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Sky Imaging FAQs

I want to set up a UVB-1, MFR, UVMFR, or SPUV site and only download data every few days on my YESDAS-2. Is unattended operation doable? What about the TSI and RSS?

Yes, absolutely. For radiometers such as the UVB-1, MFR-7, UVMFR-7 and SPUV-10, the YESDAS supports automated remote unattended operation. However, depending on the number of instruments, you will likely want to order the PCMCIA-2 memory card option.

For our TSI and RSS instruments, you can expect to collect anywhere from 1 to 32mb of data per day, depending on data rates. Thus a local PC or a 24-hour, 7 day a week Internet connection is good to have. In cases where it is infeasible to have a network connection, the TSI-880's optional DSM-420 data storage module supports 420Mb of removable storage.

Can a TSI work at high altitudes?

YES. The mirror is heated; in extreme cases where winds can exceed 75 MPH you might want to add additional external IR radiant heating elements for wintertime mountain operation. Please contact YES technical support for help in planning your installation.

Can I run a TSI from 240V or 50Hz ?

All TSI systems are pre-configured for AC line voltage prior to shipment based on the Purchase Order for 110/220, 50/60Hz.

If a TSI must be setup in a very hot region, i.e., 45C, will it operate properly?

The TSI-440 is rated to 34 degrees C; for higher temperature locations the TSI-880 is rated to 44 degrees C. We have tested the TSI-880 up to 75 degrees C for short duration conditions. However, prolonged long term heat stress on the electronics may shorten life. The true environmental heat load on the system is quite complex as much depends on the duration of any high temperature conditions as well as solar loading and prevailing wind speed. Auxiliary cooling systems and heat shields are available - consult the factory for information about permanent operation at desert sites.

Can I operate the TSI with the mirror removed, even for a short time?

No. Do not remove the mirror with the power applied to the system. The heaters are designed to keep ice and snow off the mirror and if the mirror is removed there will be no convective coupling of heated air to the thermostat and the heaters will become very hot quickly. Under no circumstance should the heaters be turned on when the mirror is removed.

Do we have to run the heater on the TSI all the time? It seems to need a lot of power.

YES. Because of the potential for condensation, you must run the heater to prevent corrosion. The heater keeps moisture dew, rain, ice and snow off the mirror and out of the NEMA electronics enclosure. The heater is thermostatically controlled, meaning that if the air temperature is higher than the set point, no power is drawn. If power consumption is an issue you can wire the heater to a separate, potentially less reliable AC feed. On the TSI-440 the actual DC power requirement is less than 1.5 amps at 12 VDC (18 watts) without the heater. The heater, when it is on, is in the neighborhood of 500 watts, so it is the dominant power sink. Keep in mind that computer will draw a significant amount of power as well.

How do fixed items in the TSI field-of-view (e.g. towers) affect processed data?

Because these objects show up as "permanent clouds", it is best to site the instrument with the best clear view as possible. In practice, the size of fixed objects in the picture vs. processing errors always represent engineering tradeoffs.

Do I need to provide a standby 12V car battery for the TSI?

Yes on the TSI-440.

No, on the TSI-880 - it includes an integral UPS subsystem.

Why do I need to have a standby battery on the TSI-440 and not the TSI-880?

The TSI-880 contains an integrated UPS subsystem with a battery and does not require an external battery.

On the TSI-440 an integral CPU calculates a solar ephemeris and continuously positions the mirror to block the direct-normal sun via a DC servo and absolute encoder. Prolonged loss of power can damage the imager's CCD, and cause loss of data. The battery also acts as a line surge and noise buffer for line brownouts. Without the battery the mirror can get misaligned from the sun and eventually damage the CCD. The cost to replace a CCD is high and is not covered under warranty. A cable on the TSI-440 permits connection to a user-supplied lead-acid auto battery (RV/Marine or "deep cycle" recommended for cold climates).

If there's an Ethernet port, what is the RS-232 port used for on a TSI?

At setup time, the TSI-880 uses the RS-232 to connect to a laptop or PC to initialize its TCP/IP address. Once this is completed you then use the Ethernet port / web interface to set the band location and other parameters.

On the model TSI-440 you use the RS-232 port to set the time and blocking band position.

Note that once this initial RS-232 setup is completed, there is no need to connect to the instrument again via RS-232 as all other functions can be performed remotely via TCP/IP over Ethernet. The main exception is on the TSI-440, where prolonged power loss may result in the external DC standby battery going completely dead - you will have to travel to the site to re-initialize the mirror. On the Model TSI-880 its internal UPS subsystem shuts down the system to conserve battery power if power is lost.

How can the TSI system handle extremely high wind conditions?

Wind below 75 MPH should not affect the system. However, at sustained speeds in excess of 75 MPH (e.g. Antarctica), install wind deflectors to dampen vibration modes. Be sure the system is well-grounded to eliminate static charge pickup that high winds create (e.g. hurricane strength in the 12 Beaufort range). The system needs to be properly anchored.

Is a TSI suitable for all weather operation?

Yes, the Model TSI-440 and TSI-880 are designed to withstand all types of weather and high winds if properly anchored to a solid base. The mirror heating system drives away dew, frost and snow.

Note that the Model TSI-880 was designed for remote unattended full time operation under difficult conditions, e.g. at airports. The lower priced Model TSI-440 was designed for applications where people are available to manage the PC that is dedicated to process the data.

Do the TSI-440 and TSI-880 require a static IP address on the Ethernet LAN segment or can we use DHCP?

Yes, a static TCP/IP address is required, and your LAN administrator needs to assign this address prior to installation. During system setup you assign this static (i.e. non-DHCP) TCP/IP address, a "network mask" and also a "gateway address" if you plan to view data from outside your LAN. You also need to know your "DNS server" address. Your local system or network administrator can provide you with this information, which will be specific to your LAN.

