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johng

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Everything posted by johng

  1. NRG released the NRG Class1 sensor last year, which contains an innovative low friction ball bearing design providing very good response characteristics. In fact, the NRG Class1 is a true ?class 1? sensor at a very attractive price. The NRG Class 1 kept the rugged cup design of the NRG #40C anemometer, as well as the proven shielded signal pick-up mechanism. I cannot say for certain that other sensors fail more easily than the rugged coil design of the NRG, as your experience suggests. Both the NRG Class1 and the NRG Windsensor P2546C use a self generating coil and magnet arrangement, requiring fewer wires and no power from the data logger. Another great benefit of such a signal arrangement is that even under a direct lightning strike, the sensor will not fail as a short (signal coils fail as an open circuit), and the remaining channels keep logging data until you can visit the site. The WindSensor has excellent first class performance characteristics, the lowest distance constant of any cup anemometer in existence, as well as superior off shore capability. You can read about the NRG Class 1 classification in the paper ?Characterization and Classification of the NRG Class 1 Anemometer for IEC 61400-12-1 Compliance? found on the NRG Class 1 product page.
  2. NRG Systems Inc., through its partnership with Wireless Innovation has made available the private APN "nrg.windlinx.com" for users of any Windlinx GSM SIM card. The private APN "nrg.windlinx.com" connects the GSM devices directly to Wireless Innovation's IP network, ?bypassing? or ?tunneling through? the internet (very similar to a VPN connection). Under this configuration, Wireless Innovation can ?see? all the way back to the device in the field, which is not possible with a public APN. This added "end to end" visibility of the network aids in troubleshooting and increases performance due to the direct path back to the WIL servers. The private APN is included with account documentation from Windlinx and the "automagic" IPK file generator found in the Windlinx website also places the APN directly into you iPack configuration file, making it's use transparent to the user. The private APN is already "backward compatible" with SIM cards already shipped - all SIMs have been provisioned with the private APN. If you wish to use the private APN with an existing Windlinx SIM, the IPK file may be updated (either on site or through use of a patch file). Note that the public APN already used by Windlinx will also continue to function. APN_Figure.pdf
  3. An excellent paper that describes wind tunnel calibrations of cup anemometers, the results of which are used for wind turbine power performance and wind resource estimates. The paper documents interference effects between tunnel boundaries and the the rotating rotors of cup anemometers (including Windsensor and Thies) not taken into effect by the IEC. Wind_tunnel_calibration_of_cup_anemometers_-_AWEA_version_June_11.pdf
  4. As you may know, our long-time vendor, Otech Engineering, closed their wind tunnel and is no longer performing calibration services. Otech Engineering, founded and directed by John Obermeier, has been a leader in providing calibration services to the global wind energy industry. We congratulate John and Otech on their remarkable 31 years of business. NRG Systems will begin calibrating our #40C and Class 1 anemometers at the new and completely independent wind tunnel based in Williston, Vermont (USA), SOH Wind Engineering LLC. SOH is led by wind engineering pioneer Svend Ole Hansen and will operate one of the world?s largest wind tunnels specializing in calibrations. Mr. Hansen?s existing wind tunnel in Copenhagen will continue to operate, enabling SOH to perform the highest quality calibrations on either side of the Atlantic. We have been planning this transition for quite some time and have prepared the following Frequently Asked Questions. When did Otech Close? End of October, 2012 Why did Otech Close? Otech Engineering will still be performing some consultancy work but have closed their wind tunnel. Can we still buy calibrated anemometers, and if so, which models? Yes - you can still buy calibrated anemometers. As before, NRG Systems offers the following calibrated anemometers: NRG #40C Anemometer NRG Class 1 Anemometer NRG GS-Class 1 Anemometer WindSensor P2546C Anemometers Hybrid Anemometer IceFree3 Anemometer NRG 40H Anemometer When did the new SOH Wind Engineering facility open? This new