Amendment P00001 - Questions and Responses.pdf

80GSFC20Q0006

Amendment P00001

Questions and Responses

Q1. Analysis shows that meeting requirement ID 13 (G/T of 21 dB/K at 2200 MHz and an elevation of 10 degrees) calls for a primary reflector of at least 10 (possibly 11) meters. Can you confirm that we are interpreting the requirement correctly?

A1. Yes, the interpretation is correct.

Q2. In reference to spec requirement #2, are you looking for 4 channels of tracking receiver or are you looking for 4 receivers, with 2 channels each?

A2. Four receive tracking channels are required: S-Band LHC & RHC, C-Band LHC & RHC.

Q3. In reference to spec requirement #3, is NASA expecting the delivery of One Multicoupler with 2 networks 1 input to 6 outputs OR 2 networks 1 input to 12 outputs where one network is for RHCP and one network is for LHCP?

A3. Two multicouplers. 1 input to 12 output unit for RHCP, and 1 input to 12 output unit for

LHCP

Q4. in case the Telemetry channels (Sigma) from the tracking feed are isolated from the Tracking channels (Delta), there will then be a total of 4 RF signals (TM sigma RHCP, TM sigma LHCP, TRK delta RHCP, TRK delta LHCP) instead of 2 (TM+TRK sigma+delta RHCP, TM+TRK sigma+delta LHCP) coming down the feed, through the cable wrap, the fiber link and up to the Multicoupler. Therefore, how do you expect the vendor to use the 12 port multicoupler on those 4 incoming RF signals?

A4. If the solution is to incorporate separate LHCP and RHCP RF tracking channels, then only the Sigma channels need to be routed through multicouplers. G/T measurement would be at output of data multicouplers.

Q5. In reference to spec requirement #4, is it necessary to have the multicouplers working down to 200 MHz ?

A6. No. It is acceptable if the multicouplers have minimum lower frequency of 400 MHz.

Q7. In reference to spec requirement #5, are the Height, Width, and Depth hard requirements?

The 87" x 24" x 30" is an older rack standard. Finding racks for these dimensions are more expensive than standard EIA 19 racks.

A7. The width and depth are required as stated. The height must support 42U.

Q8. In reference to spec requirement #6, by specifying only the output compression point the request #6 seems insufficient. Two LNAs with same output compression point, but different gains will behave differently at large input signals, because at some RF input levels only the one with higher gain will saturate. We believe the request comes from the need to make the system function in cases where a large RF power is present at the input of the LNA. In this case a better specification parameter would be the input compression point so the gain of the LNA becomes irrelevant. The dynamic range required from the LNA must be matched with the rest of the RF transport system. A good system must have a wide RF dynamic range in order preserve the G/T performance while allowing high RF receive levels for close targets. An RF link over fiber optic will present a bottleneck in the transport system due to its dynamic range limitations. We plan to use a dynamic range extender that switches between multiple level ranges to achieve the best performance. An LNA dynamic range requirement will not make the intended difference if it is not matched by all the other elements in the RF receive channel.

A8. It is acceptable for the S & C-band receive channels to have a 1 dB compression point with an LNA input of -23 dBm minimum.

Q9. In reference to spec requirement #19, a filter is mentioned here, but no rejection requirements are stated anywhere in this document. A filter rejection is correlated with its insertion loss, which in turn will impact the G/T performance by two folds: adding tens of Kelvins in noise due to resistive losses and decreasing the effective gain, with both of them taking effect before the LNA input. Without a rejection specification, a design with no filter that works within the requested frequency ranges seems to be acceptable. To calculate the G/T, the filter insertion loss must be known which implies a rejection requirement must be specified.

A9. This requirement should be clarified to say that the test inject shall be coupled or switched prior to the LNA, and any filters that the vendor may elect to include in the receive channels.

Q10. In reference to spec requirement #25-26, for the purpose of this requirement, please clarify between what points in the RF receive channel would the gain flatness be verified? From the document we suspect the output is at the multicoupler output, but for the input it is not clear what the intended setup will be.

