first and oldest lighthouse on Prince Edward Island. We had a nice exchange with good signal reports. A very nice first QSO with the KX2 digital station.

Thus far I pretty happy with this configuration. The only new piece of equipment I needed was the $6.49 USB soundcard. The laptop is small enough to fit into the small backpack with the KX2 so this should work well. Now I will have some digital capabilities for our next camping trip.