Keith and I both hope to be able to attend "Thunda Down Under" in
2015, and I've sent the organizers email requesting information on what
it takes to be treated as an on-site vendor.
Of course, it's always more fun to be at a launch when you have something
interesting to fly! Thus, while Keith and I might each show up with a
modest "travel rocket" of some sort... I've started pondering possible
larger "Altus Metrum" group projects. Since transporting a large
airframe to Australia would be a hassle, I wonder if a group project to
build an airframe in-country makes more sense? To that end, I'd be
pleased to know if any of our friends and customers in Australia want to
sign up to help with such a project?
My thoughts would be to engage in some group-think about project scope
and goals, then hope friends in-country would take on the sourcing and
preparation of suitable airframe materials. Depending on who wants to
participate and how tasks get taken up, we might plan to arrive a bit
early to help with any final assembly or other preparations,
installation of suitably fresh Altus Metrum electronics, etc.
So, to all our Aussie friends... does this sound like fun? If so,
please chime in with a reply. I don't expect the email associated with
such a project to be too heavy a load for this list to carry, but we can
always spawn a dedicated lists.gag.com list if I'm wrong.
Not working here. I tried the D72A and paired a Mobilinkd TNC1 to a Nexus 7 with a plain H/T.
Packets come across but nothing is decoded. With the Mobilinkd, I made certain it was decoding APRS packets properly off the air on 144.390 and then used a 70cm Beeline GPS. All worked fine there including packets transmitted from the D72A and off-frequency D7's.
I could "hear" the data packet on the TeleGPS coming in but no decode. Does a separate
APRS packet get sent in between the GFSK data bursts or is it mixed in with the data bursts?
If it's separate I do not hear anything that resembles the APRS sound. If it's "mixed in" with the
Altus metrum format, it sorta sounds like an APRS packet but is not decoded.
Nonetheless, if my settings are appropriate, I believe the TeleGPS I have is not behaving up
to spec if it's supposed to be able to send an APRS packet. I'll wait till I hear from Keith or
B'dale and see what they say about my settings.
I've used three rigs to attempt to decode packets (although I didn't expect much from the off
frequency D7) two of which work fine with 2 meter and 70cm off-air packets. I'm stumped.
From: Douglas Bertelsen <douglas.bertelsen(a)gmail.com>
To: Kurt <ksaves2(a)sbcglobal.net>
Sent: Saturday, January 31, 2015 9:26 AM
Subject: Re: [altusmetrum] Contact Form
Those settings gave me good packets. All else failing, can you record the audio from the radio during transmissions and post it if those settings don't work? I can compare it to what I hear and maybe give some insight.
I flew my TeleMega, serial #1639 with 1.4.1 at Balls in a 2 stager.
Ran into a few problems, as follows:
1. Unable to connect in to TeleDongle in idle mode. I had previously
found that I couldn't get a connection with the TeleMega in channels
7-9, so I was using channel 3 for this flight. I was unable to get a
connection in idle mode in Channel 3. I haven't explored other channel
or tried to re-create this problem.
2. RFI issue with Beelines. The rocket had 4 Beeline trackers in it as follows:
- 1x 100mw 70cm GPS aprox 30" above the TeleMega on 434.350
- 1x 70cm beacon aprox 6" below the TeleMega on 438.850
- 1x 16mw 70cm GPS aprox 48" below the TeleMega on 434.350
- 1x 70cm beacon aprox 48" below the TeleMega on 438.350.
With any combination of the beacons turned on, attempting to startup
the TeleMega in pad mode would result in battery voltage beeps, pad
mode beeps followed by silence, on both the radio (I was listening in
to 434.850 on my FT1DR) and buzzer (ie, no continuity beeps). After
spending an afternoon troubleshooting this, it was determined that
turning on any combination of the Beelines prior to startup would
cause this, but turning them on after the TeleMega was transmitting
didn't result in any adverse affects.
In investigating the manual post-flight, I did note the point about
twisting wires, which I did not do on this flight as I hadn't seen it
previously. I'm not certain that that would have fixed the issue or
not. It would be really really great if there was a separate manual
for each product. It's very easy to miss things when you are
intentionally skipping a significant portion of the manual since it
doesn't relate to the product you are interested in. Additionally,
this is the only time I've seen a suggestion in a manual to twist
wires. This comes in a section of the manual, that in most other
rocket electronics manuals, is reserved for things like "how to attach
wires to screw terminals" and "how to not have battery issues", which
experienced fliers have a tendency to already know and skim.
3. Accel calibration with temp. After spending an afternoon at the pad
troubleshooting the above issue, the rocket sat overnight and was
powered up within 30 minutes of sunrise. I was unable to get the
TeleMega into pad mode until it had been in the sun for 10 minutes, at
which point, it went into pad mode and read a Z accel of -5.1m/s/s. We
left the rocket in the sun for the next 45 minutes and in that time,
the Z accel when it was being held vertically had migrated from -5.1
to -3.3 to -2.2 and was continuing its upward trend. The accelerometer
was previously calibrated at room temp 2 weeks prior to the launch.
4. Angle lockout for staging-not so much a bug as it's probably
exactly what it's designed to do, but I had the telemega setup to do
staging and also staging inhibit on a backup timer. The TeleMega was
to stage if conditions were after burnout, >4 seconds into flight, <25
degrees and >400m/s. I had an additional circuit acting to open the
igniter circuit on a timer I was using for backup. This was to occur
if the angle exceeded 25 degrees at any point. Shortly after the
breakup, the inhibit circuit fired as anticipated. What I didn't
expect was for the fire circuit to fire as the rocket rolled back
within 25 degrees of vertical 2 seconds later. Fortunately the igniter
had already ripped out of the motor, so no harm was done, but this
could have been interesting had it not.
