Keith and I both hope to be able to attend "Thunda Down Under"[1] 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.
Regards,
Bdale
[1] http://thunda.com.au/
Altus Metrum releases TeleMini v3 and AltOS 1.7
TeleMini v3 is a major upgrade to our TeleMini v1 product. TeleMini
remains the worlds smallest dual-deploy altimeter with built-in
telemetry and radio beacon for tracking.
* Recording altimeter for model rocketry
* Supports dual deployment (can fire 2 ejection charges)
* 70cm ham-band transceiver for telemetry downlink and radio
direction finding
* Barometric pressure sensor good to 100k feet MSL
* Uses a single LiPo rechargeable battery
* 512kB flight data storage
* 1.7 x 0.5 inch board designed to fit inside 18mm airframe coupler
tube
http://altusmetrum.org/TeleMini
These are available today from our web store
http://shop.gag.com/flight-computers/telemini-v3.html
AltOS 1.7 includes firmware and software updates to support TeleMini
v3. The new computer software is available at
https://altusmetrum.org/AltOS
A new version of the AltosDroid application is available in the
Google Play Store.
I flew my TeleGPS equipped rocket yesterday. It was a nice flight to
10K feet and as usual AltosDroid walked me right to the rocket. No
wandering around looking for it. I had an anomaly that I didn't
understand. During the flight I received updates on the rockets
direction and distance but never heard it announce the altitude or
elevation angle. It has reported these in the past. I had GPS
enabled on my phone. The AltosDroid version is 1.6.4. Any ideas what
my have happened?
Also, it would be nice if AltosDroid reported the distance to the ground
point the rocket is above instead of the slant distance to the rocket.
It's a minor point but the distance to the sub satellite point makes
more sense to me. Otherwise as the rocket descends it sounds like the
rocket is drifting back towards you when in fact it is only getting
closer to you due to the descent. Last fall a friend launched a
rocket to 20K that had both Kate and TeleGPS on board and we were
comparing the talk back of the two systems. The results were very
close except for the distance since Kate reports the distance to the
ground point.
Terry
I just joined this Altus Metrum mailing list. I'm trying to get a bit more
information and learn more about the Telemetrum before I purchase one.
Thanks,
Scotty
Hi Scot,
I feel compelled to jump in here and state up front that I think any fears of the Altus Metrum system not meeting your needs are almost surely not an issue.
I have OVERTHOUGHT myself into problems but was saved by my 17yr old grandson and my wife neither if whom have a HAM license.
I am not an engineer but I have used Telemegas, TeleGPS's and recently purchased a Telemetrum. With a 6 element Yagi, a Teledongle and a less than $200 pc tracked rockets to 90k' (and 55k') using a Telemega which also lit the sustainer and deployed both recovery events. I have used the Telemega with a TeleBt and my Android phone to track and recover flights to 30k ft.
I regularly track and recover rockets to 12k' using a TelegGPS, the Yagi and my Android phone. I have flown the same equipment to 30k' into 90 a knot jetstream (DOH!) which shredded eveything BUT Bdale put the Telemega GPS and Telemega back together and I used the TelGPS a couple if weeks ago.
I NEVER had a problem tracking AND recovering - when the rocket was recoverable. I HAVE had all the recovery methods including a shovel method. I have one that would require a backhoe or Elon Musk's tunnel machine - unrealized.
With your background you should have no problem with any Altus Metrum system but if you should be unnable to make things work just post the unit to THE ROCKETRY FORUM and it will be gone in a NY minute.
And if I see it first it might become part of my collection of near bullet proof Altus Metrum products.
My point is that if someone as technically challenged as myself can use AM products with stellar results then a mechanical engineer who is clearly interested and persistent should be able to be successful.
I have used many tracking systems - including 800mhz units and the Big Red Bee (which I fly as a redundancy on the big flights). ALTUS METRUM answered the need for performance combined with pyro ability and use by the general rocketry community regardless of technical expertise. If you can pass the L2 test you can make this work.
One other thing: RTFM!
I should add that the assumption is that you are not planning something "off the charts".
