Re: [time-nuts] Environmental sensor recommendations

> Are there any recommendations for other off-the-shelf sensors worth looking > at? Mark, Check out ADT7420: http://www.analog.com/media/en/technical-documentation/data-sheets/ADT7420.pdf A useful white paper, including comparison of NTC RTD and IC sensors:

Re: [time-nuts] TS2100: List of root commands?

Bruce, The model originally spec'd for the TS-2100 MTI 240-0530-D *.* Here is the MRTG trace. Had a power failure in July and it settled from a previous 36 to a new 3. These are not absolute values but offset by 47640 to amplify the scale or changes of 1 in 65535 would not be visible. Therefore,

Re: [time-nuts] Environmental sensor recommendations.

I've used a few Pt100 RTDs over the years for gas flow temperature control in the 200-300C range.  At 0.385 ohms per K, the challenge of managing the noise is a lot tougher than a cheapo NTC thermistor, but I needed repeatability and stability. http://www.farnell.com/datasheets/2278399.pdf I

Re: [time-nuts] Environmental sensor recommendations

I respectfully disagree. The OCXO is not the temperature problem with the Tbolt. It is the DAC. Again this is not a product developed for time nuts it did an excellent job for its intended purpose. Over a year we worked on the Tbolt using HP 10811, OSA 8600, FRK Rb, M100 Rb with excellent

Re: [time-nuts] Environmental sensor recommendations

Mark! On Thu, 5 Apr 2018 07:13:49 + Mark Sims wrote: > I looked at the TEMPer devices, but almost all of them seem to be HID > devices that emulate a digi-monkey typing on a keyboard... NTPsec uses them in a polled mode. Very easy to work with. # temper-poll -c

[time-nuts] Environmental sensor recommendations

Long ago I did a board for evaluating high power LEDs and drivers. Iit was called Luxor and if you look through the Lady Heather code, you will see references to it. It has all the functionality (and them some) needed for an environmental sensor and temperature controller. It has 4 dual

[time-nuts] Environmental sensor recommendations

Digital temperature sensors have some advantages (like nice factory calibration), but also so issues. The IIC/SPI ones need to be mounted to a PCB and also have quite a bit of thermal mass. They also need 4-6 wire cables. They are hard to attach directly to a point that you want to

Re: [time-nuts] TS2100: List of root commands?

No control voltage change of an OCXO in a year  is amazing. What is the OCXO Bert Kehren   In a message dated 4/5/2018 10:52:11 AM Eastern Standard Time, gerh...@wittreich.org writes:   Bruce, The link Azelio Boriani shared is the source I used when doing the same project. Please, post your

Re: [time-nuts] Environmental sensor recommendations

I will comment on a couple postings: On Wed, Apr 4, 2018 at 8:00 PM, Tisha Hayes wrote: > > I would suggest that if you are looking at taking temperature sensor data > and attempting to control some type of heating/cooling device that you > implement a PID loop for

Re: [time-nuts] TS2100: List of root commands?

Sorry to interject - but I would like to upgrade a Symmetricom SyncServer S250 from oxco to rubidium. Is there an equivalent list of commands or a process to perform that upgrade? Thanks, David W8PDP Thanks, David > On Apr 5, 2018, at 5:04 AM, Azelio Boriani

Re: [time-nuts] Environmental sensor recommendations

I would like to put in a good word for the DS18B20 temperature sensor. It consumes very little power, uses the "1-Wire" protocol, and is available pre-wired in a variety of configurations, for example this https://www.adafruit.com/product/381 and this https://www.adafruit.com/product/642

[time-nuts] -- Re: Environmental sensor recommendations

When considering thermistors be sure to look at the YSI series 400 thermistors. They were developed as interchangeable sensors for medical and environmental temperature monitoring. These are well characterized and available from multiple sources in several different configurations.   73 de Walt

Re: [time-nuts] Cheap jitter measurements

Hi Whatever you want to call it (jitter / wander / noise / crud ), an Rb in a stable temperature environment ( a few degrees C per hour) will have “stuff” with the dimensions of nanoseconds when compared to a good GPS. A “normal” NTP setup with a crystal on the motherboard as it’s main

Re: [time-nuts] Environmental sensor recommendations

> The OCXO is not the temperature problem with the Tbolt. It is the DAC. So is there a better one that can be used to replace it? David -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ew via time-nuts Sent: 05 April 2018 10:43 To: time-nuts@febo.com

Re: [time-nuts] Cheap jitter measurements

>> What do you mean by "jitter" and what do you really want to do? > I mean jitter as NTP defines jitter. Whatever that is. I think you need to figure out what you want to do so you don't fool yourself. ntpd is a PLL. There is a low pass filter in the control loop. It will track the low

Re: [time-nuts] new longwave time service planned in India

India has IRNSS, their own GNSS augmentation system. FWIW, S Korea is about to start testing its own radio time signal but the range is only 500 km or so as I remember. Cheers Michael On Thu, 5 Apr 2018 at 12:23 am, Bob kb8tq wrote: > Hi > > It’s also *way* cheaper than putting

Re: [time-nuts] TS2100: List of root commands?

