APRS Radio Bags

Bob Bruninga, WB4APR

RADIO BAGS: Over the years I have tried a number of radio packaging schemes for emergency and field use, but nothing has seemed to be the perfect solution. My previous rendition was using brief-cases for each radio/APRS system. Although this provides lots of room for administrative and logistics stuff and operations plus a laptop, it doesnt take many of these briefcase systems to fill up a car and each one takes up a whole hand while carrying. ALso, they all tend to look alike..

Binder Bags: But the otherday while shopping in Wal-Mart, I noticed the colorful 3-ring binders on sale for back to school. These multi-color binders with multiple zipper pouches seemed perfectly sized for a typical portable station. The station above is a complete APRS station using the D710 including full color map display on the attached AVMAP G5 GPS. This setup includes a small set of AA nicads so that it can operate at full power from the included 3 amp laptop switching powersupply as shown below. The batteries provide the peak 8 amp current for the duration of the packet, but the 3 amp supply keeps it running and charged.

Each of the $10 binders includes a removable hard plastic 9" x 11" piece that has the 3 ring clips attached. After removing them, it makes a nice working surface as shown under the writing pad in the top photo. Also this plastic piece can be fitted with a metal bracket for holding the D700 APRS control head in a nice operating position. When packing, the hard plastic is flipped over and knotched so that it provides some protection for the control head without stressing the knobs and this puts the metal bracket down and out of the way. I just duck-taped the metal bracket on from the back as shown.

PSK-31 HF BAG: This bag contains an 817 radio, with 3 bands worth of dipole elements. We have two of these blue bags for two simultaneous demonstrattions of PSK-31 to students.

OLPC (One Laptop Per Child): The lime green bag was chosen to carry my two OLPC laptops that I hope someday to get working with APRS on XASTIR. In the mean time, they make perfect small portable email readers via WIFI. This bag is a $6 bag and does not have all the zipper pockets of the $10 bag and it is a little bit bigger. In fact, it carries two OLPC laptops (you can see one under this one).

Using these soft bags, I can pack more bang-for-the-buck than the multiple briefcase option and they are somewhat protective with their soft exterior. The one mod I should do to all of thm is add a carrying handle.. That will take a soft strap and two screws across the middle section.

The rest of this web page is copied from another application and will be edited down to this topic. later...

The TH-D7 HT is ideal for data entry at special events, and the D700 is ideal for convenient data display at the point of use. The photo above shows a D700 APRS radio control head attached to a clipboard for taking data from reporting stations... We use this system at scouting events where troops move from station to station while competing in skills competitions such as the Klondike Derby shown to the left. . Remember, APRS is much more than just vehicle tracking.

Using any DTMF radio: Not only can the special APRS radios be used for this functino, but any DTMF radio can be used in the field if an APRStt gateway is in use at the site. This software runs on a laptop and serves as a gateway to convert all DTMF reports on one frequency over to an APRS packet on the APRS channel.

From each station at every time schedule, a troop number and score is reported by HAM radio back to headquarters. In the past this was all done by voice reports from up to 20 ham radio operators with HT's, all on one voice net. 20 stations, 8 time slots, 4 troops per station, that's 640 reports. . Voice reports or a few HT keypad strokes? Your choice...

In 2007, we fielded 5 Kenwood TH-D7 HTs and the one D700 so that some operators could directly enter their information on the keypad and have the data automatically transmitted as an APRS message to the Headquarters D700 where the information was available to the HQ staff at their convenience, and not in conflict with the demands for the voice net. . At the 2008 Klondike we fielded 10 of the D7's and by using D700's also for entry, could have covered 13 of the 17 stations with APRS data entry. . See 2008 Photos near the bottom of this page.

SUCCESS! The event was an unqualified success even though the net control and other personnel were unfamiliar with these radios. . All the Netcontrol had to do was read the scores like regular email on the front panel of the radio. That is, hit OK and then DELete for each new score. Two button pushes that anyone could do. . (Does not even need to be licensed to read messages).

The photos below give operators an idea of what the user sees on the front panel of the D7. The first photo includes the the D7's Keypad, the next photo shows the MSG Menu, and then the third photo shows the MSG entry screen. Each D7 was given a callsign of STN01, STN02, STN07, etc according to where they were stationed. . This way, the data coming in from station 7, showed as being from STN07. . All data was sent to NETCON.

  • The above screen shows outgoing message number 9 reporting Troop 874 with a Score of 42. . If a digipeater is used, and the packet is successfully digipeated, then you will see MY MESSAGE flashed on the screen as confirmation.

    To enter a score, the HT user presses the MSG key and then selects LIST from the MSG Menu above. This displays the last message. He can use this message as a template and press the MSG key again to edit the troop number and score as a new message. . Then he hits the OK button and the message is sent to HQ. When the score is ACKed by HQ, then the message shows the * on the MSG screen.

    D700 CLIPBOARD DISPLAY: . When a score comes into HQ on the D700, the message instantly captures the radio front panel display for 10 seconds as shown below. . This screen shows incoming message number 1 from STN7 reporting troop number 874 with a score of 42.

    If the operator wants to read it later he can press the MSG button and select up to 15 messages from the inbox.

    Each message in the list has an envelope icon that shows if the message has been read or not. Once the data is entered into the data program, then the HQ operator can delete that message.

    It should be noted that since the D7 HT is dual band, his scoring via APRS is done independently of what he is doing on the other channel. In addition, the APRS stations can talk briefly on the data channel for back-door coordination as needed without bothering the primary voice channel. Unlike shown here, it is better to operate the APRS channel on a different band than the main event channel to minimize QRM.

