10 Latest QSO's Are:
  W6BRY(RTTY, UNITED STATES, CA)    WY7FD(RTTY, UNITED STATES, WY)    KE1F(RTTY, UNITED STATES, FL)    K4WI(RTTY, UNITED STATES, AL)    N8OO(RTTY, UNITED STATES, LA)    W4AAA(RTTY, UNITED STATES, NC)    K9WX(RTTY, UNITED STATES, IN)    N6XI(RTTY, UNITED STATES, CA)    N2BJ(RTTY, UNITED STATES, IL)    WB4HRL(RTTY, UNITED STATES, SC)    

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Analog Modes and Modulation

 

 

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Interesting APRS Videos

 

What is APRS?

 

Automatic Packet Reporting System (APRS) is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet System (APRS-IS) and distributed globally for ubiquitous and immediate access. Along with messages, alerts, announcements, and bulletins, the most visible aspect of APRS is its map display. Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet. Any station, radio, or object that has an attached GPS is automatically tracked. Other prominent map features are weather stations, alerts and objects and other map-related amateur radio volunteer activities including Search and Rescue and signal direction finding.

 

APRS has been developed since the late 1980s by Bob Bruninga, callsign WB4APR, currently a senior research engineer at the United States Naval Academy. He still maintains the main APRS website. The acronym "APRS" was derived from his callsign.


Sample APRS VHF frequencies

144.390 MHz – ColombiaChileIndonesiaMalaysiaNorth America

144.575 MHz – New Zealand

144.660 MHz – Japan

144.800 MHz – South AfricaEuropeRussia

144.930 MHz – ArgentinaUruguay

145.175 MHz – Australia

145.570 MHz – Brazil

145.525 MHz – Thailand

APRS

 

An extensive digital repeater, or "digipeater," network provides transport for APRS packets on these frequencies. Internet gateway stations (IGates) connect the on-air APRS network to the APRS Internet System (APRS-IS), which serves as a worldwide, high-bandwidth backbone for APRS data. Stations can tap into this stream directly, and a number of databases connected to the APRS-IS allow web-based access to the data as well as more advanced data-mining capabilities. A number of low-earth orbiting satellites, including the International Space Station, are capable of relaying APRS data.

 

Suggested Links for further reading on APRS: APRS.org

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Interesting CW Videos

 

What is CW?

 

A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitued and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an earl method of radio transmission, in which a carrier wave is switched on and off. Information is carried in the varying duration of the on and off periods of the signal, for example, by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves also known as "undamped waves", to distinguish this method from dampled wave transmission.


My last 10 CW QSO's are with:
Call SignCountryBandDateTime (UTC)
K9UQNUnited States40m12/31/201421:58:00
W0TTUnited States20m12/31/201421:48:00
K2TVUnited States40m12/31/201421:24:00
N6VIUnited States15m12/31/201417:56:00
N6WMUnited States10m12/31/201417:17:00
K0CAUnited States40m12/31/201416:25:00
W1MSWUnited States20m12/31/201414:45:00
WA1SUnited States20m12/31/201414:38:00
W1VTUnited States30m12/31/201414:00:00
W6SXUnited States40m12/31/201404:46:00


History of CW and Morse Code

 

Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna. The signals produced by these spark-gap transmitters consisted of brief pulses of radio frequency oscillations which died out rapidly to zero, called damped waves. The disadvantage of damped waves was that they produced electromagnetic interference that spread over the transmissions of stations at other frequencies. Mathematically, the extremely wideband excitation provided by the spark gap was bandpass filtered by the self-oscillating antenna side circuit, which, because of its simple construction, also had a relatively broad and poorly controlled filter characteristic.

 

This motivated efforts to produce radio frequency oscillations that decayed more slowly. Strictly speaking, an unmodulated continuous carrier has no bandwidth and cannot interfere with signals at other frequencies, but conveys no information either. Thus it is commonly understood that the act of keying the carrier on and off is necessary. However, in order to bring the bandwidth of the resulting signal under control, the buildup and decay of the radio frequency envelope needs to be slower than that of the early spark gap implementations.

 

When this is done, the spectrum of the signal approaches that of a continuous sinusoidal oscillation, while temporally its amplitude varies between zero and full carrier strength. As such, the resulting narrower bandwidth mode of operation is to this day described as "continuous wave". The resulting signal allows many radio stations to share a given band of frequencies without noticeable mutual interference.