What sort of local utilities are required at the site of a TSI?

Power requirements are approximately 6A @ 120 VAC 50/60Hz.

For communications, a TCP/IP connection via Ethernet is required - 10BaseT on the TSI-440 and 10/100BaseT on the TSI-880. On the TSI-880 a telephone line can also be wired to the integral modem to support direct PPP dial-in. If both Ethernet and telephone connections are impractical at the site an optional 420Mbyte Data Storage Module (DSM) supports off-grid operation via hot-swappable data collection from a remote TSI-880 system.

We highly recommend the use of a telephone line lightening protector, and some form of protection for the Ethernet lines, as an electrical storm can cause expensive damage to the instruments. YES sells a fiber-optic to Ethernet conversion kit that will isolate electrical surges.

Please see the TSI product data sheets for more information.

How do I mount a TSI mechanically at the site?

There are four 1/4-20 bolt holes in the electronics enclosure that are intended to mate to a flat, level surface. A strong table or frame can be built from "Unistrut" to hold the unit elevated, or it can be set directly on a flat roof.

Because you will need to periodically clean the mirror, access is important. If you mount it so the mirror is about 1.5m off the ground this will help to minimize image blocking when personnel are standing near the unit cleaning the mirror.

How often must the shading strap be replaced on the TSI mirror? Is a spare needed?

The TSI shadowband is a black strip of tape. It should last several years before needing replacement. You can get this locally or from YES. At very remote sites you can leave a rolled up strip of tape tucked inside the electronics enclosure. If you avoid using strong cleaners on the mirror the tape should last a long time.

What is the raw TSI image file format?

Output is in industry standard formats: raw images are JPEG, and the processed output images of cloud cover are in "portable network graphics" (PNG).

Can I run systems in remote areas without AC power via solar panels?

Yes, but there are limitations in locations that are statistically cloudy. The UVB-1, YESDAS, MFR/UVMFR, and SPUV systems all run from DC power, but solar panels require a careful assessment of the total solar resource available at your site. The minimum number of available sunlight hours (shortest day of the year), along with the worst case total power (duty cycle) determines a PV or wind system size. There are vendors who can provide turnkey solar power installations, or you could build this yourself. The solar cells are connected to a battery bank via a "charge control module", and the battery line is run to your instruments via YESDAS-2's battery connection. One such vendor is www.northerntool.com which is a good place to look for these components.

We have been careful to try to design all systems to run form DC power. However, some instruments such as the TSI and RSS require so much power (i.e. hundreds of watts) that running them off-grid is impractical. In these cases a small propane gas or diesel generator starts to make economic sense v.s large banks of solar panels.

How stable are your radiometric UV/Vis instrument calibrations?

In the April 1998 issue of the Bulletin of the American Meteorological Society a peer-reviewed paper describes the calibration stability of the US government's UV monitoring network over a four year period. This paper describes the long term calibration stability of approximately fifty YES model UVB-1, MFR-7, and UVMFR-7 instruments during a four year period, and concludes that the stability has been outstanding.

Are you planning on providing a combined UV/VIS version and/or a VIS/IR version of the RSS?

No. While it would be nice to have a combined RSS/UVRSS instrument, it is not possible to build a hybrid that works well enough without sacrificing the much needed dynamic range and wavelength resolution. Unfortunately, the state of NIR/IR array detector technology is such that extending beyond 1100nm and keeping radiometric calibration is not yet feasible. That is, if one needs more than a relative measurement. Most users need radiometrically accurate measurements in the IR for remote sensing ground truth work and scientific studies.

How important is time keeping on the TSI?

The TSI-880 supports automated synchronization of the time clock to an internet time services such as NIST's atomic clock.

On the TSI-440, time must be accurate to about one minute to keep the shadowband tracking properly. There are actually two clocks to worry about: one on the mirror that calculates the ephemeris, and a second on the PC that sets the image's time stamp. The clock on the mirror control system is quite stable, and the width of the blocking strap makes it not such a big deal if the mirror time drifts a few minutes or so. If you check the clock every month or two on the TSI itself this is adequate. If your PC is networked to the internet, a task that can be automated is setting the clock on your PC via a shareware program available from http://www.nist.gov.

If a TSI system is exposed to salt spray, will regular cleaning hurt the chrome mirror? Generally, how often will the mirror need to be replaced?

Although the mirror is made from heavy gauge chrome plated steel, it will eventually rust out (especially in high salt marine locations). Also, abrasive cleaners can accelerate corrosion. At ocean locations cleaning the dome a few times a week may be desirable, but not doing so will not hurt the mirror. If properly maintained and cleaned with a salt-free water mixed with a slight ammonia window cleaner (such as Windex), the mirror should last several years. If not properly maintained, it is unlikely the mirror would last over a year under heavy salt conditions. The chrome coating is comparable to a car bumper.
Periodic use of automotive paste wax helps prolong the life of the mirror.

An optional polished stainless steel mirror is also available which is repolished by the user periodically.

Why is the TSI-880 more expensive than the TSI-440?

Features and expandability. The TSI-440 is approximately one half the cost of the TSI-880 and represents an "entry point" to the product line.

The TSI-880 is intended for professional-duty remote service, such as government weather agencies, aviation meteorology and military applications. It was designed to support fully remote administration. The TSI-880's integral digital image processor is a primary driver of the increased price relative to the TSI-440. While TSI-880 processes images onboard, a 200 MHz+/128 MB ram Windows workstation is required to run the TSI-440's image processing application (TSI Manager). This PC can be considered a hidden cost of the TSI-440.

By comparison, the closest commercial all-weather sky imager to the TSI-880 is the Scripps-produced Whole Sky Imager (DOE/ARM owns four of these). Each of these systems cost DOE approximately 20 times the price of a TSI-880.

