CHAPTER 3

630m RECEIVERS AND

DECODERS FOR 630m MODES

Chapter 3

630m Receivers and Decoders for 630m Modes

8/18/16 Larry, W7IUV / WH2XGP…was performing receiver comparisons between the

Kenwood 590 (WH2XGP) and SDRPlay (W7IUV). Larry reported high noise but massive

local signals. He decoded four WSPR stations overnight and was decoded by 21 unique stations.

4/12/16 Merv, K9FD/KH6, [WH2XCR] is reported by right up to his sunrise by VK2XGJ and

VK2DDI and continues to have two-way reports with VK4YB and VK3ELV. The path to

Australia appears to peak earlier in the session. John, VK2XGJ, provided a screen shot (shown

below) of his WSPR console showing numerous high S/N reports for Merv’s signal very early in

the evening in Australia. He notes that “The receiver is my dear old WJ 8718a and #1 Mini-

whip.” Mainland activity was typical including reports from WG2XJM. The salt water path to

and from WE2XPQ continues to be strong.

http://watkins-johnson.terryo.org/WJ-Receivers/WJ-8718.htm

http://www.shortwaveradio.ch/radio-e/watkins-johnson-wj8718-e.htm

http://bama.edebris.com/manuals/watjohn/wj8718

8/6/16 630M RX SETUPS IN CAYMAN ISLANDS

In the Caribbean, Eden, ZF1EJ, operated two receivers, ZF1EJ and ZF1EJ/1. Historically Eden

has operated in this configuration with “ZF1EJ receiving on Elad Duo and Log antenna and

ZF1EJ/1 receiving FTDX-3000 and Mag Loop.”. Unless otherwise noted, this configuration is

the same.

ZF1EJ 24-hour WSPR activity ZF1EJ/1 24-hour WSPR activity

11/3/16 MULTIPLE SOFTWARE INSTANCES OF WSPR AND JT9

Larry, W7IUV / WH2XGP, posed a question to Joe, K1JT, about maintaining settings in

WSJTx when switching between WSPR and JT. Many of us have experienced problems with

transmit frequencies when switching between modes. Joe offers this solution:

“1. Use the *Configurations* menu to create separate configurations for JT9 and

WSPR. See the User Guide picture at Section 10.1.3. This will take several steps: you

clone an existing Configuration, say “Default”; you rename the copy as desired; then you

switch to the renamed copy. Do these steps twice — you can name the two JT9 and WSPR,

or whatever.

2. Thereafter, switch between modes by switching Configurations. This way, all setup

parameters are saved and restored separately for each mode, and I think you’ll get a “clean”

start when you switch modes.”

2/2/17 PROPOSAL: DUAL-MODE RECEPTION OF JT9 AND WSPR

Neil, W0YSE/7 / WG2XSV, posted the following proposal on the 600-meter research group

and is requesting input:

“Most of you are receiving (and some are TXing) WSPR on 630m. We are all hoping (and

expecting) being granted Part 97 amateur privileges there soon. When that happens I think JT9

will be one of the most used QSO modes as far as weak signals are concerned, especially for

DX. I usually have TWO programs running nightly on 630m, WSPR 4 and WSJT-X (for JT9)

running side by side on my screen. I would love to see many others do the same so that we

could send out JT9 beacon signals occasionally to see how it is propagating using PSKreporter

similar to WSPRNET.org What do you think? Feedback welcome…”

8/19/16 FOUR RXs RUNNING AT ONCE!

Laurence, KL7L / WE2XPQ, reports that the “Lake probe moved to tree on Eastern fringes of

Kingdom – darn underground dog fence harmonics N x 8kHz much louder here – I’ll run it and

see how it performs against “AcesHigh”probe.” Laurence indicated yesterday that it took him

three years to find the high clear “AcesHigh” probe location. He was “receive-only” during this

session and provided the following additional comments:

“I was running 4 instances last night to check decoders and the move around the block

probe ensuring I have the best sweet spot – no changes to-date my high probe relatively

close to the lake still has it to date.”

Laurence also noted a bit of drift on a few stations during the session:

A bit of drift on a Friday morning as observed on an R75, the high probe and battery power

Laurence also sent an aerial photo annotated with receive antenna locations:

WE2XPQ/1 24-hour WSPR activity WE2XPQ 24-hour WSPR activity

WG2XXM, as reported by WE2XPQ/1

KL7L 24-hour WSPR activity KL7L/1 24-hour WSPR activity

8/20/16 Laurence, KL7L / WE2XPQ, operated four sessions again, this time moving the

travelling probe (TalktomeGoose) to a new location that seems quiet enough. He spent a lot of

time looking for the right location and moved the antenna a number of times during the

process. Laurence is hearing well, providing reports for VK4YB during the session. He also

notes that “TalktomeGoose had one more VK4YB (spot) but average wasn’t as good s/n as

AcesHigh.” Laurence provided the following map showing the relative location of the travelling

probe to the high, clear probe:

8/7/16 EJTSWL WSPR2 DECODES IN QUEENSLAND

Edgar, EJTSWL, currently operating portably from Rolleston, QLD, has been reporting a

number of stations and posting screen captures to dropbox... His view of VK4YB, VK5ABN,

and VK3ELV:

VK4YB, as reported by EJTSWL

VK5ABN (top) and VK3ELV (bottom), as reported by EJTSWL

9/3/16 Edgar, EJTSWL, in Tasmania …had early reports from North America:

6/1/16 RECEIVING QRSS ON 630M WITH ARGO

Several modes--WSPR15 and very slow CW (QRSS) among others--can penetrate noise

down to deep -30dB to -40dB SNR (2.5KHz noise bandwidth, QRSS60+). Late spring and early

summer are good times to experiment with these modes on LF/MF. A narrow bandwidth allows

more noise rejection, and slowing down the information rate give you narrower bandwidth ~ 1

Hertz or less.

Today, let’s highlight QRSS. Use ON4KST reflector or 600mrg reflector to find and work

with a buddy LF/MF transmitting station who sends or will send you QRSS on 630m. The

transmit station uses a local oscillator that’s rock-stable over minutes of call-sign transmission

and hours of a session. A programmed microprocessor controls the transmitter to send QRSS at

a selectable speed.

Beforehand, do some self-training and station setup at your end. See the endnote* links to

web sites for more QRSS insights.

To set up for QRSS, I turn receiver AGC off and set RF gain and Audio Gain to hear the

noise level. Either CW or USB mode is selected to receive QRSS as audio tones. View the

ARGO screen starting with regular CW speed and then increase the QRSS# mode until you see

the QRSS signal as lines and spaces.

