Форум » Дискуссии » Operazionnie ysiliteli ,ZAP/AZP & (продолжение) » Ответить
Operazionnie ysiliteli ,ZAP/AZP & (продолжение)
milstar: 1941: First (vacuum tube) op-amp An op-amp, defined as a general-purpose, DC-coupled, high gain, inverting feedback amplifier, is first found in US Patent 2,401,779 "Summing Amplifier" filed by Karl D. Swartzel Jr. of Bell labs in 1941. This design used three vacuum tubes to achieve a gain of 90dB and operated on voltage rails of ±350V. ###################################################### It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in today's op-amps. Throughout World War II, Swartzel's design proved its value by being liberally used in the M9 artillery director designed at Bell Labs. ######################################################################### This artillery director worked with the SCR584 radar system to achieve extraordinary hit rates (near 90%) that ####################################################################### would not have been possible otherwise.[3] ########################### http://en.wikipedia.org/wiki/Operational_amplifier
milstar: https://www.eenewsanalog.com/design-center/new-phased-array-radar-architectures/page/0/3
milstar: ampling signals above the firs t Nyquist zone has become popul ar in communications, because the process is equivalent to analog demodulation. It is becoming common practice to sample IF signals directly and then use digital tec hniques to process the signal, thereby eliminating the need for an IF demodulator and filters. Clearly, howev er, as the IF frequencies become higher, the dynamic performance requirements on the ADC become more critical. The ADC input bandwidth and distortion performan ce must be adequate at the IF frequency, rather than only baseband. https://www.analog.com/media/en/training-seminars/tutorials/MT-002.pdf
milstar: The diagram above depicts how processing gain increases the performance of the ADC in the ICOM 7300. The LTC2208-14 ADC in this radio has an effective number of bits ENOB = 12.5. By itself, it can only produce dynamic range of 77 dB. However, as the sampling bandwidth is reduced from 120 million samples per second down to a 12 kHz low if, the DSP introduces another 39 dB of dynamic range. This SDR receiver processing gain is equivalent to bolting another 6.5 bits onto the ADC. http://play.fallows.ca/wp/radio/software-defined-radio/sdr-receiver-processing-gain-create-virtual-bits/
milstar: https://www.teledyne-e2v.com/content/uploads/2018/12/0869B_Dither_AN.pdf
milstar: https://apps.dtic.mil/dtic/tr/fulltext/u2/a196569.pdf he maximum scanning speed is proportional to the square of the detection bandwidth.
milstar: Oversampling R atio up to 256 from the drop -down menu located in the Configure tab , as shown in Figure 4. The low frequency 1/f noise of the system, which starts to dominate at lower output data rates less than 20 kSPS , limits the ach ievable maximum dynamic range . https://www.analog.com/media/en/technical-documentation/application-notes/AN-1279.pdf
milstar: Typically, it cannot be assumed that the SFDR across a narrow frequency band can be extrapolated to get the same performance across a wider or full Nyquist band of Fs/2. This is primarily because the frequency planning for the narrowband of the fundamental is intentionally established to filter and push higher harmonics out of the frequency band of interest. If the filter was removed, then these harmonics and other spurs would now be part of the wideband SFDR seen in the system (Figures 2 and 3). https://www.electronicdesign.com/analog/understanding-spurious-free-dynamic-range-wideband-gsps-adcs
milstar: While there are many high-performance component choices for this part of the system, even the best solutions will embed some small differential imbalances that distort the signal of interest and decrease the SFDR through the ADC. Phase mismatch between each side of the differential input signal at the front end of the ADC creates an increase in power for the harmonics of the fundamental signal. This can happen when one side of the differential signal leads the other side in time by some amount of phase relative to its period. The effect can be seen in Figure 4, when one side of a differential pair leads the other side by a small margin of periodic phase.