A10. The output is at the multicoupler output. The requirement should be clarified to state that input shall be at the test inject port.

Q11. In reference to spec requirement #47-48, we would like to use an HD (or SD) camera with 33x zoom and a focal length range of 4.6-152 mm. Because the focal length is larger, objects further away can be seen. Is this acceptable?

A11. Yes, this is acceptable.

Q12. In reference to spec requirement #58, does NASA intend to use that antenna to track overhead targets like LEO / MEO satellites? In that case, would an alternative solution based an Elevation travel (-5 to +90 deg) plus tilt be acceptable to track such overhead targets?

A12. No, NASA does not intend to autotrack overhead targets. The elevation travel requirements is for a plunge and rotate capability to measure collimation offsets.

Q13. In reference to spec requirement #59, for AZ, will three fail safes be an acceptable alternative to a hard stop? We typically have a Software set limit, then a factory set electrical limit set with firmware, then finally a mechanical switch using a cam.

A13. Yes, this is acceptable.

Q14. In reference to spec requirement #66, are those 2 spare RF cables intended to be used as replacement of other RF cable inside the cable wrap if they would become faulty or would that be for capability expansion? In the 2nd option, should the vendor then provide 2 additional RF to fiber converters (Rx and Tx) for those 2 spare RF lines to bring both RF signal back to the TM room?

A14. These cables are for expansion only in the cable wrap. Additional RF to fiber converters are not required.

Q15. In reference to spec requirement #78, we consider the Launch Acquisition mode as being equivalent to a mode / option called Multipath Clipping making sure the antenna is not moving down due to multipath. Is our understanding correct?

A15. The Multipath Clipping mode is equivalent to the launch acquisition mode that inhibits the antenna from moving down due to multipath just after launch. However, the antenna shall be able to track to the horizon on the down leg of a flight.

Q16. In reference to spec requirement #111, can NASA be more explicit on what it means by Remote control capabilities? Should that mean that the same local ACU display and control be available remotely through the network?

A16. The intent of this requirement is to have a control and monitor interface that will allow a user to send commands to the ACU and receive status information from the ACU in order to perform basic ACU operations remotely via the network interface.

Q17. In reference to spec requirement #125, is it acceptable to log only the AM DEMOD value of the currently selected receiver used for AutoTracking and not all four simultaneously?

A17. Yes, it is acceptable to only log the channel number of the currently active receiver for AM

DEMOD.

Q18. In reference to spec requirement #140, the motor back EMF constant Kv cannot be read from the drives. Is this requirement referring to the servo position loop Kv constant?

A18. Yes, this should be the servo position loop constant Kv.

Q19. In reference to spec requirement #145-146, can you confirm it is like a lag angular error test in Azimuth and Elevation?

A19. This test consists of autotracking a static target to determine the elevation and azimuth angles of the source. The antenna is moved off of the target by a negative angle in one axis. The antenna is moved back through the target to a positive angle, and the autotrack error is measured during this movement. The test is repeated in the second axis. The max and min test angle offsets should be a test parameter.

Q20.In reference to spec requirement #147, will a customer supplied spectrum analyzer or power meter be provided or is this to be part of the quotation?

A21. The vendor shall supply any meters or hardware required to execute the G/T Test.

Q22. In reference to spec requirement #153, please clarify what you exactly mean by Vibration sensor? should that be vibration sensors installed on the antenna pedestal, like Gearbox, T-head or El. Mount to monitor vibrations on the antenna? Which parts of the antenna are to be monitored for vibrations?

A22. The gearboxes should be monitored. The intent of this requirement is to establish levels that can be monitored to indicate potential faults.

Q23. In reference to spec requirement #154, Can NASA clarify what exact power is expected to be monitored on the ACU front panel? Electrical current of each phase or overall consumed power? or is that related to RF level power from the received RF signals? Since the pedestal is connected via Fiber, any status available at the ACU requires the line power to be present at the pedestal for the fiber modules to function. Therefore, would the simple fact that fiber communication is established with the pedestal be enough to satisfy requirement 154 for monitoring the line power at the pedestal?

A23. Monitoring all modular DC power supply outputs in the antenna subsystem, with monitoring capability in the ACU, is acceptable for this requirement.

Q24.In reference to spec requirement #157, is Red Hat Enterprise 7 a viable delivery option for the ACU?

A24. No, RHEL 7 is not an option.

Q25. In reference to spec requirement #160, can NASA share the Security configuration Guidelines for Windows 10 enterprises Long Term Service Branch (LTSB)?

A25. The Windows 10 security configuration NASA uses is a combination of Center for Internet Security (CIS) and Defense Information Systems Agency (DISA) Security Technical Information Guide (STIG) standards. A lot of it is basic or common knowledge for hardening systems but values, say for instance a screen saver timeout setting, are defined by NASA.

However, the configuration should be standard across all realms of IT Security. In order to forward the document, it must be encrypted. The only way to do that non-NASA to NASA user is via Large File Transfer (LFT). NASA user can invite an outside group to sign up for LFT, from there they can set up their own account information and access. The document must not be distributed, as the information is SBU.

Q26. In reference to spec requirement #200, Does the ACU count as an “information system device”?

A26. Yes, the ACU is an information system device.

Q27. In reference to spec requirement #208, please clarify how the setup for tracking accuracy should be tested on the calibrated test range specified.

A27. A calibrated range is not required for tracking accuracy testing.

Q28. In reference to spec requirement #222, can NASA confirm the formula being used to calculate the Inherent Availability (Ai) is Ai = MTBF / (MTBF + MTTR) with MTBF and MTTR being Mean Time Between Failure and Mean Time To Repair for the entire system.

A28. Yes, the formula is correct.

Q29. Our understanding of requirement ID#2 “The antenna system shall include four tracking receivers.” as well as of requirements ID# 109, 110, 124 & 125 is that NASA Wallops expects the vendor to deliver either Qty 2 of Dual channel tracking receivers or Qty 1 of Quad channel tracking receiver; each receiver channel being capable of receiving either C-band (or down-converted C-band) and S-band signals. Is our understanding correct?

A29. Yes, as long as four receive channels could be processed simultaneously, S-band RHC & LHC, and C-band RHC & LHC. Signal strength on all channels is required even if that channel is not selected (Req 124).

Q30. S-band is defined as Lower S-band 2200 – 2290MHz and Upper S-band 2360 – 2400MHz;

can NASA confirm if there is any requirement for specific rejection filters to mitigate known interferers within or close to the S-band like LTE signals around 2155-2180MHz or WCS signals in 2345-2355MHz range? Safran standard triband feed configuration includes a bandpass filter prior the LNA for each band (ie 2200 – 2400MHz for S-band and 4400 – 5150MHz for C-band) but we also have optional filters with higher roll-off (eg at 2200MHz) to better reject any adjacent interferers. The down-side of such filters is that they have a higher insertion loss and therefore degrade the G/T by 0.5 to 1dB. Note that the standard filters can be swapped at any time during the life of the antenna with a higher rejection filter if a given interferer becomes active at WFF.

A30. Rejection filters are acceptable and highly desired.

Q31. In Program Track mode, how the Ephemeris file will be provided to the ACU: by hand from a USB key through the GUI or FTP? Should the ephemeris load be automated or always be performed by an operator?

A31. The ephemeris can be loaded via memory stick and SFTP’d from a server on the network.

Q32. Req ID 92 – 105 as well as Appendices A – D of the SOW define the various slave interfaces to be supported by the ACU. Will NASA Wallop be able to provide to the contractor a simulator for each format to facilitate its testing and qualification prior to the antenna delivery to

WFF?

A32. WFF can provide data files containing actual flight or test slaving data records. A hardware simulator would not be available.

Q33. In the RFQ clauses document, it is mentioned that proposals will be evaluated on an overall system integration and adequacy of the design that meets the minimal requirements. Should the bidder assume that each of the 231 lines of the specifications in the spreadsheet are the minimal technical requirements that should be met or exceeded.

A33. Yes, that is correct.