 

In on-off carrier keying, if the carrier wave is turned on or off abruptly, communications theory can show that the bandwidth will be large; if the carrier turns on and off more gradually, the bandwidth will be smaller. The bandwidth of an on-off keyed signal is related to the data transmission rate as: Bn = BK where Bn is the necessary bandwidth in hertz, B is the keying rate in signal changes per second baud, and K is a constant related to the expected radio propagation conditions; K=1 is difficult for a human ear to decode, K=3 or K=5 is used when fading or multipath propagation is expected. What is transmitted in the extra bandwidth used by a transmitter that turns on/off more abruptly is known as key clicks. Certain types of power amplifiers used in transmission may increase the effect of key clicks.

 

The first transmitters capable of producing continuous wave, the Alexanderson alternator and vacuum tube oscillators, became widely available after World War I.

 

Early radio transmitters could not be modulated to transmit speech, and so CW radio telegraphy was the only form of communication available. CW still remained a viable form of radio communication for many years after voice transmission was perfected, because simple transmitters could be used. The low bandwidth of the code signal, due in part to low information transmission rate, allowed very selective filters to be used in the receiver which blocked out much of the atmospheric noise that would otherwise reduce the intelligibility of the signal.

 

Continuous-wave radio was called radiotelegraphy because like the telegraph, it worked by means of a simple switch to transmit Morse code. However, instead of controlling the electricity in a cross-country wire, the switch controlled the power sent to a radio transmitter. This mode is still in common use by amateur radio operators.

 

Morse Code

 

Morse code is a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment. The International Morse Code encodes the ISO basic Latin alphabet, some extra Latin letters, the Arabic numerals and a small set of punctuation and procedural signals as standardized sequences of short and long signals called "dots" and "dashes", or "dits" and "dahs". Because many non-English natural languages use more than the 26 Roman letters, extensions to the Morse alphabet exist for those languages.

 

Each character (letter or numeral) is represented by a unique sequence of dots and dashes. The duration of a dash is three times the duration of a dot. Each dot or dash is followed by a short silence, equal to the dot duration. The letters of a word are separated by a space equal to three dots (one dash), and the words are separated by a space equal to seven dots. The dot duration is the basic unit of time measurement in code transmission. For efficiency, the length of each character in Morse is approximately inversely proportional to its frequency of occurrence in English. Thus, the most common letter in English, the letter "E," has the shortest code, a single dot.

 

Morse code is most popular among amateur radio operators, although it is no longer required for licensing in most countries. Pilots and air traffic controllers usually need only a cursory understanding. Aeronautical navigational aids, such as VORs and NDBs, constantly identify in Morse code. Compared to voice, Morse code is less sensitive to poor signal conditions, yet still comprehensible to humans without a decoding device. Morse is therefore a useful alternative to synthesized speech for sending automated data to skilled listeners on voice channels. Many amateur radio repeaters, for example, identify with Morse, even though they are used for voice communications.

 

For emergency signals, Morse code can be sent by way of improvised sources that can be easily "keyed" on and off, making it one of the simplest and most versatile methods of telecommunication. The most common distress signal is SOS or three dots, three dashes and three dots, internationally recognized by treaty.

 

International Morse Code Table Morse Code
Another software tool for decoding Morse Code is called CW Skimmer. This is a cool program in that it actually puts the dots and dashes on the graphical display. You can download a trial version that is good for 30 days. A registered version costs around $75. CW Skimmer
I use a software tool called to recieve CW Morse Code and to send Morse Code. CwGet
CwType
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What is Amplitude Modulation or AM?

 

From Wikipedia, the free encyclopedia:


Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to that of the message signal being transmitted. The message signal is, for example, a function of the sound to be reproduced by a loudspeaker, or the light intensity of pixels of a television screen. This technique contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which its phase is varied.

 

AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900.[1] It remains in use today in many forms of communication; for example, it is used in portable two-way radiosVHF aircraft radiocitizens band radio, and in computer modems in the form of QAMAM is often used to refer to mediumwave AM radio broadcasting.

