gmane.technology.rocketry.altusmetrum

Altus Mentrum/Antenna Question

Xpert Grafix — 2013-06-11T18:53:05

Hello,

I am about to use my Altus Mentrum for the first time this Saturday. I have bought the Arrow 440-3 antenna. Can you tell me the best way to hook it up. I'm not sure how long of  an extension from the Teledongle I can use. I thought I read somewhere that the teledongle should be as close to the antenna as possible. But I can't find that now. Also, during the launch do you need to be pointing the antenna directly at the rocket or can you attach it to something and point it in the in a general direction of the launch. Any thoughts would be appreciated.  

Thanks
Chris

Re: Coax connecter/cable/antenna confusion

Joe Zawodny — 2013-06-01T19:53:51

I suspect your rocket is too small to for a patch antenna at the frequency
these use.
http://linux.students.engr.scu.edu/~bhorwath/presentations/Microstrip%20Patch%20Antenna%20Design.pdf

Joe


On Fri, May 31, 2013 at 7:45 PM, Peter Hackett <
peter.hackett-aP5ABqoqSTtUAgJt6FLh2g< at >public.gmane.org> wrote:

Re: Coax connecter/cable/antenna confusion

Peter Hackett — 2013-05-31T23:45:46

RE copper tape patch antenna:

"Tell me more" :-)

Specifically, how do you attach (say) a sma cable to the the copper tape?
And would I just tape 7" of the copper tape to the inside of the altimeter
bay?

I guess I can figure this out with a bit of web surfing, but ...

Is "Copper tape" something that is sticky like masking, er I mean rocket
tape
or is it more like cassette tape (copper on some sort of plastic film?)

BTW love the pics of "Behemoth Bertha" rocket on your Google+ page

Peter "A 'real' rocket would be fun" Hackett


On Fri, May 31, 2013 at 1:53 PM, Joe Zawodny <jmzawodny-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org> wrote:

Re: Coax connecter/cable/antenna confusion

Joe Zawodny — 2013-05-31T20:53:38

Why not consider building a patch antenna out of the copper tape that
hobbyists use in making stained glass.  Patch antennae are what they use on
"real" rockets.

Joe Z


On Fri, May 31, 2013 at 4:42 PM, Peter Hackett <
peter.hackett-aP5ABqoqSTtUAgJt6FLh2g< at >public.gmane.org> wrote:

Re: Coax connecter/cable/antenna confusion

Peter Hackett — 2013-05-31T20:42:06

Casey and Bdale, thanks for the info!

RE " ... when another newbie ham asked a similar question"
:-) you!

Ok, I think I understand most everything.

I did some more poking around (Casey's thread and a little Googling)

Which got me to thinking about moving the altimeter from rocket to rocket.

I found a web page which seemed to suggest I could strip off (in my case)
~ 7"
of the outer casing and outer conduct of a coax cable to form the
equivalent of
a 7" wire antenna. Does that sound right?

Give that it is true (works reasonably well) I was thinking I could buy a
(say) 5ft
sma male to <anyConnector> coax cable cut off the <anyConnector> end,
drill a cable diameter hole in the "main" side of the altimeter bay thread
the cable
through leaving enough slack to easily connect the sma male connector to the
TeleMetrum. I would then epoxy the cable as it passes from the inside to the
outside of altimeter bay. Then I would cut the cable to (say) 8" long on
the outside
of the altimeter bay and strip 7" of the outer

Re: low voltage micro servo 2.8V-4.2V

Bdale Garbee — 2013-05-31T04:38:25



That's certainly compatible with 3.3 volts.  The on-board LDO regulator
on our boards doesn't have a lot of extra current capacity, though, so
you'd either want to run the servo on the unregulated LiPo rail or use a
separate regulator to power it.

I can't speak to whether it would be useful in any rocketry application
off hand, though.

Bdale

Re: Coax connecter/cable/antenna confusion

Bdale Garbee — 2013-05-31T04:30:45


It's a bad idea for two reasons.  One is that it'll dramatically impact
the radiation pattern, as you surmise.  The second is that doing that
will put strain on the SMA connector's attachment to the board, which
isn't a good idea.  I've had to repair boards that had the SMA damaged
or sheared off because of loads put on the connector by such an antenna
setup... sadly, one was one of my own boards that I stuffed in a 54mm
airframe in a hurry at a launch a couple of years ago .. /o\


That's a better plan.


Yes.


Ok.  The SMA-BNC adapter is the optimal way to attach a TeleDongle to an
Arrow antenna.  It puts the receiver as close to the antenna feed point
as possible, which minimizes the loss between the antenna and the
receiver, giving you the best possible system noise temperature.