To get some experience with ARGO, experiment with it on 30m first with CW around

10110KHz and then QRSS at 10140.0 KHz. If you don’t already have the free QRSS display

software, download and install ARGO from http://www.sdradio.eu/weaksignals/argo/index.html

A white-on-red Argo sailboat icon should appear on your PC desktop. Click the ARGO icon to

run the program.

If its vertical waterfall or horizontal curtain display has not already started, click the

Start/Stop button in the lower right corner of the ARGO screen. To transition from the

horizontal curtain display to the vertical waterfall display, click the top-center box “Full Band

View.” To transition back to the horizontal curtain display, mouse-click in the center of the

ARGO screen.

In the ARGO “Setup” menu choose “Select Sound Card.” Then test ARGO on an HF band

by tuning your receiver to a CW station and look for that CW station on the display. ARGO is

audio display software that monitors the audio path of a PC soundcard. The HF or MF/LF band

you pick is controlled by your receiver.

At ARGO toolbar top left, pull down the Mode menu and select the first menu item “CW

(NDB)”. The horizontal curtain display shows the CW signal proceeding from left to right in

real time. If the CW signal is audibly clear but looks noisy on the display, adjust ARGO’s

Sensitivity bar or the audio gain of the RX.

At lower left, ARGO’s radio buttons for Visual Gain are labeled AGC, Lo, and Hi. Choose

which button gives you the clearest display. Mouse-adjust the Sensitivity and Contrast bars to

give a clear CW display.

Selecting Mode to be a QRSS mode will smear regular CW into extended lines on the

display for the signal. In QRSS10 mode, ARGO’s display literally slows down relative to CW

mode and QRSS3 mode. And for QRSS transmissions, the slow-down should be enough so that

the QRSS lines and spaces will be visible.

Put the Argo menu Speed on Slow for better resolution (this is not a different QRSS

speed). However, for fast CW, put Speed on Fast to space out the dits and dahs. Check to see if

you should increase the Sensitivity bar at bottom of Argo screen as the QRSS mode is increased

from 3 to 10 to 20, etc.

Use the Mode menu “User Specified Ticks” of Argo for 60 second or longer intervals at

QRSS10 mode and slower modes, to visually space apart time legends and their vertical dotted

lines.

On MF/LF you can test ARGO by observing WSPR signals using the QRSS10 mode.

WSPR2 looks like a series of fuzzy rectangles each 5 Hertz high and 2 minutes long

horizontally.

If your antenna and receiver with a display like ARGO can see WSPR stations on

630/2200m, you're ready to experiment with QRSS on these bands. Compared to WSPR's 'wide'

5 Hertz bandwidth, high QRSS modes can do better because QRSS lines from a stable

transmitter are very narrow and more easily resolved in noise.

I’ll go deeper into QRSS and ARGO in another blog post. In the meantime, peruse some

of the good information on QRSS on these web sites!

*QRSS WEB SITES

http://www.ka7oei.com/qrss1.html Intro to QRSS and software.

http://members.shaw.ca/ve7sl/136.html Scroll 70% for LF QRSS, links at bottom.

http://www.qsl.net/dl4yhf/spectra1.html Spectrum Lab.

http://www.w0ch.net/qrss/qrss.htm Intro to QRSS.

http://www.qsl.net/on7yd/136narro.htm QRSS white paper. Screenshots.

6/2/16 QRSS: DIGGING DEEPER

Yesterday’s June 1 blog described ARGO setup for QRSS and offered links for learning this

mode. You can see 630m QRSS screenshots and discussion in the KB5NJD blog many days this

season. (Blog-search keyword “wa2xrm” and then search "qrss" for rest of season). TABLE 1

gives some QRSS stations, paths and highlights.

Since QRSS is detected visually using display software, the pixels need to stand out

contrastingly on the screen against the noise background. Such contrast is best when the slant of

the QRSS line on the screen slopes up or down as little as possible, and no more than about 45

degrees.

The TX station operator should provide frequency stability so that short-timescale drift on

key-down stays within TABLE 2 drift rates. Likewise the RX station operator needs excellent

stability since it's the sum of the TX and RX drift that ARGO "sees." Such short-time stability is

vital to realize the high image contrast you need to probe deep daytime SNR, stormy nighttime

SNR, and long path storm-free nighttime SNR all year around.

The TX+RX short term drift constraints imposed by TABLE 2 go inverse-square of the

QRSS mode number, first, because the pixels need to be compacted both vertically and

horizontally. Secondly, at a given drift rate, every increase of mode number increases the slope

because ARGO shortens the time axis and stretches the vertical frequency axis. If the mode

number doubles, the slope quadruples. That quadruples ARGO’s demand for TX frequency

stability—and RX frequency stability for that matter.

Long-timescale drift over session hours should stay within one-half of an ARGO screen’s

frequency visibility range for reception convenience. Unless the receiving operator attends the

receiver to reset the frequency or uses a technique I recommend below, the higher QRSS modes

may drift up/down off the ARGO screen during an extended session unless stability is adequate.

What can you do as a QRSS TX op? Network with other QRSS ops and elmer those less

experienced who ask your advice. How do you make an inexpensive homebrew crystal oven,

where do you get affordable equipment, and other tips. Use 600mrg and ON4KST reflectors to

link up and schedule with other MF/LF ops.

What can you do as a QRSS RX op? RX stability is vital, so start with a well-chosen RX.

Also, as you know, ARGO is mainly an audio display, not a digimode decoder. That means you

can observe the same QRSS transmission under more than one ARGO QRSS “mode” selection.

Since you can’t control the frequency stability of the remote QRSS transmit station, I leverage

ARGO’s multiple-instance capability. What’s that?

Depending on the QRSS#, I open ARGO five times to nine times by repeat-clicking the

ARGO icon on the PC desktop after getting each ARGO display already. This strategy has you

set each ARGO instance to the same expected QRSS mode but each to a different overlapping

frequency range. As a whole, the 5-9 ARGO screens cover not only an expected TX frequency

but also frequencies above and below it into which the TX might drift.

Multiple ARGO screens also help find the TX when either the TX op or RX op can't

locally measure absolute frequency to nearest 1 Hertz or less. That way, even at higher QRSS#,

ARGO provides a robust RX display capability. Additionally, I open one or two instances of

ARGO at one or two lower QRSS numbers for further display flexibility.

QRSS rewards patience and experience. QRSS encourages transmissions that use a few

symbols to signify a lot of information. You can see examples of such symbolism in the various

blog posts. Frequency is an important station indicator even when you can’t make out the call

letters. Tell us your QRSS experiences! More tomorrow.

