Category Archives: Experimentation
Greg, N4KGL and I worked on a joint project to build and launch an APRS rocket payload. We finally got to launch it yesterday after a small delay due to field availability. It included the Mobilinkd bluetooth adapter, Baofeng Uv-5r HT and a eBay special android smartphone (appropriately from “Boost”).
Our goals were to:
- Have a successful launch and recover (of course!)
- Use APRS for tracking using stock Ham radio equipment and smartphone
- Use the on-board smartphone sensors to record audio and accelerometer data
- Map ground track using My Tracks for further analysis
- Laptop with a RTL-SDR dongle and USB GPS
- SDR# tuned to the APRS frequency 144.390
- APRSIS32, VNCViewer, UZ7HO SoundModem Software TNC
- VB-Cable Virtual Audio capture
- Linksys Router with DD-WRT and Homebrew antenna
Note: You can view the Google Doc prepared for this flight with more detail.
The ground station was connected via 802.11g while the rocket was sitting on the launcher. I was able to control the phone screen through VNC and start the audio recording, Sensor logger, APRS and My tracks while it was sitting on the pad waiting for launch. That capability was instrumental in starting and checking all the services prior to launch.
Field conditions were excellent, although it was a little windy at times and very hot. Greg prepared the rocket while I prepared the ground station and prepped the payload. Greg decided to try out a new rocket motor that he had never used before. It was a disposable J425R-14A high powered rocket motor. It performed flawlessly from start to finish and sounded awesome!
I was quite surprised in how the phone GPS performed. It lost GPS fix during the accent phase but quickly reacquired lock after chute deployment. I chose My Tracks to do the GPS logging because of the logging rate and it integrates well with other GPS software. I am sure there is something better/faster but this seemed to work well for this launch.
- Audio File from inside the rocket
- Comma Delimited File of Accelerometer Data
- Google Earth File from “My Tracks”
- GPX file of flight
Please visit Greg’s post for more pictures and info.
Video of Launch: The second half of the video is of smartphone audio synchronized with video, very cool!
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.
Presentation explaining the Data Modes of D-Stars (Skip to 5:50):
Updated on: July 16, 2012
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:
Components you will need for LINUX:
- GNURadio Package – I highly recommend the build script to help install the dependencies and compile all the necessary components.
- The Linux RTL-SDR driver (not needed if using the script from step 1)
- gr-osmosdr Package (also not needed if using the script from step 1)
- GQRX (optional but recommended, nice GUI interface) – Be sure to read the compile instructions
Also see an excellent post on how to use BackTrack and a offline package.
- Ham Radio Science – Post with instruction on how to setup your SDR on Windows (kind of mirrors the RTLSDR Site instructions)
- ExtIO_USRP+FCD+RTL2832+BorIP-BETA_Setup.zip and the updated librtl2832++.zip – See original page for more information on those packages
- SDR# aka SDRSharp also visit the Yahoo group for experimental releases
- DSD – For signal decoding (e.g. P25, ProVoice using QPSK, GFSK, C4FM, etc.)
Some very helpful pages:
- 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.
Amateur Radio enthusiasts have stepped up their game in Katy, TX. The South Texas Balloon Launch Team will launch a balloon at 1500 CST (2100 UTC) on Saturday, February 11th. The primary goal of the launch is to send an amateur radio balloon across the Atlantic and Mediterranean to Nanjing, China, the final estimated destination. A unique feature of the balloon is the frequency agile APRS transmitter that will change frequency according to where it is geographically located. The call sign to be used for APRS is KT5TK-11. It will also use the orbiting International Space Station as a relay to reach ground stations thousands of miles away. This will allow anyone to view the balloon’s progress as well as speed, altitude and direction.
This will be interesting to watch as it travels half way around the world.
**14 Feb 2012 Update**
Andy, W5ACM stated the most likely cause for the loss of reporting was due to frozen batteries or electronics. He has posted pictures and videos of the BLT-28 launch on his site.
