Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!genrad!decvax!harpo!seismo!rochester!rocksvax!dave From: dave@rocksvax.UUCP Newsgroups: net.auto Subject: Re: clogged traffic and other stories - (nf) Message-ID: <583@rocksvax.UUCP> Date: Wed, 22-Jun-83 12:04:55 EDT Article-I.D.: rocksvax.583 Posted: Wed Jun 22 12:04:55 1983 Date-Received: Thu, 23-Jun-83 00:14:57 EDT Lines: 35 You need no mathmatics, just a pulse generator running at an appropriate frequency for the band you run on and enough power to overcome their reflected signal. Most radars are of CW nature, that is they transmit a signal continuously. The receiver in the radar unit is coupled to the transmitter such that there is a mixing of the transmitted signal, the reference, and the incoming reflection doppler shifted in frequency. This produces 2 signals at the output of the mixer, the sum of the 2 signals freq. (20 Ghz) and a difference signal (audio). The radar filters out only the low frequency component. This is a lot like listening to carriers on an SSB receiver, a carrier off 1 Khz generates a 1 Khz tone out the receiver. By putting in a pulse stream near within the passband of their receiver you and make your own audio range signal, which is basically indistinguishable from the transmitter-reflection signal. There will be a small piece of the normal reflection signal modulating your audio signal, but the digital limiting in the frequency counter will probably filter out that small interference, looks like noise on the edges of square waves. If you run the same power as the police radar, very easy seeing most of the Gunn diodes are the same, you can easily jam/have the radar read anything you want. Let me note that only hams can legally send these transmissions, as long as you identify on morse code at the appropriate intervals and stay within our bands. K band no problem, we share that, X band is an adjacent band, ends @ 10 Ghz, radar operates @ 10.250 Ghz I think. I still think the ultimate ham project is to build a moving radar, to find out how fast that RX-7 passed my diesel Rabbit by. Of course that "calibration" pulse generater would be fun to play with, imagine plodding by a radar trap while their radar reads 98 MPH!! Dave Sewhuk Arpa: Sewhuk.HENR@PARC-MAXC uucp: {rochester, allegra, amd70}!rocksvax!dave