TABLE 1: SCREENSHOTS OF 630M QRSS 2015-16 SEASON (nowhere near exhaustive)

BlogDate TX QRSS# TIME* PATH* RX REMARKS

11/30 WA2XRM 3 02z CO-MT/AR WH2XNV/W5EST

12/01 WA2XRM 30 06z CO-IN SWL/K9

12/02 WG2XIQ 10 14z TX-IN/TN SWL/K9, KU4XR ~sunrise

12/02 WG2XIQ 30 20z-22z TX-TN/AR KU4XR, W5EST ~ sundown

12/06 WA2XRM 30 01z CO-AR W5EST

12/12 WA2XRM 120 02z-05z CO-IL K3SIW

12/12 WA2XRM 120 08z-12z CO-AR W5EST

1/3/16 G0MRF/p 3 QSO. UK-GR SV8CS, SV3DVO

1/3/16 VO1NA 3 02z NL-UK G0MRF/p

1/9/16 VE3OT 6 22z ON-PA WA3TTS

1/9/16 WH2XHA 3 22z PA-PA WA3TTS

1/10/16 VE3OT 6 ON-BC/TX VE7SL, WG2XIQ

1/13/16 WG2XIQ 30 23z TX-PA WG2XJM XIQ ran 100mw

1/15/16 VO1NA 10 02z NL-FR/NE F1AFJ, PA0RDT

1/29/16 VO1NA 3 nite to 06z NL-NE PA0RDT

2/11/16 WG2XIQ 10 04z TX-OR WG2XSV

2/17/16 F4DTL 3 21z FR-SP/GR EA5DOM, SV8CS

3/8/16 9H1BT 3 QSO. UK-Malta G3YXM also see 2/26/16 blog

*Times and Paths do not represent maximum capabilities of each QRSS#.

TABLE 2: DISPLAY SLANT ANGLE MAX.=45°: DRIFT VS. QRSS#

QRSS# MAX. 10/60min DRIFT** HALF-SCREEN FREQ RANGE

60 500/3000 mHz 2500 mHz

120 125/ 750 mHz 1200 mHz

600 5/ 30 mHz 240 mHz

1200 1/ 7 mHz 120 mHz

** Formula: Max Drift = (750mHz/hr) (120/M)2 where M is QRSS mode #.

6/3/16 COMPARE QRSS AND WSPR POWER LEVELS: DIGGING STILL DEEPER

Yesterday’s June 1-2 blogs tell some 2015-16 season highlights and TX+RX frequency drift

constraints when using ARGO to display QRSS. For best image contrast, QRSS lines should

slant up or down no more than 45° at the highest QRSS mode number in use. To prepare for a

receiving run, open ARGO five times to nine times, each instance corresponding to a different

overlapping frequency range and with the instances collectively centered around the expected

transmitter frequency.

Now let’s confront the question of what QRSS EIRP compared to WSPR EIRP can achieve

particular relative levels of SNR. Remarkably, this question involves neither propagation nor

station antennas/equipment. Both QRSS and WSPR are processed with audio software, so the

path to the answer amounts to a comparison of the software results.

A year ago, about 9:30pm CDT on June 2, 2015, I monitored 50mw QRSS60 from

WG2XIQ on the north Texas to Little Rock, Arkansas, path and got an acceptably visible trace

on ARGO—not faint and not boldly bright. See illustration, center, compared to WSPR at right.*

Think about it—50 milliwatts of QRSS60 gave visibility on ARGO when it took 5 watts of WSPR to

deliver a modest -22dB SNR under similar band conditions to one same RX and its antenna. Yes, the

data rate of QRSS60 is less than WSPR2, but the QRPPP QRSS60 signal was visibly readable!

John’s 50mw (17dBm) flea power was 20dB down from his 5 watt (37dBm) WSPR power

that yielded -22dB SNR. That -22dB SNR is well above the WSPR threshold, with lots of room

above it for stronger signals too. So I took these power levels—17dBm QRSS60 and 37dBm

WSPR--as corresponding to each other in some sense for practical experimental purposes to power-

wise relate a given QRSS mode number to WSPR. This information allowed me to fit a constant C60

= 42dB for QRSS60 in the below formula that in general depends on mode number # of QRSS:

SNRwspr= PTXwspr – PTXqrss# – C# (1)

With that constant -22dB = 37dBm – 17dBm -42dB, showing that Formula (1) works with

C#=42dB at QRSS60.

The above formula (1) makes sense because WSPR SNR should increase with WSPR

transmit power. Moreover, formula (1) also makes sense because it rearranges to give an

equivalent formula (2) that finds the QRSS TX Power PTXqrss# that corresponds to such WSPR TX

power PTXwspr.

PTXqrss# = PTXwspr - SNRwspr – C# (2)

Inspection of formula (2) shows that if band conditions changed so that more WSPR power

were needed to get the same SNR, then correspondingly more QRSS# power would be needed to

maintain visibility on ARGO. (Remember when using formula (2) that –SNRwspr is positive

when SNRwspr itself is negative.) Likewise, if band conditions similarly changed so the same

WSPR transmit power would get less SNR, then correspondingly more QRSS# power is still

needed to maintain visibility on ARGO.

Today’s TABLE shows values of constants C# that I’ve estimated to apply in the

formulas. To interpret them, imagine that one might use the same QRSS# transmit power as for

WSPR (and not go QRPPP). Then SNRwspr = – C#. In words, the TABLE indicates the

visualizing power of a given QRSS# to probe deep into noise: -42dB at QRSS60!

If, say, 5 watts WSPR delivered a WSPR-undecodable -42dB actual SNR, the TABLE

suggests 5 watts of QRSS60 could nevertheless deliver a visible ARGO image. And higher

QRSS modes could probe even deeper into noise and penetrate exceedingly challenging

propagation conditions.

To obtain the constants C#, I assumed that the QRSS power needed to get the same

visibility is proportional to the QRSS bandwidth, which is inversely proportional to the QRSS

mode number #. The TABLE converts that concept to dB, using the observed 42dB at QRSS60

as reference. The TABLE assumes apples-to-apples comparison of each QRSS# to have its

pixels distributed on the screen the same way.

From another viewpoint, the TABLE imagines that the number of signal pixels increases

with the QRSS#. Apples-to-apples, if the pixels are distributed the same way on the display

screen, then they get brighter with increasing QRSS#. The eye sees their brightness in a way

related to dB, I presume. Since my observation of XIQ at QRSS60 is subject to some error and

the psychometric properties of human vision are involved, the TABLE can only be approximate

and subject to improvement. But it’s a start.

TABLE : QRSS MODE-SPECIFIC CONSTANTS FOR POWER AND SNR FORMULAS

QRSS MODE C#

3 C3 = 30dB

10 C10 = 34dB

20 C20 = 37dB

30 C30 = 39dB

60 C60 = 42dB

120 C120 = 45dB

600 C600 = 52dB

1200 C1200=55dB * Composite screen shot shows WG2XIQ QRSS60 at left with some chopping and fading, probably due to propagation

variations and the considerable lightning static from east coast and Nebraska. G33DDC dial was set to 473.000 KHz, so

ARGO 1500 Hz delivers 474.500 KHz. For this run, ARGO display gain was set to 35 with Visual Gain button set to “AGC.” WSPR decoder has its volume

slider set at 55% (just over halfway up). The RX audio output was set to make the WSPR decoder's green volume-bar

indicator just reach 100% of its bar-slot. G33DDC dial was then reset to 474.109 KHz to center XIQ’s 6 Hertz wide 475.609 KHz WSPR signal around 1500

Hz on ARGO. At right in the screen shot, ARGO imaged the WG2XIQ 5W WSPR signal. XIQ 5W WSPR shows

comparable ARGO image contrast to earlier 50mw QRSS. The signal curvature indicates TX and/or RX frequency is

settling after the QSY to WSPR.

6/4/16 EXPLORE 630M DAYTIME WITH QRSS

The June 1-3 blogs sample some of the QRSS activity and insights available to 630m

operators. Today, let’s use QRSS to make a path loss rough estimate on a 630m short path in

December daytime afternoon relative to nighttime.

Some days that December time of year, 630m daytime propagation events open up the

band. By contrast, the focus here is on a more ordinary day when little or nothing gets through

on 630m WSPR2. 630m is the specific subject today. That’s because 2200m is open more

often in the daytime over even relatively long single-hop paths.

Recall from yesterday’s blog that the TABLE there indicated the lowest negative SNR that

QRSS can probe and still be readable or visible on the ARGO horizontal curtain display. For

QRSS30, that number was tabulated -39dB. For QRSS10, the TABLE entry is -34dB, or 5dB

less sensitive.

On December 1, 2015, 5 watt WG2XIQ near Dallas transmitted QRSS30 in the afternoon

and was visible here at W5EST in Little Rock, see illustration and endnotes.* That means the

SNR was at least as favorable as -39dB. XIQ’s QRSS10 daytime signal was unreadable, so the

SNR was no better than -34dB. The error in the SNR, with some likely error in yesterday’s QRSS

TABLE included, is accordingly estimated to be -39dB +/- 5dB SNR.

Because SNR depends on the characteristics of both the TX and RX stations, estimating the

daytime SNR alone tells whether the signal can be received, but not much more about the

ionosphere. The next step in this daytime study compares that daytime SNR with SNR in the evening

and takes the difference. Taking the difference of SNRs eliminates effects of the TX and RX station

constructions and leads to a dB path loss difference between daytime afternoon and evening

nighttime.

That December evening XIQ transmitted 5 watts WSPR2 at same power as he had used for

QRSS. His SNR at W5EST reached -5dB WSPR SNR by 0044z (1.4hr after XIQ sunset SS). XIQ

peaked at +2dB at 0732z (1:32am). I adopted the evening SNR -5dB at 0044z as more representative

for comparison purposes.

Next I subtracted the daytime afternoon estimated -39dB+/-5dB SNR from the -5dB XIQ WSPR

SNR at W5EST 0044z. I interpret the difference as D-layer absorption. The result is 34dB +/-5dB of

D-layer absorption on the 485km Dallas-Little Rock path, at roughly 38° ray elevation angle, in

the afternoon of December 1, 2015.

This is good news for 630m! The D-layer is not a daytime brick wall that would have

stopped QRSS30 on an ordinary December afternoon. It didn't.

One might ask whether the signal received over this 485km short path was only daytime ground

wave. Was there any received sky wave out there with which to measure D-layer absorption. By way

of answer, concurrently KU4XR at 1235km did receive WG2XIQ’s daytime signal (reported 12/2/15

blog). If some XIQ ground wave reached W5EST, it may have offset some D-layer absorption in the

calculation, but the stated error allows for D-layer absorption possibly higher than 34dB. Also, you

could object that the KU4XR reception signified a 630m daytime propagation event, but daytime

630m events yield WSPR SNRs into the -20s and even the weak teens.

Can you extend or improve upon this SNR differencing method? What would be the daytime

absorption other times of day and other times of year, like now? What can you tell us? GL! *NOTES: WG2XIQ QRSS AS RECEIVED AT W5EST 12/1/15 Time Remarks 12/1/2015 2258z AR SS. 2320z Dallas TX SS. 485 km. 2150-2222z 3 faint unreadable arcs 474.521KHz: TXd qrss10 "XIQ" (5min/arc), RX/argo qrss30 slow. 2224-2242z In "XIQ": the X is faint daytime prop, and solid IQ is pre-SS prop. prior to LR AR SS. TXd qrss30 "XIQ" once per 15min arc. RX/argo qrss30 slow. 2250-2306z 2nd "XIQ": the dahs in X suffered prop. "I" marks LR AR SS. Prop gives artistic view of an arch as if viewed from the air."Q" is only slightly rippled by QSB. ARGO VisGain 32 noise on dark navy background. ---------------------------------------------------------------------------------------------------------------------- (W5EST G33DDC RX dial 473.000 & ARGO 1520 Hz +/- 5 Hz received on noise-cancelled bent 80m attic dipole

connected as vertical antenna made of twinlead and top hat.)

5/23/16

PART 1: VOLTAGE AND POWER ACROSS A SPECTRUM IN THE 630/2200M BANDS

The May 17 blog discussed rms, average, peak, and peak-to-peak current or voltage

measures. The way some of them relate to each other and to power can depend on whether the

waveform is a sine wave (single frequency) or not. What happens when there are multiple

frequencies?

Fortunately, if a 630m transmitter conveys very little power in harmonics to the antenna

system, there is no practical reason to determine the combined power of harmonics and main

signal. Harmonic suppression instead is measured in relative terms--dB down from the main

signal—and the more suppression the better. You don't want a 2nd or 3rd harmonic of 630m that

would land in the broadcast band!

Turning now to multiple frequencies in-band on 630/2200m, modes like CW, QRSS, WSPR

and several other modes stay on the same frequency for tens or hundreds of milliseconds, or

more, at a time before shifting to some nearby frequency for a similarly long time. You can

speak of current and power values even when the signal assumes one frequency after another like

WSPR does in its 6 Hz bandwidth.

If there’s a duty cycle D where the RF signal is on and off, then the average power P

compared to the on-power is P = D x PON . Generally on MF/LF, however, one simply states PON

itself (in dBm or watts) and duty cycle D itself, as in WSPR transmit percentage TxPct.

Okay, so we essentially regard multiple transmit frequencies less than a few Hertz apart as

if they were a single frequency, right? Generally, yes, on the 630/2200m transmit side.

It’s the receive side I want to emphasize today and tomorrow. NOISE! Band noise is spread

all across the dial. So are lightning and static crashes. Multiple noise sources from the sky,

ground wave noise from the local region, neighborhood and home noise. Random noises (of

various noise colors), and deterministic noises. Noises from AC power lines, cars, motorized

appliances, TVs, computers. Noise plus signal itself. Regarding noise, how do we talk about

voltage, current and power?

Keep in mind that the concepts of rms, average, peak, and peak-to-peak pertain to the

waveform--the graph of voltage or current versus time. When talking about noise, I’ll focus on

rms and power because, no matter what the waveform of signal and/or noise, rms governs these

formulas:

P = Irms2 R = Vrms

2/R

P(dBm) = 10 log10 (P/.001 watt) = 10 log10 (P watts) + 30 dBm

Suppose you have a 1 microvolt rms signal S at the 50Ω input to your RX. How many dBm?

P(1uVrms ) dBm = 10 log10 [(Vrms2/R)/.001 watt) = 10 log10 [(10-6 voltsrms)

2/50Ω)/ 10-3 watt)

P(1 uVrms) dBm = -107dBm.

P(10 uVrms) dBm = -87dBm.

P(0.1 uVrms) dBm = -127dBm, etc.

How do we calculate for 1 microvolt rms of noise N? Same way! Waveform doesn’t matter.

But wait—what happens if you filter the noise? Usually, noise is such a squirrelly mess that

it’s spread evenly over a range of frequencies in the receiver bandpass. So we conventionally,

arbitrarily, speak of the noise power in a 2.5 KHz reception bandwidth. Signal-to-noise ratio is

the difference in dB of the signal power minus the noise power.

SNR(dB) = S(dBm) – N(dBm)

WSPR SNR is SNR referenced to noise power in a 2.5 KHz bandwidth. That’s 2500 Hz

bandwidth, which is far wider than the entire 200 Hz WSPR2 band on 630m or 2200m.

The WSPR decoder gives a lot of negative dB reports because it measures noise power as if

received across that 2500Hz bandwidth. If you have a receiver that can filter IF noise and/or

audio noise to less than that 2.5 KHz, 2500 Hz, then the WSPR decoder simply assumes the

reduced noise still covers 2500 Hz and increases or artificially strengthens the reported SNR

accordingly.

Negative WSPR SNR does not mean, though, that the signal is necessarily buried in the noise

on an RX waterfall or spectrum display. Suppose the software can resolve the spectrum into 10

Hz segments or bins, one of which contains your desired signal. A -20dB SNR signal, the way

that the WSPR decoder reports it, may nevertheless visually poke up about 4dB above the noise

level on the display. That’s because 4dB ~= -20dB + 10 log10(2500Hz/10Hz). There’s one-250th

the noise power in the 10Hz bin than there is in a 2500Hz bandwidth, but signal power is just as

much in the bin as in a 2500Hz bandwidth.

*https://en.wikipedia.org/wiki/Signal-to-noise_ratio

5/24/16 PART 2: HOW SIGNAL AND NOISE VOLTAGES AND POWER COMBINE

How does noise combine with other noise and how do waveforms combine with each other

generally? Noise is a big deal on 630/2200m and we try to obtain the most favorable signal-to-

noise ratio SNR that we can.

For our purposes, and with apologies to statistical gurus,* let me start with what I mean by

two waveforms being uncorrelated or correlated. I’m looking for insights that might promote

noise reduction or cancellation.

If, for each instantaneous value in one of two waveforms, the other waveform’s voltage (or

current) is equally likely to be positive or negative in value for every magnitude of the voltage

(or current) you name, the two waveforms are uncorrelated. When either waveform is the same

as the other one multiplied by an appropriate positive or negative scaling factor, the two

waveforms are correlated. (In this blog post, “correlated” does NOT require use of a so-called

correlator circuit.) You can cancel correlated waveforms with a phaser or canceller circuit, and

can’t cancel uncorrelated waveforms.

Correlated waveforms add their rms values. 2+1=3, 3+2=5, etc. Subtract rms to do partial

or complete cancellation: 2-1=1; 2-2=0.

By contrast, neither adding nor subtracting a first waveform to/from a second waveform

that’s uncorrelated with the first waveform makes them any less uncorrelated. You just get some

waveshape with additional rms either way. A sum of squares is involved because power P =

Irms2R = Vrms

2/R, and summing various power contributions means summing squares of currents

or voltages. A square root “sqrt” returns you to rms of the combined uncorrelated currents.

Uncorrelated “2+1” = sqrt(22+(+1)2) = sqrt(5) = 2.36.

Uncorrelated “2-1” = sqrt(22+(-1)2) = sqrt(5) = 2.36, same thing.

For our purposes, sine waves of different frequencies, and non-overlapping spectra in general,

are also uncorrelated.

A correlation coefficient r (or Greek letter rho ρ) numerically represents the degree to which

two waveforms are correlated. Correlation coefficient r resembles the idea of phase as regards a

sine wave. However, the correlation idea is not only pertinent to sine waves but also to other

waveshapes besides sine waves. And noise certainly is not a sine wave.

Two waveforms V1 and V2 can be divided into correlated and uncorrelated parts relative to

each other. Similarly, sine waves of identical frequency can be divided into 90° phased apart

waveforms (uncorrelated, r=0) and remainder waveforms in-phase (correlated, phase 0° or 180°,

r=+/-1.0). If a waveform V1 is a mixture of correlated and uncorrelated waveforms relative to

waveform V2, then a value for a correlation coefficient r takes a value somewhere between 0 and

plus or minus 1.

To get the power in a resistance R like a 50Ω receiver, think Irms2R. You get the power

produced by the sum of two current waveforms I1 and I2 as follows:

1) Square the sum of the rms values of the correlated currents themselves.

2) Add the squares of the rms values of the uncorrelated currents to get another sum.

3) Take the total of sum (1) plus sum (2).

] 4A) Multiply the total from step (3) times resistance R.

P = R [ ( I1corr + I2corr)2 + I1uncorr

2 + I2uncorr

2 ]

4B) For voltage waveforms V1 and V2, it works the same way except divide the total by R.

P = (1/R) [ (V1corr+V2corr)2 + V1uncorr

2 +V2uncorr

2 ]

If the correlated waveform portions might have opposite sign, the correlated portions will cancel

power out of each other when the waveforms are combined.

