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| 933.6 Mhz cops? http://interceptradio.com/bbs/viewtopic.php?f=1&t=1507 |
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| Author: | gregz [ Sun Apr 08, 2007 9:53 pm ] |
| Post subject: | 933.6 Mhz cops? |
I hear a few police calls on 933.6 Mhz. I heard "2 Ocean 3" "fife" "Lincon 3" . 95% of the time it's all quiet, then a fast paced dispatcher. and sometimes it's multiple conversations at the same time that do not hear each other (lines crossed?). It sounds like I'm hearing Snopac trunk, except from a microwave beam?? I'm listening from lynnwood. 933.6Mhz doesn't return to any thing from the FCC. I thought it was an image.. I did some calculations.. I'm using an Icom R-2 Receive system : Triple-conversion superheterodyne Intermediate frequencies : 1st 266.7 MHz, 2nd 19.65 MHz, 3rd 450 kHz which I beleives translates to (Original-133.35)/1.5=Image making me think I'm listening to an image of 1533.75 which also doesn't return to any license. any ideas? |
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| Author: | John Miles KE5FX [ Mon Apr 09, 2007 12:49 pm ] |
| Post subject: | |
When tuned to 933.6 MHz, your first LO is at either 933.6+266.7 (1200.3) or 933.6-266.7 (666.9) MHz. The image is the other frequency that could combine with the first LO to yield the same IF. So your potential image responses would be 1467 MHz or 400.2 MHz. Neither of those sound like public-service frequencies, so yes, you may have found a point-to-point link of some kind. IMD from a strong wideband carrier is also a possibility. With a strong enough 'local oscillator', almost anything in the neighborhood can be a 'mixer'... |
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