Extra Class Examination Notes | Phase Noise

What is phase noise? I must take into consideration the use of phase-locked loop (PLL) frequency synthesizers according to the Extra Class examination manual (Wolfgang, Reed, & Carman, 2007). This type of oscillator incorporates a feedback loop that samples output frequency then compares the output frequency with the desired frequency. Automatic corrections adjust the oscillator frequency.

I can understand and what about phase noise? The book tells me too think about averages as well as instance that is, on average the oscillator output frequency is near the desired value. Is that meant as desired frequency? However, if I take a sample at any moment, the actual frequency is most likely a little high or a little lower than actual, desired frequency.

Now the light bulb is on inside the mind of KA3DRR and the book follows up. I'm thinking cycles at the moment, "The phase of any cycle is likely to be slightly different from the phase of adjacent cycles" (Wolfgang, et al. 2007, p 4-25).

I'm digging this because when tuning toward a strong signal the receiver noise floor tends to increase according to the manual (Wolfgang, et al. 2007). For example, think outside the receiver passband when tuning a weak signal, and a kilowatt station begins transmitting nearby. There is an increase in receiver noise. Bingo. Its called phase noise.

I thought the nuisances of phase noise ended in the last paragraph? The principle of phase noise applies to the transmitter as well. This type of interference is aptly dubbed splatter. It's like painting RF graffiti inside the receiver.

Understanding receiver specifications is important for me and a limitation to consider is image to image-rejection ratio. I'm breaking this one because I'm a visual learner.

• 2 signals = new signal @ the sum (+) of frequencies & a new signal @ the difference (-) in frequencies.

I'm creating an example based on the manual (Wolfgang, et al. 2007, p 4-26)

• My rcvr uses a 20-MHz local oscillator (LO) for tuning at 30-MHz. The difference (-) is 10-MHz as the intermediate frequency (IF) for my rcvr.
• Suppose a signal at 5-MHz gets into the mixer as well. The sum (+) of the new signal is 10-MHz as well. Houston this is a problem. Why?
• As understood by the KA3DRR mind, the IF for both signals, is 10-MHz and both are amplified in the IF stage. Not good news for me because the 5-MHz signal is known as an image signal. [note: I answered my own question in a previous posting]

Hot Note: Radio frequency (RF) amplifier stage determines the receiver image rejection ratio and must include appropriate filtering for passing of desired signal according to the manual.

73 from the shack.

Reference: Wolfgang L, Reed D, and Carman J (2007). [8th ed.] Extra Class License Manual. ARRL-The national association for amateur radio. Newington, Ct. 06111. (pp 4-25, 26)

Poll Results | Ham Radio Operating Priveleges | Ham Radio License Continuum

My straw poll concluded a few days ago and the results are interesting though unscientific. Let's throw out the following confounding variable(s) that is, everyone who voted, voted only once. Everyone who voted, neither inflated their operating privilege or number of licensed years. That, in fact most but not all who voted, are licensed ham radio operators. And those who were not did not vote beyond no license.

My poll is face valid however I cannot claim reliability.

What Are Your Operating Privileges? (n=197).

• Only 4% of those who voted did not have a license.
• 55% (n=110) who voted are licensed as Extra followed by 33% (n=66) are Generals lastly 6% (n=12) are Technician.
• Perhaps, given the focus of this blog on RadioSport and high frequency (HF) operations, Technician (n=12) are least likely to read KA3DRR.
• I suggest, limited HF privileges for Technician, as an independent variable acting on audience traffic and years licensed. Additionally, one might consider the limited level of Technician activity on HF bands, perhaps expanding HF access may increase the likelihood of retention?

How Long Have You Been Licensed? (n=177).

• Results suggest further support for the on-going discussion regarding the life cycle of ham radio operators. That is, entry-level activity waned as a prototypical operator takes on greater life responsibilities until the mid-life era when responsibilities begin to diminish.
• I did not poll an age variable due to the sensitivity of the data in relationship to the focus of my blog.
• However, one can postulate the median age of a ham radio operator and its correlation with number of years licensed e.g. 58% (n=103) of those polled were licensed 15 years or more.
• Furthermore, ham radio is aging but one might consider the mid-life era as a recruitment platform.
• Consider ham radio's social context as the mid-life era typically results in re-organization of social activities and networks.