 

My last 10 AM QSO's are with:

Call SignCountryBandDateTime (UTC)

 

 

In electronics and telecommunications, modulation means varying some aspect of a continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or a video signal which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal, carries the information. At the receiving station, the message signal is extracted from the modulated carrier by demodulation.


In amplitude modulation, the amplitude or strength of the carrier oscillations is varied. For example, in AM radio communication, a continuous wave radio-frequency signal (a sinusoidal carrier wave) has its amplitude modulated by an audio waveform before transmission. The audio waveform modifies the amplitude of the carrier wave and determines the envelope of the waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called "double-sideband amplitude modulation" (DSB-AM) to distinguish it from more sophisticated modulation methods also based on AM.


A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects noise and electromagnetic interference in equal proportion to the signal. Increasing the received signal-to-noise ratio, say, by a factor of 10 (a 10 decibel improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to frequency modulation (FM) and digital radio where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast is not favored for music and high fidelity broadcasting, but rather for voice communications and broadcasts (sports, news, talk radio etc.).


 

In 1982, the International Telecommunication Union (ITU) designated the types of amplitude modulation:
An example graphic of an AM signal. This is 1100 WTAM in Cleveland, Ohio using an SDR software package
WTAM
An audio signal (top) may be carried by a carrier signal using AM or FM methods.
AM
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What is Frequency Modulation or FM?

 

From Wikipedia, the free encyclopedia:

 

In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave.

 

In analog frequency modulation, such as FM radio broadcasting of an audio signal representing voice or music, the instantaneous frequency deviation, the difference between the frequency of the carrier and its center frequency, is proportional to the modulating signal.


Digital data can be encoded and transmitted via FM by shifting the carrier's frequency among a predefined set of frequencies representing digits. For example one frequency can represent a binary 1 and a second can represent binary 0. This modulation technique is known as frequency-shift keying (FSK). FSK is widely used in modems such as fax modems, and can also be used to send Morse code. Radioteletype also uses FSK.


Frequency modulation is widely used for FM radio broadcasting. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via EEG,[3] two-way radio systems, music synthesis, magnetic tape-recording systems and some video-transmission systems. In radio transmission, an advantage of frequency modulation is that it has a larger signal-to-noise ratio and therefore rejects radio frequency interference better than an equal power amplitude modulation (AM) signal. For this reason, most music is broadcast over FM radio.

 

Frequency modulation and phase modulation are the two complementary principal methods of angle modulation; phase modulation is often used as an intermediate step to achieve frequency modulation. These methods contrast with amplitude modulation, in which the amplitude of the carrier wave varies, while the frequency and phase remain constant.

 

My last 10 FM QSO's are with:

Call SignCountryBandDateTime (UTC)

 

In electronics and telecommunications, modulation means varying some aspect of a continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or a video signal which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal, carries the information. At the receiving station, the message signal is extracted from the modulated carrier by demodulation.


In amplitude modulation, the amplitude or strength of the carrier oscillations is varied. For example, in AM radio communication, a continuous wave radio-frequency signal (a sinusoidal carrier wave) has its amplitude modulated by an audio waveform before transmission. The audio waveform modifies the amplitude of the carrier wave and determines the envelope of the waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called "double-sideband amplitude modulation" (DSB-AM) to distinguish it from more sophisticated modulation methods also based on AM.


A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects noise and electromagnetic interference in equal proportion to the signal. Increasing the received signal-to-noise ratio, say, by a factor of 10 (a 10 decibel improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to frequency modulation (FM) and digital radio where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast is not favored for music and high fidelity broadcasting, but rather for voice communications and broadcasts (sports, news, talk radio etc.).


Edwin Howard Armstrong (1890-1954) was an American electrical engineer who invented wideband frequency modulation (FM) radio.[11] He patented the regenerative circuit in 1914, the superheterodyne receiver in 1918 and the super-regenerative circuit in 1922.[12] Armstrong presented his paper, "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation", (which first described FM radio) before the New York section of the Institute of Radio Engineers on November 6, 1935. The paper was published in 1936.