Finally, an upcoming option for the TSI-880 is a night time imager, expanding the Model TSI-880 to full 24x7 day-night operation.

How difficult was it to develop the cloud cover image processing algorithm?

Developing this proprietary algorithm was not easy and took several programmer-years. The hardware had to be specially developed to accommodate automatic image processing. There are many techniques that were carefully tested involved in getting the cloud cover accurately under a variety of conditions. NOAA later compared TSI results to trained human observers with excellent results.

Testing the algorithm under widely varying sky and weather conditions was just as time consuming as the R&D effort itself of the hardware and software.

Can the TSI detect lightning activity?

No. Detecting lightning is technically very difficult as you have to be lucky enough to captrue the stroke precisely when the CCD is acquiring the image open, which is statistically highly unlikely. To capture lighting automatically, a much different technical approach for the detector would be required, such as a streak camera or a phosphorized CCD. The YESDAQ back end image capture database software would also need to be modified as natural lighting events always occur asynchronously.

The TSI-880 and TSI-440 systems are not supplied with a PC. What cables are supplied?

Both the TSI-440 and TSI-880 are supplied with a 10' AC power cord, and a 50 ft Ethernet connection 10Base-T RJ-45 cable for direct connection to your network hub. An internal surge protector helps to protect your hub. However, many customers prefer to use fiber optic Ethernet isolators to help reduce the chance of lightning damaging their hub (we supply this as an optional kit or you can buy it locally). Each TSI-880 system contains its own image processing system and can provide data in real time to any user with a web browser (that is, there is no client software like that used on the TSI-440 system). In addition, the TSI-880 integrates with the optional YESDAQ Data Visualization Engine software for collecting data from one or more TSI-880s into a database, or even by transferring up to 420 MB via a data storage module from a remote non-connected TSI-880 system. YESDAQ data can then be viewed with a simple web browser by any user on the Internet. TSI-440 data is viewable locally on the PC via the TSI Manager application that is provided with each TSI-440 system. It is the customer's responsibility to provide a network connection between a TSI-440 and the Windows NT PC that processes the data.

How is a TSI instrument supposed to be grounded?

The TSI-440 and TSI-880 are packaged in metal NEMA enclosures with a heavy ground wire for customer attachment to a local ground rod or existing roof lightning rod system. We recommend that you do not connect this ground to the to AC power ground.

How much cabling can be used between the TSI and the LAN hub connection?

This is governed by the rules of Ethernet: 100 meters with 10BaseT, but many hundreds of meters with fiber optics. See your local system administrator or refer to one of the many excellent references on Ethernet cabling located on the Internet.

Does the TSI-440 have the ability to have its clock automatically updated from an outside source (for instance, via communication with our system) to keep the time stamp coordinated with the rest of our instrumentation?

No--on the TSI-440, the processing PC actually sets the time stamp on all image files so its time must be accurately maintained. Unfortunately, since motherboard clocks on PCs tend to not have good long term stability, we strongly recommend that you have the PC that runs the TSI software synchronized to NIST time via the Internet via NTP. See http://www.nist.gov for free software to do this. (However, the TSI-880 can stay synchronized to NIST as long as an active Internet connection is available.)

Are TSI data (image files) stored as ASCII or are they stored in some proprietary format that nothing but YESDAQ can understand?

The TSI is based to a great extent on open standards. On the TSI-440, data are stored in JPEG files organized by date as a file-in-a-directory.

On the TSI-880, as with the TSI-440, JPEGs can be accessed directly via a web browser. TSI-880 data are optionally stored in YESDAQ. With YESDAQ, SQL queries such as "select for me all the clear days from July through August" are possible. YESDAQ also creates MPEG-1 digital videos of a day's data. You can access TSI-880 data stored in YESDAQ via a number of methods, including mySQL statements, http, JDBC, ODBC and Perl or C/JAVA native language interfaces.

Does the TSI take images at night?

No. Due to the working signal-to-noise ratios available to CCDs, to work at the extremely low-light level found during night operation, a much more expensive liquid-cooled CCD is required. This would make the system cost roughly 20 times higher.

Is YESDAQ the only way to run the TSI-880?

No. You can setup and run the TSI-880 via the web to get up to the minute sky data without any client software. YESDAQ permits an added functionality of collecting all historical data from one or more instruments via TCP/IP or Data Storage Module connections and presenting live or past data to users via the web. No special client software is required as only a browser is necessary. Unlike the TSI-440, YESDAQ can also create day-long MPEG automations of sky data and stores all data for later access via web/ODBC/JDBC/C-interface. Finally, NO. You can run the TSI-880 without the YESDAQ option. In this configuration, the last two hours of data are available for viewing. Adding YESDAQ supports the reprocessing of collected data with alternate image processing settings.

Is TSI-880 processing identical to the TSI-440?

No. The TSI-880 operates on raw CCD images while the TSI-440 must operate on color table-compressed JPEG images. Controlling the TSI-880 processing is different than the TSI-440 as you control it via the administrative setup tab. You can change processing system settings on the fly via the administration password. Note the TSI-880 has several other features such as animation and panoramic display that the TSI-440 lacks, as well as the Data Storage Module slot and the ability to connect via PPP/modem for telephone or "off grid" operation at sites without phone lines. The TSI-880 is the preferred solution for truly remote operation.

If a TSI system is run unattended and data is periodically downloaded once a day, what is the data volume in compressed mode going to be?

The TSI-440 has no storage capability - all storage and processing is done via a local networked Windows NT/2000 workstation, which is typically located adjacent to the TSI-440 or via a customer-supplied network located somewhere on the internet. Raw TSI-440 or TSI-880 unprocessed sky images take up about 30K bytes each. Because these are JPEG images, they are already compressed. Processed cloud data is approximately 6Knytes more so the volume per sample is about 36Kbytes. TSI systems do not collect images at night, therefore you need to know the total number of daylight hours to get the exact storage requirement for a given day. The storage volume depends on your sampling rate, which is typically once every 1-10 minutes. With today's multi-Gbyte drives, storage should not be a big problem, but figure on 10Gb/year given one minute sampling.