V1corr= -V2corr means V1corr + V2corr = 0.

Think of one waveform’s rms as negative in that case, if you like.

If you can provide two correlated versions of a significant portion of the noise power that’s in

the receiver bandpass, you can reduce or cancel the correlated noise power portion by in-phase

subtraction or 180° out-of-phase addition. More about noise cancellation in another blog post!

* https://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient (See

illustrations, for instance. My definition is sufficient for our radio purposes, but some other wiki-

illustrated instances also yield no-correlation r=0. I also assume the MF/LF signal and noise

waveforms have zero DC level.)

5/25/16 PART 3: NOISE CANCELLING, PRELIMINARY CONSIDERATIONS

Reception of MF/LF radio signals is hampered by the presence of noise from a variety of

local and distant sources. When a radio receiver apparatus has sufficient gain in its amplifiers to

adjust the received signal to a desired level, the noise is likely also increased along with the

signal. Accordingly, signal-to-noise ratio (SNR) is a better measure of reception quality than

mere receiver gain.

Let’s start by improving signal S in the signal to noise ratio S/N (SNR) picture. After

that, we can start talking about band noise reduction. I’m assuming that one has already put up

the antenna(s) in a reasonably low-noise location and eliminated local QRN or rejected noise and

common-mode through antenna and ATU/coupler construction and careful grounding practices.

One achieves adequate total radiated power at the outset with a vertical

antenna establishing favorably-high degree-amperes by both a tall height of the vertical and RF

current uniformity due to a top hat (this blog April 2, 3, 4). Degree-amperes strongly affect the

radiation resistance and the radiated power level.

Unfortunately, even with adequate radiated power, if the RF is mostly being launched at

angles exceeding 10° elevation, then very little of the radiated power will be coupled into long

paths. For long path transmission, the issue of low-angle elevation pattern importantly confronts

us (May 7, 9, 10, 13 this blog).

The low-angle elevation performance of an electrically-short vertical that you see on

the FF Plot feature of EZNEC Demo depends mostly on the quality of the grounding system

and hardly at all on the height of the typical MF/LF electrically-short vertical. You can satisfy

yourself of this, as I did, by antenna modeling different examples of verticals and ground

parameters.

So a good radial system contributes quite significantly to long path performance, not to

mention overall antenna/grounding system efficiency. If either the TX vertical itself or a

separate RX vertical (or E-probe) is used for reception, good grounding and radials likewise

contribute to long path reception performance by improving the signal S in signal to noise ratio

S/N (SNR).

Effective solid-angle A “area” of antenna pattern lobes in steradians at a specified

number of dB down can also be a helpful indicator of antenna reception capability for signals in

the direction of a lobe. https://en.wikipedia.org/wiki/Steradian The solid angle of a whole sphere

is 4π steradians, so the half-sphere above the horizon subtends 2π steradians.

A Beamwidth Figure of Merit 2π/A at, say, 3dB down can describe the ability of an

antenna to reject band noise from directions other than the lobes.

EZNEC Demo reports an elevation beamwidth angle WELEV on the FF plot at 3dB down.

For instance, an electrically-short vertical has an elevation beamwidth WELEV of about 50°

elevation and an azimuth beamwidth WAZ of 360° (full circle).

You can use the Azimuth plot selection of FF Plot to see the beamwidth WAZ in azimuth

degrees. For a vertical antenna WAZ = 360° is obvious without Azimuth FF Plot, of course. But

for a bidirectional or unidirectional loop you probably would want to use Azimuth FF Plot. To

get a useful Azimuth plot, first select an elevation angle ϕ (phi) measured upward from the

horizon to the middle of a lobe found from the FF Plot elevation pattern. For a loop, estimate

the total steradians for all strong lobes.

Approximate Solid angle A ~= (WAZWELEV cosϕ)/57.32 One electrically short vertical antenna example subtends an angle A where

A~= (50° x 360° cos(50°/2))/57.32 = 4.97 steradians.

Beamwidth Figure of Merit 2π/A for the example vertical is about 1.3 (not very much). As

you can see, a vertical does not reject much band noise except at very high elevation angles.

6/22/16 WSPR2 WATERFALL REVEALS UNDECODED TRACES: AND A 2016-17

SEASON PREDICTION?

Roger, VK4YB, … relates some excitement from the session: [near n. hemi. summer solstice]

Steve, VE7SL, reports …a nice surprise with a decode of VK4YB:

6/23/16 Roger, VK4YB, observed that WH2XGP was only a couple of dB beyond the WSPR

decode threshold at the same time that he was -6 dB S/N at WH2XCR followed by -9 dB S/N in

the next transmit cycle. Roger notes that not even single digit reports at the half-way point will

always result in decodes on the longer path.

6/26/16 Ken, K5DNL / WG2XXM, received…a single report from Roger, VK4YB, seven

minutes after sunrise in Oklahoma:

6/23/16 TABLET LF/MF RECEIVER (TRANSCEIVER)?

This is a blue-sky topic that may be achievable now or in the next few years. I wonder if

combining a commercially available tablet computer with an SDR (software defined radio) could

be an interesting homebrew project for MF/LF. You would use the touch-screen feature of the

tablet to load the software and control the SDR. Couple the SDR USB output into a microUSB

port of the tablet if that’s possible. USB may be expandable to provide this connectivity and

provide control input to/from a transmitter microcontroller as well. Bluetooth® wireless

connectivity can couple the tablet to likewise enabled devices.

Compare the approach with Flex Maestro SmartSDR in their Maestro™ transceiver.

http://www.flexradio.com/amateur-products/flex-6000-signature-series/maestro/ That unit uses

an 8” touch screen with pull down menus to perform a variety of reception display and noise mitigation functions. https://www.flexradio.com/downloads/smartsdr-software-users-guide-pdf/

What would be the difference between a tablet MF/LF receiver and any other SDR with

PC/laptop or recent transceiver with built-in SDR? The light weight of the tablet and touch

control would make a homebrew physical combo possible and give the combo portability for use

with battery power for extended periods in at least a receive-only mode. You can load a lot of

apps into a tablet, which MF/LF seems to invite what with digital modes, decoders and display

software.

At home, one can load various LF/MF-specific software packages, links and apps from the

internet using the internet connectivity a tablet computer comes with. At home, internet access

for a tablet computer to upload its WSPR spots is likewise right at hand.

In the field, consider how to obtain internet access for a tablet computer to upload its

WSPR spots. If the portable operation is near a friend’s house, then the friend may be willing to

have you link through a wireless modem there. Hams in some regions may have mesh networks

with internet connectivity. What tips can you offer?

