58 -- DIGITAL VOICE LOGGING RECORDING SYSTEM

This Amendment is issued to answer questions in response to Combined Synopsis/Solicitation N00421-06-T-0083. The closing date of 27 March 2006, is extended through 31 March 2006, 3:30 PM EST. If you have already submitted a proposal, you may submit revisions to the proposal or re-submit your proposal in its entirety. The Contracting Officer for this procurement is Josephine A. Scully, phone (301) 995-8117 or e-mail: [email protected]. QUESTIONS & ANSWERS: QUESTION 1. Section 3.13.1.1: Does the FSK adhere to the Bell 103 Standard? If not, which Bell standard does it adhere to? RESPONSE 1: No. The interface does not adhere to a published standard. This is a specialized interface designed specifically to provide a means to store radar sweep information on a analog reel-to-reel tape recorder. QUESTIONS 2, 3, & 4. Section 3.13.1.1: What are the various baud rates that must be met for the FSK input and FSK output? What is the time duration that the various tones appear at the input of the FSK? What is the time duration that the various tones need to appear at the output of the FSK? RESPONSE 2, 3, & 4: The FSK signal in question is a frequency modulated square wave that operates with a selectable base carrier wave of 4.8KHz or 24 KHz. Please refer to http://www.ee.unb.ca/thesis97/ee4000u/Chapter4.htm for an example. FS FSK Interface. The TTL/75ohm beacon target report messages received from the Video Signal Processor VSP (the VSP or the Magnetic Tape Recorder in the case of AATC) contain range, azimuth, identity codes, and coded barometric altitude. The input data format consists of five 16 bit words plus an 8 bit parity check character. The message is sent from the VSP to the SDC, serially, using a frequency shift keying (FSK) technique with a nominal data rate of either 4,800 (slow) or 24,000 (fast) bits per second. The start of each 88 bit message is indicated by one cycle of either 2.4 kHz square wave (400 microsecond period) (slow) or 12 kHz square wave (80 microsecond period) (fast). The binary value, ONE or ZERO, of each succeeding bit is indicated by one cycle of either 4.8 kHz (slow) or 24 kHz (fast) for a ZERO and by two cycles of either 9.6 kHz (slow) or 48 kHZ (fast) for a ONE. The FSK receiver circuits accept the FSK data format and detect the binary value of each bit in the message.