facility became operational in Q4 2012, and calibrations for NRG Systems anemometers began January 2013. How can I identify which tunnel was used to calibrate a particular sensor? The best way to identify the calibration tunnel used is to download the sensor calibration report from the NRG Technical Support webpage. Each calibration report identifies the test facility and all relevant parameters. The first sensor calibrated in the new facility shipped from NRG January 30, 2013 and had serial number 179500213300. What are the differences between the SOH Wind Engineering, SOH Denmark, and the Otech tunnel facilities? Size - specifically the size of the cross-sectional area of the test section is the main difference between the three tunnels. The tunnel cross sections are: Otech (0.61 X 0.61m) SOH ApS: 4-16 m/s calibration (1.7m X 1.2m), 4-26 m/s calibration (1.7m X 0.6m) SOH Wind Engineering (3m X 3m) The size of the wind tunnel test section matters because the uncertainty of the calibration is reduced with increased tunnel cross section. The large 3m X 3m tunnel cross section of the new SOH wind tunnels will eliminate blockage effects, a known systematic bias that increases the uncertainty of anemometer calibrations. What is NRG Systems relationship with the new facility? Does NRG own the new tunnel facility? NRG Systems has no ownership stake in the new tunnel facility; it is independently operated by SOH Wind Engineering. It is in NRG Systems' interest to achieve the most accurate anemometer calibrations for our sensors so the total anemometer uncertainty is minimized, helping our customers achieve their goal of reducing overall uncertainty. Is SOH Wind Engineering (USA) a member of MEASNET ? Yes - The SOH Wind Engineering laboratory acheived MEASNET membership March of 2015. What is MEASNET ? MEASNET stands for the Measuring Network of Wind Energy Institutes. In simple terms, it is a group of commercial institutions who continuously collaborate to ensure that each member offers measurements of equally high quality for the worldwide industry. What are the capabilities of the new facility? The SOH Wind Engineering facility currently contains two parallel tunnels and two more will be added, each having a 3m X 3m cross section. The tunnels can be combined to create a larger test section of up to 12m X 3m. At the 3m x 3m cross-sectional size, the tunnels will be capable of producing wind velocities of up to 20 meters per second, with capabilities up to 100 meters per second using smaller cross-sections. For example a 2.5m x 2.5m insert will allow speeds up to 28 meters per second. How does the facility performance compare to other calibration facilities? The SOH Wind Engineering wind tunnel is one of the largest calibration wind tunnels in the world which means the effects of blockage are truly negligible. Because the effects of blockage are negligible, the calibration uncertainty is minimized relative to smaller tunnels. What is the new consensus transfer function? The consensus transfer function remains unchanged. It was derived from consensus wind tunnel data in 1998 and remains an excellent predictor of the output of the NRG #40C Anemometer. The user may decide whether to use the consensus transfer function or the individual slope and offset calibration values. What international standards does the SOH Wind Engineering facility follow? ISO 17025 "General requirements for the competence of testing and calibration laboratories" is the main internationally recognized standard for establishing and maintaining a Quality Management System for calibration facilities. The SOH Wind Engineering facility achieved ISO 17025 accreditation December 2012. I purchased SOH WE-calibrated sensors calibrated before the MEASNET certification was finalized. Has the calibration process changed? The calibration procedure has not changed. SOH WE has been using the same calibration procedure used by MEASNET since opening in 2013 (IEC 61400-12-1 Annex F). This change simply means that anemometers calibrated at SOH WE are now officially certified by MEASNET. Will I still be able to purchase sensors from the SOH Copenhagen tunnel? Yes, RNRG will still offer MEASNET anemometers calibrated at the SOH Copenhagen site on an as-needed basis. Who can I talk to in order to learn more about the new calibration facility technical details? NRG Technical Support ? support@nrgsystems.com Should we talk with SOH directly using the contact info on the SOH website? NRG Technical Support and Sales continue to be the main point-of-contact for all anemometer calibrations and can answer your questions.
  5. The attached note which explains how to format an NRG-supplied SD card using a Windows 7 computer and SD card reader. TSB011_SymphoniePLUS3_SDCard_Formatting.pdf
  6. Hello - Sensor life is highly dependent on the environmental conditions the sensor operates under. In our experience, extreme ice, lightning, poor grounding, electrostatic discharge (ESD), highly corrosive environments, extreme winds, wind blown dust and poor handling can all lessen or end the life of a sensor (it is important to remember these items are not covered under the standard two year warranty). Mechanical sensors with moving parts such as wind vanes and anemometers also have different characteristics than non-mechanical sensors such as a temperature or pressure sensor, which do not contain moving parts. That said, typical wind resource assessment campaigns are designed to be 1-2 years long and NRG attempts to make the designs as robust as possible to meet or exceed this timeframe. If you have any further questions please contact us at support@nrgsystems.com.
  7. NRG Systems receives many questions regarding anemometer accuracy, uncertainty and performance. The application note "#40 Anemometer Uncertainty" found in the Technical Support Documentation area of the website addresses uncertainty and measurement, anemometer classification number and calibration uncertainty. http://www.nrgsystems.com/TechSupport/Documentation.aspx
  8. NRG iPack Patch File Email Size Modern email clients such as Outlook will create large emails if left at the default settings. The patch file emails can easily default to 7k bytes or larger. Patch file emails need to be kept as compact as possible. When an email containing a patch is detected by the iPack, the entire email is downloaded to the iPack; if the email is too large, the download takes longer and the patch file may not be applied. The situation is exacerbated by systems inherently running slower data rates such as the Satellite iPack (Satellite runs slower data rates compared to its terrestrial cousins GSM and CDMA). How to make a smaller email using Outlook In Outlook, it is possible to create emails that are well under 1k bytes in size (500 to 700 bytes is achievable). Once you start an email, go to options>Plain Text. Delete your signature and prevent any ?confidentiality statement? from being appended (you made need to work with your IT administrator to have the confidentiality notice removed for specific emails). Using the plain text email format and removing any signature lines makes the patch email as compact as possible, increasing the patch success rate. Other Email Clients There are other email clients besides Outlook, and the same strategy should be applied to those as well. Create the smallest size patch email as possible by turning off rich formatting options.
  9. For information regarding how Windlinx may help you with your wind measurements, please see www.windlinx.com. Also be sure to explore this forum area which includes detailed information for installers of NRG iPacks.
  10. We understand not everyone wants to use Windlinx just yet. If you wish to use your own cellular and internet provider, please follow these guidlines. Q: I do not want to use WindLinx wireless services ? how do I opt out of this service? A: Depending on the type of iPack purchased, you can opt out of using WindLinx services as follows: iPack GSM/GPRS Quadband ? Remove and discard the factory installed GSM SIM from iPack-it will not work in any other device. Replace with GSM SIM from your preferred service provider. iPack CDMA ?Wireless Innovation customer support: msat@wi-ltd.net. Once deactivated by Wireless Innovation, you will need to contact Verizon to have the iPack registered for the Verizon CDMA network. In Canada, it does not make sense to remove a Windlinx based unit from Windlinx - the unit cannot be activated directly on TELUS or BELL. iPack Iridium Satellite - WindLinx service is an integrated part of this iPack and cannot be changed.
  11. It is possible to upgrade older Verizon based CDMA iPacks (SN 3531NNNN) for use on Windlinx! To do so, contact NRG for an RMA and let us know that you want to upgrade the iPack for Windlinx use (the unit does have to be returned to NRG for update). NRG will go through the iPack, make the necessary configuration changes and obtain a Windlinx Activation form for the unit. Once you have the activation form, you can go through the windlinx portal to activate the device and generate the IPK file. Only the Verizon based (SN 3531NNNN) CDMA iPacks can be updated.
  12. Prior to Windlinx' introduction in June 2010, the TELUS based CDMA iPack (SN 4222NNNN) was used for serivce in Canada. Intiialization was sometimes tricky for the TELUS based units and the TELUS based units were the only CDMA choice. For those of you that are used to the TELUS iPacks, Windlinx should be much simpler! With Windlinx, the user can purchase a Windlinx CDMA iPack (SN 3861NNNN) which will roam onto TELUS and BELL Mobility in Canada. These units are pre-initialized at NRG and no further intialization is required in the field. Just place the Windlinx generated IPK file into the unit and place a test data call. Notes Do not remove the 3861 CDMA iPack from Windlinx to try and go directly to TELUS or another Canadien based provider. The iPack is not directly compatible with those networks and there will not be a way to initialize the unit in Canada. The unit works through roaming agreements into Canada. You may notice the MDN of the iPack looks foreign - that is normal. Do not try to initialize the Windlinx iPack (SN 3861NNNN). The TELUS iPacks (SN 4222NNNN) cannot be updated to Windlinx
  13. There are some differences when installing a Windlinx Ready CDMA iPack (SN 3861NNNN) compared to the older CDMA iPack (3531NNNN). First off, the unit has already been initialized and call tested at NRG. This is important to note as the installer no longer has to perform the over the air programming (initialize iPack) step in the field. This means the installer does not need to be in a Verizon home area to activate the unit! What to do - pre-installation Make sure you have the specific activation form that was included with the iPack (and was also emailed to the purchaser of the iPack). Follow the instructions on the activation form and go to portal.windlinx.net to activate the device. Once a Windlinx account for your company has been established, there is an activation wizard to add the CDMA iPack which requires you to enter information from the activation sheet. This should take only a few minutes. Once the activation request is submitted, Wireless Innovation will activate the iPack; a typical activation is completed well under one business day. Once the device has been activated, you can generate an IPK file for your iPack. Be sure to know the email address you want the data sent to (along with any CC addresses), the subject line of the email and the call frequency (one day, 3 day, etc). All other parameters will be automagically generated by the wizard. You will see a link called "generate ipk file" - just enter the information and click "generate and download". You now have an IPK file that you can save to your computer and/or email directly to the installer from Windlinx. The IPK file will automagically be saved under that iPack in Windlinx so it does not get lost! You can always log back in and download the file. What to do - in the field This applies for all of North America (USA and Canada) Make sure you have the Windlinx generated IPK file for your iPack / site! Load the IPK file as you normally would using SDR Place a data call using the call now feature of Symphonie to test the system. Done! What NOT to do - pre-installation If you intend to use the Windlinx system, do NOT contact Verizon to activate a cell account. Do NOT contact an internet provider to set up specific mailboxes for the iPack. What NOT to do - in the field Do NOT intialize the iPack! The iPack is shipped pre-initialized. --- For more information see www.windlinx.com.
  14. Hi - Your method will give you the correct one minute average. However, one minute averages are not typically used in the windpower industry. I've added some more information below, in case it is helpful for you. For the resource assessment side of wind power, the industry has standardized on 2 second accumulation and 10 minute averages. That is, determine the frequency for each 2 second period of time and then average all those at the end of 10 minutes. It is also good to track min / max and standard deviation for each 10 minute period. Thanks!