On the TSI-880 an optional data storage module (DSM) lets you move the images from a remote location that may not be connected to the Internet. You can also choose not to save images once they are processed, which reduces storage requirements further.

Tell me about images from a live system aboard the USS Ron Brown and the Japanese Miria vessel operated by DOE's Brookhaven National Laboratory?

This is essentially a MFR-7 coupled to a TSI imager, built by DOE. It makes measurement of direct, diffuse solar radiation, cloud cover and optical depth aboard ship.

How are images on the TSI-880 stored long term?

Images on the TSI-880 are stored long term via YESDAQ, which collects images into a SQL database and presents these to users on a LAN or the internet via its own web server. Multiple TSI-880s can be linked to a central YESDAQ. Data is retrieved either in real time or at user-determined intervals via TCP/IP. YESDAQ allows you to browse either real-time images or past data, as well as view full-day MPEG animations. If you also want to reprocess the raw images, for example using a different cloud filter setting, YESDAQ permits you to re-run the processing on sets of collected images. The TSI-880 internal memory stores about a day's worth of images, which then can be sent on to YESDAQ for permanent storage via TCP/IP. However, the TSI-880's optional removable DSM-420 Data Storage Module expands local storage to 420 MB, which represents several week's worth of data.

On the TSI-440, there is no local storage. Images are stored on a Windows 9x/NT workstation that must be direct wired to the TSI-440 via ethernet. It is up to the user to back up this data.

How do we display the real-time images from a TSI-440 on our local Intranet web page?

On the TSI-880 the web server is built into the system itself, as well as the YESDAQ system. On the TSI-440 an external processing PC is required. If it is connected to the Internet and assuming that you have exiting web servers running on that PC or another machine, you just need to point a web server to the location of the file that is created on the PC. If you cannot use a tool such as SAMBA to link the disk volume of the PC to the web server, you can also setup an automated file transfer (FTP) agent to "push" the recent file to the web server's disk volume. The TSI-880's built-in processing computer and web server makes this easy: all you do is point a browser at it.

In terms of image quality and size, is there any difference between TSI-880 and TSI-440?

No, on stored images,
Yes, on processing of cloud cover.

Images are stored as JPEG files. However, prior to processing, the TSI-440 has to work on the JPEG compressed images and these images are color-table compressed. The TSI-880 processes raw uncompressed imager data prior to processing and does a better job under hazy conditions. Once the data are processed, the archived JPEG data files are similar in size.

On the TSI data sheet, it indicates the typical image size is about 25 KB. Could you provide us with the max image size so that we can have a rough estimate of image bandwidth and storage requirements?

The color unprocessed (raw) sky images are stored as 20K-30K .JPEG data files on the TSI-440 are stored in files on the NT workstation and can be looked at via the TSI Manager application. Because they are JPEG files you can use nearly any image display application that supports this popular standard to view them. The processed output files are about 5K each and are .PNG files. note that since the system uses JPEG the compression will vary a bit depending on the complexity of the image, about 32K is the upper limit but this is rare.

Figure about 10 Gb/year for a 30 second sample rate.

How can we set up the TSI so that the strap on the mirror can block the sunlight automatically?

Simply aim the system either geographically north or south. Both theTSI-440 and TSI-880 have integral ephemeris-controlled mirror control servos with absolute encoders for continuous feedback. So you do not have to touch it once it is aligned north/south as it does this automatically

What is the maintenance required for a TSI-440 or TSI-880? Is there an annual maintenance fee?

TSI systems come with a 1 year warranty and are designed for continuous duty exposure. About once every other week it is helpful to wipe the mirror with a soft cloth and glass cleaner such as Windex. The frequency depends on the amount of pollen in the air, but is not critical.

Waxing the mirror every couple of months is mandatory. The closer to the ocean the site is, the more likely the mirror will corrode over time. However, this is a field replaceable part and there is a short MPEG video at:

This MPEG video/audio clip explains how to replace the mirror. Your browser or media player should load this automatically and play it, and you need speakers and an audio card to hear the audio.

On the TSI-880 the internal UPS battery will require replacement every 5 years. The TSI-440 requries that you supply a car battery.

There is also a surge suppressor on the Ethernet but we recommend that you use fiber optic isolation to protect your LAN - even though the TSI has a ground wire to the case, a direct lightning hit might hurt the Ethernet hub on your LAN. With fiber optics this isn't a problem.

Our policy on long term maintenance contracts is 10% of the current instrument price per year and covers all problems, including lightning hits.

What is the average lifetime of a TSI?

We have designed systems for minimum life of approximately 10 years. Actual life will be highly dependent on the site salt and moisture levels as well as other factors such as local maintenance. For example, ocean sites may suffer corrosion faster. The all-metal NEMA enclosures used in the TSI are quite tough. The TSI-880 is generally more mechanically rugged and has a removable arm for rapid transport and deployment, whereas the TSI-440 arm is fixed, requiring much larger transit cases.

Does YES sell reusable flight cases for the TSI?

Yes, flight cases are available. We highly recommend the use of these flight cases for moving TSI systems.

I got a 'JAVA.LANG.EXCEPTION' error on my TSI-880. Why is this?

A probable cause is the imager's Ethernet connection (between the camera and the image processor in the TSI-880) is lost or miswired.

Verify the RJ45 Ethernet cable running between the imager and the image processing CPU in the lower chassis is fully seated and is inserted in the proper Ethernet port. Do not plug the imager cable into the external "LAN" port, that should run to the nearest hub in your local facility.

