1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-06a71 Center Point of Contact: JPLa71 Submitted by: Wilson HarkinsSubject: Verification of RF Hardware Design Performance Early in the Design Phase Practice: Analyses are performed early in the design of radio frequency (R
2、F) hardware to determine hardware imposed limitations which affect radio performance. These limitations include distortion, bandwidth constraints, transfer function non-linearity, non-zero rise and fall transition time, and signal-to-noise ratio (SNR) degradation. The effects of these hardware perfo
3、rmance impediments are measured and recorded. Performance evaluation is a reliability concern because RF hardware performance is sensitive to thermal and other environmental conditions, and reliability testing is constrained by RF temperature limitations.Abstract: Preferred Practice for Design no no
4、ise of any type was included. The specific products of this Cassini RFS analysis were:1. Development of a model of the telemetry channel which includes the nonzero rise and fall times of the telemetry waveforms, the non-linearities in the X-band downlink carrier phase modulator, and the non-linearit
5、ies in the ground receiver demodulation process.2. Characterization of the distortion introduced in the telemetry signal by the nonzero rise and fall times.3. Characterization of the distortion of the demodulated actual telemetry waveform at the ground receiver output due to the combined effect of t
6、he nonzero transition times and the non-linearities in the carrier phase modulator and phase modulator.The modeled parameters were tabulated to verify compliance with Cassini downlink mission requirements.Technical Rationale:Provided by IHSNot for ResaleNo reproduction or networking permitted withou
7、t license from IHS-,-,-Early in the design phase, when the radio architecture and design concept are selected, it is necessary to understand assembly-level hardware limitations and their effect on radio performance. Given the subsystem complexity, it is often difficult to pinpoint the exact cause of
8、 unexpected test results once the subsystem has been integrated.References1. “RFS Downlink Telemetry Analysis Report,“ Robert Mueller (Jet Propulsion Laboratory) IOM 3367-93-392 of 8/24/93, Cassini Project.2. Spurious Radiated Interference Awareness, Reliability Preferred Practice No. PD-AP-1310Impa
9、ct of Non-Practice: The performance of the delivered product may be compromised if the hardware imposed limitations are not evaluated early in the design phase. Once the hardware is delivered, it is too late to select an alternative radio architecture, and there are few opportunities to mitigate the
10、 impact of any constraints on radio performance. Lacking insight into RF hardware characteristics, test engineers may waste valuable engineering hours determining the basis for the variance between expected and observed performance. For flight projects, costly problem/failure reports and project wai
11、vers will likely be processed due to the lack of an early understanding of hardware limitations.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-04-06a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
