Wide range receiver

[JPKNHTP]

-JPKNHTP

[ezpcb]

of course it is possible, there're already many many all band receiver. I have a IC R-20 all band receiver wich covers up to 3.3G Hz, with AM, FM, SSB, CW demodulation. I don't know wether it can receive space shuttle (I believe now days the space shuttle use digital communication) but I listen to the air plane control or the police every day, sometimes I can hear cordless phone.<p>A wide range local oscillator, a mixer, a IF amplifier and a lf amplifier can make a wide range receiver, but just theoritically. When start to build a receiver many factor must be concernned.<p>[ October 08, 2005: Message edited by: ezpcb.com ]</p>

[Dean Huster]

BUILDING a receiver like that for us mere mortals is an impossibility. There's a heckuva lot of research and design that goes into those Kenwood, ICOM, JRC, etc. wide-band receivers (they typically cover from LF through the low GHz frequencies) in order to get good sensitivity, selectivity and low noise, all of which are horribly interrelated such that improving one specification usually compromises another.<p>My brother-in-law managed to buy one for a song from a newly-made widow. For some reason, they never remain low-bid items on ebay.<p>Dean

[rshayes]

Usually such a reciever is built with a first conversion up to an IF above the tuning range (ie, a GHz or two). The local oscillator is usually even higher. Then you have several conversions to bring the signal down to a low frequency where you can get good selectivity. These IF frequencies are in the tuning range of the receiver, so the shielding has to be very good to avoid spurious responses.<p>Overall, the performance is likely to be inferior to a well designed receiver made for a specific frequency range and communications mode.

[philba]

as other have said, to cover a really wide spectrum is an engineering challenge. <p>What kind of coverage are you looking for? ELF to Radar? Seriously, unbounded problems are always harder to solve than bounded ones. I'd start with the range you want to receive and go from there.

[cato]

http://www-pao.ksc.nasa.gov/kscpao/rele ... /51-97.htm

[Robert Reed]

JPK----<p>The widest range receiever I have designed and built was the front end of a synthesised communication test set. The only simple ?? way to accomplish this was to totally eliminate All RF stages and only broadband tune this area. You must take antenna directly into a mixwer stage and then on to customary IF conversions and so forth. We needed fairly flat response across a relative ly wide tuning range and yet maintain some degree of sensitivity. This unit had a two to one tuning range and a flat sensitivity of 2 microvlots for 12 DB SINAD ( a measure of signal to noise ratio).Although this does not meet the standards of a top notch receiever,it fulfilled the requirements needed for its purpose. This same reciever with a properly designed front end, would achieve a SINAD sensitivity of 0.25 microvolts,but that same front end would have defeated a simplistic and flat tuning range. In order to truly have an extremely wide range communications receiever capable of picking up real world signals,you need a front end capable of delivering this to the mixer. To accomplish this, tuning of the local oscllator is accompanied by (varactor) tuning of the front end at the same time and auotmatic band switching at the proper points. This is a very involved design process and would probably involve a team of engineers and a decent research lab and a couple of months to complete ( way beyond the hobbyists cababilitys). However if the signals you want to receive are still relatively strong (and airborne creates its own helluva antenna tower by virtue of its flying altitude) , the direct antenna to mixer approach would work for you and it is simple. Only other alternative would be to buy a commercial unit, but a good one would probably cost in the neighborhood of $2500 .

[jimandy]

Dean Huster wrote
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr> ...a song from a newly-made widow <hr></blockquote><p>Slightly off topic but that phrase caught my eye and led to some interesting imaginations. Sorry Dean, the devil made me say it. <p>(added) and now that I re-read it I notice the judiciuosly placed hyphen.<p>[ October 08, 2005: Message edited by: jimandy ]</p>