How many days worth of images can be stored on the TSI? Of course it depends on the sampling rate, but can it hold, say, 14 days worth? What do you recommend as far as storage is concerned?

This has a complex answer, due to the multiple topologies possible: the TSI-880 has the ability to show you up to 2 hours of real time data (e.g. for aviation requirements) via a web browser and animation. The TSI-880 also has an optional PCMCIA slot that accepts a DSM-420 "data storage module" that stores up to 420Mb of images locally. Depending on the time of year, a DSM stores 2-4 weeks of 30 second data or 4-8 weeks of one minute data. An example of a live TSI-880 system you can view is at:

When using a browser, note there's no way to "look back" at this data once you close the web browser. To do that you must use YESDAQ.

The optional DSM-420 permits the TCP/IP link to go down without losing the data for run to several weeks. You can also hot swap it if the system is not able to be installed on a LAN. To a look back in time at historical data, the optional YESDAQ software extends this storage to as much disk space as you can throw at it, that is, it databases the images. You see this on the demo located at: 

You can store as much as you want on a MS-Windows NT4/2000/XP Pro workstation that YESDAQ runs on. You need a live 10/100BaseT network connection between the two to view real time data. YESDAQ also affords live ODBC connection to Microsoft Windows applications to let you perform multi-sensor data fusion and statistical analysis.

Summary: if you want only real time data, buy a TSI-880. If you want to be able to look back in time and study or mine intelligence from the data, add YESDAQ software. Finally, if you are remote site or you need to operate off the LAN, buy the DSM-420 data storage moduel option. The TSI-880 data sheet discusses the various network topologies that are possible.

Which model TSI should I choose and why?

There are several differences between the two TSI Models.
  1. Performance: the TSI-880 is a true professional garde, stand alone sensor and does the image processing on board. It is also able to withstand higher temperature swings compared to the TSI-440 and its internal image processing CPU and power supply are field replaceable units.
  2. Cost: the lower cost TSI-440 was developed earlier and is about half the cost of the TSI-880. However, cost is not simple as the TSI-440 requires a local PC to process its image data whereas the TSI-880 is an "internet appliance." The cost of a PC may seem low at first, but over the life cycle of the sensor it can be significant. And PCs don't last very long, and require climate control, etc.
  3. Design: the TSI-440 imager arm is not removable as it is on the TSI-880. Further, the TSI-880 is modular and has three user-replaceable modules: the core CPU, the power supply unit and the Imager arm assembly. If a TSI-440 needs service the whole unit must be swapped. The TSI-880 is also easier to ship/transport as the arm is removable.
  4. Software Features: the TSI-880 provides online panoramic views and also works with optional YESDAQ database to log historical data. Further, the optional Data Storage Module (DSM-420) option for the 880 permits operation "off the internet". Also, the 880 processes raw binary images while the 440 processes slightly compressed JPEG images, which translates into the 880 having higher accuracy at thin cloud detection vs. the 440. Finally, the 880 is fully remote controllable, you can move the mirror alignment and software masks from anywhere on the internet.

A TSI-880 located at the Albany National Weather Service Office, point your browser at:

You will need to do this during your local nighttime, while the sun is up in the eastern US.
Be sure to click on animations - > panoramic and wait a few minutes to see what happens.

... and a YESDAQ logging its data is at:

Why when I point IE to the TSI-880 do I get a "unable to connect to TSI server" message?

If you can see the URL of the TSI-880 but you get this error message, you either have a TCP/IP connectivity problem, or potentially you are running the Sun Java Virtual Machine (JVM) in IE.

Microsoft (who makes Internet Explorer - IE) and Sun (who controls Java) are now producing incompatible versions of Java. Java runs in what is called the Java Virtual Machine (JVM). Newer versions of Windows are letting you choose which JVM you want to run, Sun's or Microsoft's. Some web sites require that Sun's Java is required to view them, and if you have installed the Sun JVM plugin to view it, it sets up by default, IE uses the Sun JVM.

If you view the URL of a TSI-880 and get a "unable to connect to TSI server" dialog box, and the System Docto" checks the system and returns all "OK's", go to your MS-Windows control panel and using the Sun JVM icon, tell the Sun Java Virtual Machine control not to use Internet Explorer. Once this is changed, restart the browser and the TSI-880 should display properly.

With the TSI-440 and TSI-880, can we implement the display of live sky images/percentage of sky cover on a web site as well as building up an image achieve?

Yes. Both the TSI-880 and TSI-440 present live data of the latest sky image via the web, but the actual mechanism they use to store the data is quite different.

On the TSI-440, you must run the TSI Manager application on a NT/2000 workstation. TSI Manager writes out the latest sky image data to a html data file, and you then point your organization's web server to this file via an html link. Note that on the TSI-440 the file is only the latest image, and you cannot browse past data via the web interface. The TSI-440 does not support sky animations like the TSI-880 does. TSI Manager stores the data as files and you must browse the data from the NT/2000 workstation that TSI Manager runs on - there is no database functionality possible on the TSI-440.

The TSI-880 contains its own web server and is therefore a Internet appliance. You can archive and browse the TSI-880 archive via the web via the optional YESDAQ/data visualization engine system. Because the TSI-880 data is presented via a built-in web server, it supports animations of recently acquired sky data, producing a time lapse film of sky conditions with the need for special client software - these are done via the browser. The TSI-880 also supports remote archived data browsing from anywhere on the Internet via the YESDAQ/DVE package. YESDAQ is an SQL database that permits anyone to access the TSI-880 as well as MFR-7, and YESDAS-2 connected UVB-1 or TSP-700s and the RSS-1024.

TSI-880 data is acquired by YESDAQ via a link modules over TCP/IP. Users can access data via the web or ODBC/JDBC to MS Windows analysis programs such as MatLab or Splus. This permits statistical queries such as "show me all the clear days in April over the past n years" that would be tedious to do manually.

