After a trip to our County EOC with our local club president, KK4DKT (Marv) and a short demonstration I wanted to know more about D-Stars. A quick search on the ‘net yielded some good information and a few youtube videos that explained the data portion of D-Stars Voice channel (DV).
Apparently there is a slow speed data channel that is transmitted on every DV transmission. By slow I mean 1200 baud. Slow is not all bad though, you can transmit GPS data, text messages, small files and text bulletins. When in a communications blackout situation that slow speed link can be vital to emergency operations.
That lead me to the D-RATS software. D-RATS (D-STARS spelled backwards) is so named because it has a full featured set of communications tools to take advantage of the slow (or high) speed D-Stars data channels. The author of the software didn’t stop there though. He added support for network, AFSK 1200 using TNC’s or AGWPE compatible soundmodems, serial and the DV Dongle. In the package he includes the ability to setup your own “Rat”flector that acts like a hub for communications of all connected nodes or devices.
I was able to successfully use chat, QST (broadcast to all connected nodes), file transfer, email (to another connected node and winlink) and the connectivity tools using network and packet AFSK 1200. All without a D-Stars radio! I think it is an excellent piece of software that will enable connectivity using several different modes.
For example I setup my home station connected to my “Rat”flector and my PK-232 TNC. My mobile setup consisted of a laptop with the UZ7HO Soundmodem software, D-RATS and audio/PTT cables connected to a mobile radio. As a test I drove about five miles away and attempted to connect to the home station. Success! Right-clicking in the stations sidebar and selecting “Ping all stations” brought up my home station and allowed me to connect in the Files sections. I initiated a test transfer of a Rich Text document (170KB) and began to drive home. The entire file transferred successfully in about 5 minutes while on the move. I was officially impressed.
Final thoughts: Don’t overlook D-RATS for personal, EOC, or club use. Even without a D-Stars system in place it has a lot of capability. When you do get that D-Star radio or your EOC implements it you will already be familiar with the functionality and operation. It is a great addition to your “Ham shack” or “to-go” kit.
I am sorry to report that the Bay County/Panama City, FL Echolink Node N4JTC-R is decommissioned as of May 1st, 2013. Our local club W4RYZ is looking for a replacement node to cover the area. Sorry for the inconvenience this will cause anyone.
UPDATE: On 27 Apr 2013 the phonesats are officially silent. Use can still use this guide for many other current and future satellites.
The recent launch of the PhoneSats got my SDR and satellite juices flowing again. This time I decided to automate things because work seems to get in the way of my satellite listening fun. I found a combination that works great and incorporates FREE software and inexpensive hardware.
Please visit the Phonesat.org page for the latest information on the cubesats. NOTE: They are not solar powered and are expected to fail about a week after deployment which occurred on April 21st 2013.
Setup Orbitron first by setting your Home location. It will use your Grid square to translate to the lat/long coordinates.
Click the Load TLE button and browse to the PhoneSat.txt file. Select the PHONESAT satellite in the Satellites list.
Select the Rotor/Radio tab. Input the Downlink frequency, for Phonesats it is 437.425 Mhz.
Click the Driver drop down box and select MyDDE
Click the Activate button. This will prompt you to browse for the driver. Go to the folder you copied it to under the program directory (C:\Program Files\Orbitron\mydde or C:\Program Files (x86)\Orbitron\mydde)
The MyDDE status window should now be displayed with Satellite data
Launch HDSDR and confirm the USB Dongle is functioning.
Left-click the EXTIO button and turn on the Tuner AGC and RTL AGC.
NOTE: I ran into an issue that required me to launch HDSDR with “Run as Administrator” or I would end up with a ExtIO DLL not active error. Right-click on the HDSDR icon and select “Run as Administrator”. If you want the settings to be persistent you check the run as administrator box located under the compatibility tab while in the shortcut properties.
Click on the Options button then Select DDE Client. Set the format to Orbitron and the Sync Type to Tune. If you would like to record the Satellite passes automatically check the “Record all satellite passes” box.
