AmateurRadio.com

My Gadget Gangster Parallax Propellor board has just modulated its first APRS packets. This is not down to any clever programming by me. I simply used the Spin APRS Object published by Richard, G3CWI based on code by Alex Erlank.

Richard had to make some changes to get Alex’s code to work and I had to change a few things as well. Mostly they involved replacing Richard’s callsign and position with my own! The AFSK output was connected to the mic input of my old TH-205E using a 0.1uF DC blocking capacitor. There is enough idle time at the start of the packet for VOX to be used if the transceiver supports it. Mine doesn’t, so for test purposes I manually keyed the radio’s PTT.

I found that my packets were not decoded by the Kenwood TM-D710 TNC when I used the option to include a path such as WIDE1-1,WIDE2-1. I’m not up to debugging the code. However, Richard had mentioned that calls less than 6 characters long needed to be padded with spaces so thanks to an inspired guess I found that that this applies to paths like WIDE1 as well.

There is a GPS object included with the code. I haven’t tried the Propellor with my GPS module yet, mainly because the GPS doesn’t pick up any satellites from inside the shack so I’d need to rig up a battery supply and take all the kit out to the garden to test it, where it’s damp and cold. (Yes I know, I’m a wimp.)

The AX25 object contains a section intriguingly called “demodulator” which has been removed. So it seems that there may be some Spin code that would enable the Propeller to be used as a TNC to decode and display APRS packets. That isn’t something I had particularly planned to do, but it would be interesting to see if it works better than the WB8WGA PIC based TNC that I built a year ago which is a bit fussy about the level of the input audio.

One of the options with the Propeller is a touch screen colour TFT display panel. With one of those a suitably clever person could make a very nice standalone APRS terminal. I think there’s an Ethernet module as well, so it could even be an IGate…

I have made some progress with the FreeTrak PIC based APRS tracker. I found a slightly newer version of the PICFlash programming software. At first this gave exactly the same warning message as the original version. But after a bit of random clicking I tried again and this time the software reported that it was writing to the chip. It verified OK as well. I don’t know exactly what I did, but at least that hurdle was now passed.

FreeTrak configuration

I set the DIP switches on the EasyPIC board to link the PIC pins used for serial I/O to the serial output. That didn’t seem to work the first time, either, but at the second attempt at powering up I saw the configuration prompt appear in the terminal window. I was able to complete the FreeTrak configuration with the PIC in the development board.

Next, I changed a DIP switch to put the chip in Run mode. Using a utility called NMEAGen I began sending simulated GPS messages to it using the same serial connection I used for configuration. The LED began flashing at 1 second intervals and using a crystal earpiece on the output pin I could hear the familiar sound of 1200baud packet bursts. I don’t know why it appears to be transmitting at 1 second intervals, but perhaps it is something to do with the simulated GPS data.

FreeTrak schematic

So FreeTrak appears to be working. All I need to do now is build it on to a circuit board and attach it to my GPS module and a radio. Here’s where I could use a little help from readers. The AFSK audio output of the FreeTrak uses an obsolete op-amp which is unobtainable. I presume I could just replace this with a simple transistor amplifier stage using a 2N3904 or similar, but do I really need anything at all, given that the audio will drive a sensitive microphone input? Could I get away with just a DC blocking capacitor and a trimpot to set the level?

The other thing I’m unsure about is how to interface the FreeTrak to my GPS module. I think the circuit shown is intended to work with GPS devices that use 5V TTL or even RS-232 signal levels. The data sheet for my bare GPS module states quite clearly that the absolute maximum voltage on any of the pins is 3.3V. The serial lines on the PIC measure close to 5V. How to connect them?

Introduction:

• Only 317 days until the end of the world as we know it!

Announcements:

• The Black Sparrow Media application for iPad, iPhone and iPod has been submitted to the iTunes store. It is just awaiting validation from Apple, which may take up to two weeks. We’ll let everyone know when it’s available.
• Special Event Station W0S (Whiskey Zero Sierra) will be operating from the Titanic Branson Museum from April 13-15, 2012, commemorating the 100th anniversary of the Titanic disaster. Russ, K5TUX, will be operating the station at some point.