On the rocket end, I really prefer the wire whip.  The only reason to
use an SMA is if you're installing the board in something like an
aluminum or carbon fiber airframe section (both are more or less opaque
to RF signals) wh

Re: Coax connecter/cable/antenna confusion

Casey Barker — 2013-05-31T03:31:27

Just for humor, I'll point you to a thread about two years ago when another
newbie ham asked a similar question:

http://lists.gag.com/pipermail/altusmetrum/2011-February/000036.html

In short, don't bend the antenna back over the board. Better to stick it
out the top of the bay next to your chute. Wire antennas are pretty robust
and don't need a lot of protection. And yes, you'll need an SMA-to-BNC, but
you can probably pick one up at HRO if you're in the neighborhood.

Casey


On Thu, May 30, 2013 at 7:42 PM, Peter Hackett <
peter.hackett-aP5ABqoqSTtUAgJt6FLh2g< at >public.gmane.org> wrote:

Coax connecter/cable/antenna confusion

Peter Hackett — 2013-05-31T02:42:16

I recently bought a Telemetrum Starter Kit from the Garbee and Garbee Web
Store.
There is a combo box where you can choose "1/4 wave wire" or "SMA connector
+ $5.00"
I didn't really give it much thought, but I picked "SMA connector" (I think
I may have
thought: "it cost more, it must be better")

When I got the starter set, I realized that that it wasn't "in addition to
a 1/4 wave wire"
but "instead of". So ... I went back to the gag.com site and found the Whip
Antenna
and bought that.

Then I got to thinking about how I would install the altimeter with whip
antenna in a
rocket. (Good time to start thinking about it, eh? :-)

My (first) target rocket for the Telemetrum is a Giant Leap Vertical
Assault 3.0.
and it doesn't have "acres" of space.

So my first question is:

Can I just bend the whip antenna into a horse-shoe shape to get it to fit
into the
altimeter bay? (I guess the really question is "Will this significantly
compromise the
performance of the antenna?") And if it is "a bad idea" what should I do

low voltage micro servo 2.8V-4.2V

George Shaiffer — 2013-05-30T18:39:27

Any chance this will meet voltage/torque/ speed requirements? The servos should be outther challenge is to locate them at a decent price. George Shaiffer  HobbyKing HK15318B Low Voltage Micro Servo 2.2g / .11kg / .08sec

  

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Specs:
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Stall Torque (2.8V): 0.07kg.cm
Stall Torque (4.2v): 0.11kg.cm
Weight: 2.2g


PRODUCT ID: 9225000025Weight (g)2.2Torque (kg)0.11Speed (Sec/60deg)0.08A(mm)20B(mm)16C(mm)17D(mm)8E(mm)23F(mm)10Update/Add my own data
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Re: Suggestion for future versions

Bdale Garbee — 2013-05-28T21:35:35


I have no idea.  I've seen muscle wire advertised, but have never used
any so don't know much about it.

Bdale

Re: Suggestion for future versions

George Shaiffer — 2013-05-28T20:43:35

I haven't looked into them in depth but think I have seen some dc to dc converter chips that might do 
the required level shifting.  DC in and different DC out but have no idea if it is up or down nor the effect on
current.  Will look into this to see what I can find.  My interest lies with controlling a parachute lines to fly it
back to a defined ground point.  
George
 
Below is an example of what I'm thinking about 3.3 V in  5.0V out  but is there enought current?  Also do the park flyer servos( small indoor outdoor electric planes, helios, etc?) run on lower voltage and current?
DescriptionThe AS1337 is a synchronous, fixed frequency, high efficiency DC-DC boost converter capable of supplying 3.3V at 200mA from two AA Cells. Compact size and minimum external parts requirements make these devices perfect for modern portable devices.
The AS1337 offers automatic powersave mode to increase efficiency at light loads. For input voltages higher than VOUT, the AS1337 will switch in a step down mode, so t

Re: Suggestion for future versions

Thomas Müller — 2013-05-28T20:04:39

Thanks for the long reply.

Oh, I did not recognize the operating voltage problem.

Most servos will just work fine with a 3.3V PWM signal as long as you 
supply 5V to the power connection of the servo. I am not sure if that is 
risky for the MC ?
But since you have to use another battery / regulator, you will not add 
much complexity when adding an additional MC, for example an arduino.

I just thought it would be cool if you could simply plug in an servo to 
the altimeter, and did not recognize the problem with the operating voltage.

Best
Thomas


Am 27.05.2013 06:55, schrieb Bdale Garbee:

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Re: Suggestion for future versions

Thomas Müller — 2013-05-28T19:46:08

You are right, it is easy to use an arduino for that, you do not even 
need a shield. DF robots cheapduino would be great for that. You could 
use an analog port to listen to the Telemetrum and the PWM port to talk 
to the servo.


Spacetec (http://www.spacetecrocketry.com/) is also offering a 
commercial solution for the problem.
Which will convert the igniter signal of any altimeter to an servo 
signal. It also simulates the behaviour of an igniter to the altimeter.