Finally, while YESDAQ does not support the TSI-440, it can import previously stored TSI-440 data manually for users upgrading to the TSI-880.

Note that some web browsers such as Mozilla and Safari may need an updated JVM to display the TSI-880 data correctly.

Is the TSI being used by the US National Weather service?

Yes, the US National Oceanic and Atmospheric Administration (NOAA), the parent agency of the National Weather Service, has TSI-440s at 5 SURFRAD sites. There is also a live TSI-880 system at the Albany, New York NWS office at http://tsi880.asrc.cestm.albany.edu

Operational TSI systems are located all over the planet but many are behind firewalls due to agency security policies. The original TSI concept was developed in part by a partnership between USDA, NOAA and YES.

What is the spatial resolution of images from a TSI imager?

The TSI output image resolution is fixed. While the raw JPEG pictures are in a rectangular format, the usable data comes from the round, active area of the mirror which has an effective resolution of approximately 260 x 260 pixels.

Can I get spectroradiometric information from a TSI image?

Spectroradiometers always give results in terms of power-per-unit-area-per-unit-wavelength. The CCD images have colors and intensities that are relative due to auto-brightness that adapts to sky conditions and thus pixels cannot be calibrated or temperature-corrected.

Can we set up a simple ftp daemon to ftp images directly from a TSI-440 or TSI-880 to pull data files to a remote system instead of buying YESDAQ/DVE?

For security reasons, FTP is not implemented on the TSI-880. However, on the TSI-880 you can use a program or script that issues a http command to get the latest cloud cover data. Also, YESDAQ provides a collection agent (running as a Windows NT service) that retrieves image data from each remote TSI instrument and loads it into the database. A YESDAQ web server then permits browsers anywhere on the Internet to browse data. You can always get at the raw files by right-clicking on the object in the browser. For the large data volume a TSI-880 can produce, ftp technology is too unreliable and prone to router hang-ups. We therefore selected the http protocol which is more robust. If the collection agent encounters loss of network connectivity or other problems it retries and fills in the gaps in data, using the local memory buffer in the TSI-880. YESDAQ does not collect live data from TSI-440s as they have no local processing capability.

In summary, YESDAQ lets you get TSI-880 data several ways:

  1. http://web image (just link it to a page to see incoming / processed images)
  2. an ASCII text file that you can read via another application (in % cloud cover only)
  3. RS-232 port output at 9600 baud (in % thin, opaque, and sunshine cover only)
  4. MPEG-1 animations of a series of images.
  5. via ODBC or JDBC into third party MS Windows analysis applications such as MatLab/Plus/Excel/statistics program
  6. via a native JAVA or C language interface directly to the SQL database engine

Does TSI stop collecting data during the nighttime?

YES. Data are not stored at night, but power remains on to keep moisture off the system. However, you can adjust how low the sun elevation has to be before data acquisition stops. Also, you can adjust the minimum solar zenith angle for processing cloud cover data. This is important because as the sun gets low the images get too dark to resolve the color differences. You can take data down to the horizon, although the image processing worsens as the images get darker.

How much bandwidth is required by the TSI-440 and TSI-880 assuming one minute sampling rate?

Network bandwidth required for both the TSI-440 and TSI-880 is about 30Kbytes/minute.

How does the CCD deal with the sun saturating and washing out the CCD?

Both the TSI-880 and TSI-440 have an automated rotating shadow mask driven by an ephemeris CPU control system with absolute-encoder. If ever frozen in place by rime ice, the heaters will eventually melt the ice, and the absolute encoder will resume tracking.

What are white horizontal lines across a TSI raw image?

This should not occur during normal operation. If it does, you should cover the CCD immediately until you fix the shadowband alignment problem. White horizontal lines indicate that the camera is being exposed to excessive light, that is, the blocking band is out of alignment allowing direct sunlight to get to the CCD. It generally indicates improper alignment, band settings, improper time or latitude/longitude settings. This can be verified remotely on the TSI-440 by initiating the Check Alignment feature on TSI Manager, or the setup tab on the TSI-880.

Is there a heater/cooler in the TSI system?

There is a large, AC line-powered, thermostatically-controlled heater under the mirror to keep moisture off it. The electronics inside the NEMA enclosure also tend to keep it dry inside. There is no system cooler.

Do birds seem to bother the TSI mirror?

Not usually. While we have observed that birds do not seem to like sitting on the TSI, periodic cleaning is a good idea. If your site is in an area with a strong bird population, you may want to add some sharp prongs on top of the TSI imager to prevent birds from landing and blocking the image, or dirtying the mirror just to be on the safe side. These can be purchased at major building material supply vendors.

Can the TSI indicate cloud base distance?

The TSI detects the percent of cloud - but like the Cyclops it has no depth perception. We have considered the R&D of multi-TSI systems for stereoscopic viewing of clouds (at least two TSI systems would be needed for such an application). However, while an interesting problem, we feel that conventional ceilometers are more cost-effective for this application.

What sort of CCD is used–is it for video motion or still picture?

The CCD imager used is a still frame camera, and not a low cost NTSC / PAL type motion video camera. The maximum practical sampling (frame) rate is two frames a minute, about 1/1000th as fast as the 30 frames/second of a video camera. The CCD used offers much better low light performance and better spatial sampling compared to a consumer-type video camera. A slower frame rate permits longer CCD integration times and also allows higher color stability, critical to getting good cloud detection performance. As clouds do not move very fast, using video would be a waste of bandwidth.

Can the TSI software be fine-tuned in terms of sensitivity? On the animated TSI demo that I downloaded, I noticed that some thin clouds don't get recognized, which would pertain to high altitude cirrus clouds as well. Can the user adjust the sensitivity?