Try this: On Thu, Apr 5, 2018 at 2:29 AM, Bruce Lane wrote: > Fellow time-tickers, > > I just finished conversion of one of my TS2100's to OCXO, and I'm now > in the process of tweaking the

[time-nuts] Environmental sensor recommendations

I looked at the TEMPer devices, but almost all of them seem to be HID devices that emulate a digi-monkey typing on a keyboard... tis' not something Heather wants to work with. Also, none of them seem to do air pressure. They do have a device that does temperature and humidity and can emulate

Re: [time-nuts] Environmental sensor recommendations

If you use an "interchangeable" NTC like https://br.mouser.com/ProductDetail/US-Sensor/PS103J2 you can skip the calibration part. Edésio On Thu, Apr 05, 2018 at 09:20:56AM -0400, Bob kb8tq wrote: > Hi > > By far the highest resolution sensor you will come across is a thermistor. It > also has a

Re: [time-nuts] Environmental sensor recommendations

Mark, Thanks for doing this ! Aside of the "commercial" sensors, will you open the API or data format for the community ? In such way, we could tailor our existed "telemetry devices" to be connected to LH ! I see lot of perspectives here. Seismic, radiation, lighting, main, air, light,

Re: [time-nuts] Environmental sensor recommendations

Hi Mark, SparkFun have some boards that have multiple sensors. They *used* to do one with a USB connection that had temperature, pressure, humidity, and light! But I see that is now "retired" ( https://www.sparkfun.com/products/retired/8311 ) and has been replaced by an Arduino shield:

Re: [time-nuts] Environmental sensor recommendations

Hi By far the highest resolution sensor you will come across is a thermistor. It also has a pretty narrow range in terms of maintaining high resolution. That’s fine for something with a target temperature ( OCXO oven) and not so fine for monitoring outdoor temperature year round. If you

Re: [time-nuts] Environmental sensor recommendations

Peter, Yes, that's my current favorite turn-key environmental sensor as well. Sure, you can home-brew a slightly cheaper solution. And the Arduino world is full of random sensor examples, which you are free to deploy and debug. But the Sparkfun unit just works; out of the box. From the first

Re: [time-nuts] Environmental sensor recommendations.

Why has no one mentioned thermocouples? I had some experience with thermistors a few years back designing thermal attenuators and equalizers for CATV. NTC thermistors can have a large change of resistance for a unit change in temperature. They aren't linear, but there are formulas for computing

Re: [time-nuts] TS2100: List of root commands?

Bruce, The link Azelio Boriani shared is the source I used when doing the same project. Please, post your results. MIne has been running for several years now without any issues. I track the OCXO control voltage register in the 2100. It has 65535 steps and over long periods (1 year) that control

Re: [time-nuts] Environmental sensor recommendations.

On 5 April 2018 at 15:44, John Green wrote: > Why has no one mentioned thermocouples? > I had some experience with thermistors a few years back designing thermal > attenuators and equalizers for CATV. NTC thermistors can have a large > change of resistance for a unit change in

Re: [time-nuts] Environmental sensor recommendations.

Hi Thermocouples are *really* low output voltage devices at “normal” temperatures. That gets you in to fairly fancy measurement setups ( no “just strap it to an ADC input” stuff). They also require cold junction compensation. They measure offset temperature to that junction. You do a lot of

Re: [time-nuts] Environmental sensor recommendations

HI Quite true. The down side is that I can buy a bag of 100 parts that are +/- 0.25 C at 25C for a lower delivered price as one piece of the calibrated parts. It’s a lot easier to glue down and throw away the cheap ones …. Bob > On Apr 5, 2018, at 10:15 AM, Edesio Costa e Silva

Re: [time-nuts] Environmental sensor recommendations.

Hi John, Thermocouples are very robust, and have a very wide operating range. However they require extremely accurate voltage measurements to get to sub degree temperature accuracy. On top of that they require a local temperature sensor to measure the 'reference' temperature (Or an actual