Anyway, hopefully this helps alleviate frustration for at least
someone. I understand the issues now and they're more annoyances that
I can live with than anything. As I hadn't seen them documented
previously, I figured I'd put them out there. Let me know if anyone
has further questions or needs more elaboration.
Thanks for the help you provided to me and the Teams at the NASA SLP
Launches this weekend. It's good to know that your depth in the sport goes
far beyond the great products you produce.
Art Woodling and the Alabama A&M Rocket Team
If I remember correctly, it's just a very simple XML file which is easily edited in a text file
> On Apr 12, 2015, at 4:45 PM, Kevin Ruland <kruland(a)sunflower.com> wrote:
> I got to use my TeleGPS for the first time yesterday. The second time I flew it was the only reason I was able to recover my rocket!
> When I downloaded the data, it included both launches. This was even after the unit was powered off between flights. I had thought the TeleGPS would hold multiple tracks in memory. If I'm mistaken, that's ok, but then are there any useful tools for editing kml files so I can segment the individual flights?
> altusmetrum mailing list
I got to use my TeleGPS for the first time yesterday. The second time I
flew it was the only reason I was able to recover my rocket!
When I downloaded the data, it included both launches. This was even
after the unit was powered off between flights. I had thought the
TeleGPS would hold multiple tracks in memory. If I'm mistaken, that's
ok, but then are there any useful tools for editing kml files so I can
segment the individual flights?
wexpeter <wexpeter(a)gmail.com> writes:
> Have used Telemetrums over the last few years - very happy with the
Thanks for the kind words, Peter!
> A university rocketry club my son is in is considering a carbon fiber
> HPR. They are considering 900MHz — I am trying to convince them to get
> the license and use the Telemetrum. Question is what others have used
> for an antenna. My assumption is it has to be external if carbon
> airframe. Single external wire? Other suggestion? Clearly some gain on
> the ground will be important.They are thinking possible max altitude
> of 50K. Any suggestion greatly appreciated.
> Peter Wexler
I'm going to CC our mailing list on this reply in case others want to
chime in, because the whole issue of what to do for antennas on
predominantly CF airframes is a fairly frequent question to us.
My personal preference is to include a non-CF section in the airframe.
For example, make the walls of the electronics bay out of glass, or use
a glass nosecone, into which the various antennas can be places. The
reason this is a big win is that you're actually worrying about *2*
antennas, not one .. the GPS patch needs a clean look at the sky or you
won't get a GPS lock, and the signal from the UHF downlink antenna
obviously needs to be able to propagate out from the airframe.
In our original TeleMetrum design, we were forced for several reasons to
use a GPS patch antenna with an integrated preamp that had a short piece
of small diameter coax wrapped around the board plugged into a U.FL
connector on the board. With those boards, remoting the GPS antenna was
at least theoretically pretty easy. You could disconnect that cable,
put in a U.FL extension or U.FL to SMA adapter cable, and put the
amplified GPS antenna of your choice somewhere else in the airframe.
But in practice, this often turned out to be a real pain. The U.FL
connectors aren't really designed for many insert/remove cycles (think
10'ish), adapters are expensive / heavy, as are standalone amplified GPS
antennas. Thus, not many people actually did this...
In our current products, all of the GPS antennas are passive patches
soldered directly to the board. The front-end on the u-blox MAX-7Q GPS
receivers we're using now is sensitive enough that this works out pretty
well, and the inclusion of a SAW filter plus *very* carefully designed
layout keeps the UHF transmitter from swamping the GPS receiver input.
The downside is that remoting the GPS antenna has gotten a lot harder
with current products like TeleMetrum v2.0 and TeleMega.
We no longer offer a purchase-time option for putting an SMA connector
on the board instead of a wire whip antenna, but the footprint is still
there, and I still sell the right SMA connectors. We've observed that
downlink signals from a simple wire soldered to the board are often much
stronger than when you put a "commercial" antenna on an SMA .. this
is partly because most "rubber ducks" are actually really lousy antennas
(including the ones we used to sell, sadly!), and partly because the
design of the PCB is such that a simple 1/4 wave whip on the end of the
board gets an exceptionally good signal "launch". So, if you really want
to remotely mount a UHF downlink antenna, it's not hard to do, but we
don't usually recommend it. For a good example of when/why you might
want to do it, have a look at my write-up for YikStik3, particularly the
description of my "fintenna" and the associated photos taken during the
The performance of the fin-can downlink on that airframe, once I
re-tuned everything with the Pro75 6xl case in place, was
*outstanding*. I really wish I still had that airframe... on its maiden
flight it set new personal speed and altitude records for me. But, like
so many others, it was lost in the fire.
Bottom line? It's *possible* to remote antennas from our products, but
it's not something to be taken lightly. By far, the better approach is
to include an RF-translucent section somewhere in the airframe to house
There are so many different "900 Mhz" products out there that I can't
speak to them without more details, but you're unlikely to find anything
operating on that band that gives a more satisfying result than using
one or more of our products... ;-)
I hope this helps!
In talking to Keith & Bdale, it sounds like the TeleBT 2.0 will be out very soon
> On Apr 10, 2015, at 10:26 AM, Jonathan DuBose <jmdubose2000(a)yahoo.com> wrote:
> Any plans to get the TeleBt in stock soon?
> Jonathan DuBose
> altusmetrum mailing list