Click the Manual connect button and it should give you a green connection successful message.
The TUNE indicator on HDSDR should be synced with the Doppler readout in Orbitron. If the Record all satellites option was checked when a satellite comes into view at AOS it will automatically record based on the options set in HDSDR.
Launch UZ7HO’s Sound Modem program
In the Modem settings change the modem type to VHF AX.25 1200 baud.
Select your input sound device to either Stereo Mix if you have one or you can download VAC (Virtual Audio Cable)
Another option would be to use a separate computer or use a Stereo cable loopback. (Actual audio cable looped back to input)
To access the record options, right-click on the red record button. There are a three ways to record on HDSDR: Full RF, IF RF and AF. Full RF will give you the largest file size but capture the entire RF session to go back and replay and analyze. If you are only interested in the audio portion pick the AF recording option for the smallest file size. I like to record the Full RF to see what I missed or see how far the Doppler settings were off. In the case of the Phonesats you can see all three satellites clearly at different frequencies although they are all transmitting on 437.425 Mhz due to Doppler shift. Very cool to see it visually!
If you are running Windows 7/8 Pro you may need to add User modify rights to the Program directories (C:\Program Files\HDSDR and C:\Program Files\Orbitron). You can install the software in a Non-Program Files location (e.g. User Documents) to avoid this step.
Use “Run as administrator” when launching HDSDR
Be sure no other programs are running in the background causing your system to slow down. The SDR decoding can be CPU intensive.
Make sure EXTIO_RTL.dll is located in the program directory C:\Program Files\HDSDR or C:\Program Files (x86)\HDSDR
I hope you enjoy some satellite listening!
Home Location settings
Orbitron with MyDDE
HDSDR and DDE Client
HDSDR DDE Settings
HDSDR Recording options
HDSDR and Orbitron while PhoneSat is in view
Doppler clearly displayed by the slanting of the signal
HDSDR and Orbitron while PhoneSat is in view
HDSDR and Orbitron while PhoneSat is in view
UZ7HO AX.25 Settings
Capture using Sound Blaster X-fi
All Software running
SDR-Radio.com IQ Data File Analysis Tool of PhoneSat “Bell”
SDR Radios are the latest and greatest things to come along in Ham Radio since solid state was invented. Ok, well that may be a stretch, but it certainly has made some incredible advances in SWL and Ham radio. Thanks to the ingenuity of some super smart people we can all enjoy an inexpensive alternative to some of the VHF and UHF dongles out on the market. Interesting enough a product that was meant to be a DVB-T, DAB and DAB+ tuner actually makes a great SDR Radio!
There is a specific model chipset that is required to utilize the SDR tuner. It requires the e4000 tuner and the Realtek RTL2832 chipset. Unfortunately on my first try I received an upgraded DVB dongle that had a newer chipset that is not compatible with any SDR software. I was a little disappointed at first but I am using it for local ATSC channels for my PC so no big loss. I later found that Reddit maintains a list of compatible tuners. I ended up ordering a Newsky TV28T from Aliexpress.com which had the correct tuner/chipset and worked perfectly. I was surprised at how well it actually worked, I was receiving the NOAA weather radio broadcast, our local airport tower communications, APRS, neighborhood weather stations, and some FRS chatter. I originally wanted to use it for the reception of Amateur radio satellites/Cubesats which I am sure it will work well for but I haven’t had a chance to try it. Pretty amazing stuff considering it was less than $30 shipped.
Using the Windows software was the easiest way to get this SDR to tick. I enjoy using Linux but I was already used to using HDSDR and wanted a “quick fix” for my SDR listening enjoyment. Fortunately there is a fairly straight forward way to use Windows and the DVB dongle. I followed instructions such as those on the Ham Radio Science Blog and was up and running in no time. I won’t list all the steps here for the Windows setup as this webpage does a good job at outlining all the steps.