    GOUGE SHEET: To help operators unfamiliar with the D7 HT, we have also prepared a gouge sheet to help those operators. It steps them through the process of entering a score. Get the ENTRY Gouge Sheet and the NETCON Gouge Sheet. . Also download station lat/longs for Kinder Farm Klondike Derby 2008.

    OTHER APRS SUPPORT: Of course, all those D7 operators and NETCOM can also see the usual APRS displays and position information for knowledge about where where other operators are (although 121 miles shown is not typical of a local event!). . And please do not think that you need GPS for keeping track of these radios! . GPS's and their wires and cables are just a nuisance at most events. . Instead, just use a table of positions for stations, or a map with a grid on it, and the operators can easily place their position at any time. See this map we used in 2008:

    Just estimating a position to 10% within a grid shown above, and your position is reported to the nearest 60 feet! . Anyone should be able to do this. . Now if the other stations do have GPS connected, then their course and speed and altitude can also be observed on the D7 as shown to the right:

    APRS MAP: Or anyone running APRS can see all this live on their map displays. . The display below is of an old APRSdos laptop being used for the event. The stations are shown with their Tactical Callsigns of CS4 or BS3, etc depending on their station number of whether they were Boy Scouts of CubScouts:

    WORKS AS-IS! . Notice that this application required no software, no setup, no special hardware, no GPS units, no Laptops, and no computers. . Participating APRS operators simply bring along their D7 or D700 equipment and it is ready to go. It might appear that this is a lot of hardware to do a simple voice report, but when there are 20 people making reports on a single voice channel, even if only 5 of them can use APRS, it is much easier for them and HQ not to have to wait for their voice turn to report. And HQ can offload the incoming message data at their convenience, and not at the crunch demands of the Voice net.

    Statistically, we found that an APRS station could enter four separate scores in about a minute (4 scores per event period) whereas a voice station could report all 4 scores in about the same time including call-up and sign-offs. But what is not obvious here, is that the voice method has a very high overhead:

  • The Voice station had to closely monitor the voice channel, (distracting)
  • The Voice operator maybe had to wait up to a minute or two for the channel to clear
  • The NETCON is interrupted for every call that comes in
  • Voice scores compete with other comms needs on the voice channel
  • Phonetics and repeats, and transcription errors are frequent
  • But with APRS, data is entered at senders convenience and received at receivers convenience

    Also, the non-data-savy operators at net control turned out to be positive about the experience, because it removed the stress of having to be responsive to voice traffic on call, whereas they could view the APRS scores at any time at their convenience. In fact, they could turn the D700 front panel over to a non-licensed volunteer to take the data. Thus conserving our voice operators for other tasks. Do NOT plan on using the same D700 for messages and other voice tasks, however, since the PTT interrrupts the message screen, and you cannot see the message screen while talking.

    KLONDIKE DERBY 2008: The photos below show the overall map plan. The Boy Scout troops went around the red path and the Weblos Dens went around the Green trail. . Net control this year was in a warm house on the grounds just south of this picture.

    WB4APR was stationed at Cub Scout station 4 with his Communications Trailer and 10 KW High-power Emergency Power System. . The van comes with a half dozen signs depending on the occasion. . In this case, the Naval Academy Radio Club callsign was on display. . The solar panels on the roof of the Prius provide about 200 Watts of solar power. . Only the bottom of the 55' push up mast is shown.

    National Jamboree? . We can do this at the National Jamboree too. APRS can be used to track the locations of all the troops, and also all the official vehicles and assets. APRS radios can communicate bulletins, announcements and scores and can be the universal communications system there. We can ask all troops to bring FRS radios and use those for data input, then APRS for assemillation and distribution and display. . Here are the Jamboree mapsof FT AP Hill in Virginia:

    APRS TOUCHTONE or APRS-DTMF: This all boils down to what I wanted to do with APRStt back in the year 2000 when I introduced the APRS-TouchTone program. It let ANY HT be used as an APRS posit/message/data entry device just like the D7 HT. The only difference is that ANY HT sends the keystrokes using DTMF to the central APRStt program where it converts the key presses into the exact same messages that a D7 does itself. This turns any HT into a D7 for data and message entry. . but with the expense of only one DTMF-to-APRS laptop doing the work for the whole event.

    Please See: . APRStt web page which describes this APRStt program and system.

    VOICE RESPONSE: Since the APRStt user does not have the advanteage of the D7 HT's display to verify the correctness of his data, the APRStt main engine at net control speaks back the response for verification. This ANY-HT-TTpad data entry and ANY-HT-Voice-Response, was intended to turn APRS into a system that could be used at EVERY event, because anyone with any HT could participate.

    SOUND CARD SOFTWARE NEEDED: . The problem is that I wrote APRStt in DOS and so it needed an external $5 DTMF chip hooked to the parallel port and an 8 resistor voice synthesizer. Although the parts count was under $10 total and hooked to the parallel port of any PC, such circuits implemented in DOS were dead ended. The whole purpose of my APRStt project was to inspire the new generation of APRS authors to implement the entire APRStt process in a Windows PC using nothing but a soundcard. The soundcard would decode the DTMF codes from the users and speak back the repsonses. A complete APRS system for ANY HT. But now, 7 years later, we are still waiting... for someone to be inspired to dupilcate the functionality of APRStt into Windows and sound cards...

    Bob Bruninga, WB4APR