Sexy Developer

수신단이 IF 트랜스포머에 의한 주파수 낮춤을 하지 않고 송신단이 체배기등을 사용하지 않는지는 실물을 뜯어 보지 못했고, 웹사이트에서도 회로도를 제공하지 않아서 알수는 없지만 어쨌던 PC 용 소프트웨어와 DSP (디지탈 신호 처리 칩) 로 구성되어 실제 운용이 가능한 SDR (Software Difined Radio) 무전기이다. 위에 말...

새로 영입한 녀석인데, AVR 의 ATmega8515 와 인텔 8051 호환의 AT89S52 를 보드 한개에서 시험해 볼수 있는 마시테크 ( http://www.masitech.co.kr ) 사의 제품.   왜나라 야에스의 단파 라디오를 적외선 리모콘으로 조정하기 위한 어플리케이션을 만들기 위해 이것 저것 테스트를 해보려고 구입했다. 어쨌던 새로운 친구의 등장으로 우...

어제는 저번주에 신청한 미해군 전자 기술 독학 교습서 (?) 쯤으로 해석되는 CD-ROM 으로 된 E-Book 이 도착했다. 특급항공우편은 언제나 딱 1주일이면 오는군.   내용은 아래와 같다. 어떤가, 재미날거 같지 않은가? --; 모든 내용은 웹사이트에서 볼 수 있다... 근데 왜 샀냐고? 뭐 여러가지 이유가... ^^;   Naval Electrical Engineering Training Series CD ROM $19.95 (항공...

현충일 밤, 나의 Primary Radio 인 FT-857D 가 개조를 위해 배를 갈랐다. 배를 가른 후 작업전 모습이다. 근데 공구가 고장나서 아직 수술이 안 끝났다. 불쌍한넘. --;

SINGLE-SIDEBAND   You know from studying the single-sideband transmitter material in this chapter you may transmit only one sideband of an AM signal and retain the information transmitted. Now you will see how a single-sideband signal is received.   Advantages   Figure 2-11 illustrates the transmitted signal for both AM and ssb. Ssb communications has several advantages. When you eliminate the carrier and one sideband, all of the transmitted power is concentrated in the other sideband. Also, an ssb signal occupies a smaller portion of the frequency spectrum in comparison to the AM signal. This gives us two advantages, narrower receiver bandpass and the ability to place more signals in a small portion of the frequency spectrum.   Figure 2-11.—Comparison of AM and SSB transmitted signals.   SSB communications systems have some drawbacks. The process of producing an ssb signal is somewhat more complicated than simple amplitude modulation, and frequency stabil...

  Synchronous demodulation / detection ! Today's radio receivers offer very high levels of performance and boast many facilities. Many radio receivers incorporate memories, phase locked loops, direct digital synthesis, digital signal processing and much more. One facility that can be very useful on the short wave bands is synchronous detection or synchronous demodulation as this can give much improved performance for receiving amplitude modulation (AM) transmissions. Unfortunately little is written about this form of modulation, and often it is a matter of accepting that it must be better than any normal options because it is included as a feature in the receiver specification. ! Synchronous detection is used for the detection or demodulation of amplitude modulation (AM). This form of modulation is still widely used for broadcasting on the long, medium and short wave bands despite the fact that there are more efficient forms of modulation that can be used today. The main reason for...

  Synchronous Vs Envelope Detection Updated 10/05/01 Some demodulators provide a choice between envelope and synchronous detection modes. When running the FCC Proof of Performance tests, its important to use the proper detection mode. Especially when measuring differential phase. Let's take a look at the two modes and see what they have to offer. Envelope Detectors Envelope detectors are usually considered to be the simplest form of detector. In fact, they can be quite complicated or they can be as simple as a diode and a low-pass filter. The performance of an envelope detector, when used to demodulate a television signal, is limited by the relative amplitudes of the signal being demodulated (bigger is better), and an effect called quadrature distortion. Quadrature distortion is a result of the asymmetry of our television signal. It's vestigial sideband coming from the modulator or transmitter and nearly single sideband within the television's IF circuit. One nice thing abo...