After using the Windows setup for a while I decided to give the Linux offerings a try. It wasn’t that all that difficult after putting all the pieces together.
If you would like to give Linux a try here a few links to hopefully make it easier for you:
AB9IL Blog - More information about the RTL DVB-T tuner
SuperKuh – Many links and info on the Realtek RTL2832U/Elonics E4000
Important Notes: My DVB dongle was off-frequency by 21khz but the ExtIO plugin for HDSDR makes it easy to correct for the frequency error. You can right-click the ExtIO button on the HDSDR interface to bring up the Tuned frequency adjustment. Left-clicking the same button brings up the normal ExtIO options. On the Linux side of things GQRX has an option to adjust the ppm value for frequency adjustment. To access the option click View, then Input Controls on the menu bar. A Tab will appear under the Squelch control labeled Input Controls. From there you can correct for frequency errors. I used my APRS signal and the built-in 1200 AFSK Decoder dial it in.
Last weekend at our local club tailgate (W4RYZ) I picked up a Kenwood TS-520 at a bargain price. It took me a while to decide if I wanted to buy it or not. It was big and scary looking with only analog dials and it had tubes! I am sure at this point some more seasoned Hams are probably laughing at me, but for a Solid State guy this was pretty daunting! The seller was kind enough to print off the manual and several FAQ’s for the rig prior to the tailgate so I had a great starting point.
I shouldn’t have even turned it on until I read the manual through at least once because I thought it was broke when I first powered it up. The meter swung all the way to the right and I had no audio. I turned it off, checked a few things and turned it back on, same thing! I wasn’t sure what was wrong so I went to the manual. They had a nice list of dial settings for initial receive and transmit. After reviewing the list I had one of those “duh!” moments. The RF gain was all the way DOWN, instead of up. A rookie mistake I know, we all have those at some point. I turned it back on with the RF gain up and there was the beautiful sound of a slightly off SSB signal. The WAWWA WAWAA WAA voice was quickly tuned in to a very legible SSB conversation. Off I went to fire up the SDR receiver to see what frequency they were on and could see that the dial was off by 32Khz or so and I had to calibrate both main and sub dials. I also noticed right away the TS-520 was receiving much better than the SDR but they were on two different antennas so I thought it was the antenna that made the difference.
I soon figured out how the 25Khz cal signal worked, I also figured out how to tune the rig for transmit. Since I didn’t have a microphone for the the rig I built an audio breakout box for the High impedance MIC I had on hand and the PTT switch. After a few attempts at tuning and listening for a station to contact on 20M I heard ZW7MGY, a special event station in remembrance of the radio operators of the Titanic. I jumped in and gave my call. He picked out another stronger station, when he finished that QSO I called again. This time he clearly called back my entire callsign, I was like YES! That was Brazil station over 4200 miles away. That old rig still had it! I tuned in 40M and started calling CQ more confident that the rig was working and pickup up an Arkansas station, K5RPD. I was impressed. All I really did was calibrate some dials, set the RF Bias and followed the directions and I was on the air.
Don’t be afraid to try other types of radio gear, just read the manual first.
Old equipment is still a great way to enjoy the hobby. Even with all the fancy screens, filters, buttons, computer interfaces, and software it is still just about getting on the air, making new contacts and enjoying yourself.
Go out to tailgates, Hamfests and other gatherings, you never know who you are going to meet and what equipment you will come across.
The TS-520 is a great transceiver with a sensitive receiver, I tuned in a station listened for a few minutes switched the antenna to the SDR and compared signals and the TS-520 was by far more sensitive to weak signals. It seemed to beat my IC-756 but only by a small margin. Those were subjective comparisons without any “real” measurements but I trust my ear. The tuning process was quite simple when you break it down. There were several resources on the web that I used to help me understand how to accomplish it without hurting the rig. It is a classic rig and I can see why so many people hold it in high regard, it is a venerable piece of equipment that I am proud to now own. It sure makes my Ham shack look more authentic!