Since the tablet touch screen mediates primary user commands, it needs to be convenient to

reach and control by touch. Slant the tablet to your taste in a homebrew physical combo instead

of mounting it straight up in the usual all-rectangular homebrew type of unit.

A tablet works nicely with a wireless keyboard and wireless mouse if you prefer entering

information that way. Otherwise, summon the usual tablet virtual keyboard on its touchscreen.

Doing things homebrew allows you to use a larger sized tablet than a manufacturer’s touch

screen might provide.

If you already have a tablet on hand, it costs you nothing more to reuse it. Purchased or

reused, you can occasionally disconnect it from a homebrew combination and use it for other

purposes whenever you like.

Some tablet questions to think over when planning such a project:

1) Can the tablet's microUSB to expandable connectivity couple USB to SDR, etc.?

2) Can you get wireless connectivity to/from SDR and other shack devices instead?

3) Does the tablet have the processing power to load SDR software and run it satisfactorily?

4) Is tablet’s RF noise minimal already or can you RF-isolate the SDR from tablet noise?

5) Can you control the transmitter and T/R switching with the tablet if you wish? Or vice-versa?

6) Can you play the tablet through a shack projector for station visitors and still maintain the other

connectivity and run the system at full speed?

Local noise isolation and thermal compatibility are plainly vital to a homebrew combination

of a commercial tablet with an SDR. I recently investigated one commercial tablet’s noise

performance on 630m. With good circuit positioning and design, the noise or thermal issues

should be minimal and able to accommodate LF/MF signal reception. Prefer toroid cores, and

avoid inductors wound on ferrite rods. If you use a loopstick antenna, mount it as far as you can

from the tablet, which should be noise-isolated to the extent possible.

This post has suggested a few pieces of the puzzle of homebrewing a combo of tablet

and MF/LF receiver. Can it indeed be done? Are we still a couple years away from the right

tablets at the right prices? Please tell us any pertinent experience you may have on construction

and performance of a tablet integrated with an MF/LF SDR. A tablet can be expensive, so if you

know a less expensive and equally-effective touch screen system for homebrew purposes, please

tell us about it.

6/24/16 INVESTIGATING ONE TABLET AND MF/LF SDR

Yesterday’s blog discussed in concept a homebrew combo using a tablet and an SDR.

Today, I offer a case study investigating specific products on hand here to suggest ways of

combining whatever particular tablet and SDR you might actually have.

I use a software defined WinRadio G33DDC Excalibur Pro because it has MF/LF

performance with good stability and waterfall frequency magnification down to 10Hz/inch so

WSPR lines are plainly visible. Datasheet: http://www.winradio.com/home/g33ddc.htm .

Software downloads to run this SDR are operating system specific—Windows, Mac, and Linux.

Plainly, the tablet and SDR can benefit from software suites that play with each other.

Samsung Galaxy Tab™ S2 tablet runs on the Android™ operating system. Software

compatibility is an important checkoff criterion for this tablet vis-à-vis this SDR. You can

remotely control the G33DDC via a server. http://www.winradio.com/home/g33ddc-cso.htm

Is there an app to connect the tablet and this SDR? Good question.

See a G31DDC screen playing on the S2 tablet at:

https://www.youtube.com/watch?v=h6lhfKIqmkM .

I don’t know of such an app. If you do find an app and you go outside trusted web sites to

get apps, scrutinize the site very carefully and be ready to manage virus risk regardless.

The above YouTube video “Show More” option indicates Wi-Fi remote control on the

tablet to control the SDR, with a VNC connection by Wi-Fi.

https://www.realvnc.com/products/viewerplus/1.0/docs/ae1052032.html . Audio streaming in the

YouTube video employed VLC, see http://www.videolan.org/vlc/index.html . I’ll not go into

details since your equipment will be different.

My tablet noise check was informative: On battery power alone, the tablet delivered 630m

rushing-river noise when placed near a 100uH inductor on a ferrite rod in my local-noise

canceller here at W5EST 6/21/16. The noise emanated entirely from the lower right corner of the

rear of that tablet as viewed with the portrait-oriented tablet with main homescreen button at

bottom.

Switching noise increased considerably with the tablet’s charger connected to AC power

and plugged into the tablet turned on. In a homebrew tablet/SDR combo, the charger would best

be replaced with a non-noisy charger or power supply with same voltage and at least as much

current capacity. The 630m noise is current-based and not capacitive coupled because no noise

occurs when the disconnected microUSB charging cord end is put very near the 100uH noise-

pickup inductor. To reduce the noise, the usual common mode chokes were unavailing when

applied to the microUSB charging cord. No surprise, this is 630m! Neither snap-on ferrite nor 5T

USB cable wound a on large rectangular core stopped the switching PS (power supply) noise

coupling into the inductor on 630m.

I experimented with a small HDMI converter which did not itself noticeably add more

noise. http://www.pcadvisor.co.uk/how-to/google-android/how-connect-android-tv-summary-

3533870/ One site says the S2 tablet doesn’t work with either a MHL or Slimport cable adapter,

and I was unable to project with an MHL HDMI converter.

http://forums.androidcentral.com/ask-question/594761-there-hdmi-cable-adapter-samsung-

galaxy-tab-s2.html

Fortunately, you can plug a wireless display receiver (adapter) to the projector’s HDMI

socket, such as the Actiontec® ScreenBeamTM

Mini 2 . (Some projectors don’t self-power the

adapter via that HDMI port, so plug in wall wart & microUSB cable to the adapter to power it

whence the projector shows a default image until the tablet takes over.)

To connect the adapter to the tablet, down-swipe the homescreen pulldown menu and click

on “Quick connect.” Then click on “Audio path” and connect the audio to your choice of HDMI

via the adapter, or to tablet speaker, or to USB headphones. That way, you mirror the tablet

screen to the projector wall display and the tablet audio to a better sound system via the projector

if you wish.

You can access a USB flash drive from the S2 tablet by using a short USB-to-microUSB

cable. But if you want to connect a USB2 flash drive to this tablet and have the SDR connected

by USB as well, then a powered USB hub is needed. The S2 tablet does not power a USB hub.

The USB hub should be a unit that has a microUSB socket on it that accepts the tablet charger

cord and powers the USB hub and tablet as well.

If you know other good tips for combining this and other tablets with an SDR, let us know. I

did not have any other company’s tablet nor any other SDR products to compare. GL with this

topic. And with Field Day, 2016, Saturday and Sunday!

