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Vor localizer4/30/2024 ![]() ![]() What are the details of how the 90 degree phase shifter is used? I have a few questions about some of the responses. It was Way Cool to hook up an indicator to my laptop and have it With a "calibration" slider it worked just fine. However, the phase shift was constant, and And this shift was different for eachĬomputer I tried it on. Sound card was AC coupled, and the coupling cap or caps produced a serious phase shift at 30Hz. The problem with getting an accurate zero on it was that the The hard part was doing the FM modulation of the 9960Hz. Signals algorithmically, using a sine table. It generates both the 30Hz and the 9960 Hz My laptop is particularly bad in this respect, unfortunately. In practice, however, most audio cards have nonlinear group delay, so the calibration is way off. Since the VOR signal is all audio, it is possible to write a PC sound card application to synthesize it. A 90deg phase shifter and second multiplier drive the to/from. The two 30Hz tones are multipled the product drives the meter. This is followed by an RC phase shift network and summer to yield a ref phase delayed by the OBS selection. This ref phase and the OBS knob drive a resolver (sin/cos transformer). The 9960Hz carrier is FM demodulated (the old KI-201 uses a Foster-Seely). The AM demod output is called "composite VOR." That feeds a VOR/LOC converter which behaves pretty much as you describe. The old KX-170 NAV RX is simply a wideband AM receiver. At radial zero (mag North), the demodulated 30Hz tone from the ref subcarrier and the baseband 30Hz tone appear in phase. The rotating cardioid carrier sums with the omni carrier resulting in a baseband 30Hz AM tone, the phase of which varies with the bearing from the VOR. In addition, the same carrier, unmodulated, is driven onto an cardioid array which is electrically rotated at 30Hz. In brief, a conventional VOR site transmits an omnidirectional AM signal with 1040Hz CW ID and 9960Hz FM subcarrier modulated at 30Hz (the reference). For more 18O degrees set the TO flag, for lessĮither "Avionics Navigation Systems" by Kayton and Fried or "Principles of Avionics" by Helfrick have satisfactory explanations. I think a second comparitor detects the more-than less-than 180ĭegrees out of phase state between the OBS signal and the received ![]() Is phase shifted by the OBS then compared to a phase shited signal There is nothing on the net, what book might be reecommended? Or,Ĭould someone can confirm or correct my idea that the ref 30HZ signal Sources but I'd love to get a pointer to a definitive answer. I have formed my own notion based on what I have gleaned form various Reciever determeines course and sets the TO / FROM flag without a lot How (in terms of mixers, limiters, loc osc, and the like) a VOR I have done a lot of searching on the internet for a description of ![]() VOR Receiver Theory of Operation VOR Receiver Theory of Operation Philip Greenspun's Homepage : Philip Greenspun's Homepage Discussion Forums : Aviation : One Thread
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