[SS2S-Main] Re: temperature measurement

  • From: "Nev Blyth" <nev.blyth@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Tue, 25 Mar 2014 18:03:00 -0700 (PDT)

👍👍—
Nev Blyth
VK1HNB
0407 923 182

On Wed, Mar 26, 2014 at 11:39 AM, Ken Biba <ken@xxxxxxxxxxxxxx> wrote:

> I have written an article for Sport Rocketry on the S4 program ... should be 
> out soon.   It is really intended as the next step from TARC ... focussed on 
> doing science payloads rather than just rockets.   And since the telemetry is 
> using WiFi and Internet protocols ... we now can do telemetry anywhere on the 
> Internet.
> A big step up from isolated embedded avionics.
> K
> Ken Biba
>> On Mar 25, 2014, at 5:13 PM, "Nev Blyth" <nev.blyth@xxxxxxxxx> wrote:
>> 
>> Great find Ken - new stuff popping up all the time it seems.  I may end up 
>> flying both modules now, and comparing performance.
>> 
>> The SSU S4 program looks excellent.
>> 
>> N
>> —
>> Nev Blyth
>> VK1HNB
>> 0407 923 182
>> 
>> 
>>> On Wed, Mar 26, 2014 at 10:22 AM, Ken Biba <ken@xxxxxxxxxxxxxx> wrote:
>>> 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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