  15. johng

    MMC CARD

    Hi - I'm not sure if you are having trouble formatting a new MMC or are having trouble reading the data off an MMC. If you are having trouble reading the MMC, you may want to contact us at support@nrgsystems.com for an RMA in order to return the card to NRG. If you are having trouble formatting a MMC, I have provided some additional information below: Symphonie MMC Card Compatibilty (http://www.nrgsystems.com/TechSupport/KnowledgeBase.aspx?id=156&category=13) Not all MMC cards are alike. Some MMC cards will not perform well or at all in a Symphonie logger. For this reason, it is important to use MMC cards supplied by NRG. NRG performs lot tests on the MMC cards we provide to assure compatibility. If you are in a real bind and need to use a MMC purchased locally, choose the smallest available MMC size you can. Larger cards do not typically perform as reliably as a 16 or 32 MB card. If a MMC does not format in a Symphonie logger on the first attempt, it is recommended that the MMC is not used. Never format your MMC on Windows - Always format your MMC in a Symphonie logger. SD (Secure Digital) cards cannot be used in Symphonie. The SD cards have a slightly different form factor and will not fit into a Symphonie correctly. Further, the SD communication protocol is different from the standard MMC. MMC Plus cards will also not work. Keep a few spare MMC cards on hand. Always use NRG supplied MMC cards with Symphonie.
  16. johng

    #40c on a Nomad2

    Hi - The "H" in #40H stands for "Hall Effect". The #40 and #40H anemometers are essentially the same except for the signal pickup transducer. The #40 uses a 600 ohm signal coil and the 40H uses a Hall Effect device. Both the coil and the Hall Effect device pick up the magnet's field as it rotates past them. The 40H is an "active" device and requires DC excitation from the logger in order to function. The coil version is passive and generates it's own signal from the magnet! For the 40H, the logger circuit will also need a properly sized "pull-up" resistor. For more detailed information see the application note "#40H Hall Effect Maximum Anemometer".
  17. Hi Michael, Using an SQL based data system makes sense for those like yourselves who are processing lots of data. In your example, even though you have installed SDR in two different directories on your computer, both instances of SDR will use the same SDR registry entries. The registry contains all the file location preferences found under File>Options. The best you will be able to do is to run SDR off of two computers OR create 2 sets of file locations, including site files (again in the File>Options tab) and switch between them. In this case, you will actually have two sets of site files (*.nsd) to switch between. Thanks!
  18. The Preferred Roaming List (PRL) is essentially a mini database that is stored inside a mobile phone that contains information about the service provider and cellular system. For more information see: http://en.wikipedia.org/wiki/Preferred_Roaming_List Over The Air Programming (OTAP) allows information to be transfered from the cellular system to the mobile device (CDMA iPack). If you have a Verizon handheld cellphone, you may be familiar with the *228 OTAP service code to arrive at a menu of phone options. The NRG CDMA iPack uses *22899 as the default OTAP code (which can be found in the SDR phone programming window). When you "Initialize" the CDMA iPack (from the logger keypad or SDR), the OTAP process is intiated. For more information see: http://en.wikipedia.org/wiki/Over-the-air_programming OTAP must be performed in a HOME network to properly Provision the CDMA iPack. During the OTAP process, PRL information is also exchanged from the cellular system to the iPack.
  19. Hi - Unfortunately, NRG does not release the binary description of the RWD files as it is considered a proprietary format. However, you can call instances of SDR software to translate the RWD files to TXT, and also to import them into the NRG site file (*.nsd) which uses a MicroSoft Access compatible database. For more information, please see: http://forum.nrgsystems.com/forums/t/149.aspx
  20. Hi - Here is some further clarification. Mean Bias Mean bias is defined as the average of the 10 minute wind speed differences between two anemometers over each week. The second sensor in the pair is subtracted from the first for each 10 minute interval. Those results are then averaged over the week. That result is the mean bias for the week. Ratio Ratio is defined as the average of the 10 minute ratios between two anemometers over each week. The first sensor in the pair is divided by the second sensor for each 10 minute interval. Those results are then averaged over the week. That result is the ratio for the week. Correlation R R is the statistical correlation of the 10 minute averages for each week, where Ch1 is the X parameter and Ch2 is the Y parameter. Ratio SD Ratio SD is the statistical standard deviation of the 10 minute ratios for each week.
  21. Hi Matt, Unfortunately, it is not possible to automate exports from SDR. The complete list is included in these application notes: Automation of Symphonie Data Retriever Automation of E-mail Extraction for SymphoniePLUS Thanks!
  22. Hi Erick, Great question. The vane minimums are intentionally 0 for a Symphonie logger. Wind direction is unlike wind speed where min and max values do need to be monitored. For wind direction, the average and standard deviation are the useful parameters to monitor. While we are talking about vane min and max I think it is worth mentioning that SymphoniePLUS has slightly different behavior from the Symphonie. For SymphoniePlus, the function of the vane maximum value has been changed. In Symphonie, the vane max values were reserved for direction of maximum gust and the vane minimum values were always 0. In SymphoniePLUS, both the vane max and vane min will always appear as 0 to the user. SymphoniePLUS does NOT display direction of gust; all other reported values remain unchanged from Symphonie. Here is some more information form our knowledgebase: http://www.nrgsystems.com/TechSupport/KnowledgeBase.aspx?id=231&category=13 Symphonie - Vane Maxima and Minima in SDR and Direction of Gust (does not apply to SymphoniePLUS) Vane Max values are reserved for direction of gust. Vane Min is never used and is always 0. Each speed channel keeps track of the highest 2 second gust for each 10 minute averaging interval. When that gust occurs, the direction of the gust is also recorded by a corresponding wind vane (if installed). Vane maximum is only updated when a new maximum occurs. Here is how the 2 second speed gusts are mapped to vane channels: CH 1 >> CH 7 CH 2 >> CH 8 CH 3 >> CH 9 (if using a vane SCM) CH 4 (if using a #40 SCM) >> CH 10 (if using a vane SCM) CH 5 (if using a #40 SCM) >> CH 11 (if using a vane SCM) CH 6 (if using a #40 SCM) >> CH 12 (if using a vane SCM) When an anemometer is stopped for the whole interval (either no sensor, no wind, or frozen), Vane Max will be 0. If you are not using a vane SCM on an analog channel, the max value will be the highest 2 second sample for the analog channel itself.
  23. All data in the field is stamped with Coordinated Universal Time (UTC). The time zone is really like a scale factor / offset for the ?raw? time. So if the crew makes an error in the time / time zone at install, Symphonie will fix its UTC when it calls a time server, and the time zone can be set in the SDR site file (data processing stage). Effects of improperly programmed time / timezones: ? If the iPack doesn?t successfully talk to the time server, the time will stay incorrect and the UTC itself will be incorrect. ? Files will not go midnight ? midnight local time, they?ll be some other 24 hour period (like 3AM to 3 AM). ? Call time is entered in local time - the call will not happen at the programmed time (but it will still call). NRG is located in the eastern United States and loggers ship from NRG with the time zone defaulted to Eastern Time USA (-5 UTC).