I would advocate merging Technician and General into one license. Is there a positive relationship between HF operation and retention? Perhaps. Secondly, re-organize methodologies and focus recruitment resources on the mid-life era.

73 from the shack.

TR4W Contest Logger | Beta Version

RadioSport software developers take a bold leap and make history at the same time. Dmitriy Gulyaev UA4WLI stated, "Approximately on 80 percents program is based on source code of the TR LOG program, kindly given by Larry Tyree N6TR, author of TR LOG and Andrew Melanyin UA3DPX." What does this mean? RadioSport software development is moving toward open source coding. And UA4WLI's TR4W Contest Logger is leading the way. This is an exciting moment for RadioSport. Perhaps new applications will follow based on open source coding of contest logging software in the near future. Right on N6TR, UA3DPX, and UA4LWI. Contest on.

Extra Class Examination Notes | Blocking | Dynamic Range | Intermodulation Distortion (IMD) Dynamic Range

Sensitivity is a basic receiver specification and is understood as the smallest detectable input-signal level.

Selectivity, on the other hand, is defined as a receiver's ability to separate signals and/or reject unwanted signal energy from various locales within the receiver i.e. front end, IF section, audio circuit, or local-oscillator (LO) chain according to the Extra Class license manual (Wolfgang, Reed & Carman, 2007).

What is Blocking and IMD Dynamic Range?

Dynamic Range.

• Dynamic range is receiver capacity and its ability to tolerate strong signals outside the normal passband.
• It is a ratio between minimum discernible signal (MDS) [note: noise figure and sensitivity p 4-18] and the loudest tolerable signal w/out manifestation of audible distortion products.

First Order Response.

• Perfect linear stages produce outputs that change according to the input. For example according to the Extra Class license manual, if an input signal changes by 1dB, the output signal changes by 1 dB hence first order response (Wolfgang, et al. 2007, p 4-20).
• Note: no stage is perfect thus if two or more signals combine new signals are produced at the sum and difference in frequencies of the input signals. My receiver produced intermodulation distortion (IMD) products. [sub-note: intermodulation distortion is not in the manual definition section].
• IMD product frequency and amplitude relies on the order of IMD response therefore first, second, and third-order responses.

Second Order Response.

• My receiver IMD products will change 2dB for every 1dB of input-signal change. {Fascinating}

Third Order Response.

• 3dB for every 1dB of input-signal change. [note: this is an assumption that input-signals are equally level]

Order Responses.

• If input-signal changes by 1dB then output signal changes by 1dB, First order response.
• Second order response is 2dB change for every 1dB of input-signal.
• 3dB for every 1dB of input-signal change, Third order response.

IMD Dynamic Range.

• Measurement of the impact of spurious signal production on the receiver when two or more signals are combined.
• When IMD dynamic range threshold is exceeded then ghost signals appear in the receiver passband along with desired signal.

Blocking Dynamic Range.

• Difference in signal power between noise floor and 1dB signal that causes gain compression in the receiver. [note: when range is exceeded my receiver lost its ability to amplify a weak signal]
• Refer to Figure 4-19 page 4.23 for further explanation.
• Refer to Figure 4.20 page 4.24 regarding dynamic-range performance.

I'm reading my Yaesu FT100 receiver specifications such as sensitivity, image rejection, intermediate frequencies (IF) rejection, and selectivity. Am I looking at image rejection better than 70db {1.8 - 30 MHz} and IF rejection better than 70dB {1.8 - 30 MHz} because any signal greater than 70dB will suppress weak signals in my receiver?

The Extra Class license manual suggested a receiver with poor dynamic range produced IMD and blocking from strong adjacent signals (Wolfgang, et al. 2007).

73 from the shack.

Reference: Wolfgang L, Reed D, and Carman J (2007). [8th ed.] Extra Class License Manual. ARRL-The national association for amateur radio. Newington, Ct. 06111. (pp 4-18, 20)

QST | National Contest Journal | Subscribed

No hesitation. My membership in the American Radio Relay League (ARRL) was renewed and I purchased a National Contest Journal (NCJ) subscription as well. The NCJ is RadioSport knowledge and I'm in a lifelong learning mode. And I wanted to plug into the NCJ USB port so to speak. Likewise, my QST renewal moreso my membership dues, is paid. The ARRL is our best advocate. Numbers speak in Washington and elsewhere. We have spectrum to defend and goals to achieve in the coming decades. I'm looking forward to my first-ever NCJ copy in the near future! Contest on.