6/27/16 RECEIVE 630M WITH ASUS TABLET USING ELAD SDR

Ken SWL/K9 e-mailed that his Asus tablet (T100TA)* runs Windows 10 and receives

630m using an Elad FDM-S2 sdr.**

HDSDR software on the tablet supports the sdr hardware http://www.hdsdr.de/ . WSJT-X on

the tablet decodes the resulting audio of WSPR and other digital modes.

The sdr/tablet grounds are connected together and to the third wire ground at the receptacle.

The receptacle feeds the tablet power supply. The tablet powers the sdr via USB.

The switching power supply for the tablet has only a two-wire plug... hot and neutral, no

ground. So, for grounding, a special 120v ac plug only has the ground connected, not the hot and

neutral wires, and brings out the third wire ground. This 3 prong plug for a ground plugs into the

wall socket in addition to the plug for the tablet PS. The hot and neutral blades of this plug have

no wiring attached to them. A 4 foot #14 solid jumper wire with alligator clips on both

ends completes this ground connection. One clip goes to the #14 solid wire from the plug. The

other end with the jumper connects directly to the sdr/tablet ground.

* https://www.asus.com/us/2-in-1-PCs/ASUS_Transformer_Book_T100TA/specifications/

**http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiI9t

aOl7_NAhVJJCYKHbX5BC0QFggcMAA&url=http%3A%2F%2Fsdr.eladit.com%2FFDM-

S2%2520Sampler%2Felad%2520fdm-

s2%2520user%2520manual%2520rev%25201.05.pdf&v6u=https%3A%2F%2Fs-v6exp1-

ds.metric.gstatic.com%2Fgen_204%3Fip%3D2602%3A304%3A78fb%3Ace70%3A4179%3Ae

435%3Ab35c%3A475e%26ts%3D1466720356986905%26auth%3Dcr2g4ffqgfetqekpgrihu3kjki

bnwfrz%26rndm%3D0.6267167205771424&v6s=2&v6t=2157&usg=AFQjCNEEoDjkAXW0b

K_vgy6gAf8dYyCOzw&bvm=bv.125221236,d.eWE

10/31/16 KIWI-SDR: MULTIPLE STATIONS ON 630M WSPR

Doug, K4LY / WH2XZO, activated a number of KiwiSDR systems remotely on the

Internet for use as WSPR decoders so those stations contributed to the elevated numbers. He

provided these comments as well as a list of stations activated during the evening session:

“Using KiwiSDR software and listening to the radio spectrum from different places

around the world has been a new and exciting experience for me. KiwiSDR allows the

listener to activate the participating station on WSPR, and the learning curve for me was

difficult because I wanted to make it work like the WSJT WSPR programs which is

unnecessary. It works just fine with its own 300 Hz bandwidth which requires a 474.95

not a 474.20 RX frequency.

Many stations have set their software to time out after 30 minutes or some other short

time, so activating a station for a night of WSPR may not be possible. In other cases

internet glitches disconnect the station after short periods of time.

Last night I activated the following stations who decoded one or more 630M WSPR

stations- KB8SPI, EN82; KD4HSO, KC MO; KB1KW, FN43; KC4YPD, CM97, and

N4TVC, Alexandria VA. I also activated other stations who had too much line noise, or

whose clocks were off, and could not decode signals.”

http://www.rtl-sdr.com/kiwisdr-30-mhz-bandwidth-sdr-for-hf/

https://www.kickstarter.com/projects/1575992013/kiwisdr-beaglebone-software-defined-radio-

sdr-with

11/13/16 VO1NA: TRANSATLANTIC CW QSO AND RECEPTIONS by John WG2XIQ:

Another early evening highlight was the two-way non-cross band QSO between Kees,

PE5T, and Joe, VO1NA. Kees reported that Joe was a solid RST 559 and was using a

beverage antenna to listen and a 160-meter inverted L with loading coil and about 300-

watts TPO for transmitting. Congrats to both on what may be one of only a handful of trans-

Atlantic CW QSO’s completed thus far on 630-meters. Kees also reports that he completed a

QSO with VO1HP at RST 559 on 472.5 kHz at 0038z but its unclear at this time whether that

was a two-way direct QSO or cross band.

Others in Europe reported VO1NA’s calls as well. Geoff, G0LUJ indicates that he

operated CW-Skimmer and captured a nice image that was strong enough for the software to

decode. That’s remarkable! He provided the following comments:

“The Rig is an IC7100 and the antenna is a Wellbrook ALA100LN, with a loop of 20m

circumference. For the rest of the month I’ll run CW Skimmer on 472.5 kHz (and up 3 kHz) in

the hope of hearing others on CW (I’ll keep decoding WSPR as well).”

I hope others will take advantage of Geoff’s skimmer while it is on the air and try to “ring the

bell”. Geoff provided reception details for VO1NA which can be viewed here.

VO1NA in CW Skimmer at G0LUJ

Eberhard, DL3ZID, reported the following details and screen capture on the RSGB-LF

reflector for VO1NA’s CW signal:

“my rx: FT817 , aktive antenna 10m up DL4YHF-Speclab QRSS3 – Window

watch 477.700 all other QRG are busy by NDB

2016-11-12 22:05 first T on 477.700 kHz

2016-11-13 02:40 best

2016-11-13 03:30 fade out

all time QSB down to nil”

VO1NA at DL3ZID

Roloef, PA0RDT, reported aural copy on VO1NA and provided both a screen capture of the

overnight plot of Joe’s signal from the Perseus SDR and a real-time visualization of the signal in

500-Hz bandwidth which can be viewed here.

VO1NA CW at PA0RDT

Dick, K4JJW…submitted the following comments and report:

“Hi John: Heard you this evening on 474.5 Hz in QSO with WD2XSH starting at

01:21Z. Could not copy WD2XSH. You were just above the noise but good copy at about

S1 on my ICOM 7700 and 160’ inverted L tuned to 160m. I couldn’t hear you on my

K9AY loop. According to my log, you are at a bearing of 267 deg. from me and 1155

miles. Nice to hear you after 61 years on the air and my first VLF receiving experience.

Have fun…. 73 Dick Goodwin K4JJW New Bern, NC FM15″

12/18/16 630M RECEIVING STATION USES ANTIQUE RADIO AND G5RV ANTENNA

Neil WG2XSV reports:

“We have a new listener, Larry, W7HGC at the bottom of my list [of stations I received]

this morning. He lives 3 miles from me. He spent about 2 hours here in my shack yesterday

learning about 630m. Here is a list of who Larry received this session:

He could hardly believe that he could hear XXP in AZ, and now I see that he even decoded

XXM in OK. I’ll bet that blew him away this morning….His antenna was a G5RV, and

rcvr is an old 32 tube (all tubes soldered into the circuit) radio. Larry is now thinking

about how to get an experimental license…”