  24. There are several good posts on the iPack battery in our Knowledge Base that are worth repeating here. To summarize, charge your iPack battery before deploying the iPack! Details follow... --- Important Tip: keep your iPack battery charged prior to installation, it will discharge over time If the iPack is left in storage without a logger connected, the battery "shelf life" is about 3 months; at that point the battery should be recharged prior to installation of the iPack. The iPack circuitry is always active and draws current in the uA range from the battery. It is normal for office testing to be performed with the logger and iPack before field installation... If the logger and iPack are left connected without any PV charging the system, the iPack battery will completely run down in about 3 to 4 weeks. This is due to the 2.5 mA current draw of the 2 V regulator in the iPack. The iPack feeds the logger power instead of the D-Cells when connected to the logger. A good protocol would be to always "top off" the battery before deployment. A 15 VDC 500 mA source [universal iPack Charger, 100-240VAC Input (item: 3615)] connected to the PV input can recharge the iPack battery in about 4 hours. If the battery has completely discharged, you really should use a wall charger whenever possible...a PV panel may take a up to a few days to recharge a completely discharged battery, depending on solar conditions. Also, if you choose to use a PV panel to recharge a completely discharged battery, do so without connecting the logger to reduce the charge time. If the logger is connected to the iPack (especially with sensors that require significant power), the charging efforts can be severely hampered. All iPacks are charged prior to shipment from NRG. --- How can I check the iPack battery? The correct place to check the iPack battery voltage from the attached Symphonie Logger is to go to: [Home] [3][4] This is the Utilities=>iPack screen The iPack battery voltage will show in "real time" with 2 second updates. Another screen, which shows the iPack voltage, is the Status=>iPack screen...[Home] [2] [3]...this screen shows the status of the iPack as of the last call attempt...it is historical, not real time. Yet another place to see a battery voltage is the logger status screen...[Home] [2] [1]...this will show the voltage the logger is running on and will range from 1.25 to 2.05 Volts. If the iPack battery is fully charged; it powers a 2 V regulator inside the iPack which then powers the logger. You should see 2 V here if everything is working correctly between the logger and the iPack. With just the logger D-Cells you will see 1.5 V. The battery can also be removed from the iPack and tested with a voltmeter - it is important to have a test load on the battery, which will simulate the phone being turned on. Measuring an unloaded battery will NOT necessarily provide meaningful readings. A 25-Watt light bulb makes a good test load for the battery. Measure the voltage across the battery and then again with the light bulb connected to the battery...for a healthy battery, the voltage range should drop to 11.1 V to 11.7 V with bulb on, and float up to 12.7 V to 13.1 V or so with bulb off. If the bulb starts bright and then quickly dims within a minute or so, the battery has lost capacity and should be recharged or replaced. --- iPack voltmeter reading doesn't match battery voltage shown in SDR The iPack Voltmeter SCM will show higher voltage readings because the iPack is off most of the time when measurements are logged. The voltage sent with the file that shows up on the SDR screen is lower because this instantaneous voltage measurement is taken when the iPack is awake and the phone is on. On the Symphonie logger's display, the voltage shown under the iPack status menu shows the voltage when the iPack is powered up (at the end of the call). The voltage shown on the Symphonie screen during a voice call is the battery voltage before the phone is powered up but while the iPack is powered up in preparation for making a call. It is interesting to look at the iPack voltmeter SCM data with SDR and select "minimum". You will be able to clearly see the battery voltage decrease during a call. This can be helpful in evaluating how the battery responds to and recovers from making a call. Excessive voltage drop or slow recovery can indicate a weakened battery. --- Connecting extra PV panels to the iPack Under most conditions, the normal 5 Watt PV panel provides adequate solar charging for the iPack. In some situations, it is advantageous to add additional PV. The easiest method is to add a second 5 Watt PV panel to create a total of 10 Watts. On very rare occasion, certain users have asked if they can go to 20 Watts of PV. The only situation where it might not be a good idea to use this size panel is if the iPack battery is completely dead and the 20 W panel is connected on a day with very bright sun so that it is generating the maximum amount of power. This could cause the charge controller to overheat. However, under normal circumstances (connecting the 20 W solar panel to an iPack with a healthy, charged battery), this is not an issue and using the 20 W panel will not cause any damage to the iPack. --- Why an iPack is needed to power BP-20 and RH-5 sensors on Symphonie The NRG BP-20 sensor requires a supply voltage between 7 and 35 volts while the RH-5 requires a supply voltage between 10 and 36 volts. A Symphonie logger cannot supply these voltages without an iPack. The iPack contains a 2300 mA-hr 12 V sealed rechargeable battery in order to power communications (phones) and these sensors. ---
  25. There is a good explanation of CDMA Cellular technology at wikipedia... http://en.wikipedia.org/wiki/CDMA2000 CDMA is typically found in the USA and Canada. NRG CDMA iPacks typically use 1XRTT connection technology. Most CDMA carriers no longer support "circuit switched" connections, although the NRG iPacks still do (just in case).
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