VK9X Christmas Island DXpedition | July 8th Thru July 20th

VK9X is in the DXpedition box and I'm ready with 50-watts into copper wire at 30-feet. The VK9X Christmas Island team is, CT1BWW, EA3GHZ, EA5EOR and EC5BME. Their activity plans include 160- thru 10-Meters on the following modes, CW, SSB, SSTV, RTTY, and PSK31 according to ARRL DX News. Additionally, QSL via EA4URE or via home calls for that DXpedition QSL card collection.

For more information about VK9X click here.

73 from the shack.

David, K2DBK said, "As a VE [Volunteer Examiner], one of the things that I suggest..."

Read comment here.

Excellent points and well received.

• Consistently pass practice examinations.
• Score significantly higher than actual passing score.
• Take time and absorb the material.
• Confidence with the study material, consistently passing practice examinations in the high 90s, and reading for practical knowledge breeds success.

I'm looking forward to immersing myself in the material this weekend and taking at least one practice examination.

Thanks for the comment!

73 from the shack.

2008 Field Day

Sometimes a challenge presents in an interesting way and Yoda said something along this line in The Empire Strikes Back, "Either you do or do not."

Field Day began in earnest and Larry, W7CB presented the Extra Class examination challenge. The words of Yoda drifted through my thoughts. Either I do or I do not. No one would really care except for me and I confronted the question, "What if I do not succeed?"

Remember the scene in Empire Strikes Back when Yoda challenged Luke to lift his X-wing fighter from the swamp? And how Luke responded?

Later in the film, Yoda demanded young Luke be prepared for the next step, his confrontation with Darth Vader. In the meantime, I knew in my ham radio bones that preparedness is essential when confronting the Extra Class examination. And prepared I was not.

Too many gaps in my knowledge. Too little time in the book. What if I took the examination anyways? Certainly, a remote possibility existed somewhere in the thousands but if I did not, I would never know. Times have really changed since sitting down in the Federal Communication Commission's examination room in Buffalo, New York. That was almost 30-years ago.

I took the examination in the great outdoors while a nice northwesterly breeze made Field Day bearable in Templeton, California. I filled out the necessary paperwork and opened the exam. My testing anxiety faded giving way to, "I know that question" or "I understand that problem."

Yet the gaps in my knowledge and too little time in the book presented to big an obstacle. I felt frustrated like one is close but not close enough. And that is not good enough. I scored in the low 50-percent just like the practice examinations. Interesting but not unremarkable.

What I took away besides meeting extraordinary people who are ham radio operators during Field Day weekend? I can pass the Extra Class examination in the very near future. And I want that lower 25 kHz really bad.

73 from the shack.

Don, AC7FA said "[We]...may have worked you as W7DK."

Read comment here.

I bet we worked each other on 80-Meter CW underneath that blazing starry sky. Every hertz on the band enjoyed a signal. It was as congested as the 405 in Los Angeles. I tuned up around 11 o'clock in the evening and what a hoot! The N1MM rate meter pegged at 60-plus. However, keeping in mind accuracy counted as if one is handling emergency traffic and getting the exchange correct, was utmost on my mind.

I finally ran out of voltage around 2 o'clock in the morning and bunked out in the back of my Explorer. I left the light on for Larry, W7CB who picked up on 80-Meter LSB, a little later. He scored a phenomenal two-hours of continuous traffic.

Don, many thanks goes out to W7DK and yourself, for adding a traffic QSO to the W6R Field Day log.

73 from the shack.

2008 Field Day

I enjoyed a lot of ham radio fun this weekend as Field Day 2008 roared across the ionosphere. There is much to talk about and this week will cover my W6R operating experience. Many thanks to Paso Robles Amateur Radio Club (PRARC) for their hard work and stellar attitude. A big thanks goes out to Larry, W7CB who welcomed me with the spirit of ham radio. I had a 4-star good time operating 40- and 80-Meter CW/LSB with Larry's Kenwood TS930S into a dipole at 35-feet. I briefly operated 20-Meter CW in the evening with Ron, W6FM's IC-756 Pro III as well. And too those who worked diligently in the background providing logistical support? A hardy right on! How does one start? Always from the beginning...