Jonathan DuBose, NAR 80588, TRA 11505, LEVEL 3, KK6DMM
Sent via the Samsung GALAXY S® 5, an AT&T 4G LTE smartphone
-------- Original message --------
From: Scott Myers <ac8de(a)ameritech.net>
Date: 4/13/17 7:47 PM (GMT-05:00)
To: w9ya(a)qrparci.net, 'Altus Metrum' <altusmetrum(a)lists.gag.com>
Subject: Re: [altusmetrum] New Member
Bob,
Very interesting. I'll give that a test while I'm at it. Thanks,
Scotty AC8DE
-----Original Message-----
From: altusmetrum [mailto:altusmetrum-bounces@lists.gag.com] On Behalf Of w9ya
Sent: Thursday, April 13, 2017 6:23 PM
To: Altus Metrum
Subject: Re: [altusmetrum] New Member
Well, my point was that the helical/helix wound antenna would seem to be a problem compared to the "more orthodox" 1/4 wave.....but actually it works better because as the rocket spins and dips and dives through the entire flight profile, the nulls fill in nicely with an antenna of this kind....THERE, I said it, instead of implying it !! (Much better , I am sure.)
As for "detuning".... you can check this rather easily using the rssi feature in the ground station software. I think you will find that unless you are placing the antenna right on top of your hardware, that it really isn't much of a problem, and even less of a problem with the helix/helical style antennas.
Or put another way, go make some measurements of your own using the ground station's rssi feature and an sma connector on the xmitter for easy changes for ab easy afternoon of measurements. I am sure it will be quite "illuminating" for ya.... (pun intended....hi hi..) <- That's what we did a few years back, and the antenna I linked in the earlier message is "the cat's meow".
es vy 73 om de bob w9ya
P.S... Oh yeah, we also mount our flight electronics using "plastic"
hardware (screws, washers, nuts...etc.) so that not only is that less conductive stuff...but also so that they will break before the circuit board will during hard landing. AND, *if* the board can be suspended by the cabling over a fiber-glass or wood surface; you will have done yourself proud.
On Thu, Apr 13, 2017 at 1:20 PM, Scott Myers <ac8de(a)ameritech.net> wrote:
> Sure, I've got a 7 element Arrow 440 yagi I've owned for many years that I've used for foxhunting and rocketry.
>
> I'll say that if your transmitter's antenna didn't get detuned too much in the installation or end up with some weird sympathetic harmonic with some metal in close proximity, I'll agree that the receiving antenna is the more important piece of the puzzle. But if by chance you end up with your transmitter badly detuned, you'll struggle. I've had such things happen over the years with other ham radio projects. But as BDale pointed out to me, this is usually the exception rather than the rule and based on my radio experience, I'd have to concur. I'm just doing my homework to make sure I don't end up in the "glitch" zone.
>
> With my track record...
>
> Scotty
>
> -----Original Message-----
> From: altusmetrum [mailto:altusmetrum-bounces@lists.gag.com] On Behalf
> Of w9ya
> Sent: Thursday, April 13, 2017 2:52 PM
> To: Altus Metrum
> Subject: Re: [altusmetrum] New Member
>
> Hey Keith, Scott and the gang;
>
> Around here (New Mexico) we (at least 5 of us, last count) are using these. We are very pleased (so far) with them. We have been using them for about 5 years-ish. They sure seem to fill in the nulls nicely and the loss over a perfect situation seems to be less than 20% or so...
> (Filling in the nulls when using high gain yagi antennas for reception
> is much more important than the small losses at the transmitter. <-
> You *ARE* using yagis for the receivers right ????)
>
>
> http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=ant-
> 433-cw-rh-sma-nd
>
> Part number at DigiKey is: ANT-433-CW-RH-SMA-ND
>
>
> Hope this helps !
>
> es vy 73 om de Bob w9ya
>
> On Thu, Apr 13, 2017 at 9:23 AM, Keith Packard <keithp(a)keithp.com> wrote:
>> Scott Myers <ac8de(a)ameritech.net> writes:
>>
>>> My first question is on the uplink/downlink frequencies. It simply
>>> states
>>> 433 MHz. I assume this to be an approximate frequency in the 70 cm
>>> band and not the actual exact frequencies. Rarely is something
>>> right at
>>> 433.000 MHz.
