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Status of the Chroma-Matic “Trials and Tribulations With the Black Art of RF”

Status of the Chroma-Matic “Trials and Tribulations With the Black Art of RF” 27 October, 2006 Alan Stummer. Present Status. Embedded software (Rabbit) mostly ready. Panel software ready. ADWin software ready. Monitor software ready.

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Status of the Chroma-Matic “Trials and Tribulations With the Black Art of RF”

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  1. Status of the Chroma-Matic “Trials and Tribulations With the Black Art of RF” 27 October, 2006 Alan Stummer

  2. Present Status • Embedded software (Rabbit) mostly ready. • Panel software ready. • ADWin software ready. • Monitor software ready. • Hardware tested but problems with electrical beat frequency. • Still no full system test.

  3. Rosa Current Lock-in Amp Piezo Reference Laser λ1 To Experiment 87Rb LIA Tuneable Laser λ2To Experiment ÷16 Piezo PLL Current Ftune DDS 983MHz AD9858 Eval Module Fig.1 Laser Tuning Configuration

  4. Issues With Present Configuration 1. Improper output from dividers. The Hittite HMC363 et al require higher input power at “low” frequencies such as <100MHz. The particular ROSA (Receiver Optical Sub-Assembly) used is at the low end of the output spec. Fig. 2 HMC363 at 29MHz and ~300mVp-p input 2. Relatively high minimum beat frequency. With the rule of thumb that the frequency into the filters should be at least 10 times the bandwidth required for the laser current, and with the fixed prescaler modulus of 16 built into the DDS evaluation board, the minimum beat frequency is 0.5MHz * 10 *16 = 80MHz.

  5. Rosa Rosa Rosa Rosa Possible Receiver Configurations PCB DDS Existing: Divider is tri-state at f < 100MHz, needs higher power from LIA (Limiting Amp, AKA Post Amp). CON: fmin is 0.5MHz * 10 * 16 = 80MHz 0) ÷8 ÷2 LIA PCB DDS New LIA: Possible to get one with higher output? CON: fmin is 0.5MHz * 10 * 16 = 80MHz ÷8 ÷2 1) LIA PCB DDS New Ext. Dividers 1: Possible to find ones that accept lower input levels? PRO: good, short RF connections. CON: fmin is 0.5MHz * 10 * 16 = 80MHz ÷8 ÷2 2) LIA PCB DDS New Ext. Dividers 2: Possible to find ones that accept lower input levels? Programmable or switch selectable? PRO: good, short RF connections. CON: fmin is 0.5MHz * 10 = 5MHz 3) ÷2n LIA

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