As the name implies, wideband FM (WFM) requires a wider signal bandwidth than amplitude modulation by an equivalent modulating signal; this also makes the signal more robust against noise and interference. Frequency modulation is also more robust against signal-amplitude-fading phenomena. As a result, FM was chosen as the modulation standard for high frequency, high fidelity radio transmission, hence the term "FM radio" (although for many years the BBC called it "VHF radio" because commercial FM broadcasting uses part of the VHF band - the FM broadcast band). FM receivers employ a special detector for FM signals and exhibit a phenomenon known as the capture effect, in which the tuner "captures" the stronger of two stations on the same frequency while rejecting the other (compare this with a similar situation on an AM receiver, where both stations can be heard simultaneously). However, frequency drift or a lack of selectivity may cause one station to be overtaken by another on an adjacent channel. Frequency drift was a problem in early (or inexpensive) receivers; inadequate selectivity may affect any tuner.


An FM signal can also be used to carry a stereo signal; this is done with multiplexing and demultiplexing before and after the FM process. The FM modulation and demodulation process is identical in stereo and monaural processes. A high-efficiency radio-frequency switching amplifier can be used to transmit FM signals (and other constant-amplitude signals). For a given signal strength (measured at the receiver antenna), switching amplifiers use less battery power and typically cost less than a linear amplifier. This gives FM another advantage over other modulation methods requiring linear amplifiers, such as AM and QAM.


FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech. Analog TV sound is also broadcast using FM. Narrowband FM is used for voice communications in commercial and amateur radio settings. In broadcast services, where audio fidelity is important, wideband FM is generally used. In two-way radio, narrowband FM (NBFM) is used to conserve bandwidth for land mobile, marine mobile and other radio services.


 

An audio signal (top) may be carried by a carrier signal using AM or FM methods.
AM
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What is Single Side Band or SSB?

 

Single-sideband modulation (SSB) or Single-sideband suppressed-carrier (SSB-SC) is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth.

 

Amplitude modulation produces a modulated output signal that has twice the bandwidth of the original baseband signal. Single-sideband modulation avoids this bandwidth doubling, and the power wasted on a carrier, at the cost of somewhat increased device complexity.

 

My last 10 SSB QSO's are with:

Call SignCountryBandDateTime (UTC)
CE7VPQChile20m07/05/202020:11:00
S57DXSlovenia20m12/07/201915:12:00
S51DXSlovenia20m11/17/201815:10:00
CE1TTChile20m02/04/201721:16:00
VA7SRYCanada20m02/04/201721:14:00
VE7SCCCanada20m02/04/201721:09:00
PY6RTBrazil20m02/04/201721:00:00
EA7GXSpain20m02/04/201720:48:00
MW0ZZKWales40m04/10/201603:27:00
WB9DBDUnited States40m04/09/201623:44:00

 

Only the sidebands contain the information being transmitted. Both the upper and lower sidebands are identical. You only need one of them to extract the modulation information. The RF carrier, which does not contain any information, requires two-thirds fo the total transmission power. By not transmitting the carrier an one of the sidebands, the transmission efficiency is greatly increased and the bandwidth required is decreased.

 

On HF and by agreements worldwide, all stations transmitting SSB use LSB on 160 meters through 75 meters, USB on 60 meters, back to LSB on 40 meters and then all bands above 40 meters use USB. This agreement makes life easy when switching bands. Every one knows which modes are used on which bands.

 

Since the fidelity of the SSB voice transmission has been altered somewhat through various filters in the process of producing the sideband that is not too wide, usually only the most important portions or characteristics of the voice frequencies needed to communicate are allowed through, and this causes the lack of true AM or FM fidelity to the transmission, but the communication, (understandable), portions of the voice characteristics remain, which is all that is needed in the first place. The information contained in the average human voice needed to understand the voice is contained within about the first 3000hz of the human hearing range. Frequencies of the human voice beyond this range are not needed for communication purposes and are filtered out in the modulation process. So the average bandwidth of a SSB signal is about 3000hz wide with all of the voice characteristics needed within that range to be understandable.

 

For further reading, I would like to suggest the Wikipedia page the discusses Single Sideband Modulation as well as the information provided at HamUniverse.com.

An example block diagram of a SSB transmitter is shown on the right SSB Transmitter
An example graphic of the two sidebands and the carrier is shown to the right. AM SSB
One of the transmitters I own is the Flex Radio 3000 Software Defined Radio. One of the cool features is the Panadapter view. This gives me the ability to directly see a SSB modulated signal so I can zero in on a QSO. SDR

 

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