USA = 144.390 MHz FM
mid-Atlantic = 145.825 MHz (International Space Station packet digipeater frequency)
Europe = 144.800 MHz FM
Links – will be adding more as I find them
- South Texas Balloon Launch Team Page for BLT-28
- APRS.fi Tracking Page and APRS.fi Balloon Telemetry Page – cool!
- DB0ANF APRS Tracking Page
- FindU Tracking page
- JFindU – Stations Near Balloon and last I-Gate used
- JFindU – Packets heard in the last hour – Newest at bottom of Page
- ISS APRS Page – Shows all APRS objects that were relayed by the International Space Station
- SouthGate Amateur Radio News
- ARRL News Release
SDR? What does that mean? I know I asked myself the same question when first looking into how to get on the air on with the HF bands. After a visit to a local Hamfast and talking to some very helpful Hams, I was turned onto the SoftRock SDR. My mind was filled with SoftRocks and SDR’s and more questions… I still wasn’t very clear on how it actually worked. I knew three things: You needed a computer, SDR stood for Software Defined Radio and I really wanted one.
Whenever I “Googled” SoftRock the top links were pointing to Tony Parks, KB9YIG site: http://www.kb9yig.com/ and WB5RVZ, http://www.wb5rvz.com/sdr/. Ok, I thought I will check out these kits and see if I can afford one. What was shocking to see was how inexpensive the kits are. Only one problem, every kit said to “Come Back Soon”. Just on a whim I decided to email the admin, which of course turned out to be Tony himself. I wanted to see when some kits would come available. He just happened to have some SoftRock Lite II Combined Receiver Kits available. I just couldn’t wait to get my first SDR!
I recently had the privilege to attend a SEARS (SouthEast Alabama Rocket Society) rocket launch this past Saturday, October 15, 2011 with Greg, N4KGL and Sonny, KK4CVV. It was a blast (pardon the pun). A great bunch of folks just out doing what they love and enjoying every minute of it. Ok, what does the have to do with Ham Radio? Greg Lane, N4KGL mounted a 20m Beacon inside a high power rocket to launch it over 1500 feet in anticipation that other QRP’ers were listening.
Greg prepared the RMS rocket motor, put in fresh batteries, packed the chute and put it on the launching rail. The proposed time to launch was at 1700 UTC. Everything was on schedule until the operational check of the beacon. With Greg’s portable Hamstick dipole raised and listening on the beacon frequency of 14.060 Mhz just a steady tone was heard. I assisted him in posting to www.qrpspots.com to notify of the five minute delay in launch time to troubleshoot the beacon problem. Greg quickly went out to the launch pad and fixed the issue. Beacon was loud and clear.
Ready to launch. 5..4..3..2..1 … We have lift off! Great launch! Listening carefully.. No Beacon.
Uh, Houston, we have a problem. Post flight recovery revealed that the forces acting on the rocket ripped the beacon from the antenna and parachute part of the tube. The beacon transmitter free fell to earth while the other parts of the rocket came down nice and slow by parachute. Thankfully Greg found all the pieces with the help of his Grandson. Despite the failure it was a great launch and a great day. I am sure Greg will go back to the drawing board to make the beacon fly another day… Enjoy the video. 73
Visit www.N4KGL.info for more information.
Today was a good day for SSTV images. I was trying to capture a stored image of hurricane Irene from ARISSat-1, no such luck. I did however capture some very nice images. I was able to grab two of them during the afternoon pass today. With the new image I performed a little analysis and concluded that the camera lens or mirror assembly was definitely contaminated by something, presumably the battery electrolyte.
I did an overlay image and outlined the concentration of the blurred image and the red/blue hue outline on the magenta images. The images are reversed by a mirror assembly located on the Y axis of the cube according to a design review fact sheet. This means, from what I can tell, is that the RED and MAGENTA images share a mirror assembly. When you flip and reverse the images it becomes clear that the mirror assembly share the same artifacts in the images. Below are the images along with the original captured images by my station.
The red lines are from the original blurred RED image. The black outlines represent the red/blue hue from the MAGENTA capture image from today. The basic outline match when you flip and reverse the images as a mirror would. Very interesting…
First Image received today, the best to date. I used a hand-held 4 element Yagi
Ok, this is just a theory. I do not know the exact construction so this is simply conjecture.
