APRS

🇫🇷 Version française

APRS (beta)

SatMe receives and sends APRS on the ISS digipeater (145.825 MHz) and on the terrestrial network (144.800 MHz). It works with three kinds of radio: the phone with an IC-9700, a KISS radio such as the Kenwood TH-D72, or a Yaesu FT3D. The page is marked Beta.

Open it from the ⋮ menu › APRS.

Map of the stations heard, with the ISS track · hunting a station · messages and APRS Thursday.

The page at a glance

At the top, a status strip always shows the radio, where it works (Auto, ISS, Terrestrial), how it is doing, and the one button that matters:

• ▶ Listen / ■ Stop listening with the phone and the IC-9700;
• Connect / Disconnect with a KISS radio or an FT3D.

Below it, six tabs:

Tab	What it holds
Map	Stations heard on OpenStreetMap, Topo, Dark or offline map; the ISS track; the station hunt
Messages	Conversations with acks, APRS Thursday buttons and today's participants
Send	Position, status, message, APRSPH; path; preview of the frame; the transmit button
Packets	Every frame heard and sent, with filters
Trophies	The day's tally, APRS contacts, records, badges
Settings	The radio, where to work, USB connection, my station, IC-9700 audio

Choose the radio

In Settings › APRS radio:

Radio	Receive	Transmit
Phone · IC-9700	The audio of a recording (USB sound card of the IC-9700, microphone, Bluetooth, SDR dongle), decoded by SatMe	Through the IC-9700: CAT keys the rig, the audio goes out on its USB sound card
KISS radio (TH-D72…)	The radio decodes and passes each frame over USB	The radio modulates and transmits the frame it is given
Yaesu FT3D (positions)	The FT3D passes each station it decodes (waypoint output)	None: the FT3D transmits from its own menu

Where to work

Settings › Where to work:

• Auto: the ISS during its passes, the terrestrial network the rest of the time. SatMe switches by itself, radio and path included.
• ISS · 145.825: the ISS digipeater, path ARISS, Doppler tracked over CAT.
• Terrestrial · 144.800: the terrestrial network, path WIDE1-1,WIDE2-1.
• Leave it (KISS radio only): SatMe does not touch the radio's frequency.

On the ISS, SatMe picks the ISS APRS transmitter and puts the rig in FM.

Phone and IC-9700

1. In Settings › Recording, choose the USB sound card source: the IC-9700 sends its audio down the USB cable.
2. Choose the CAT radio Icom IC-9700 (Rig control).
3. On the APRS page, tap ▶ Listen.

Listen does everything: it connects CAT, tunes the IC-9700 as Where to work says (the ISS with its Doppler, or 144.800 MHz FM out of satellite mode with the Doppler on hold), turns decoding on and starts the recording that the decoder listens to. In Auto, it moves to the ISS as it rises and back to terrestrial after. ■ Stop listening gives the Doppler back.

An older recording, or a WAV from the rig's SD card, can be run through the decoder: Settings › Re-decode a recording.

KISS radio (Kenwood TH-D72)

1. On the TH-D72: PC port speed 9600.
2. USB cable from the radio to the phone, with an OTG adapter.
3. On the APRS page, choose KISS radio, then tap Connect in the status strip.

Connect does it all: SatMe reads the band in use, tunes it to the frequency of Where to work (FM, simplex, no tone), starts the radio's TNC in packet mode, then switches it to KISS. Nothing is transmitted.

• In KISS, the radio's screen no longer shows the stations: the phone does.
• Do not press the TNC key while connected: it stops KISS. If it happens, the strip says not in KISS and Switch back to KISS fixes it.
• Disconnect leaves KISS and switches the TNC off; the radio has its own APRS back.
• Follow the ISS Doppler (Auto or ISS): during a pass the radio follows in 5 kHz steps (145.830 → 145.825 → 145.820), two changes at most, each with about 5 seconds of silence while the radio leaves KISS and comes back.
• In Auto, SatMe moves the radio between 144.800 and 145.825 by itself, at most once a minute.

USB connection of a KISS radio · APRS settings: radio and where to work.

Yaesu FT3D

1. FT3D setup menu, COM port: OUTPUT on WAY.P, same speed as in SatMe (9600 for instance).
2. FT3D APRS on, on the right frequency, squelch just closed.
3. USB cable with an OTG adapter, choose Yaesu FT3D (positions), tap Connect.

The stations the FT3D decodes appear with their position. No messages, no path, no transmit from SatMe.

Sending

Send tab: choose Position, Status, Message or APRSPH, the path (ARISS, WIDE1-1,WIDE2-1 or none), check the frame preview, then the red button.

Before anything goes out, SatMe checks:

• a callsign is set;
• the last frame is at least 20 s old;
• the rig is in FM, not in satellite mode, on 145.825 MHz ± 10 kHz or 144.800 MHz ± 10 kHz;
• the rig is not already transmitting.

With the IC-9700, SatMe keys, plays the audio, then unkeys and checks the rig is back on receive. A frame is decoded back by SatMe before it is played: one that would not decode is not sent. Tests without transmitting (Test: speaker, Test: WAV file) are in Settings › IC-9700 audio.

With a KISS radio, SatMe cannot read the frequency once in KISS: when it tuned the radio itself, nothing to confirm; otherwise tick The radio is on 145.825 MHz (ISS) or 144.800 MHz, FM.

Sending a position · every frame heard and sent.

Messages and APRS Thursday

• One conversation per station: yours on the right with ✓ acked once the ack arrives, theirs on the left with ✓ Ack to acknowledge.
• APRS Thursday: Join (CQ HOTG), Stay (K HOTG), Leave (U HOTG) each send a message to ANSRVR. Today's participants are listed: tap one to write to them.

Map and hunt

• Today / 7 days, Around / World, base map OpenStreetMap, Topo, Dark, Offline. Pinch to zoom, drag to pan.
• Each station heard through the ISS is linked to where the ISS was at that moment; locators heard are tinted; weather stations in orange.
• Tap a station (map or list) to hunt it: distance, course, and an arrow that follows the phone held flat.
• Weather reports are decoded: temperature, wind and gusts, rain, humidity, pressure.

Trophies

Tally of the day and APRS contacts · records and badges.

• When the ISS repeats your own frame, SatMe cheers: banner, buzz, notification, and who else was on that pass (switch Cheer the good moments in Settings).
• The day's tally (stations, countries, locators, frames via the ISS, sent, repeated, acked, contacts) can be shared as a picture.
• APRS contacts: a message acknowledged one way or the other. Those made through the ISS go to the log with To the log (mode PKT, 145.825 MHz). See Logbook.
• Since the start: locators, countries, distance record, and 14 badges. Kept apart from the 7-day history: clearing the list does not take them away.

My station

SSID, approximate position, ISS beacon.

• SSID: none, -6, -7, -9 or -10, added to the callsign from the settings.
• Approximate position: your positions go out shifted by less than 500 m, always by the same offset (drawn once); Draw another offset picks a new one.
• Beacon as the ISS passes: off by default. Once switched on, it sends your position by itself, once per pass, when the ISS is above 15°, only if the radio can be checked (IC-9700 on CAT, or a KISS radio whose frequency read is 145.825 MHz).

Tips

• The page is in beta. Not yet tried on real hardware: IC-9700 APRS transmit, the IC-9700 switching to terrestrial, the TH-D72 driven from the phone over OTG (tested from a PC with the real radio), other KISS TNCs.
• Frames are kept 7 days (Settings › Other › Clear APRS history).
• Nothing on the phone with the TH-D72? See the FAQ.