milstar: https://www.analog.com/media/en/training-seminars/tutorials/MT-003.pdf
milstar: https://www.analog.com/en/technical-articles/28-nm-adcs-enable-next-gen-electronic-warfare-rec-sys.html Next-Generation Electronic Warfare Receiver Systems
milstar: AD9208 14 bit 2*1.5 GSPS 0.022 mkm CMOS https://www.analog.com/media/en/technical-documentation/data-sheets/AD9208.pdf SFDR Fin 2600 mhz 78 db Fin 1800 mhz 81 db Fin 900 mhz 78 db ENOB 9.6 -9,7 SINAD 59.7-9
milstar: https://www.analog.com/en/technical-articles/Use-Noise-Spectral-Density-to-Evaluate-ADCs-in-Software-Defined-Systems.html
milstar: For example, GSM specs call for receivers that can accurately digitize signals from -13 dBm to -104 dBm in the presence of many other signals (Figure 1)—a 91-dB dynamic range! This implies that the spurious-free dynamic range (SFDR) of the converter and analog front end must be about 95 to 100 dBFS. SFDR for a converted signal with a given amplitude is the log ratio (dB) of that amplitude to the largest spurious frequency component found in the converter's Nyquist spectrum (0 to Fs/2 Hz). https://www.analog.com/en/analog-dialogue/articles/wideband-radios-need-wide-dynamic-range-converters.html
milstar: Head room: When A/D converters receive multiple channels in a broadband architecture, each signal level must be considerably less than full scale of the converter.One signal alone may use the full-scale range of the converter, but when two signals may be present, each must be half-amplitude (-6 dB), assuming equal signal power, to prevent output clipping as these signals sum together at their peaks. Each doubling of the number of signals requires individual levels to be reduced by 6 dB. For example, -12 dBFS for 4 channels, -18 dBFS for 8 channels. A multi-channel radio must have enough dynamic range to account for the SNR lost through reduced usable signal levels. In addition, radio designers keep from 3 to 15 dB in reserve as headroom at the top of the ADC range to prevent clipping that comes from inevitable high incoming peak-to-rms ratios and saturation as additional signals come in band as new callers enter the cell zone.
milstar: Converters for such radios require a sample rate at least twice the highest frequency (Nyquist rate), i.e., 20 MSPS minimum for signal range from dc to 10 MHz, and generally with at least 20% additional margin, raising the required encode rate to about 25 MSPS.
milstar: https://www.winradio.com/home/g35ddci-s.htm Receiver type Direct-sampling, digitally down-converting software-defined receiver Frequency range 1 kHz to 45 MHz SFDR 111 dB min. (preamp off) 108 dB min. (preamp on) MDS -128 dBm @ 10 MHz, 500 Hz BW (preamp off) -135 dBm @ 10 MHz, 500 Hz BW (preamp on) ADC 16 bit, 100 MSPS https://www.winradio.com/home/g35ddci.htm This is the first time a receiver of such advanced specification and unique combination of features is being offered to the general marketplace. The receiver is intended for government, military, security, surveillance, broadcast monitoring, industrial and demanding consumer applications.
milstar: https://www.winradio.com/home/g39ddce-s.htm
milstar: http://www.ti.com/lit/ug/tidubs6/tidubs6.pdf radar RF sampling with 2*14 bit ADC 2*1.5 GSPS
milstar: https://www.analog.com/media/en/technical-documentation/data-sheets/238718fa.pdf 8.192V P-P Differential Inputs http://www.ti.com/lit/an/slyt090/slyt090.pdf 8.192 v p-p = +22dbm http://wa8lmf.net/miscinfo/dBm-to-Microvolts.pdf input signal level 7 dB below full-scale input (–7 dBFS) seems to give good results and is commonly used.
milstar: SFDR = 2/3 (IIP3 - Noise Floor) SFDR = 2/3 (IIP3 - Noise Floor) - SNR(min) Both are correct , the second one is more general form as if the minimum SNR=0dB (i.e. the noise equal to the signal) then u get the first form but if u need to have the minimum detectable signal larger than the noise by a certain factor (SNR_min) then use the second regards, SFDR = [(2/3)(IIP3 – MDS)] where Noise Floor = -174dBm/Hz + 10log(B) + NF where NF -Noise Figure
полная версия страницы