I have been following ARISSat-1 since the day it launched and probably too closely I might add.. I received a SSTV image on 13 August 2011 0036 UTC. I have been puzzled by it ever since receiving it. I thought it might just be a focus issue, but I looked up the specs on the cameras and they are fixed lenses. Being out of focus should not be an issue with these cameras.
I checked the estimated time of battery failure (12 August 2011) and the dates of other “Red RS01S” stamped images and the one I found looked similar around the time of failure.
Received by me on 13 August 2011 0036 UTC:
Received by VR2RC, VR2GY, VR2UIO, VR2UGP, VR2VBU on 12 August 2011 1206 UTC
I also looked at the specs on the batteries and supposedly they are leak proof. The batteries use potassium hydroxide for the electrolyte and I am not sure if it was in a liquid state or not. Either way it looks like a leak should not of escaped the confines of the battery. However, lets imagine it did, is the liquid coating the camera lens at the time? Will it evaporate into space or damage other components? I have looked at recent Red camera images and they look normal.
Say my theory is way off, that begs the question: what is the cause of the “blurriness” in these two images? Either way we are fortunate to have the cells open instead of short so it will continue to operate off the solar cells.
Any ideas? Please email me at jason [at] n4jtc.com
See the ARRISSat-1 Power System page for more information on the power system.
On the 16 August 2011 0034 UTC pass I wanted to try some telemetry decoding and create a video demonstration for those that would like to see how it works. The pass was a high elevation daylight pass so I figured my chances were pretty good to get some data. I was able to grab two frames of telemetry and two frames of the Kursk experiment. The audio was added later and I had some synchronization issues so you may notice the audio off slightly.
Success! After a few failed attempts, I finally was able to decode the BPSK Telemetry. It was the 0832 CDT, 1332 UTC pass over my QTH in Panama City, FL. Max EL was only 15 degrees.
- Rig – Kenwood TR-9000 All mode 2m transceiver
- Antenna – Homebrew 4 element Yagi on a 7 foot PVC Mast
- Dell Mini 9 netbook with a 1/8 Male-Male stereo cable
- Droid X with HamSatDroid for Tracking
I tried a few times to record the file and then play it back through the ARISSATTLM program, but the decoding just didn’t happen. I finally decided to “go live” with the software and just adjust it on the fly. That worked very well for me.
Here are a few hints if you decide to try it: Start by reading the Quick Start Guide, this a super handy thing to review first. You will also need the ARISSATTLM software. Get familiar with the operation of the software and do a test run with some CW audio, that will help you when the moment finally arrives when you hear ARISSat-1 poke it’s head above the horizon. I tested several antennas for this, a 1/4 wave ground plane, Discone, J-Pole and the homemade Yagi. The Yagi was by far the best antenna and it was the closest to the ground at 7 feet, where as the others where between 20 and 45 ft high. I learned that the Yagi in the vertical orientation seemed to work best for my situation but others may have different results. The Yagi was also one of the cheapest, a few pieces of PVC, heavy gauge wire and a SO-239 connector. Try this for a Homebrew Yagi.
As the Quick Start Guide states, start at 145.919 SSB USB and listen for the CW tone. Don’t stay there too long as the CW quickly shifts down the scale. Listen to the audio file below to get an idea what you will be listening for. Be quick and keep the CW “bump” to the right of the yellow line. There are blue and orange lines located at the top of the tuning indicator, it is best to locate the CW somewhere to the right of the yellow but within the blue limit line. If you can hold it there you will be rewarded with successful decoded telemetry as indicated on the bottom of the tuning indicator.
I have included a WAV file to give you an idea what it should sound like. You will hear me manually changing the frequency to keep the CW in tune, or above the yellow line on the tuning indicator. SSB BPSK Audio File: 08.06.2011-08.38.01 – Trimmed – Yagi SSB.
Screenshot of the decoded telemetry:
Here is SSTV from the same pass as well as the FM Audio: 08.06.2011-08.38.01-ARISSat-1
Used to illustrate the ability of the telemetry to still get decoded even in weak signal conditions.