[SS2S-Main] Re: temperature measurement

  • From: Ken Biba <ken@xxxxxxxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Tue, 25 Mar 2014 16:21:46 -0700

I am currently liking this uBlox package from Sparkfun ... 
https://www.sparkfun.com/products/11571 - for $40.    Small footprint, the 
antenna seems sufficient.

We are now using it on the S4 rocketry Arduino science payload that we are 
doing with NASA and Sonoma State University.   s4.sonoma.edu.

K

Ken Biba


> On Mar 25, 2014, at 4:14 PM, "Nev Blyth" <nev.blyth@xxxxxxxxx> wrote:
> 
> Cheers Ken - yes, your experiences are valuable indeed, and the Ublox 
> certainly has the support for these kind of high dynamics applications.
> 
> Will let you know what I learn in the future.
> 
> N
> —
> Nev Blyth
> VK1HNB
> 0407 923 182
> 
> 
>> On Wed, Mar 26, 2014 at 10:06 AM, Ken Biba <ken@xxxxxxxxxxxxxx> wrote:
>> Nev:
>> 
>> Should do great for recovery location ... it is the trajectory location that 
>> separates the GPS chipsets IMO.
>> 
>> Our flights are to 70-180k' MSL ... tickling Mach 3 ... so we are testing 
>> the limits of modern comercial GPS chipsets.   So far the best has been 
>> uBlox.   Altus Metrum used to use the MediaTek, but recently switched to 
>> uBlox.
>> 
>> But this chipset does have "similar" specs - 515 m/s velocity, 40 km 
>> altitude ... I would be curious about the dynamics.
>> 
>> I would have to dig out my old spreadsheets .. but there is such an obvious 
>> difference between a chipset that is prepared to deal with dynamics and one 
>> that is not.   Most of my testing ahs been with SiRF, uBlox and Trimble 
>> chipsets.   Getting lock is not sufficient .. .what is interesting is that 
>> reported location, under lock, is dramatically false for SiRF ... while 
>> largely accurate for uBlox and Trimble (when set to high dynamic mode) up to 
>> modest accelerations (<6-8 g).
>> 
>> K
>> 
>> Ken Biba
>> 
>> 
>>> On Mar 25, 2014, at 3:54 PM, "Nev Blyth" <nev.blyth@xxxxxxxxx> wrote:
>>> 
>>> Hi Ken
>>> 
>>> (Apologies for getting OT here).
>>> 
>>> I've only flown the MTK3339 based module three times - on H & I motors. 
>>> During those flights (3K ft only) I was not directly logging the NMEA 
>>> stream on board - rather I was using a simple telemetry system to stream 
>>> the NMEA to a recording ground station. Those flights showed valid data 
>>> throughout, but admittedly, the dynamics were rather benign in the scheme 
>>> of things.  I'll have a look at the altimeter log for velocities.
>>> 
>>> The axis of the GPS patch antenna was aligned normal to the vehicle's axis. 
>>> Admittedly, my main motivation was recovery location, not trajectory 
>>> recording, but I'll take what I get!
>>> 
>>> Nev B
>>> VK1HNB
>>> —
>>> Nev Blyth
>>> VK1HNB
>>> 0407 923 182
>>> 
>>> 
>>>> On Wed, Mar 26, 2014 at 8:20 AM, Ken Biba <ken@xxxxxxxxxxxxxx> wrote:
>>>> Nev:
>>>> 
>>>> 
>>>> Now I'm curious.   I fly the uBlox in large part because its signal 
>>>> processing seems to do really well for high dynamic flight (and while it 
>>>> has a spec limit of 50km, the factory says it will report above that 
>>>> altitude, though with diminished precision).   It does stop reporting 
>>>> above the spec limit of ~515m/s ... though does resume reporting when the 
>>>> speed drops below that.
>>>> 
>>>> Many GPS chipsets perform poorly in high dynamic rocket flight ... since 
>>>> the signal processing is biased to solve the 2D problem with high 
>>>> precision rather than the fast changing 3D problem.   The uBlox has a 
>>>> specific configuration parameter to set the movement model ... I don't see 
>>>> that on the MediaTek manual.
>>>> 
>>>> Do you configure in default mode?
>>>> 
>>>> Ken
>>>> 
>>>> 
>>>> 
>>>>> On Mar 25, 2014, at 2:08 PM, Nev Blyth <nev.blyth@xxxxxxxxx> wrote:
>>>>> 
>>>>> Nathan - the adafruit GPS module is excellent - has flown multiple times 
>>>>> in my high-power rockets and maintained a solid lock throughout the whole 
>>>>> flight. If I recall, the module is programmable, has PPS output and the 
>>>>> price is excellent.  Would be interesting to compare against the ublox 
>>>>> offerings.  The external antenna connection is a bonus for me.
>>>>> 
>>>>> Cheers,
>>>>> 
>>>>> Nev. B
>>>>> 
>>>>> ___________________
>>>>> Nev. Blyth, VK1HNB
>>>>> Canberra, ACT, Australia
>>>>> @nevblyth
>>>>> facebook.com/nevblyth
>>>>> 
>>>>> 
>>>>>> On 26 March 2014 05:40, Nathan Asdourian <rawliquid@xxxxxxxxx> wrote:
>>>>>> you would be much better off with a ublox that is fully configurable and 
>>>>>> reprogrammable,  not to mention the latest version has a compass module 
>>>>>> in it.... i think it's more than $40 though it is the unit from 
>>>>>> 3drobotics.com and what i use in my helis
>>>>>> 
>>>>>>> On Mar 25, 2014 10:47 AM, "Rick Maschek" <rickmaschek@xxxxxxxxxxxxxx> 
>>>>>>> wrote:
>>>>>>> Hi Nathan,
>>>>>>> 
>>>>>>> and this may be going up on our next Near Space balloon launch: 
>>>>>>> 
>>>>>>> http://www.adafruit.com/products/746 
>>>>>>> 
>>>>>>> Are bitcoins worth anything anymore?
>>>>>>> 
>>>>>>> Rick
>>>>>>> 
>>>>>>> 
>>>>>>> On Tuesday, March 25, 2014 6:37 AM, Nathan Asdourian 
>>>>>>> <rawliquid@xxxxxxxxx> wrote:
>>>>>>> Please forgive me if these items are irrelevant due to the extremes 
>>>>>>> needing to be dealt with but I just saw a new board get released here a 
>>>>>>> few weeks ago,  and all the related things seem to be under $20
>>>>>>> http://www.adafruit.com/index.php?main_page=adasearch&q=thermocouple
>>>>>>> And of course if anyone has some bitcoin stashed away,  they will 
>>>>>>> accept that for payment...
>>>>>>> On Mar 24, 2014 9:20 PM, "Lampe, Mattias SLC CT PEK" 
>>>>>>> <mattias.lampe@xxxxxxxxxxx> wrote:
>>>>>>> Hi Richard,
>>>>>>> 
>>>>>>> my personal choice would probably be to use an integrated chip that 
>>>>>>> does everything, including D/A-conversion, e.g. the MAX6675:
>>>>>>> 
>>>>>>> http://item.taobao.com/item.htm?spm=a230r.1.14.48.TLryFm&id=13831142184
>>>>>>> 
>>>>>>> Since it may be more convenient for you to use the existing DAC, you 
>>>>>>> may prefer one of the older chips with analog output, though. AD595 
>>>>>>> would be a good choice:
>>>>>>> 
>>>>>>> https://www.sparkfun.com/products/306
>>>>>>> 
>>>>>>> Of course you'll need to have a loot at the datasheets to see whether 
>>>>>>> the devices match the temperature range you need.
>>>>>>> 
>>>>>>> Hope it helps.
>>>>>>> 
>>>>>>> 
>>>>>>> Have a good day!
>>>>>>> 
>>>>>>> Mattias
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> >-----Original Message-----
>>>>>>> >From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-
>>>>>>> >bounce@xxxxxxxxxxxxx] On Behalf Of Richard Nakka
>>>>>>> >Sent: Monday, March 24, 2014 10:33 PM
>>>>>>> >To: sugarshot@xxxxxxxxxxxxx
>>>>>>> >Subject: [SS2S-Main] temperature measurement
>>>>>>> >
>>>>>>> >For an upcoming motor test, we would like to use thermocouples
>>>>>>> >(k-type?) to measure motor casing and nozzle temperatures.
>>>>>>> >We would like to use an 8-channel DATAQ unit for the data acquisition.
>>>>>>> >
>>>>>>> >We understand there are challenges to this due to small voltage
>>>>>>> >signal, non-linear temperature-voltage relationship and the need (?)
>>>>>>> >for a reference junction compensation.
>>>>>>> >
>>>>>>> >Question to list members: Can anyone give advice on how to do this?
>>>>>>> >What kind of amp would we need? Could anyone be of assistance in
>>>>>>> >designing/building such?
>>>>>>> >
>>>>>>> >
>>>>>>> >thanks in advance
>>>>>>> >Richard
> 

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