APRS SkyCommand HF Remote Base

STATUS: . Our prototype in Annapolis Maryland works, but Ikeep getting distracted with other projects and forget to keep it up. See below.

OBJECTIVE: SkyCommand is built-in and allows any D7 walkie talkie or D700 mobile radio to be used as a front panel remote control for any SkyCommand enabled HF radio such as the TS-570, 870 and 2000 (shown below). This web page describes what we have learned about SkyCommand and how we have configured it for generic operation, meaning that the radio can be operated and monitored by a group of users and so that the same settings can be used at other SkyCommand sites as well without any re-configuration by users. This page also covers our planned remote base in Annapolis Maryland using SkyCommand.

OUR PLANS: . We want to set up SKY COMMAND to a remote-base HF station at the Naval Academy over on the Greenbury Point antenna site that members of our club can use as shown below. . The prototype is on the air in my office, and is accessible by anyone local with a D7 or D700 VHF transceiver or APRSdos using sky-command . . During the evolution of this capability, here are some additional thoughts and ideas:

  • Ideas and lessons learned in developing the Generic Sky Command concept.
  • Using 220, 900, and 1296 instead of 2m VHF band for audio link
  • Suggestions for future SkyCommand III ideas to make this even better in future implementations.

    SKYCOMMAND MOBILE RADIO's DISPLAY: Remote control of the HF radio is via the tuning knob or microphone keypad of the mobile radio as shown below. . The radio display shows the HF operating frequency and modes.

    GROUP OPERATIONS: . What is really neat is that everyone in range of the HF base, can set their own mobile or handheld's to the SkyCommand channels and participate at the same time! . On the front panel of all radios, everyone will see the current operating parameters of the HF radio and all will hear the HF radio on VHF. . Further, anyone can join in the HF transmissions if they are using the designated PL. . But the good news is that everyone that is only monitoring can set a different PL before entering skycommand and they can then all talk back and forth for coordination purposes on the UHF command channel, but only the station that has the correct PL will be transmitted on HF.

    This means it is easy to operate this HF SkyCommand remote base as an HF link in a group effort, and ALL of this can be done by the users with nothing but their STOCK D7 and D700 radios! Here are the settings for the Annapolis Sky Command Radio:

    See Kenwoods detail notes for additional details if needed.

    SKYCOMMAND AT CAMPOREE: To avoid co-band interference from two HF SSB stations and my PSK-31 and SSTV demo, I located a TS-2000 about 1000 feet away from the JOTA station and operated it remotely with a D7 HT using skycommand. The TS-2000 was set in the Solar Trailer for conveniet access to power. By switching between VFO A/B on 14.230 SSTV and 14.070 PSK-31, I could demonstrate either mode to the scouts. The audio out of the D7 then fed into the LINE-IN of four laptops on 2 tables for the scouts to watch either SSTV or PSK-31.

    There was no co-band interference even though we were listening on 14.070 amd 14.230 and the other JOTA station was making SSB contacts also on 20 meters! We were only 30 feet apart (beacuse my HF receiver was acutally 1000' away).

    The remote TS2000 ran all day on some solar panels and a fishing-pole 16' vertical. It was unattended out by the main gate. Sun never came out, but the 15 amp nominal solar panels did provide up to about 5 amps in the heavily overcast day.

    AUDIO FOR ALL! A side benefit was that ANYONE anywhere at the Jamboree, could tune in the SKYCOMMND link on 147.57 and hear the HF audio, and if they had a laptop, they could see all the same SSTV and PSK31 that we could. This is a fantastic way for the scouts to really get some hands-on experiece back in thir camps on their own time. As it was, there were 12 sessions all day, with each session at the ham area broken up into 3 sub-groups so that each kid only got about 10 minutes or less at the PSK/SSTV station. But with the 2m audio link of the Skycommand, the other scouts and dads that had 2m HT's could go back to their various camps and demonstrate PSK-31 and SSTV on their own time.