Yes, you can adjust the threshold to permit a seasonal or site-specific micro-climate bias. You can also adjust how many degrees elevation (up from the horizon) gets processed, which we call the horizon cutoff. Tempered against this idea is that most people ultimately crave a sort of standard algorithm. That reduces the risk of "apples vs. oranges" comparisons.

Does the CCD use Red/Green/Blue filters to get false colors? What is 24 bit color?

No, there is no moving filter as would be required on a monochrome CCD. The imager used is a 24 bit color CCD. This means for each pixel, three separate bytes each represent Red, Green and Blue. So 8+8+8=24 bits.

Does the TSI calculate percentage of sky coverage and output an actual number, or is some programming involved?

TSI software converts raw color sky images into a cloud fraction "processed" file. A separate optional SQL database package for the TSI-880 called YESDAQ permits connection to existing data collection networks.

Does the TSI require periodic calibration?

No. However, as the mirror ages you will need to replace it. A short demo showing how to do this is located at:

This is a MPEG video/audio 1 minute clip that explains how to replace the mirror. Your browser or media player should load this automatically and play it, and you need speakers and an audio card to hear the audio.

We also own your UVB-1 pyranometer. Could you explain any benefits of obtaining the TSI working in conjunction with it.

Clouds affect UV to a high degree. There has been interest in trying to estimate UV from % cloud cover, but at the moment this is an academic area of research. In principle, it should be possible to directly correlate the two measurements, enhancing confidence in the measurements.

Does the TSI software take into consideration the curvature of the sky and calculate cloud cover appropriately?

No. All pixels are weighted equally.

Does the TSI have to be mounted in a particular position? Can you rotate the mirror or configure the software to have it "point north"?

A TSI either has to point geographically north or south. The image processing and mirror rotation algorithms rely on this. The aiming precision required is about 1-2 degrees.

Is the TSI software compatible across multiple software platforms?

On the TSI-880 the only software required is a Java-enabled browser.

On the TSI-440 the processing of images can take place on a Windows 9x/NT/2000/XP PC. Image processing can take place either in real time ("on line") or later ("off line"). The TSI-440's Ethernet interface communicates to a remotely located PC running the software.

For remote sites we recommend using the TSI-880.

What is the policy of TSI software upgrades?

One year of free upgrades. TSI software has been well tested by YES and at government-sponsored instrument inter-comparisons. However, just as with other cutting-edge technologies, the TSI software is constantly changing and improving. We also actively work with our user base testing and developing new retrieval algorithms (e.g., learning to calculate UV-B from a knowledge of the clouds and the ephemeris.)

On the built-in Ethernet connection, what type of connectors are provided (e.g. BNC 10Base2 or RJ-45 for 10BaseT)?

RJ-45 10BaseT on the TSI-440 and RJ-45 10/100BaseT on the TSI-880. It is not necessary to have a local PC at the site once you have initialized the rotating mirror electronics. A local PC is only required to process and store images if you want a local display. Generally, on the TSI-440 you'll want to run TSI Manager on a remote machine that is safe and warm via TCP/IP and the Internet. However, you can also have a local PC at the site to store images from a TSI-440. This PC will need to be equipped with a 10-BaseT NIC adapter. The TSI contains its own 4-port RJ45 hub. One of the RJ45 ports is switchable as an uplink port - so you can direct wire it to your hub, while a PC is also connected.

What is off-line or on-line image processing with regards to the TSI-440's TSI Manager application?

On a TSI-440, the TSI Manager software can run either as "on line" or "off line" depending on your needs. Off line means that you can simply collect images onto a file system and then run the image analysis (hopefully on a networked environment) on a faster machine networked to the same file system. On line means you run the image collection and the processing on the same PC in real time. The TSI-440 image processing requires a Pentium class 200 MHz PC with Windows 9x/NT (NT preferred), at least 1 Gb of disk space and 32 Mb of RAM minimum (128 MB preferred).

On the TSI-880 image reprocessing is performed via YESDAQ, and can be done in real time. YESDAQ also supports reprocessing of the original data using different image processing settings.

How long can the TSI be operated unattended?

As long as power is maintained to the instrument, and the mirror kept free of dirt, deposits, or bird debris, the TSI can be operated unattended indefinitely. The networking connection between a TSI-440 and the PC acquiring and processing the images is a key reliability issue. You also need to think about AC power quality from a system-level point of view. On the TSI-880 an integral UPS keeps the system running during brief outages and shuts the system down in an orderly fashion if power is lost for more than a few minutes. The TSI-880 image processing system is self-contained and up to 720 images are locally buffered until the connection is restored and data collection via YESDAQ resumes. On the TSI-440, if the network connection is lost data is lost

Can the TSI detect thin cirrus clouds?

A TSI instrument can distinguish between high thin cirrus and thick cloud cover, but there is an inherent limit to what the TSI determines to be thin vs. what is thick or what is clear (just as with human observers). The main difference is that the TSI is consistent, while human observers are generally not. So the TSI software filters the image into just two categories - clear and cloud. A user-adjustable threshold permits you to separate the two categories by setting the point at which the TSI determines that a cloud qualifies as "a cloud."

When accessing the TSI-880 web interface, a java.net.ConnectException dialog box informs us that "Unable to Connect to TSI Server". Upon clicking "OK", the doctor checks the system and informs that all is OK, but we can not get to the image.

The TSI-880 web interface is built on a Java Applet, and may have trouble with the Sun JVM plugin. If you have recenly installed the Sun JVM, you need to turn off your web browser integration with it, by going into the Sun Java control panel and on the browsers tab, uncheck Internet Explorer. Then restart your browser.

We are using a DSM Memory where the TSI strores the images. To upload the data on a desktop computer there is this DSM software that in the first place stores the data and in a second step the data should be.

Customer installed DSM-Link on another Laptop computer, and the program now works fine.