Feedback:

• Scott, AD7MI, asks for help linking APRS and his his Davis Vantage Pro2 weather station with Xastir. Our hosts suggest trying one or both of these:
  • Meteo – Davis weather station platform software for Linux. You can subscribe to the Meteo mailing list by sending a subscription request to [email protected]. It has been several years since Meteo was updated, and is still not at version 1.0. You must download the .tar file from the web site as it does not appear in the distribution repositories.
  • wview- Cross-platform weather station software. It does need an internet connection if you are going to contribute information to various weather sites, such as:
    • Citizen Weather Observer Program (CWOP)
    • Weather Underground
    • Weather For You
    • awekas

    This program is under active development. Even if it requires a work-around to perform as you wish, it may be worth the trouble. If you’ve ever configured a Linksys router, the web interface of wview looks a lot like that. wview has a support site via Google Groups at http://groups.google.com/group/wview.

Let us know how you get on, Scott!

We received a donation from Bill H. Thanks, Big Poppa!

Contact Info:

• Contact Richard at [email protected], Russ at [email protected], or both at the same time at [email protected].
• Listen to the live stream every other Tuesday at 8:00pm Central time. Check the LHS web site for dates.
• Leave us a voice mail at 1-909-LHS-SHOW (1-909-547-7469), or record an introduction to the podcast.
• Sign up for the LHS mailing list.
• Sign up for the MAGNetcon mailing list.
• LHS merchandise is available at the Merch link on Web site. Check out the Badgerwear or buy one of the other LHS-branded items at PrintFection.com/lhs or Cafe Press. Thanks!
• Thanks to Dave from Gamma Leonis for the theme music.

Music:

• To be added.

A couple of weeks ago I came across FreeTrak, a PIC based APRS tracker developed by N0QBH. I have wanted to build a small ‘grab-and-go’ tracker for a while now. The FoxTrak works fine but is too big and bulky by the time it is paired with an HT. The TH-D72 is too much hassle as I need strong reading glasses to see the LCD screen and inevitably go out with some essential menu option disabled. Consequently these days I rarely bother taking APRS with me when Olga and I go for a walk around town.

I sent off for a couple of PIC 16F628A microcontrollers, thinking that I could program them in my EasyPIC5 development board. But when I tried, I immediately hit a snag.

My PICFlash programmer detects a PIC 12F508 instead of a PIC 16F628A.

I don’t think I’ve been sold a fake MCU. If I remove the 16F628A so there is no micro plugged in at all I still receive the same warning. So I don’t know what to do. I’ve bricked too many PIC chips by programming them with the wrong settings to try crossing my fingers and clicking Yes. So it looks like my FreeTrak project is not going to get off the ground.

My daughter and I made the short trip to the No Label Brewing Company in Katy TX to watch the South Texas Balloon Launch Team launch a helium balloon aimed at Nanjing China. Thanks to Tom AE5QB for letting us know about this event!

To track the balloon in real time go to : http://aprs.fi/?call=a%2FKT5TK-11&_s=mb

From the press release of the South Texas Balloon Launch Team:

The South Texas Balloon Launch Team is pleased to announce the upcoming launch of its twenty-eighth, helium-filled, unmanned balloon in twenty one years. The purpose of this flight is to establish a world record for distance by floating a balloon from Katy, Texas to Nanjing, China.

The balloon will be released at approximately 3 P.M. CST on Saturday, February 11, 2012. The site of the launch is at the western end of the No Label Brewery complex at 5373 First St., Katy Texas, near the old rice grain silos.

The public is invited to this free event, with a special invitation to science students and teachers. Free helium-filled balloons will be available to the first 100 students. Sorry, no pets allowed in the balloon area.

The balloon payload package weighs only about five ounces (150 grams) and contains a high altitude GPS tracking system and a VHF amateur radio transmitter. To conserve weight and battery life, no camera equipment will be on board. The maximum altitude is expected to be above 100,000 feet, with horizontal speeds between 100 and 150 MPH. The balloon size will increase from about five feet to about 39 feet at maximum elevation. Recovery of the payload package is not expected.