>>
>> Right, the radios are designed to operate in the neighborhood of
>> 435MHz, but you can configure whatever frequency you like around that.
>>
>>> Are there separate uplink and downlink frequencies (full duplex) or
>>> does it switch on/off transmit/receive at each transceiver
>>> (Telmetrum and
>>> Teledongle) using the same exact frequency.
>>
>> During flight, it's a unidirectional transmission from flight
>> computer to the ground. This lets you have multiple ground stations
>> tracking the same flight, and makes the communication work better
>> over long distances.
>>
>> For bi-directional communication in 'idle' mode, it's a half-duplex
>> channel on a single frequency. Doing full-duplex communication would
>> be very difficult in a single band, and would require separate
>> transmit and receive radios which we don't have.
>>
>>> How wide is the data bandwidth in KHz?
>>
>> We're using 38.4kbps and 20.5kHz deviation GFSK, yielding a bandwidth
>> of about 100kHz.
>>
>>> (I think they are all coded and using "telegraph" messaging
>>> handshaking to avoid conflict with another Telemetrum, but I could
>>> be
>>> wrong.)
>>
>> No, telemetry is uni-directional, so any receiver tuned to the right
>> frequency will see the data.
>>
>>> I see there is a starter "kit" that uses the Teledongle. But there
>>> is also the TeleBT, which seems to do everything the Teledongle
>>> does, PLUS adds bluetooth for use with the Android App. It seems
>>> that starting with the TeleBT would the better choice and don't even
>>> buy the Teledongle, but I wanted to make sure I wasn't missing something on this.
>>
>> Agreed. The TeleDongle is a bit cheaper and smaller, but that's about it.
>>
>>> I saw the history on older versions with the problems with pyro
>>> events and battery rail sag and that it is supposed to be solved now.
>>> (An age-old problem on many avionics packages.)
>>
>> We have added a comparator to the pyro circuit which monitors the
>> voltage coming in to the electronics power supply. This cuts off the
>> pyro firing circuit when the voltage sags below that necessary to
>> keep the flight computer processor running. There's a ballast
>> capacitor at that point in the circuit, so the circuit ends up
>> pulsing current into the pyro device. With a short across the pyro
>> terminals, we end up hitting about a 90% duty cycle.
>>
>> This requires using a lipo without a current limiting circuit, which
>> is what we provide in our store.
>>
>>> I think I'd rather put a second LiPo on the Telemetrum and give the
>>> pyro events their own rail and simply avoid any potential rail sag
>>> issue.
>>
>> I'd encourage you to check out what we've done and see if you still
>> think this is necessary. You increase the complexity of the system as
>> you now rely on both batteries working correctly for the pyro
>> circuits to fire.
>>
>>> Just a small LiPo should do the job. I'm guessing others have done
>>> this and I read where that is an option on the board. I'd like
>>> feedback on that.
>>
>> I have seen lots of people using two batteries, and in fact, you can
>> use a higher voltage if you like -- the pyro circuits are designed to
>> support up to 15V or so.
>>
>>> Of course downside is mass of the connector soldered to the board
>>> and having to support the feed line to account for high-G conditions
>>> so the connector isn't broken from the board.
>>
>> Our new boards have metal on both sides of the board so that the
>> edge-launch SMA is at least better supported, but yes, we've seen
>> multiple boards snapped at the SMA connector due to high G loads.
>>
>>> I'd like some feedback and discussion on the use of the SMA connector.
>>> I can't figure out how to order the Telemetrum with that option
>>> anyway. Perhaps it is a field mod?
>>
>> We used to have it on the price list; I'm not sure how Bdale manages
>> it these days. But, the boards are designed to work well with a
>> simple wire whip, so unless you're going to mount it in an airframe
>> that requires an external antenna, it really is nice to just use it
>> as designed. I've run the wire through the ebay bulkhead and up
>> alongside recovery systems in several airframes with good results.
>>
>> --
>> -keith
>>
>> _______________________________________________
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>>
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