We get frequently "blurred" images in the morning. I think it is due to moisture condensating on the lens of the camera, although I haven't been able to check this in the field. It doesn't seem to affect the cloudcover estimate however. Are you aware of a

Yes, there's a bit of moisture inside the imager, and this is not good long term. Open the enclosure box and put in a LOT of desiccant packs (you can order these from an industrial supply house). In the CCD housing itself, to save time you might be able to put a few small paper desiccant packs up inside, like the ones you find in a vitamin bottle. See if you can carefully tuck them in, after you remove the lens cover. You may have to remove the bottom of the imager housing to really get access, and inspecting it this way might be a good idea. Contact YES for more detailed instructions.

When I dial into the TSI-880 via phone line modem, I cannot access the TSI web page and image. However, when accessing it via the Ethernet connection, everything works fine.

The PPP address is set to the same IP as the Ethernet. This is not allowed. The Etherent IP address MUST be different than the PPP address.

Recommended action is to change the PPP address in the setup screens.

There are "spots" on the TSI mirror, what do I do?

The mirror isn't made of glass, it is actually polished stainless steel. This is a chemical spot and not hard to resolve. So the polished stainless steel mirror needs to be buffed out to bring it back. Unlike chrome plated steel that we've historically used (that eventually rusts), stainless is brought back via polishing.
  1. Polish the mirror using a consumer-type power car buffer. Walmart sells these power buffers for $20 USD. Use the terry cloth pad that comes with the buffer. The spot should disappear in a few minutes of buffing.
  2. If it does not disappear after five minutes of dry power polishing, add a SMALL amount of ULTRA FINE auto polishing compound (also called "rubbing compound"). This looks like paste wax but has a fine grit in it and is available at car care centers and is designed to buff out scratches from car paint). Rubbing compound will tend to dull up the finish around the spot so be very careful not to use more than a drop at a time. I doubt you will need to use rubbing compound as the terry cloth that the power polisher comes with is probably rough enough to do the job alone without any grit.
  3. Once the mirror looks good again, hand wax it using a good quality car paste wax. Might want to put on two coats, this will help keep the bird do do from getting to the stainless.
  4. Use care to avoid getting wax or rubbing compound on the black shadowband tape as it will turn it gray with exposure to the sun.

While looking over sky images today, I noticed that after the first three to four pictures of the day, the sun tracking strip stopped moving. The strip did not move for the remainder of the day.

Try checking the RJ11 connector at the optical encoder and at the other end on the SEI adapter for any damage. Check the supply voltage going to the SEI adapter (black plug). Next, try removing and reseating all push on connectors one by one. Do you see any sign of corrosion or water seeping in to the chassis?

Is it possible to get ASCII data from the cloud cover results?

On the left side of the TSI DVE within YESDAQ, select "Day->cloud cover".

Now, look atop the page and select "report" instead of "graph", then press "go" at right.

Then copy/paste from that report, once you've decided which images to include.

There's also a neat tool out on the net called "wget" that you can use to grab text from web pages.

The TSI-440 won't report the time and azimuth after I plug in a "straight through" serial cable and verify all the comm settings are correct. Why?

Initiate a 'T' command on the comm software and set the LAT/LONG and TIME/DATE correctly. Additionally, verify that the PLATFORM HEADING value is set to ZERO.

The unit will be located on a remote roof and assigned an IP. A lab computer will have a scheduler run a program as a command line in the background every 8, 12 or 24 hours to download data and process it. What is the command line program and arguments?

There are no command-line arguments for the TSI Manager program. It is best to leave the application running at all times. It will take data only during daylight hours.

What is the setting in tsi.properties to add to the properties file that will give cloud fraction data around the zenith?

It is:

there's also:

Make sure you've exited the program before editing the values.

About Percentage clouds: For the filter you have parameters of Clear/Thin and Thin/Opaque also Sunny, Your suggestion in the help menu is 40, 60 and 50. My question is can you explain your software algorithms to select those values?

The basic idea is to replace the "trained observer". Since there is no absolute definition of thin and opaque clouds, we set the default values to agree with the judgement of an observer on the ground. So the best way to set the values is to go outside on a partly cloudy day, decide where the thin and opaque reqions are, and set the thresholds to match as closely as possible.

Our software algorithms are proprietary and we do not share that information.

Is the lens filter neutral density, or a spectral notch filter, or...? If so, can we use this to our advantage in processing the sky image data further? Any references?

The camera filter for the TSI is neutral density. Basically the filter is used to protect the CCD from sunlight reflection off the mirror in case the shadowband is not aligned correctly or if there is a problem where the mirror stops turning.
For processing the sky image data. please refer to the TSI-440 user manual.

The image is processed and shows clouds along the shodowband and the camara mast. How can I improve this problem? I have calibrated the filters and it is still there.

The problem appears to be with the Image alignment and/or shadowband alignment settings. Refer to section 4-14 - 4-17 of the TSI 440 user manual for detailed instructions on how to adjust these settings.

The mirror stepper motor control (most probably in the encoder feedback control) apparently looses count occasionally and sometimes completely to cause it to run at full speed. The encoder people recomend a lower operating temperature. 35 deg C is your ma

Your roof location is too warm.

Two options:

1. Move the TSI-440 to a cooler location or

2. Upgrade to a TSI-880.

The TSI's image cloud cover filter contains a mask that blocks out the band and the sun on the mirror's image. However, the filter's band mask does not go up to the zenith point, so this portion of the image, therefore, still contains the visual part.

The software filter for the shadowband is adjustable and you should be able to extend it. Using the TSI Manager software, click on Actions in the top toolbar, then on adjust Sky filter. Then under shadowband mask adjust the top setting until it is where you desire it to be. (0 should be near the center of the mirror)
Also refer to section 5-7 of the user manual.