    TWO LINKS NEXT TIME, To avoid switching back and forth, next time I hope we can set up two separate links. One each on PSK31 and SSTV. Fortunately at work we have two TS2000's, but if I didnt, it would be just as easy to nail up a pair of old 2m HT's to some old HF receivers and accomplish the same thing. No need for the fancy SKY commmand, since I was always within 1000' and could exercise appropriate transmitter control manually.

    GROUP SKYCOMMAND! There was another special benefit. ANYONE at camp that also had a D7 or D700 could also operate SKYCOMMAND at the same time. Anyone can set their D700 and D7 to the SAME generic callsigns as our skycommand and then their radio will display the same REMOTE HF front panel as ours. So in effect, anyone in camp can SEE what HF freq the remote HF is on, and could even control it. They can even use the VHF channel for coordination chatting, see the Group notes above. See the details on http://aprs.org/skycommand.html SCOUT DEMOS: This same technique can be used for regular meeting-night scout demos even in windowless meeting rooms in basements. Just set up the HF rig in the parking lot and using a low-power RF link, transmit it in doors to any laptop to display SSTV or PSK. No remote control needed since these two modes use FIXED HF channels and so no remote tuninig is needed.

    ANY RADIO AS THE COMMANDER: Since SkyCommand is simply AX.25 UI packets, you can actually use any packet station to remote control the skycommand radio. Just use Packet on the transporter frequenceies to send and receive the sky commands, and UHF radio with PL to then talk. You monitor the rmote base on VHF. Of course, it is rather lengthy to type in the commands and a little quirky to be able to decipher the radio responnses, but it can be done.

    APRS software: . to make this easier, I added the skycommands to APRSdos to make it trivial to operate a SKY COMMAND remote base using only your packet station and APRS. This way any radio can be used for the DATA and voice links. . This allows any station running packet to also participate in the SkyCommand system, not just the D7's and D700's.

    For a power point presentation on TS-2000 and D7 setup photos, see Kenwood's SkyCommand Setup

    OTHER HF RADIOS: . The advantage of the TS-2000 radio is that it has SKYCOMMAND fully integrated and internal. . It is just plug-and-play. . But other Kenwood HF radios can be used for SkyCommand too. THe only difference is that they need a dedicated TH-D7 HT to serve as the transporter interface to the HF rig as shown below:

    Our Annapolis Plans: So you can see what we are thinking about, I sketched a long wire over the re-touched photo below of one of the three remaining 600' "Eiffel" towers in Annapolis . The example long wire offers almost 6 dBi of gain on 80 meters. Higher gains on higher bands. Yes those are full size 100' trees below the legs of the tower!. . We hope we can encourage a group of dedicated friends of the Academy or local emergency services communicators and engineers to help do the antenna work and enclosure.


    These antennas were the old Navy VLF transmitting site for communiations with submarines. . After demolishing a dozen of the 300 to 1200 foot tall antenna towers and only leaving the three 600 footers, the dozens of acres are currently being held as a natural area nature preserve. . Hence, it is quite RF quiet and about a mile away from the Naval Academy noise sources. . See the map below. . It is also surrounded by Bay water with a good ground-plane for low-take-off angle HF communications. See some other photos:

  • The three remaining 600' towers like the one above.
  • One tower base. The base leg even dwarfs trees under it,
  • 300' tower with WB4APR-1 Digi on it (they gave me 2 weeks to vacate. But blew it up a week early!)
  • Demolition charges for the 600' and 1200' towers
  • Complete high-res photos of the demolition of the first 300' towers (long time to download)

    The idea is to install an HF transceiver (TS-2000) with SKY COMMAND in a weather proof enclosure at the base of the tower and then to feed long-wire sloper antennas in 3 cardinal directions off the 3 legs of the tower. . An antenna switch selects the proper antenna. . Some quick assessments of the antenna pattern with EZNEC show that low angle radiation is very good as shown below:

    Unfortuntely, yours truely is saturated and can only kibitz due to many other projects such as PCsat, PCSAT2, ANDE and RAFT satellites. But we thought that there may be enough local interest to assist with this project.

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