But that is introducing another electronic, with another power supply, 
which can fail.

Best
Thomas
Am 28.05.2013 21:33, schrieb Peter Hackett:

Re: Suggestion for future versions

Peter Hackett — 2013-05-28T19:33:31

I'm no expert, but if the goal is to "get it done" I would use an Arduino
and a daughter board ("Shield")
that knew how to talk servo. If you have some technical experience, the
Arduino is very easy to
use. You hardly need to understand what "programming C" means. My 15 year
old son pick it up
in a few days without any help from me.

Given the above, you'd just need to have a very simple way to communicate
from the TeleMetrum to the Arduino.
E.g. pyro output(?)

Not to say it wouldn't be cool to be able to do everything from the
TeleMetrum/Mega/NextGen.

I'm interested in experimenting with a steerable parachute for rocket
recovery. (Just for the challenge
and fun of it.)


On Sun, May 26, 2013 at 9:55 PM, Bdale Garbee <bdale-wvU4uTqWWAI< at >public.gmane.org> wrote:

Re: Suggestion for future versions

2013-05-28T18:15:03

Re: Suggestion for future versions

Bdale Garbee — 2013-05-27T04:55:01



Interesting .. I've never actually seen someone using an RC-style servo
for deployment before.  As you say, there's no conceptual reason we
couldn't do that... but in practice there are some issues I'll address
below. 


To drive an RC-style servo, you need to be able to PWM an output pin,
which is easiest to do if that pin is connected to a timer with PWM
support, but of course also possible to do with a GPIO and software PWM
generation.  That part isn't hard.  The difficult part is that all the
servos I know of run at 5V, and all of our products are 3.3V using
single-cell LiPo batteries with 3.7V nominal and 4.2V fully charged.  So
at minimum, you'd need a separate battery / regulator to generate the 5V
that is required, and you'd need a level shifter (transistor) on the PWM
output to enable it to drive a 5V input.  

My son and I are actually working right now on a board to control 12
such servos for a robotic arm project using the same STM32L151 part
that's on TeleMega.  I haven't loaded the first pro

Suggestion for future versions

Thomas Müller — 2013-05-26T10:20:02

Hi everybody,

there is one thing I would really like to see in future versions of 
TeleMetrum or TeleMega.
It is the possibility to control a servo. Very few altimeters can do 
that, for example the Altimax.
http://rockets.aquarix.de/download/doku/ALTIMAXG2_Documentation_en.pdf

It is very useful for controlling servo releases for serial dual deploy 
like spacetecs SRM2. They are pretty common in Europe.

In principle you need only a analog/digital output which can be freely 
controlled.
Sure it is possible to use another microcontroller to convert the 
ignitor output into a servo signal, but that introduces one additional 
part to rocket design.

Maybe that is even possible with the actual TeleMetrum design, just with 
a software change?

Is there some output accessible? As far as I understand the companion 
port it is only a SPI interface.
Port 3 and 4 on the debug port seem for me to be regularly unused 
digital IO ports.
Can they be used?


Best
Thomas

Re: Altus Metrum releases TeleBT, AltosDroid,and AltOS 1.2.1

Peter Hackett — 2013-05-22T18:26:44

This ROCKS! You the MAN! (men)


On Tue, May 21, 2013 at 8:47 PM, Bdale Garbee <bdale-wvU4uTqWWAI< at >public.gmane.org> wrote:

Altus Metrum releases TeleBT, AltosDroid,and AltOS 1.2.1

Bdale Garbee — 2013-05-22T03:47:36

Altus Metrum releases TeleBT, AltosDroid, and AltOS 1.2.1

BLACK FOREST, Colorado USA

Altus Metrum is pleased to announce the immediate availability of TeleBT, 
and version 1.2.1 of our AltOS software including an Android application.

TeleBT is a new ground station designed to allow tracking and recovery of 
your rocket with an Android device.  TeleBT incorporates a 70cm radio to
communicate with Altus Metrum flight computers, and a Bluetooth radio that
connects with Android phones and tables, and with computers running Linux
that have a Bluetooth interface.  TeleBT also has a micro USB connector 
used to charge the internal battery, and for connection to computers
running Linux, Mac OS X, and Windows.  More information about TeleBT is
available at http://altusmetrum.org/TeleBT.

Our new Android application, AltosDroid, is available for free from the 
Google Play store, and works on most current Android devices.  AltosDroid 
monitors your rocket flight, reporting status on the screen and
through voice synt

Re: TeleMega v0.3 successful test flight

Elaine Russell — 2013-05-20T15:01:07

Awesome! I'll see you in Geneseo on the weekend. I'll be flying my Telemini
for the first time.
Elaine
On May 20, 2013 10:58 AM, "Bdale Garbee" <bdale-wvU4uTqWWAI< at >public.gmane.org> wrote: