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TSI-440 Frequently Asked Questions

FAQ Legend:All Products
Product Class (Sky Imaging)
This Product (TSI-440)

4. Instrument Selection

1. 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.

2. 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.

3. How are images on the TSI-880 stored long term? How are images stored on the TSI-440?

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. Multipel 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.

4. 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 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).

5. 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.

6. 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

7. 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.

8. 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 bettery 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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 browses 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.

15. 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.

16. 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.

17. 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.

18. 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.

19. 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.

20. We want to display the real time images from a TSI-440 on our local Intranet web page. I understand that if the template.html file is present in the computer's installation directory, then the software will automatically write a file called recent.html to the html directory with the correct parameters for displaying the current image. My question is: is it necessary to be running a separate HTTP server on the TSI computer, and if so, is there one that you recommend? If a separate server is not required, does the TSI Manager software have some capability to handle the http request?

On the TSI-880 the web server is built into the system itself, as well as the YEDAQ 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 tot he 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.

21. 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 theTSI-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.

22. 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 are 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.

23. 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.

24. Which model TSI should I chose 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:


25. 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.



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This page was last updated on Monday, September 11, 2006 .