Yesterday my TeleGPS/TeleBTAndroid Phone system decided to report height
above sea level instead of height above ground.
I had tracked a friends TeleMega on another frequency. It reported
height above ground as expected. Then I switched over to the frequency
that my TeleGPS was on and I was getting reports above sea level. It
was a low altitude flight that I was using as a practice flight after
the winter layoff so I just went ahead and flew it. Does anyone have an
idea as to what happened?
It has been a while since I used my TeleGPS and I am having problems. I can connect to it via ALTOS with a USB cable but not with the tele Dongle or Tele BT. I know the call sign and channel is correct on all devices. Any suggestions? Also, what LED's should light up when I plug in the battery. None are lit and I know the battery is charged.
The pad side safe/arm switch is useful, but is not as good as it could be.
The schematic doesn't include this switch but it appears to switch +12V
to v_pyro. Which means that when this switch is closed, many single
point failure modes come into play. If a MOSFET has failed that output
will fire. If the driver to a MOSFET has failed it will fire. Low
probability events but the consequences could be serious. If you are
lucky the motor doesn't CATO and you just have to change your armor.
Use a relay instead to provide v_pyro. The relay is controlled by the
system and closed when an arm command is received. This way everyone is
at a safe distance when those single point failure modes come into play.
The single pad side safe/arm switch is placed in series with the relay
coil so it can be disabled. In series with the relay output is another
The alarm outputs are then not controlled by a GPIO output but by the
presence of 12V on the output of this relay. You get a warning when
the system arms or when the relay fails.
You will need another source (3.3V) of power to drive the continuity
check. A diode and a resistor does the job. (A PFET with its source to
v_pyro and gate to 3.3V provides the alarm output.)
A 40A automotive relay should be adequate here since it would not be
switched under load. It is better than the rocker switch. (Relays plus a
socket can be purchased for $5 a set at All Electronics.)
The DARS launch controllers have used this idea since 2004. No relays
have died yet.
The Earthlink servers have been down for over a week now so you will
probably have to use the Wayback Machine version:
The gate drive (3.3V) to the output FETs is a little weak. I like the
MIC5018 driver in situations like this to make sure that they are fully
enhanced. Not so much for extra output current but to reduce power
The cheaper the crook, the gaudier the patter. - Sam Spade
I saw the announcement of this new launch system and while looking at it
I noticed something missing: a removable safety interlock.
Both NFPA 1122 and 1127 require that launch systems include a removable
safety interlock in series with the launch switch. TRA uses NFPA 1127 as
their safety code and NAR requires following the NFPA codes at all NAR
launches. So this is a problem.
But perhaps I just missed it. I tried looking at the gschem schematic
and that didn't help at first. All symbols missing. Having to download
that huge mess of a library just to get the symbols used here is annoying.
It appears from the schematic that both the safe/arm switch and launch
switch pull down a GPIO pin. The fix is to replace the silly guarded
toggle switch with a key switch for safe/arm. Also, wire the launch
switch in series with the safe/arm switch. So that pushing the launch
button does nothing if the system is not armed. This is in addition to
whatever firmware safeguards are in place.
Put a lanyard on the key so the LCO can hang it around his neck when not
in use. (Stash a spare key inside the case.)
Those switch connections make me nervous. They connect unprotected GPIO
pins to parts that are being handled by the user. Sure the switch body
will provide some protection from ESD but how much? A series resistor
would help a lot. Large enough to limit currents in the ESD diodes on
the GPIO pins but small enough to work with the internal pullups.
Oh, I thought that the FCC prohibited encryption for amateur radio:
47 CFR 97.309(b) Has that changed?
The cheaper the crook, the gaudier the patter. - Sam Spade
Altus Metrum announces Wireless Launch Control System
We're pleased to announce the availability of a new wireless launch
control system, TeleLaunch. The system initially consists of two new
products, TeleLCO and TeleFireEight. TeleLCO can control up to 99
TeleFire boxes, with up to 8 channels each, for a total of up to 792
TeleLaunch uses Altus Metrum's robust wireless technology originally
developed for telemetry from our flight computers, augmented with
AES cryptographic checksums to maximize the safety of launch operations.
TeleLCO provides visible indication of channel continuity on the currently
selected TeleFire box, and supports both individual launches and drag races.
TeleLCO uses an internal LiPo battery that charges with a USB cable, and
is packaged in a bright orange Pelican box.
TeleFireEight supports up to 8 launch rods/rails, and has a built-in
sealed-lead-acid battery for easy setup and use. Each unit has a hard
SAFE/ARM switch that completely disconnects pyro power for safety, includes
a continuous display of continuity, and has both a strobe light and siren
to convey arming status. TeleFire is packaged in a mil-spec 50-cal steel
ammo box painted bright orange, and outputs are via US-standard AC
electric outlets with weather-protecting covers.
Each TeleLaunch system ships with everything needed to be fully functional
out of the box, except for per-rail/rod clip leads.
More information can be found online at http://altusmetrum.org/TeleLaunch
TeleLaunch products will be available only through the shop.gag.com web
store, and are available to order now. Unlike other Altus Metrum products,
TeleLaunch components are assembled in small batches and thus may not always
be ready to ship immediately.