Individuals may follow the balloon’s progress on the Internet by logging onto APRS, filling in the “track callsign” field with “kt5tk-11”, and change the “show last” to 24 hours.

The South Texas Balloon Launch Team is composed of about twenty active amateur radio “Ham” operators from a variety of occupations who donate their time and expertise.

We appreciate the continued support by No Label Brewing Company for our amateur radio projects.

Yesterday a packet from the USA dropped on to the doormat. It was the LCD UI module from Gadget Gangster. The cheap international shipping option is pretty quick!

LCD UI module ready for assembly

On opening the envelope I was taken by surprise as I hadn’t realized the module was a kit. But there aren’t too many components and they are all through-hole so I should be able to manage it. I will take my time and double check everything to ensure I don’t do anything stupid like solder headers on the wrong side of the board. More than a few K2 builders have done that!

The instructions on the Gadget Gangster website are very comprehensive with several colour photos showing different stages of assembly. But on checking the parts against the parts list I found that I was missing one 2×8-pin header socket. Fortunately I found one (a pack of 2 actually) for a couple of quid from a UK based eBay component supplier so I should have it in a couple of days. eBay is my main source of electronic components these days as the usual sources like Farnell or Maplin all have hefty minimum order and postage charges that make ordering the single part you need to complete a project quite uneconomic.

Kits and Parts Universal RF Amplifier

 A few days earlier I received another kit from the USA: a QRP RF amplifier from Kits and Parts. I got this with the idea of using it with my Propeller beacon but it is probably too good for that. The beacon really needs only a simple class C amplifier to raise its output to a couple of hundred milliwatts. I had been tempted to go for a couple of watts but whilst WSPRing on 20m today and monitoring the signal on the K2 I noticed a weak in-band spurious around 14.05 MHz which no low-pass filter will eliminate. So it is probably best to stick to QRPp if using the Propeller as an RF source.

Another new arrival in the G4ILO shack was a GPS module from Hong Kong. This was used, ex-equipment, and cost about £12 including postage. I’m not sure what I am going to use it for but if I don’t put it in the beacon to provide a time reference (and locator) for WSPR it would be interesting to try to make an APRS tracker using the Propeller chip.

So many projects! But I am convinced that having this amateur radio hobby to give me so many different and interesting activities is the reason I remain cheerful and positive unlike so many people who have the same health condition and seem to fall into a slough of despond and hopelessness. I may never complete them but at least they give me something to stop me dwelling on darker thoughts.

This is one of the coolest stories for the year I think. Ron Meadows, K6RPT and his son, Lee, launched a high altitude balloon along with the group they lead, the California NEAR Project, on December 11th. The balloon was caught in the jet stream at an altitude between 105,000 and 115,000 feet.

Picture of California Near Space Project's Twitter Feed

From there, the balloon was carried east at a speed of about 150 miles an hour and traveled across the United States, all along the way transmitting it’s APRS beacon of K6RPT-11. It then continued to travel across the Atlantic Ocean to Spain into the Mediterranean Sea. The balloon had traveled 6236 great circle miles in just 57 hours.

From the Southgate ARC website:

The balloon, which bore the call sign K6RPT-11 and could be tracked via APRS, traveled through California, Nevada, Utah, Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, Pennsylvania, Maryland, Delaware and New Jersey. “When the balloon left the New Jersey shore behind, it was received by coastal stations as far away as Nova Scotia,” explained CNSP Team Member Don Ferguson, KD6IRE. “When it exceeded the range of these stations, we lost track of it and feared that we would not hear from the balloon again.”

The balloon finally came down December 14th, when it burst off the coast of Algeria.

This is a pretty exciting event and sure to peak the interests of people and perhaps inspire some to try High Altitude Ballooning themselves. This flight for the California Near Space Project was by far a huge success and I can’t wait to read more about their future flights.

For more details on this story, head over to the article on the Southgate ARC website and visit the California Near Space Project website.