ExtraClassSylalbus2009jan-AD7FO

Recommendations

Info

Rev 2.02 E4D Receiver performance characteristics, part 2: blocking dynamic range, intermodulation and crossmodulation interference; 3rd order intercept; desensitization; preselection E4D01 The difference in dB between the level of an incoming signal which will cause 1 dB of gain compression, and the level of the noise floor is the blocking dynamic range of a receiver. E4D02 Cross modulation of the desired signal and desensitization from strong adjacent signals are two types of problems caused by poor dynamic range in a communications receiver. E4D03 Intermodulation interference between two repeaters can occur when the repeaters are in close proximity and the signals mix in one or both transmitter final amplifiers. E4D04 An effective way to reduce or eliminate intermodulation interference between two repeater transmitters operating in close proximity to one another is to install a properly terminated circulator at the output of the transmitter. E4D05 If a receiver tuned to 146.70 MHz receives an intermodulation-product signal whenever a nearby transmitter transmits on 146.52 MHz, the two most likely frequencies for the other interfering signal is 146.34 MHz and 146.61 MHz. Intermodulation products are the result of two frequencies being mixed together to give the sum and difference of those frequencies. To make maters more complex harmonics of one or both of the initial frequencies or the mixed frequencies can mix and create additional sum and difference frequencies, sometimes very close to the tuned frequency of your receiver. See page 8-22 and 23 in the Extra Class License Manual for more information. In this example: Fimd= 2f1- f2 or f2 = 2f1 – Fimd Fimd=146.70, F1 = 146.52, F2 = Unknown interfering signal f2 = 2f1 – 146. 70 or 2(146.52) – 146.70 or 146.34 MHz 2f1 = f1 + 146.70 or 146.52 +146.70 or 146.61 MHz E4D06 If the signals of two transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated, the signals are called intermodulation interference. E4D07 The most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal is that the off-frequency, unwanted signal is heard in addition to the desired signal. E4D08 Nonlinear circuits or devices cause intermodulation in an electronic circuit. E4D09 The purpose of the preselector in a communications receiver is to improve the rejection of unwanted signals. E4D10 A third-order intercept level of 40 dBm with respect to receiver performance means a pair of 40 dBm signals will theoretically generate the same output on the third order intermodulation frequency as on the input frequency. Jack Tiley <strong>AD7FO</strong> Page 34 3/15/2009
Rev 2.02 E4D11 Third-order intermodulation products within a receiver are of particular interest compared to other products. This is because the third-order product of two signals which are in the band is likely to be within the band. E4D12 Desensitization is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency. E4D13 Strong adjacent-channel signals can cause receiver desensitization. E4D14 Decreasing the RF bandwidth of the receiver is a way to reduce the likelihood of receiver desensitization. E4E Noise suppression: system noise; electrical appliance noise; line noise; locating noise sources; DSP noise reduction; noise blankers E4E01 Ignition Noise can often be reduced by use of a receiver noise blanker. E4E02 Broadband “white” noise, ignition noise and power line noise are types of receiver noise that can often be reduced with a DSP noise filter. E4E03 Signals which appear correlated (mathematically similar) across a wide bandwidth might be able to be removed from desired signals with a receiver noise blanker. E4E04 Conducted and radiated noise caused by an automobile alternator can be suppressed by connecting the radio's power leads directly to the battery and by installing Feed Through capacitors in line with the alternator leads. E4E05 Noise from an electric motor can be suppressed by installing a brute-force AC-line filter in series with the motor leads. E4E06 Thunderstorms are a major cause of atmospheric static. Jack Tiley <strong>AD7FO</strong> Page 35 3/15/2009
Page 1 and 2: Rev 2.02 Preparing for the Extra cl
Page 3 and 4: Rev 2.02 Guide to using this syllab
Page 5 and 6: Rev 2.02 SUBELEMENT E4 -- AMATEUR R
Page 7 and 8: Rev 2.02 ELEMENT 4 - EXTRA CLASS QU
Page 9 and 10: Rev 2.02 E1A09 (Band Plan Chart) Th
Page 11 and 12: Rev 2.02 E1B13 (FCC Rules) Communic
Page 13 and 14: Rev 2.02 E1D08 (FCC Rules) The 2 me
Page 15 and 16: Rev 2.02 E1E20 (FCC Rules) You must
Page 17 and 18: Rev 2.02 SUBELEMENT E2 - OPERATING
Page 19 and 20: Rev 2.02 E2A13 Geosynchronous satel
Page 21 and 22: Rev 2.02 E2B17 Immunity from fading
Page 23 and 24: Rev 2.02 E2D02 The definition of
Page 25 and 26: Rev 2.02 SUBELEMENT E3 -- RADIO WAV
Page 27 and 28: Rev 2.02 E3C01 Auroral activity cau
Page 29 and 30: Rev 2.02 E4A06 A spectrum analyzer
Page 31 and 32: Rev 2.02 E4B09 High impedance input
Page 33: Rev 2.02 E4C06 If t he thermal nois
Page 37 and 38: Rev 2.02 SUBELEMENT E5 -- ELECTRICA
Page 39 and 40: Rev 2.02 E5B Time constants and pha
Page 41 and 42: Rev 2.02 Example 2: To find the ang
Page 43 and 44: Rev 2.02 j 50 -j 25 E5B12 The phase
Page 45 and 46: Rev 2.02 j 600 -j300 E5C04 In polar
Page 47 and 48: Rev 2.02 Parallel circuit solutions
Page 49 and 50: Rev 2.02 R=300 Ω XL= (2 π FL) or
Page 51 and 52: Rev 2.02 Power Factor represents th
Page 53 and 54: Rev 2.02 SUBELEMENT E6 -- CIRCUIT C
Page 55 and 56: Rev 2.02 Field-effect transistors e
Page 57 and 58: Rev 2.02 E6B12 Junction diodes are
Page 59 and 60: Rev 2.02 E6D02 Cathode ray tube (CR
Page 61 and 62: Rev 2.02 E6E04 The technique used t
Page 63 and 64: Rev 2.02 E6F07 Cadmium sulfide will
Page 65 and 66: Rev 2.02 E7A07 An AND gate produces
Page 67 and 68: Rev 2.02 When a Class C rather than
Page 69 and 70: Rev 2.02 E7C01 In a low-pass filter
Page 71 and 72: Rev 2.02 E7D02 One characteristic o
Page 73 and 74: Rev 2.02 E7E05 A pre-emphasis netwo
Page 75 and 76: Rev 2.02 E7F08 One purpose of a mar
Page 77 and 78: Rev 2.02 E7G17 The typical output i
Page 79 and 80: Rev 2.02 E7H19 A phase-locked loop
Page 81 and 82: Rev 2.02 E8A06 The approximate rati
Page 83 and 84: Rev 2.02 E8B13 In time division mul
Page 85 and 86:
Rev 2.02 E8D07 An electromagnetic w
Page 87 and 88:
Rev 2.02 E9A10 Antenna bandwidth is
Page 89 and 90:
Rev 2.02 E9B10 The “Method of Mom
Page 91 and 92:
Rev 2.02 E9C09 The elevation angle
Page 93 and 94:
Rev 2.02 E9D09 An advantage of usin
Page 95 and 96:
Rev 2.02 E9E08 An SWR greater than
Page 97 and 98:
Rev 2.02 E9F11 A 1/8-wavelength tra
Page 99 and 100:
Rev 2.02 E9H05 The main drawback of
Page 101 and 102:
Rev 2.02 SUBELEMENT E0 -- SAFETY [1
Page 103 and 104:
Rev 2.02 Jack Tiley AD7FO Page 103
Page 105 and 106:
Rev 2.02 Capacitors in series C= __
Page 107 and 108:
Rev 2.02 Impedance of complex serie
Page 109 and 110:
Rev 2.02 Calculating Component valu
Page 111 and 112:
Rev 2.02 AC Voltage Calculations Th
Page 113:
Rev 2.02 Jack Tiley AD7FO Page 113
show all

ExtraClassSylalbus2009jan-AD7FO

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?