Alan Stummer, Research Lab Technologist
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Downloads
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I am curious who uses what. Are these webpages a waste of time, or are they any help to others? Are the circuits, software and utilities appearing in other labs? Please send your comments or suggestions or what you have used (or not) or schematics of your version or pictures or anything! Email me, or be creative and send a postcard! I want to hear from the vacuum! |
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NOTICE: This webpage and associated files is provided for reference only. This is not a kit site! It is a collection of my work here at the University of Toronto in the Physics department. If you are considering using any schematics, designs, or anything else from here then be warned that you had better know something of what you are about to do. No design is guaranteed in any way, including workable schematic, board layout, HDL code, embedded software, user software, component selection, documentation, webpages, or anything. All that said, if it says here it works then for me it worked. To make the project work may have involved undocumented additions, changes, deletions, tweaks, tunings, alterations, modifications, adjustments, waving of a wand while wearing a pointy black hat, appeals to electron deities and just plain doing whatever it takes to make the project work. |
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For Joseph Thywissen's labs, March'08. Generates an RF sequence in the sub-100MHz range used for RF evaporation of MOTs, RF splitting of a DFG or just to blank out annoying radios in adjacent labs.
The PhaseOMatic is a Rabbit processor controlled DDS similar to the MicroMatic project except for a lower frequency DDS, with some RF extras. Specifically, A Rabbit Semiconductor 's RCM3200 module gets a sequence to run from the host computer over TCP/IP and uses that sequence, controls an Analog Devices' AD9854 300MSPS DDS eval board through their respective parallel ports. In plain English, the computer overseeing the whole experiment ("host") figures out what frequencies, phases and amplitudes of RF frequencies are needed, compiles that into a sequence, sends that sequence to the Rabbit on the DDS, then starts the experiment. The experiment's real-time ADwin controller - which had also received its sequence from the host - simply tells the Rabbit when to step the DDS to the next setup of frequency, phase and amplitude.
Included are some RF extras such as repeatable phase turning on and off, adjustable phase for a second RF output plus preamplification and filtering.
The Rabbit's Dynamic C embedded software code is identical for the AD9858 MicroMatic project and this, the AD9854 PhaseOMatic project. A single #define selects between the two DDS types and the compiled file reflects the specifics of that DDS.
Set the frequency. This is described in the General Purpose DDS project, among others which use the same host protocols. In that project, refer to the document describing the protocols, but use the IP address from this project.
There are two RF outputs: RF1 as the reference phase, and, RF2 which shifts phase relative to RF1. The analog input "Gain 1" sets the amplitude of RF1, such that -10V is zero amplitude and +10V is full, but no connection to "Gain 1" gives normalized 0.5 amplitude. RF2 has two gain controls: "Gain 2A" sets the amplitude for the phase of RF1 (AKA "I"), while "Gain 2B" sets the amplitude for the phase of RF1 + 90° (AKA "Q"). For example, if no gain voltages are applied, RF2 will be the same amplitude as RF1 but advanced 45°. Example 2: Gain 1 is not connected (therefore 50%), Gain 2A is +10V (100% of I) and Gain 2B is -10V (0% of Q) so the result at RF2 is that it is the same as RF1. Example 3: Gain 1 is not connected, Gain 2A is -10V (0% of I) and Gain 2B is +10V (100% of Q) so the result at RF2 is 90° ahead of RF1.
Another complication: the "Quadrant" input (TTL levels) will invert RF2, effectively adding 180°.
Finally, there are "RF Enable In" and "RF Enable Out" connectors. These are TTL level signals. Generally, the RF Enable In will appear at the RF Enable out, however, the latter will only update when RF1 crosses a certain phase, set internally by a trimpot. This is to ensure that external signals can be coordinated with the phase of the RF1 (an implicitly RF2) to ensure a repeatable RF signal.
Note that TTL signals are 0V to +0.7V for logic "0" and +2.0V to +3.3V for a logic "1". Logic input currents are negligible.
| Sorry, no more chance for asking direct questions, queries, broken links, problems, flak, slings, arrows, kudos, criticism, comments, brickbats, corrections or suggestions. |
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